Refactor Everything (#250)

Cargo.lock

@@ -13,6 +13,7 @@ dependencies = [
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "tempdir 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-width 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "utilities 0.0.0",
 ]
 
 [[package]]
@@ -247,6 +248,10 @@ name = "utf8-ranges"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "utilities"
+version = "0.0.0"
+
 [[package]]
 name = "vec_map"
 version = "0.8.0"

Cargo.toml

@@ -19,3 +19,6 @@ libc          = "^0.2.21"
 regex         = "^0.2.2"
 tempdir       = "^0.3.5"
 unicode-width = "^0.1.3"
+
+[dev-dependencies.utilities]
+path = "utilities"

justfile

@@ -1,13 +1,24 @@
+bt='0'
+
+export RUST_BACKTRACE=bt
+
 test: build
-	cargo test --lib
+	cargo test
+
+@spam:
+	{ \
+		figlet test; \
+		cargo build --color always 2>&1; \
+		cargo test  --color always -- --color always 2>&1; \
+	} | less
 
 # only run tests matching PATTERN
 filter PATTERN: build
-	cargo test --lib {{PATTERN}}
+	cargo test {{PATTERN}}
 
 # test with backtrace
 backtrace:
-	RUST_BACKTRACE=1 cargo test --lib
+	RUST_BACKTRACE=1 cargo test
 
 build:
 	cargo build
@@ -63,7 +74,7 @@ sloc:
 	echo Checking for long lines...
 	! grep --color -En '.{101}' src/*.rs
 
-rename FROM TO:
+replace FROM TO:
 	find src -name '*.rs' | xargs sed -i '' -E 's/{{FROM}}/{{TO}}/g'
 
 nop:

src/assignment_evaluator.rs

@@ -0,0 +1,179 @@
+use common::*;
+
+use brev;
+
+pub fn evaluate_assignments<'a>(
+  assignments: &Map<&'a str, Expression<'a>>,
+  overrides:   &Map<&str, &str>,
+  quiet:       bool,
+  shell:       &'a str,
+) -> Result<Map<&'a str, String>, RuntimeError<'a>> {
+  let mut evaluator = AssignmentEvaluator {
+    assignments: assignments,
+    evaluated:   empty(),
+    exports:     &empty(),
+    overrides:   overrides,
+    quiet:       quiet,
+    scope:       &empty(),
+    shell:       shell,
+  };
+
+  for name in assignments.keys() {
+    evaluator.evaluate_assignment(name)?;
+  }
+
+  Ok(evaluator.evaluated)
+}
+
+fn run_backtick<'a, 'b>(
+  raw:     &str,
+  token:   &Token<'a>,
+  scope:   &Map<&'a str, String>,
+  exports: &Set<&'a str>,
+  quiet:   bool,
+  shell:   &'b str,
+) -> Result<String, RuntimeError<'a>> {
+  let mut cmd = Command::new(shell);
+
+  cmd.export_environment_variables(scope, exports)?;
+
+  cmd.arg("-cu")
+     .arg(raw);
+
+  cmd.stderr(if quiet {
+    process::Stdio::null()
+  } else {
+    process::Stdio::inherit()
+  });
+
+  brev::output(cmd).map_err(|output_error| RuntimeError::Backtick{token: token.clone(), output_error})
+}
+
+pub struct AssignmentEvaluator<'a: 'b, 'b> {
+  pub assignments: &'b Map<&'a str, Expression<'a>>,
+  pub evaluated:   Map<&'a str, String>,
+  pub exports:     &'b Set<&'a str>,
+  pub overrides:   &'b Map<&'b str, &'b str>,
+  pub quiet:       bool,
+  pub scope:       &'b Map<&'a str, String>,
+  pub shell:       &'b str,
+}
+
+impl<'a, 'b> AssignmentEvaluator<'a, 'b> {
+  pub fn evaluate_line(
+    &mut self,
+    line:      &[Fragment<'a>],
+    arguments: &Map<&str, Cow<str>>
+  ) -> Result<String, RuntimeError<'a>> {
+    let mut evaluated = String::new();
+    for fragment in line {
+      match *fragment {
+        Fragment::Text{ref text} => evaluated += text.lexeme,
+        Fragment::Expression{ref expression} => {
+          evaluated += &self.evaluate_expression(expression, arguments)?;
+        }
+      }
+    }
+    Ok(evaluated)
+  }
+
+  fn evaluate_assignment(&mut self, name: &'a str) -> Result<(), RuntimeError<'a>> {
+    if self.evaluated.contains_key(name) {
+      return Ok(());
+    }
+
+    if let Some(expression) = self.assignments.get(name) {
+      if let Some(value) = self.overrides.get(name) {
+        self.evaluated.insert(name, value.to_string());
+      } else {
+        let value = self.evaluate_expression(expression, &empty())?;
+        self.evaluated.insert(name, value);
+      }
+    } else {
+      return Err(RuntimeError::Internal {
+        message: format!("attempted to evaluated unknown assignment {}", name)
+      });
+    }
+
+    Ok(())
+  }
+
+  fn evaluate_expression(
+    &mut self,
+    expression: &Expression<'a>,
+    arguments: &Map<&str, Cow<str>>
+  ) -> Result<String, RuntimeError<'a>> {
+    Ok(match *expression {
+      Expression::Variable{name, ..} => {
+        if self.evaluated.contains_key(name) {
+          self.evaluated[name].clone()
+        } else if self.scope.contains_key(name) {
+          self.scope[name].clone()
+        } else if self.assignments.contains_key(name) {
+          self.evaluate_assignment(name)?;
+          self.evaluated[name].clone()
+        } else if arguments.contains_key(name) {
+          arguments[name].to_string()
+        } else {
+          return Err(RuntimeError::Internal {
+            message: format!("attempted to evaluate undefined variable `{}`", name)
+          });
+        }
+      }
+      Expression::String{ref cooked_string} => cooked_string.cooked.clone(),
+      Expression::Backtick{raw, ref token} => {
+        run_backtick(raw, token, self.scope, self.exports, self.quiet, self.shell)?
+      }
+      Expression::Concatination{ref lhs, ref rhs} => {
+        self.evaluate_expression(lhs, arguments)?
+          +
+        &self.evaluate_expression(rhs, arguments)?
+      }
+    })
+  }
+}
+
+
+#[cfg(test)]
+mod test {
+  use super::*;
+  use brev::OutputError;
+  use testing::parse_success;
+  use Configuration;
+
+#[test]
+fn backtick_code() {
+  match parse_success("a:\n echo {{`f() { return 100; }; f`}}")
+        .run(&["a"], &Default::default()).unwrap_err() {
+    RuntimeError::Backtick{token, output_error: OutputError::Code(code)} => {
+      assert_eq!(code, 100);
+      assert_eq!(token.lexeme, "`f() { return 100; }; f`");
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn export_assignment_backtick() {
+  let text = r#"
+export exported_variable = "A"
+b = `echo $exported_variable`
+
+recipe:
+  echo {{b}}
+"#;
+
+  let options = Configuration {
+    quiet: true,
+    ..Default::default()
+  };
+
+  match parse_success(text).run(&["recipe"], &options).unwrap_err() {
+    RuntimeError::Backtick{token, output_error: OutputError::Code(_)} => {
+      assert_eq!(token.lexeme, "`echo $exported_variable`");
+    },
+    other => panic!("expected a backtick code errror, but got: {}", other),
+  }
+}
+
+}

src/assignment_resolver.rs

@@ -0,0 +1,129 @@
+use common::*;
+
+pub fn resolve_assignments<'a>(
+  assignments:       &Map<&'a str, Expression<'a>>,
+  assignment_tokens: &Map<&'a str, Token<'a>>,
+) -> Result<(), CompilationError<'a>> {
+
+  let mut resolver = AssignmentResolver {
+    assignments:       assignments,
+    assignment_tokens: assignment_tokens,
+    stack:             empty(),
+    seen:              empty(),
+    evaluated:         empty(),
+  };
+
+  for name in assignments.keys() {
+    resolver.resolve_assignment(name)?;
+  }
+
+  Ok(())
+}
+
+struct AssignmentResolver<'a: 'b, 'b> {
+  assignments:       &'b Map<&'a str, Expression<'a>>,
+  assignment_tokens: &'b Map<&'a str, Token<'a>>,
+  stack:             Vec<&'a str>,
+  seen:              Set<&'a str>,
+  evaluated:         Set<&'a str>,
+}
+
+impl<'a: 'b, 'b> AssignmentResolver<'a, 'b> {
+  fn resolve_assignment(&mut self, name: &'a str) -> Result<(), CompilationError<'a>> {
+    if self.evaluated.contains(name) {
+      return Ok(());
+    }
+
+    self.seen.insert(name);
+    self.stack.push(name);
+
+    if let Some(expression) = self.assignments.get(name) {
+      self.resolve_expression(expression)?;
+      self.evaluated.insert(name);
+    } else {
+      let message = format!("attempted to resolve unknown assignment `{}`", name);
+      return Err(CompilationError {
+        text:   "",
+        index:  0,
+        line:   0,
+        column: 0,
+        width:  None,
+        kind:   CompilationErrorKind::Internal{message}
+      });
+    }
+    Ok(())
+  }
+
+  fn resolve_expression(&mut self, expression: &Expression<'a>) -> Result<(), CompilationError<'a>> {
+    match *expression {
+      Expression::Variable{name, ref token} => {
+        if self.evaluated.contains(name) {
+          return Ok(());
+        } else if self.seen.contains(name) {
+          let token = &self.assignment_tokens[name];
+          self.stack.push(name);
+          return Err(token.error(CompilationErrorKind::CircularVariableDependency {
+            variable: name,
+            circle:   self.stack.clone(),
+          }));
+        } else if self.assignments.contains_key(name) {
+          self.resolve_assignment(name)?;
+        } else {
+          return Err(token.error(CompilationErrorKind::UndefinedVariable{variable: name}));
+        }
+      }
+      Expression::Concatination{ref lhs, ref rhs} => {
+        self.resolve_expression(lhs)?;
+        self.resolve_expression(rhs)?;
+      }
+      Expression::String{..} | Expression::Backtick{..} => {}
+    }
+    Ok(())
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use testing::parse_error;
+  use super::*;
+
+#[test]
+fn circular_variable_dependency() {
+  let text = "a = b\nb = a";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  0,
+    line:   0,
+    column: 0,
+    width:  Some(1),
+    kind:   CompilationErrorKind::CircularVariableDependency{variable: "a", circle: vec!["a", "b", "a"]}
+  });
+}
+
+
+#[test]
+fn self_variable_dependency() {
+  let text = "a = a";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  0,
+    line:   0,
+    column: 0,
+    width:  Some(1),
+    kind:   CompilationErrorKind::CircularVariableDependency{variable: "a", circle: vec!["a", "a"]}
+  });
+}
+#[test]
+fn unknown_expression_variable() {
+  let text = "x = yy";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  4,
+    line:   0,
+    column: 4,
+    width:  Some(2),
+    kind:   CompilationErrorKind::UndefinedVariable{variable: "yy"},
+  });
+}
+
+}

src/color.rs

@@ -1,7 +1,8 @@
 extern crate ansi_term;
 extern crate atty;
 
-use prelude::*;
+use common::*;
+
 use self::ansi_term::{Style, Prefix, Suffix, ANSIGenericString};
 use self::ansi_term::Color::*;
 use self::atty::is as is_atty;

src/command_ext.rs

@@ -0,0 +1,28 @@
+use common::*;
+
+pub trait CommandExt {
+  fn export_environment_variables<'a>(
+    &mut self,
+    scope: &Map<&'a str, String>,
+    exports: &Set<&'a str>
+  ) -> Result<(), RuntimeError<'a>>;
+}
+
+impl CommandExt for Command {
+  fn export_environment_variables<'a>(
+    &mut self,
+    scope: &Map<&'a str, String>,
+    exports: &Set<&'a str>
+  ) -> Result<(), RuntimeError<'a>> {
+    for name in exports {
+      if let Some(value) = scope.get(name) {
+        self.env(name, value);
+      } else {
+        return Err(RuntimeError::Internal {
+          message: format!("scope does not contain exported variable `{}`",  name),
+        });
+      }
+    }
+    Ok(())
+  }
+}

src/compilation_error.rs

@@ -0,0 +1,141 @@
+use common::*;
+
+use misc::{Or, write_error_context, show_whitespace};
+
+#[derive(Debug, PartialEq)]
+pub struct CompilationError<'a> {
+  pub text:   &'a str,
+  pub index:  usize,
+  pub line:   usize,
+  pub column: usize,
+  pub width:  Option<usize>,
+  pub kind:   CompilationErrorKind<'a>,
+}
+
+#[derive(Debug, PartialEq)]
+pub enum CompilationErrorKind<'a> {
+  CircularRecipeDependency{recipe: &'a str, circle: Vec<&'a str>},
+  CircularVariableDependency{variable: &'a str, circle: Vec<&'a str>},
+  DependencyHasParameters{recipe: &'a str, dependency: &'a str},
+  DuplicateDependency{recipe: &'a str, dependency: &'a str},
+  DuplicateParameter{recipe: &'a str, parameter: &'a str},
+  DuplicateRecipe{recipe: &'a str, first: usize},
+  DuplicateVariable{variable: &'a str},
+  ExtraLeadingWhitespace,
+  InconsistentLeadingWhitespace{expected: &'a str, found: &'a str},
+  Internal{message: String},
+  InvalidEscapeSequence{character: char},
+  MixedLeadingWhitespace{whitespace: &'a str},
+  OuterShebang,
+  ParameterShadowsVariable{parameter: &'a str},
+  RequiredParameterFollowsDefaultParameter{parameter: &'a str},
+  ParameterFollowsVariadicParameter{parameter: &'a str},
+  UndefinedVariable{variable: &'a str},
+  UnexpectedToken{expected: Vec<TokenKind>, found: TokenKind},
+  UnknownDependency{recipe: &'a str, unknown: &'a str},
+  UnknownStartOfToken,
+  UnterminatedString,
+}
+
+impl<'a> Display for CompilationError<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    use CompilationErrorKind::*;
+    let error   = Color::fmt(f).error();
+    let message = Color::fmt(f).message();
+
+    write!(f, "{} {}", error.paint("error:"), message.prefix())?;
+
+    match self.kind {
+      CircularRecipeDependency{recipe, ref circle} => {
+        if circle.len() == 2 {
+          writeln!(f, "Recipe `{}` depends on itself", recipe)?;
+        } else {
+          writeln!(f, "Recipe `{}` has circular dependency `{}`",
+                      recipe, circle.join(" -> "))?;
+        }
+      }
+      CircularVariableDependency{variable, ref circle} => {
+        if circle.len() == 2 {
+          writeln!(f, "Variable `{}` is defined in terms of itself", variable)?;
+        } else {
+          writeln!(f, "Variable `{}` depends on its own value: `{}`",
+                      variable, circle.join(" -> "))?;
+        }
+      }
+      InvalidEscapeSequence{character} => {
+        writeln!(f, "`\\{}` is not a valid escape sequence",
+                    character.escape_default().collect::<String>())?;
+      }
+      DuplicateParameter{recipe, parameter} => {
+        writeln!(f, "Recipe `{}` has duplicate parameter `{}`", recipe, parameter)?;
+      }
+      DuplicateVariable{variable} => {
+        writeln!(f, "Variable `{}` has multiple definitions", variable)?;
+      }
+      UnexpectedToken{ref expected, found} => {
+        writeln!(f, "Expected {}, but found {}", Or(expected), found)?;
+      }
+      DuplicateDependency{recipe, dependency} => {
+        writeln!(f, "Recipe `{}` has duplicate dependency `{}`", recipe, dependency)?;
+      }
+      DuplicateRecipe{recipe, first} => {
+        writeln!(f, "Recipe `{}` first defined on line {} is redefined on line {}",
+                    recipe, first + 1, self.line + 1)?;
+      }
+      DependencyHasParameters{recipe, dependency} => {
+        writeln!(f, "Recipe `{}` depends on `{}` which requires arguments. \
+                    Dependencies may not require arguments", recipe, dependency)?;
+      }
+      ParameterShadowsVariable{parameter} => {
+        writeln!(f, "Parameter `{}` shadows variable of the same name", parameter)?;
+      }
+      RequiredParameterFollowsDefaultParameter{parameter} => {
+        writeln!(f, "Non-default parameter `{}` follows default parameter", parameter)?;
+      }
+      ParameterFollowsVariadicParameter{parameter} => {
+        writeln!(f, "Parameter `{}` follows variadic parameter", parameter)?;
+      }
+      MixedLeadingWhitespace{whitespace} => {
+        writeln!(f,
+          "Found a mix of tabs and spaces in leading whitespace: `{}`\n\
+          Leading whitespace may consist of tabs or spaces, but not both",
+          show_whitespace(whitespace)
+        )?;
+      }
+      ExtraLeadingWhitespace => {
+        writeln!(f, "Recipe line has extra leading whitespace")?;
+      }
+      InconsistentLeadingWhitespace{expected, found} => {
+        writeln!(f,
+          "Recipe line has inconsistent leading whitespace. \
+           Recipe started with `{}` but found line with `{}`",
+          show_whitespace(expected), show_whitespace(found)
+        )?;
+      }
+      OuterShebang => {
+        writeln!(f, "`#!` is reserved syntax outside of recipes")?;
+      }
+      UnknownDependency{recipe, unknown} => {
+        writeln!(f, "Recipe `{}` has unknown dependency `{}`", recipe, unknown)?;
+      }
+      UndefinedVariable{variable} => {
+        writeln!(f, "Variable `{}` not defined", variable)?;
+      }
+      UnknownStartOfToken => {
+        writeln!(f, "Unknown start of token:")?;
+      }
+      UnterminatedString => {
+        writeln!(f, "Unterminated string")?;
+      }
+      Internal{ref message} => {
+        writeln!(f, "Internal error, this may indicate a bug in just: {}\n\
+                     consider filing an issue: https://github.com/casey/just/issues/new",
+                     message)?;
+      }
+    }
+
+    write!(f, "{}", message.suffix())?;
+
+    write_error_context(f, self.text, self.index, self.line, self.column, self.width)
+  }
+}

src/configuration.rs

@@ -0,0 +1,29 @@
+use common::*;
+
+pub const DEFAULT_SHELL: &'static str = "sh";
+
+pub struct Configuration<'a> {
+  pub dry_run:   bool,
+  pub evaluate:  bool,
+  pub highlight: bool,
+  pub overrides: Map<&'a str, &'a str>,
+  pub quiet:     bool,
+  pub shell:     &'a str,
+  pub color:     Color,
+  pub verbose:   bool,
+}
+
+impl<'a> Default for Configuration<'a> {
+  fn default() -> Configuration<'static> {
+    Configuration {
+      dry_run:   false,
+      evaluate:  false,
+      highlight: false,
+      overrides: empty(),
+      quiet:     false,
+      shell:     DEFAULT_SHELL,
+      color:     default(),
+      verbose:   false,
+    }
+  }
+}

src/cooked_string.rs

@@ -0,0 +1,48 @@
+use common::*;
+
+#[derive(PartialEq, Debug)]
+pub struct CookedString<'a> {
+  pub raw:    &'a str,
+  pub cooked: String,
+}
+
+impl<'a> CookedString<'a> {
+  pub fn new(token: &Token<'a>) -> Result<CookedString<'a>, CompilationError<'a>> {
+    let raw = &token.lexeme[1..token.lexeme.len()-1];
+
+    if let TokenKind::RawString = token.kind {
+      Ok(CookedString{raw: raw, cooked: raw.to_string()})
+    } else if let TokenKind::StringToken = token.kind {
+      let mut cooked = String::new();
+      let mut escape = false;
+      for c in raw.chars() {
+        if escape {
+          match c {
+            'n'   => cooked.push('\n'),
+            'r'   => cooked.push('\r'),
+            't'   => cooked.push('\t'),
+            '\\'  => cooked.push('\\'),
+            '"'   => cooked.push('"'),
+            other => return Err(token.error(CompilationErrorKind::InvalidEscapeSequence {
+              character: other,
+            })),
+          }
+          escape = false;
+          continue;
+        }
+        if c == '\\' {
+          escape = true;
+          continue;
+        }
+        cooked.push(c);
+      }
+      Ok(CookedString{raw: raw, cooked: cooked})
+    } else {
+      Err(token.error(CompilationErrorKind::Internal {
+        message: "cook_string() called on non-string token".to_string()
+      }))
+    }
+  }
+}
+
+

src/expression.rs

@@ -0,0 +1,49 @@
+use common::*;
+
+#[derive(PartialEq, Debug)]
+pub enum Expression<'a> {
+  Variable{name: &'a str, token: Token<'a>},
+  String{cooked_string: CookedString<'a>},
+  Backtick{raw: &'a str, token: Token<'a>},
+  Concatination{lhs: Box<Expression<'a>>, rhs: Box<Expression<'a>>},
+}
+
+impl<'a> Expression<'a> {
+  pub fn variables(&'a self) -> Variables<'a> {
+    Variables {
+      stack: vec![self],
+    }
+  }
+}
+
+impl<'a> Display for Expression<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    match *self {
+      Expression::Backtick     {raw, ..          } => write!(f, "`{}`", raw)?,
+      Expression::Concatination{ref lhs, ref rhs } => write!(f, "{} + {}", lhs, rhs)?,
+      Expression::String       {ref cooked_string} => write!(f, "\"{}\"", cooked_string.raw)?,
+      Expression::Variable     {name, ..         } => write!(f, "{}", name)?,
+    }
+    Ok(())
+  }
+}
+
+pub struct Variables<'a> {
+  stack: Vec<&'a Expression<'a>>,
+}
+
+impl<'a> Iterator for Variables<'a> {
+  type Item = &'a Token<'a>;
+
+  fn next(&mut self) -> Option<&'a Token<'a>> {
+    match self.stack.pop() {
+      None | Some(&Expression::String{..}) | Some(&Expression::Backtick{..}) => None,
+      Some(&Expression::Variable{ref token,..})          => Some(token),
+      Some(&Expression::Concatination{ref lhs, ref rhs}) => {
+        self.stack.push(lhs);
+        self.stack.push(rhs);
+        self.next()
+      }
+    }
+  }
+}

src/fragment.rs

@@ -0,0 +1,17 @@
+use common::*;
+
+#[derive(PartialEq, Debug)]
+pub enum Fragment<'a> {
+  Text{text: Token<'a>},
+  Expression{expression: Expression<'a>},
+}
+
+impl<'a> Fragment<'a> {
+  pub fn continuation(&self) -> bool {
+    match *self {
+      Fragment::Text{ref text} => text.lexeme.ends_with('\\'),
+      _ => false,
+    }
+  }
+}
+

src/justfile.rs

@@ -0,0 +1,345 @@
+use common::*;
+
+use edit_distance::edit_distance;
+use assignment_evaluator::evaluate_assignments;
+use range_ext::RangeExt;
+
+pub struct Justfile<'a> {
+  pub recipes:     Map<&'a str, Recipe<'a>>,
+  pub assignments: Map<&'a str, Expression<'a>>,
+  pub exports:     Set<&'a str>,
+}
+
+impl<'a, 'b> Justfile<'a> where 'a: 'b {
+  pub fn first(&self) -> Option<&Recipe> {
+    let mut first: Option<&Recipe> = None;
+    for recipe in self.recipes.values() {
+      if let Some(first_recipe) = first {
+        if recipe.line_number < first_recipe.line_number {
+          first = Some(recipe)
+        }
+      } else {
+        first = Some(recipe);
+      }
+    }
+    first
+  }
+
+  pub fn count(&self) -> usize {
+    self.recipes.len()
+  }
+
+  pub fn suggest(&self, name: &str) -> Option<&'a str> {
+    let mut suggestions = self.recipes.keys()
+      .map(|suggestion| (edit_distance(suggestion, name), suggestion))
+      .collect::<Vec<_>>();
+    suggestions.sort();
+    if let Some(&(distance, suggestion)) = suggestions.first() {
+      if distance < 3 {
+        return Some(suggestion)
+      }
+    }
+    None
+  }
+
+  pub fn run(
+    &'a self,
+    arguments: &[&'a str],
+    options:   &Configuration<'a>,
+  ) -> Result<(), RuntimeError<'a>> {
+    let unknown_overrides = options.overrides.keys().cloned()
+      .filter(|name| !self.assignments.contains_key(name))
+      .collect::<Vec<_>>();
+
+    if !unknown_overrides.is_empty() {
+      return Err(RuntimeError::UnknownOverrides{overrides: unknown_overrides});
+    }
+
+    let scope = evaluate_assignments(
+      &self.assignments,
+      &options.overrides,
+      options.quiet,
+      options.shell,
+    )?;
+
+    if options.evaluate {
+      let mut width = 0;
+      for name in scope.keys() {
+        width = cmp::max(name.len(), width);
+      }
+
+      for (name, value) in scope {
+        println!("{0:1$} = \"{2}\"", name, width, value);
+      }
+      return Ok(());
+    }
+
+    let mut missing = vec![];
+    let mut grouped = vec![];
+    let mut rest    = arguments;
+
+    while let Some((argument, mut tail)) = rest.split_first() {
+      if let Some(recipe) = self.recipes.get(argument) {
+        if recipe.parameters.is_empty() {
+          grouped.push((recipe, &tail[0..0]));
+        } else {
+          let argument_range = recipe.argument_range();
+          let argument_count = cmp::min(tail.len(), recipe.max_arguments());
+          if !argument_range.range_contains(argument_count) {
+            return Err(RuntimeError::ArgumentCountMismatch {
+              recipe: recipe.name,
+              found:  tail.len(),
+              min:    recipe.min_arguments(),
+              max:    recipe.max_arguments(),
+            });
+          }
+          grouped.push((recipe, &tail[0..argument_count]));
+          tail = &tail[argument_count..];
+        }
+      } else {
+        missing.push(*argument);
+      }
+      rest = tail;
+    }
+
+    if !missing.is_empty() {
+      let suggestion = if missing.len() == 1 {
+        self.suggest(missing.first().unwrap())
+      } else {
+        None
+      };
+      return Err(RuntimeError::UnknownRecipes{recipes: missing, suggestion: suggestion});
+    }
+
+    let mut ran = empty();
+    for (recipe, arguments) in grouped {
+      self.run_recipe(recipe, arguments, &scope, &mut ran, options)?
+    }
+
+    Ok(())
+  }
+
+  fn run_recipe<'c>(
+    &'c self,
+    recipe:    &Recipe<'a>,
+    arguments: &[&'a str],
+    scope:     &Map<&'c str, String>,
+    ran:       &mut Set<&'a str>,
+    options:   &Configuration<'a>,
+  ) -> Result<(), RuntimeError> {
+    for dependency_name in &recipe.dependencies {
+      if !ran.contains(dependency_name) {
+        self.run_recipe(&self.recipes[dependency_name], &[], scope, ran, options)?;
+      }
+    }
+    recipe.run(arguments, scope, &self.exports, options)?;
+    ran.insert(recipe.name);
+    Ok(())
+  }
+}
+
+impl<'a> Display for Justfile<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    let mut items = self.recipes.len() + self.assignments.len();
+    for (name, expression) in &self.assignments {
+      if self.exports.contains(name) {
+        write!(f, "export ")?;
+      }
+      write!(f, "{} = {}", name, expression)?;
+      items -= 1;
+      if items != 0 {
+        write!(f, "\n\n")?;
+      }
+    }
+    for recipe in self.recipes.values() {
+      write!(f, "{}", recipe)?;
+      items -= 1;
+      if items != 0 {
+        write!(f, "\n\n")?;
+      }
+    }
+    Ok(())
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+  use testing::parse_success;
+
+  #[test]
+  fn unknown_recipes() {
+    match parse_success("a:\nb:\nc:").run(&["a", "x", "y", "z"], &Default::default()).unwrap_err() {
+      RuntimeError::UnknownRecipes{recipes, suggestion} => {
+        assert_eq!(recipes, &["x", "y", "z"]);
+        assert_eq!(suggestion, None);
+      }
+      other => panic!("expected an unknown recipe error, but got: {}", other),
+    }
+  }
+
+
+#[test]
+fn run_shebang() {
+  // this test exists to make sure that shebang recipes
+  // run correctly. although this script is still
+  // executed by a shell its behavior depends on the value of a
+  // variable and continuing even though a command fails,
+  // whereas in plain recipes variables are not available
+  // in subsequent lines and execution stops when a line
+  // fails
+  let text = "
+a:
+ #!/usr/bin/env sh
+ code=200
+  x() { return $code; }
+    x
+      x
+";
+
+  match parse_success(text).run(&["a"], &Default::default()).unwrap_err() {
+    RuntimeError::Code{recipe, line_number, code} => {
+      assert_eq!(recipe, "a");
+      assert_eq!(code, 200);
+      assert_eq!(line_number, None);
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+#[test]
+fn code_error() {
+  match parse_success("fail:\n @exit 100")
+    .run(&["fail"], &Default::default()).unwrap_err() {
+    RuntimeError::Code{recipe, line_number, code} => {
+      assert_eq!(recipe, "fail");
+      assert_eq!(code, 100);
+      assert_eq!(line_number, Some(2));
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn run_args() {
+  let text = r#"
+a return code:
+ @x() { {{return}} {{code + "0"}}; }; x"#;
+
+  match parse_success(text).run(&["a", "return", "15"], &Default::default()).unwrap_err() {
+    RuntimeError::Code{recipe, line_number, code} => {
+      assert_eq!(recipe, "a");
+      assert_eq!(code, 150);
+      assert_eq!(line_number, Some(3));
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn missing_some_arguments() {
+  match parse_success("a b c d:").run(&["a", "b", "c"], &Default::default()).unwrap_err() {
+    RuntimeError::ArgumentCountMismatch{recipe, found, min, max} => {
+      assert_eq!(recipe, "a");
+      assert_eq!(found, 2);
+      assert_eq!(min, 3);
+      assert_eq!(max, 3);
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn missing_some_arguments_variadic() {
+  match parse_success("a b c +d:").run(&["a", "B", "C"], &Default::default()).unwrap_err() {
+    RuntimeError::ArgumentCountMismatch{recipe, found, min, max} => {
+      assert_eq!(recipe, "a");
+      assert_eq!(found, 2);
+      assert_eq!(min, 3);
+      assert_eq!(max, usize::MAX - 1);
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn missing_all_arguments() {
+  match parse_success("a b c d:\n echo {{b}}{{c}}{{d}}")
+        .run(&["a"], &Default::default()).unwrap_err() {
+    RuntimeError::ArgumentCountMismatch{recipe, found, min, max} => {
+      assert_eq!(recipe, "a");
+      assert_eq!(found, 0);
+      assert_eq!(min, 3);
+      assert_eq!(max, 3);
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn missing_some_defaults() {
+  match parse_success("a b c d='hello':").run(&["a", "b"], &Default::default()).unwrap_err() {
+    RuntimeError::ArgumentCountMismatch{recipe, found, min, max} => {
+      assert_eq!(recipe, "a");
+      assert_eq!(found, 1);
+      assert_eq!(min, 2);
+      assert_eq!(max, 3);
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn missing_all_defaults() {
+  match parse_success("a b c='r' d='h':").run(&["a"], &Default::default()).unwrap_err() {
+    RuntimeError::ArgumentCountMismatch{recipe, found, min, max} => {
+      assert_eq!(recipe, "a");
+      assert_eq!(found, 0);
+      assert_eq!(min, 1);
+      assert_eq!(max, 3);
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn unknown_overrides() {
+  let mut options: Configuration = Default::default();
+  options.overrides.insert("foo", "bar");
+  options.overrides.insert("baz", "bob");
+  match parse_success("a:\n echo {{`f() { return 100; }; f`}}")
+        .run(&["a"], &options).unwrap_err() {
+    RuntimeError::UnknownOverrides{overrides} => {
+      assert_eq!(overrides, &["baz", "foo"]);
+    },
+    other => panic!("expected a code run error, but got: {}", other),
+  }
+}
+
+#[test]
+fn export_failure() {
+  let text = r#"
+export foo = "a"
+baz = "c"
+export bar = "b"
+export abc = foo + bar + baz
+
+wut:
+  echo $foo $bar $baz
+"#;
+
+  let options = Configuration {
+    quiet: true,
+    ..Default::default()
+  };
+
+  match parse_success(text).run(&["wut"], &options).unwrap_err() {
+    RuntimeError::Code{code: _, line_number, recipe} => {
+      assert_eq!(recipe, "wut");
+      assert_eq!(line_number, Some(8));
+    },
+    other => panic!("expected a recipe code errror, but got: {}", other),
+  }
+}
+
+
+}

src/main.rs

@@ -1,5 +1,82 @@
-extern crate just;
+#[macro_use]
+extern crate lazy_static;
+extern crate ansi_term;
+extern crate brev;
+extern crate clap;
+extern crate edit_distance;
+extern crate itertools;
+extern crate libc;
+extern crate regex;
+extern crate tempdir;
+extern crate unicode_width;
+
+mod platform;
+mod run;
+mod color;
+mod compilation_error;
+mod runtime_error;
+mod misc;
+mod justfile;
+mod recipe;
+mod token;
+mod parser;
+mod tokenizer;
+mod cooked_string;
+mod recipe_resolver;
+mod assignment_resolver;
+mod assignment_evaluator;
+mod configuration;
+mod parameter;
+mod expression;
+mod fragment;
+mod shebang;
+mod command_ext;
+mod range_ext;
+
+#[cfg(test)] mod testing;
+
+use tokenizer::tokenize;
+
+mod common {
+  pub use std::borrow::Cow;
+  pub use std::collections::{BTreeMap as Map, BTreeSet as Set};
+  pub use std::fmt::Display;
+  pub use std::io::prelude::*;
+  pub use std::ops::Range;
+  pub use std::path::{Path, PathBuf};
+  pub use std::process::Command;
+  pub use std::{cmp, env, fs, fmt, io, iter, process, vec, usize};
+
+  pub use color::Color;
+  pub use libc::{EXIT_FAILURE, EXIT_SUCCESS};
+  pub use regex::Regex;
+  pub use tempdir::TempDir;
+
+  pub use assignment_evaluator::AssignmentEvaluator;
+  pub use command_ext::CommandExt;
+  pub use compilation_error::{CompilationError, CompilationErrorKind};
+  pub use configuration::Configuration;
+  pub use cooked_string::CookedString;
+  pub use expression::Expression;
+  pub use fragment::Fragment;
+  pub use justfile::Justfile;
+  pub use misc::{default, empty};
+  pub use parameter::Parameter;
+  pub use parser::Parser;
+  pub use recipe::Recipe;
+  pub use runtime_error::RuntimeError;
+  pub use shebang::Shebang;
+  pub use token::{Token, TokenKind};
+}
+
+use common::*;
+
+fn compile(text: &str) -> Result<Justfile, CompilationError> {
+  let tokens = tokenize(text)?;
+  let parser = Parser::new(text, tokens);
+  parser.justfile()
+}
 
 fn main() {
-  just::app();
+  run::run();
 }

src/misc.rs

@@ -0,0 +1,149 @@
+use common::*;
+
+use unicode_width::UnicodeWidthChar;
+
+pub fn show_whitespace(text: &str) -> String {
+  text.chars().map(|c| match c { '\t' => '␉', ' ' => '␠', _ => c }).collect()
+}
+
+pub fn default<T: Default>() -> T {
+  Default::default()
+}
+
+pub fn empty<T, C: iter::FromIterator<T>>() -> C {
+  iter::empty().collect()
+}
+
+pub fn ticks<T: Display>(ts: &[T]) -> Vec<Tick<T>> {
+  ts.iter().map(Tick).collect()
+}
+
+pub fn maybe_s(n: usize) -> &'static str {
+  if n == 1 {
+    ""
+  } else {
+    "s"
+  }
+}
+
+pub fn conjoin<T: Display>(
+  f:           &mut fmt::Formatter,
+  values:      &[T],
+  conjunction: &str,
+) -> Result<(), fmt::Error> {
+    match values.len() {
+      0 => {},
+      1 => write!(f, "{}", values[0])?,
+      2 => write!(f, "{} {} {}", values[0], conjunction, values[1])?,
+      _ => for (i, item) in values.iter().enumerate() {
+        write!(f, "{}", item)?;
+        if i == values.len() - 1 {
+        } else if i == values.len() - 2 {
+          write!(f, ", {} ", conjunction)?;
+        } else {
+          write!(f, ", ")?
+        }
+      },
+    }
+    Ok(())
+}
+
+pub fn write_error_context(
+  f:      &mut fmt::Formatter,
+  text:   &str,
+  index:  usize,
+  line:   usize,
+  column: usize,
+  width:  Option<usize>,
+) -> Result<(), fmt::Error> {
+  let line_number = line + 1;
+  let red = Color::fmt(f).error();
+  match text.lines().nth(line) {
+    Some(line) => {
+      let mut i = 0;
+      let mut space_column = 0;
+      let mut space_line   = String::new();
+      let mut space_width  = 0;
+      for c in line.chars() {
+        if c == '\t' {
+          space_line.push_str("    ");
+          if i < column {
+            space_column += 4;
+          }
+          if i >= column && i < column + width.unwrap_or(1) {
+            space_width += 4;
+          }
+        } else {
+          if i < column {
+            space_column += UnicodeWidthChar::width(c).unwrap_or(0);
+
+          }
+          if i >= column && i < column + width.unwrap_or(1) {
+            space_width += UnicodeWidthChar::width(c).unwrap_or(0);
+          }
+          space_line.push(c);
+        }
+        i += c.len_utf8();
+      }
+      let line_number_width = line_number.to_string().len();
+      write!(f, "{0:1$} |\n", "", line_number_width)?;
+      write!(f, "{} | {}\n", line_number, space_line)?;
+      write!(f, "{0:1$} |", "", line_number_width)?;
+      if width == None {
+        write!(f, " {0:1$}{2}^{3}", "", space_column, red.prefix(), red.suffix())?;
+      } else {
+        write!(f, " {0:1$}{2}{3:^<4$}{5}", "", space_column,
+                  red.prefix(), "", space_width, red.suffix())?;
+      }
+    },
+    None => if index != text.len() {
+      write!(f, "internal error: Error has invalid line number: {}", line_number)?
+    },
+  }
+  Ok(())
+}
+
+pub struct And<'a, T: 'a + Display>(pub &'a [T]);
+
+impl<'a, T: Display> Display for And<'a, T> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    conjoin(f, self.0, "and")
+  }
+}
+
+pub struct Or <'a, T: 'a + Display>(pub &'a [T]);
+
+impl<'a, T: Display> Display for Or<'a, T> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    conjoin(f, self.0, "or")
+  }
+}
+
+pub struct Tick<'a, T: 'a + Display>(pub &'a T);
+
+impl<'a, T: Display> Display for Tick<'a, T> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    write!(f, "`{}`", self.0)
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+
+  #[test]
+  fn conjoin_or() {
+    assert_eq!("1",             Or(&[1      ]).to_string());
+    assert_eq!("1 or 2",        Or(&[1,2    ]).to_string());
+    assert_eq!("1, 2, or 3",    Or(&[1,2,3  ]).to_string());
+    assert_eq!("1, 2, 3, or 4", Or(&[1,2,3,4]).to_string());
+  }
+
+  #[test]
+  fn conjoin_and() {
+    assert_eq!("1",              And(&[1      ]).to_string());
+    assert_eq!("1 and 2",        And(&[1,2    ]).to_string());
+    assert_eq!("1, 2, and 3",    And(&[1,2,3  ]).to_string());
+    assert_eq!("1, 2, 3, and 4", And(&[1,2,3,4]).to_string());
+  }
+}

src/parameter.rs

@@ -0,0 +1,25 @@
+use common::*;
+
+#[derive(PartialEq, Debug)]
+pub struct Parameter<'a> {
+  pub default:  Option<String>,
+  pub name:     &'a str,
+  pub token:    Token<'a>,
+  pub variadic: bool,
+}
+
+impl<'a> Display for Parameter<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    let color = Color::fmt(f);
+    if self.variadic {
+      write!(f, "{}", color.annotation().paint("+"))?;
+    }
+    write!(f, "{}", color.parameter().paint(self.name))?;
+    if let Some(ref default) = self.default {
+      let escaped = default.chars().flat_map(char::escape_default).collect::<String>();;
+      write!(f, r#"='{}'"#, color.string().paint(&escaped))?;
+    }
+    Ok(())
+  }
+}
+

src/parser.rs

@@ -0,0 +1,848 @@
+use common::*;
+
+use itertools;
+use token::TokenKind::*;
+use recipe_resolver::resolve_recipes;
+use assignment_resolver::resolve_assignments;
+
+pub struct Parser<'a> {
+  text:              &'a str,
+  tokens:            itertools::PutBack<vec::IntoIter<Token<'a>>>,
+  recipes:           Map<&'a str, Recipe<'a>>,
+  assignments:       Map<&'a str, Expression<'a>>,
+  assignment_tokens: Map<&'a str, Token<'a>>,
+  exports:           Set<&'a str>,
+}
+
+impl<'a> Parser<'a> {
+  pub fn new(text: &'a str, tokens: Vec<Token<'a>>) -> Parser<'a> {
+    Parser {
+      text:              text,
+      tokens:            itertools::put_back(tokens),
+      recipes:           empty(),
+      assignments:       empty(),
+      assignment_tokens: empty(),
+      exports:           empty(),
+    }
+  }
+
+  fn peek(&mut self, kind: TokenKind) -> bool {
+    let next = self.tokens.next().unwrap();
+    let result = next.kind == kind;
+    self.tokens.put_back(next);
+    result
+  }
+
+  fn accept(&mut self, kind: TokenKind) -> Option<Token<'a>> {
+    if self.peek(kind) {
+      self.tokens.next()
+    } else {
+      None
+    }
+  }
+
+  fn accept_any(&mut self, kinds: &[TokenKind]) -> Option<Token<'a>> {
+    for kind in kinds {
+      if self.peek(*kind) {
+        return self.tokens.next();
+      }
+    }
+    None
+  }
+
+  fn accepted(&mut self, kind: TokenKind) -> bool {
+    self.accept(kind).is_some()
+  }
+
+  fn expect(&mut self, kind: TokenKind) -> Option<Token<'a>> {
+    if self.peek(kind) {
+      self.tokens.next();
+      None
+    } else {
+      self.tokens.next()
+    }
+  }
+
+  fn expect_eol(&mut self) -> Option<Token<'a>> {
+    self.accepted(Comment);
+    if self.peek(Eol) {
+      self.accept(Eol);
+      None
+    } else if self.peek(Eof) {
+      None
+    } else {
+      self.tokens.next()
+    }
+  }
+
+  fn unexpected_token(&self, found: &Token<'a>, expected: &[TokenKind]) -> CompilationError<'a> {
+    found.error(CompilationErrorKind::UnexpectedToken {
+      expected: expected.to_vec(),
+      found:    found.kind,
+    })
+  }
+
+  fn recipe(
+    &mut self,
+    name:  Token<'a>,
+    doc:   Option<Token<'a>>,
+    quiet: bool,
+  ) -> Result<(), CompilationError<'a>> {
+    if let Some(recipe) = self.recipes.get(name.lexeme) {
+      return Err(name.error(CompilationErrorKind::DuplicateRecipe {
+        recipe: recipe.name,
+        first:  recipe.line_number
+      }));
+    }
+
+    let mut parsed_parameter_with_default = false;
+    let mut parsed_variadic_parameter = false;
+    let mut parameters: Vec<Parameter> = vec![];
+    loop {
+      let plus = self.accept(Plus);
+
+      let parameter = match self.accept(Name) {
+        Some(parameter) => parameter,
+        None            => if let Some(plus) = plus {
+          return Err(self.unexpected_token(&plus, &[Name]));
+        } else {
+          break
+        },
+      };
+
+      let variadic = plus.is_some();
+
+      if parsed_variadic_parameter {
+        return Err(parameter.error(CompilationErrorKind::ParameterFollowsVariadicParameter {
+          parameter: parameter.lexeme,
+        }));
+      }
+
+      if parameters.iter().any(|p| p.name == parameter.lexeme) {
+        return Err(parameter.error(CompilationErrorKind::DuplicateParameter {
+          recipe: name.lexeme, parameter: parameter.lexeme
+        }));
+      }
+
+      let default;
+      if self.accepted(Equals) {
+        if let Some(string) = self.accept_any(&[StringToken, RawString]) {
+          default = Some(CookedString::new(&string)?.cooked);
+        } else {
+          let unexpected = self.tokens.next().unwrap();
+          return Err(self.unexpected_token(&unexpected, &[StringToken, RawString]));
+        }
+      } else {
+        default = None
+      }
+
+      if parsed_parameter_with_default && default.is_none() {
+        return Err(parameter.error(CompilationErrorKind::RequiredParameterFollowsDefaultParameter{
+          parameter: parameter.lexeme,
+        }));
+      }
+
+      parsed_parameter_with_default |= default.is_some();
+      parsed_variadic_parameter = variadic;
+
+      parameters.push(Parameter {
+        default:  default,
+        name:     parameter.lexeme,
+        token:    parameter,
+        variadic: variadic,
+      });
+    }
+
+    if let Some(token) = self.expect(Colon) {
+      // if we haven't accepted any parameters, an equals
+      // would have been fine as part of an assignment
+      if parameters.is_empty() {
+        return Err(self.unexpected_token(&token, &[Name, Plus, Colon, Equals]));
+      } else {
+        return Err(self.unexpected_token(&token, &[Name, Plus, Colon]));
+      }
+    }
+
+    let mut dependencies = vec![];
+    let mut dependency_tokens = vec![];
+    while let Some(dependency) = self.accept(Name) {
+      if dependencies.contains(&dependency.lexeme) {
+        return Err(dependency.error(CompilationErrorKind::DuplicateDependency {
+          recipe:     name.lexeme,
+          dependency: dependency.lexeme
+        }));
+      }
+      dependencies.push(dependency.lexeme);
+      dependency_tokens.push(dependency);
+    }
+
+    if let Some(token) = self.expect_eol() {
+      return Err(self.unexpected_token(&token, &[Name, Eol, Eof]));
+    }
+
+    let mut lines: Vec<Vec<Fragment>> = vec![];
+    let mut shebang = false;
+
+    if self.accepted(Indent) {
+      while !self.accepted(Dedent) {
+        if self.accepted(Eol) {
+          lines.push(vec![]);
+          continue;
+        }
+        if let Some(token) = self.expect(Line) {
+          return Err(token.error(CompilationErrorKind::Internal{
+            message: format!("Expected a line but got {}", token.kind)
+          }))
+        }
+        let mut fragments = vec![];
+
+        while !(self.accepted(Eol) || self.peek(Dedent)) {
+          if let Some(token) = self.accept(Text) {
+            if fragments.is_empty() {
+              if lines.is_empty() {
+                if token.lexeme.starts_with("#!") {
+                  shebang = true;
+                }
+              } else if !shebang
+                && !lines.last().and_then(|line| line.last())
+                  .map(Fragment::continuation).unwrap_or(false)
+                && (token.lexeme.starts_with(' ') || token.lexeme.starts_with('\t')) {
+                return Err(token.error(CompilationErrorKind::ExtraLeadingWhitespace));
+              }
+            }
+            fragments.push(Fragment::Text{text: token});
+          } else if let Some(token) = self.expect(InterpolationStart) {
+            return Err(self.unexpected_token(&token, &[Text, InterpolationStart, Eol]));
+          } else {
+            fragments.push(Fragment::Expression{
+              expression: self.expression(true)?
+            });
+            if let Some(token) = self.expect(InterpolationEnd) {
+              return Err(self.unexpected_token(&token, &[InterpolationEnd]));
+            }
+          }
+        }
+
+        lines.push(fragments);
+      }
+    }
+
+    self.recipes.insert(name.lexeme, Recipe {
+      line_number:       name.line,
+      name:              name.lexeme,
+      doc:               doc.map(|t| t.lexeme[1..].trim()),
+      dependencies:      dependencies,
+      dependency_tokens: dependency_tokens,
+      parameters:        parameters,
+      private:           &name.lexeme[0..1] == "_",
+      lines:             lines,
+      shebang:           shebang,
+      quiet:             quiet,
+    });
+
+    Ok(())
+  }
+
+  fn expression(&mut self, interpolation: bool) -> Result<Expression<'a>, CompilationError<'a>> {
+    let first = self.tokens.next().unwrap();
+    let lhs = match first.kind {
+      Name        => Expression::Variable {name: first.lexeme, token: first},
+      Backtick    => Expression::Backtick {
+        raw:   &first.lexeme[1..first.lexeme.len()-1],
+        token: first
+      },
+      RawString | StringToken => {
+        Expression::String{cooked_string: CookedString::new(&first)?}
+      }
+      _ => return Err(self.unexpected_token(&first, &[Name, StringToken])),
+    };
+
+    if self.accepted(Plus) {
+      let rhs = self.expression(interpolation)?;
+      Ok(Expression::Concatination{lhs: Box::new(lhs), rhs: Box::new(rhs)})
+    } else if interpolation && self.peek(InterpolationEnd) {
+      Ok(lhs)
+    } else if let Some(token) = self.expect_eol() {
+      if interpolation {
+        return Err(self.unexpected_token(&token, &[Plus, Eol, InterpolationEnd]))
+      } else {
+        Err(self.unexpected_token(&token, &[Plus, Eol]))
+      }
+    } else {
+      Ok(lhs)
+    }
+  }
+
+  fn assignment(&mut self, name: Token<'a>, export: bool) -> Result<(), CompilationError<'a>> {
+    if self.assignments.contains_key(name.lexeme) {
+      return Err(name.error(CompilationErrorKind::DuplicateVariable {variable: name.lexeme}));
+    }
+    if export {
+      self.exports.insert(name.lexeme);
+    }
+    let expression = self.expression(false)?;
+    self.assignments.insert(name.lexeme, expression);
+    self.assignment_tokens.insert(name.lexeme, name);
+    Ok(())
+  }
+
+  pub fn justfile(mut self) -> Result<Justfile<'a>, CompilationError<'a>> {
+    let mut doc = None;
+    loop {
+      match self.tokens.next() {
+        Some(token) => match token.kind {
+          Eof => break,
+          Eol => {
+            doc = None;
+            continue;
+          }
+          Comment => {
+            if let Some(token) = self.expect_eol() {
+              return Err(token.error(CompilationErrorKind::Internal {
+                message: format!("found comment followed by {}", token.kind),
+              }));
+            }
+            doc = Some(token);
+          }
+          At => if let Some(name) = self.accept(Name) {
+            self.recipe(name, doc, true)?;
+            doc = None;
+          } else {
+            let unexpected = &self.tokens.next().unwrap();
+            return Err(self.unexpected_token(unexpected, &[Name]));
+          },
+          Name => if token.lexeme == "export" {
+            let next = self.tokens.next().unwrap();
+            if next.kind == Name && self.accepted(Equals) {
+              self.assignment(next, true)?;
+              doc = None;
+            } else {
+              self.tokens.put_back(next);
+              self.recipe(token, doc, false)?;
+              doc = None;
+            }
+          } else if self.accepted(Equals) {
+            self.assignment(token, false)?;
+            doc = None;
+          } else {
+            self.recipe(token, doc, false)?;
+            doc = None;
+          },
+          _ => return Err(self.unexpected_token(&token, &[Name, At])),
+        },
+        None => return Err(CompilationError {
+          text:   self.text,
+          index:  0,
+          line:   0,
+          column: 0,
+          width:  None,
+          kind:   CompilationErrorKind::Internal {
+            message: "unexpected end of token stream".to_string()
+          }
+        }),
+      }
+    }
+
+    if let Some(token) = self.tokens.next() {
+      return Err(token.error(CompilationErrorKind::Internal {
+        message: format!("unexpected token remaining after parsing completed: {:?}", token.kind)
+      }))
+    }
+
+    resolve_recipes(&self.recipes, &self.assignments, self.text)?;
+
+    for recipe in self.recipes.values() {
+      for parameter in &recipe.parameters {
+        if self.assignments.contains_key(parameter.token.lexeme) {
+          return Err(parameter.token.error(CompilationErrorKind::ParameterShadowsVariable {
+            parameter: parameter.token.lexeme
+          }));
+        }
+      }
+
+      for dependency in &recipe.dependency_tokens {
+        if !self.recipes[dependency.lexeme].parameters.is_empty() {
+          return Err(dependency.error(CompilationErrorKind::DependencyHasParameters {
+            recipe: recipe.name,
+            dependency: dependency.lexeme,
+          }));
+        }
+      }
+    }
+
+    resolve_assignments(&self.assignments, &self.assignment_tokens)?;
+
+    Ok(Justfile {
+      recipes:     self.recipes,
+      assignments: self.assignments,
+      exports:     self.exports,
+    })
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+  use brev;
+  use testing::parse_success;
+  use testing::parse_error;
+
+fn parse_summary(input: &str, output: &str) {
+  let justfile = parse_success(input);
+  let s = format!("{:#}", justfile);
+  if s != output {
+    println!("got:\n\"{}\"\n", s);
+    println!("\texpected:\n\"{}\"", output);
+    assert_eq!(s, output);
+  }
+}
+
+#[test]
+fn parse_empty() {
+  parse_summary("
+
+# hello
+
+
+  ", "");
+}
+
+#[test]
+fn parse_string_default() {
+  parse_summary(r#"
+
+foo a="b\t":
+
+
+  "#, r#"foo a='b\t':"#);
+}
+
+#[test]
+fn parse_variadic() {
+  parse_summary(r#"
+
+foo +a:
+
+
+  "#, r#"foo +a:"#);
+}
+
+#[test]
+fn parse_variadic_string_default() {
+  parse_summary(r#"
+
+foo +a="Hello":
+
+
+  "#, r#"foo +a='Hello':"#);
+}
+
+#[test]
+fn parse_raw_string_default() {
+  parse_summary(r#"
+
+foo a='b\t':
+
+
+  "#, r#"foo a='b\\t':"#);
+}
+
+#[test]
+fn parse_export() {
+  parse_summary(r#"
+export a = "hello"
+
+  "#, r#"export a = "hello""#);
+}
+
+
+#[test]
+fn parse_complex() {
+  parse_summary("
+x:
+y:
+z:
+foo = \"xx\"
+bar = foo
+goodbye = \"y\"
+hello a b    c   : x y    z #hello
+  #! blah
+  #blarg
+  {{ foo + bar}}abc{{ goodbye\t  + \"x\" }}xyz
+  1
+  2
+  3
+", "bar = foo
+
+foo = \"xx\"
+
+goodbye = \"y\"
+
+hello a b c: x y z
+    #! blah
+    #blarg
+    {{foo + bar}}abc{{goodbye + \"x\"}}xyz
+    1
+    2
+    3
+
+x:
+
+y:
+
+z:");
+}
+
+#[test]
+fn parse_shebang() {
+  parse_summary("
+practicum = 'hello'
+install:
+\t#!/bin/sh
+\tif [[ -f {{practicum}} ]]; then
+\t\treturn
+\tfi
+", "practicum = \"hello\"
+
+install:
+    #!/bin/sh
+    if [[ -f {{practicum}} ]]; then
+    \treturn
+    fi"
+  );
+}
+
+#[test]
+fn parse_assignments() {
+  parse_summary(
+r#"a = "0"
+c = a + b + a + b
+b = "1"
+"#,
+
+r#"a = "0"
+
+b = "1"
+
+c = a + b + a + b"#);
+}
+
+#[test]
+fn parse_assignment_backticks() {
+  parse_summary(
+"a = `echo hello`
+c = a + b + a + b
+b = `echo goodbye`",
+
+"a = `echo hello`
+
+b = `echo goodbye`
+
+c = a + b + a + b");
+}
+
+#[test]
+fn parse_interpolation_backticks() {
+  parse_summary(
+r#"a:
+ echo {{  `echo hello` + "blarg"   }} {{   `echo bob`   }}"#,
+r#"a:
+    echo {{`echo hello` + "blarg"}} {{`echo bob`}}"#,
+ );
+}
+
+#[test]
+fn missing_colon() {
+  let text = "a b c\nd e f";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  5,
+    line:   0,
+    column: 5,
+    width:  Some(1),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![Name, Plus, Colon], found: Eol},
+  });
+}
+
+#[test]
+fn missing_default_eol() {
+  let text = "hello arg=\n";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  10,
+    line:   0,
+    column: 10,
+    width:  Some(1),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![StringToken, RawString], found: Eol},
+  });
+}
+
+#[test]
+fn missing_default_eof() {
+  let text = "hello arg=";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  10,
+    line:   0,
+    column: 10,
+    width:  Some(0),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![StringToken, RawString], found: Eof},
+  });
+}
+
+#[test]
+fn missing_default_colon() {
+  let text = "hello arg=:";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  10,
+    line:   0,
+    column: 10,
+    width:  Some(1),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![StringToken, RawString], found: Colon},
+  });
+}
+
+#[test]
+fn missing_default_backtick() {
+  let text = "hello arg=`hello`";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  10,
+    line:   0,
+    column: 10,
+    width:  Some(7),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![StringToken, RawString], found: Backtick},
+  });
+}
+
+#[test]
+fn parameter_after_variadic() {
+  let text = "foo +a bbb:";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  7,
+    line:   0,
+    column: 7,
+    width:  Some(3),
+    kind:   CompilationErrorKind::ParameterFollowsVariadicParameter{parameter: "bbb"}
+  });
+}
+
+#[test]
+fn required_after_default() {
+  let text = "hello arg='foo' bar:";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  16,
+    line:   0,
+    column: 16,
+    width:  Some(3),
+    kind:   CompilationErrorKind::RequiredParameterFollowsDefaultParameter{parameter: "bar"},
+  });
+}
+
+#[test]
+fn missing_eol() {
+  let text = "a b c: z =";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  9,
+    line:   0,
+    column: 9,
+    width:  Some(1),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![Name, Eol, Eof], found: Equals},
+  });
+}
+
+#[test]
+fn eof_test() {
+  parse_summary("x:\ny:\nz:\na b c: x y z", "a b c: x y z\n\nx:\n\ny:\n\nz:");
+}
+
+#[test]
+fn duplicate_parameter() {
+  let text = "a b b:";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  4,
+    line:   0,
+    column: 4,
+    width:  Some(1),
+    kind:   CompilationErrorKind::DuplicateParameter{recipe: "a", parameter: "b"}
+  });
+}
+
+#[test]
+fn parameter_shadows_varible() {
+  let text = "foo = \"h\"\na foo:";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  12,
+    line:   1,
+    column: 2,
+    width:  Some(3),
+    kind:   CompilationErrorKind::ParameterShadowsVariable{parameter: "foo"}
+  });
+}
+
+#[test]
+fn dependency_has_parameters() {
+  let text = "foo arg:\nb: foo";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  12,
+    line:   1,
+    column: 3,
+    width:  Some(3),
+    kind:   CompilationErrorKind::DependencyHasParameters{recipe: "b", dependency: "foo"}
+  });
+}
+
+
+#[test]
+fn duplicate_dependency() {
+  let text = "a b c: b c z z";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  13,
+    line:   0,
+    column: 13,
+    width:  Some(1),
+    kind:   CompilationErrorKind::DuplicateDependency{recipe: "a", dependency: "z"}
+  });
+}
+
+#[test]
+fn duplicate_recipe() {
+  let text = "a:\nb:\na:";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  6,
+    line:   2,
+    column: 0,
+    width:  Some(1),
+    kind:   CompilationErrorKind::DuplicateRecipe{recipe: "a", first: 0}
+  });
+}
+
+#[test]
+fn duplicate_variable() {
+  let text = "a = \"0\"\na = \"0\"";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  8,
+    line:   1,
+    column: 0,
+    width:  Some(1),
+    kind:   CompilationErrorKind::DuplicateVariable{variable: "a"}
+  });
+}
+
+#[test]
+fn string_quote_escape() {
+  parse_summary(
+    r#"a = "hello\"""#,
+    r#"a = "hello\"""#
+  );
+}
+
+#[test]
+fn string_escapes() {
+  parse_summary(
+    r#"a = "\n\t\r\"\\""#,
+    r#"a = "\n\t\r\"\\""#
+  );
+}
+
+#[test]
+fn parameters() {
+  parse_summary(
+"a b c:
+  {{b}} {{c}}",
+"a b c:
+    {{b}} {{c}}",
+  );
+}
+
+
+
+#[test]
+fn extra_whitespace() {
+  let text = "a:\n blah\n  blarg";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  10,
+    line:   2,
+    column: 1,
+    width:  Some(6),
+    kind:   CompilationErrorKind::ExtraLeadingWhitespace
+  });
+
+  // extra leading whitespace is okay in a shebang recipe
+  parse_success("a:\n #!\n  print(1)");
+}
+#[test]
+fn interpolation_outside_of_recipe() {
+  let text = "{{";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  0,
+    line:   0,
+    column: 0,
+    width:  Some(2),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![Name, At], found: InterpolationStart},
+  });
+}
+#[test]
+fn unclosed_interpolation_delimiter() {
+  let text = "a:\n echo {{ foo";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  15,
+    line:   1,
+    column: 12,
+    width:  Some(0),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![Plus, Eol, InterpolationEnd], found: Dedent},
+  });
+}
+
+#[test]
+fn plus_following_parameter() {
+  let text = "a b c+:";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  5,
+    line:   0,
+    column: 5,
+    width:  Some(1),
+    kind:   CompilationErrorKind::UnexpectedToken{expected: vec![Name], found: Plus},
+  });
+}
+
+#[test]
+fn readme_test() {
+  let mut justfiles = vec![];
+  let mut current = None;
+
+  for line in brev::slurp("README.asc").lines() {
+    if let Some(mut justfile) = current {
+      if line == "```" {
+        justfiles.push(justfile);
+        current = None;
+      } else {
+        justfile += line;
+        justfile += "\n";
+        current = Some(justfile);
+      }
+    } else if line == "```make" {
+      current = Some(String::new());
+    }
+  }
+
+  for justfile in justfiles {
+    parse_success(&justfile);
+  }
+}
+
+}

src/platform.rs

@@ -1,4 +1,6 @@
-use ::prelude::*;
+use common::*;
+
+use brev;
 
 pub struct Platform;
 
@@ -6,7 +8,7 @@ pub trait PlatformInterface {
   /// Construct a command equivelant to running the script at `path` with the
   /// shebang line `shebang`
   fn make_shebang_command(path: &Path, command: &str, argument: Option<&str>)
-    -> Result<process::Command, super::OutputError>;
+    -> Result<Command, brev::OutputError>;
 
   /// Set the execute permission on the file pointed to by `path`
   fn set_execute_permission(path: &Path) -> Result<(), io::Error>;
@@ -18,10 +20,10 @@ pub trait PlatformInterface {
 #[cfg(unix)]
 impl PlatformInterface for Platform {
   fn make_shebang_command(path: &Path, _command: &str, _argument: Option<&str>)
-    -> Result<process::Command, super::OutputError>
+    -> Result<Command, brev::OutputError>
   {
     // shebang scripts can be executed directly on unix
-    Ok(process::Command::new(path))
+    Ok(Command::new(path))
   }
 
   fn set_execute_permission(path: &Path) -> Result<(), io::Error> {
@@ -47,14 +49,14 @@ impl PlatformInterface for Platform {
 #[cfg(windows)]
 impl PlatformInterface for Platform {
   fn make_shebang_command(path: &Path, command: &str, argument: Option<&str>)
-    -> Result<process::Command, super::OutputError>
+    -> Result<Command, brev::OutputError>
   {
     // Translate path to the interpreter from unix style to windows style
-    let mut cygpath = process::Command::new("cygpath");
+    let mut cygpath = Command::new("cygpath");
     cygpath.arg("--windows");
     cygpath.arg(command);
 
-    let mut cmd = process::Command::new(super::output(cygpath)?);
+    let mut cmd = Command::new(brev::output(cygpath)?);
     if let Some(argument) = argument {
       cmd.arg(argument);
     }

src/range_ext.rs

@@ -0,0 +1,25 @@
+use common::*;
+
+pub trait RangeExt<T> {
+  fn range_contains(&self, i: T) -> bool;
+}
+
+impl<T> RangeExt<T> for Range<T> where T: PartialOrd + Copy {
+  fn range_contains(&self,  i: T) -> bool {
+    i >= self.start && i < self.end
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+
+  #[test]
+  fn range() {
+    assert!( ( 0.. 1).range_contains( 0));
+    assert!( (10..20).range_contains(15));
+    assert!(!( 0.. 0).range_contains( 0));
+    assert!(!( 1..10).range_contains( 0));
+    assert!(!( 1..10).range_contains(10));
+  }
+}

src/recipe.rs

@@ -0,0 +1,281 @@
+use common::*;
+
+use std::process::{ExitStatus, Command, Stdio};
+
+use platform::{Platform, PlatformInterface};
+
+/// Return a `RuntimeError::Signal` if the process was terminated by a signal,
+/// otherwise return an `RuntimeError::UnknownFailure`
+fn error_from_signal(
+  recipe:      &str,
+  line_number: Option<usize>,
+  exit_status: ExitStatus
+) -> RuntimeError {
+  match Platform::signal_from_exit_status(exit_status) {
+    Some(signal) => RuntimeError::Signal{recipe: recipe, line_number: line_number, signal: signal},
+    None => RuntimeError::Unknown{recipe: recipe, line_number: line_number},
+  }
+}
+
+#[derive(PartialEq, Debug)]
+pub struct Recipe<'a> {
+  pub dependencies:      Vec<&'a str>,
+  pub dependency_tokens: Vec<Token<'a>>,
+  pub doc:               Option<&'a str>,
+  pub line_number:       usize,
+  pub lines:             Vec<Vec<Fragment<'a>>>,
+  pub name:              &'a str,
+  pub parameters:        Vec<Parameter<'a>>,
+  pub private:           bool,
+  pub quiet:             bool,
+  pub shebang:           bool,
+}
+
+impl<'a> Recipe<'a> {
+  pub fn argument_range(&self) -> Range<usize> {
+    self.min_arguments()..self.max_arguments() + 1
+  }
+
+  pub fn min_arguments(&self) -> usize {
+    self.parameters.iter().filter(|p| !p.default.is_some()).count()
+  }
+
+  pub fn max_arguments(&self) -> usize {
+    if self.parameters.iter().any(|p| p.variadic) {
+      usize::MAX - 1
+    } else {
+      self.parameters.len()
+    }
+  }
+
+  pub fn run(
+    &self,
+    arguments: &[&'a str],
+    scope:     &Map<&'a str, String>,
+    exports:   &Set<&'a str>,
+    options:   &Configuration,
+  ) -> Result<(), RuntimeError<'a>> {
+    if options.verbose {
+      let color = options.color.stderr().banner();
+      eprintln!("{}===> Running recipe `{}`...{}", color.prefix(), self.name, color.suffix());
+    }
+
+    let mut argument_map = Map::new();
+
+    let mut rest = arguments;
+    for parameter in &self.parameters {
+      let value = if rest.is_empty() {
+        match parameter.default {
+          Some(ref default) => Cow::Borrowed(default.as_str()),
+          None => return Err(RuntimeError::Internal{
+            message: "missing parameter without default".to_string()
+          }),
+        }
+      } else if parameter.variadic {
+        let value = Cow::Owned(rest.to_vec().join(" "));
+        rest = &[];
+        value
+      } else {
+        let value = Cow::Borrowed(rest[0]);
+        rest = &rest[1..];
+        value
+      };
+      argument_map.insert(parameter.name, value);
+    }
+
+    let mut evaluator = AssignmentEvaluator {
+      evaluated:   empty(),
+      scope:       scope,
+      exports:     exports,
+      assignments: &empty(),
+      overrides:   &empty(),
+      quiet:       options.quiet,
+      shell:       options.shell,
+    };
+
+    if self.shebang {
+      let mut evaluated_lines = vec![];
+      for line in &self.lines {
+        evaluated_lines.push(evaluator.evaluate_line(line, &argument_map)?);
+      }
+
+      if options.dry_run || self.quiet {
+        for line in &evaluated_lines {
+          eprintln!("{}", line);
+        }
+      }
+
+      if options.dry_run {
+        return Ok(());
+      }
+
+      let tmp = TempDir::new("just")
+        .map_err(|error| RuntimeError::TmpdirIoError{recipe: self.name, io_error: error})?;
+      let mut path = tmp.path().to_path_buf();
+      path.push(self.name);
+      {
+        let mut f = fs::File::create(&path)
+          .map_err(|error| RuntimeError::TmpdirIoError{recipe: self.name, io_error: error})?;
+        let mut text = String::new();
+        // add the shebang
+        text += &evaluated_lines[0];
+        text += "\n";
+        // add blank lines so that lines in the generated script
+        // have the same line number as the corresponding lines
+        // in the justfile
+        for _ in 1..(self.line_number + 2) {
+          text += "\n"
+        }
+        for line in &evaluated_lines[1..] {
+          text += line;
+          text += "\n";
+        }
+        f.write_all(text.as_bytes())
+         .map_err(|error| RuntimeError::TmpdirIoError{recipe: self.name, io_error: error})?;
+      }
+
+      // make the script executable
+      Platform::set_execute_permission(&path)
+        .map_err(|error| RuntimeError::TmpdirIoError{recipe: self.name, io_error: error})?;
+
+      let shebang_line = evaluated_lines.first()
+        .ok_or_else(|| RuntimeError::Internal {
+          message: "evaluated_lines was empty".to_string()
+        })?;
+
+      let Shebang{interpreter, argument} = Shebang::new(shebang_line)
+        .ok_or_else(|| RuntimeError::Internal {
+          message: format!("bad shebang line: {}", shebang_line)
+        })?;
+
+      // create a command to run the script
+      let mut command = Platform::make_shebang_command(&path, interpreter, argument)
+        .map_err(|output_error| RuntimeError::Cygpath{recipe: self.name, output_error: output_error})?;
+
+      command.export_environment_variables(scope, exports)?;
+
+      // run it!
+      match command.status() {
+        Ok(exit_status) => if let Some(code) = exit_status.code() {
+          if code != 0 {
+            return Err(RuntimeError::Code{recipe: self.name, line_number: None, code: code})
+          }
+        } else {
+          return Err(error_from_signal(self.name, None, exit_status))
+        },
+        Err(io_error) => return Err(RuntimeError::Shebang {
+          recipe:   self.name,
+          command:  interpreter.to_string(),
+          argument: argument.map(String::from),
+          io_error: io_error
+        })
+      };
+    } else {
+      let mut lines = self.lines.iter().peekable();
+      let mut line_number = self.line_number + 1;
+      loop {
+        if lines.peek().is_none() {
+          break;
+        }
+        let mut evaluated = String::new();
+        loop {
+          if lines.peek().is_none() {
+            break;
+          }
+          let line = lines.next().unwrap();
+          line_number += 1;
+          evaluated += &evaluator.evaluate_line(line, &argument_map)?;
+          if line.last().map(Fragment::continuation).unwrap_or(false) {
+            evaluated.pop();
+          } else {
+            break;
+          }
+        }
+        let mut command = evaluated.as_str();
+        let quiet_command = command.starts_with('@');
+        if quiet_command {
+          command = &command[1..];
+        }
+
+        if command == "" {
+          continue;
+        }
+
+        if options.dry_run || options.verbose || !((quiet_command ^ self.quiet) || options.quiet) {
+          let color = if options.highlight {
+            options.color.command()
+          } else {
+            options.color
+          };
+          eprintln!("{}", color.stderr().paint(command));
+        }
+
+        if options.dry_run {
+          continue;
+        }
+
+        let mut cmd = Command::new(options.shell);
+
+        cmd.arg("-cu").arg(command);
+
+        if options.quiet {
+          cmd.stderr(Stdio::null());
+          cmd.stdout(Stdio::null());
+        }
+
+        cmd.export_environment_variables(scope, exports)?;
+
+        match cmd.status() {
+          Ok(exit_status) => if let Some(code) = exit_status.code() {
+            if code != 0 {
+              return Err(RuntimeError::Code{
+                recipe: self.name, line_number: Some(line_number), code: code
+              });
+            }
+          } else {
+            return Err(error_from_signal(self.name, Some(line_number), exit_status));
+          },
+          Err(io_error) => return Err(RuntimeError::IoError{
+            recipe: self.name, io_error: io_error}),
+        };
+      }
+    }
+    Ok(())
+  }
+}
+
+impl<'a> Display for Recipe<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    if let Some(doc) = self.doc {
+      writeln!(f, "# {}", doc)?;
+    }
+    write!(f, "{}", self.name)?;
+    for parameter in &self.parameters {
+      write!(f, " {}", parameter)?;
+    }
+    write!(f, ":")?;
+    for dependency in &self.dependencies {
+      write!(f, " {}", dependency)?;
+    }
+
+    for (i, pieces) in self.lines.iter().enumerate() {
+      if i == 0 {
+        writeln!(f, "")?;
+      }
+      for (j, piece) in pieces.iter().enumerate() {
+        if j == 0 {
+          write!(f, "    ")?;
+        }
+        match *piece {
+          Fragment::Text{ref text} => write!(f, "{}", text.lexeme)?,
+          Fragment::Expression{ref expression, ..} =>
+            write!(f, "{}{}{}", "{{", expression, "}}")?,
+        }
+      }
+      if i + 1 < self.lines.len() {
+        write!(f, "\n")?;
+      }
+    }
+    Ok(())
+  }
+}

src/recipe_resolver.rs

@@ -0,0 +1,171 @@
+use common::*;
+
+pub fn resolve_recipes<'a>(
+  recipes:     &Map<&'a str, Recipe<'a>>,
+  assignments: &Map<&'a str, Expression<'a>>,
+  text:        &'a str,
+) -> Result<(), CompilationError<'a>> {
+  let mut resolver = RecipeResolver {
+    seen:              empty(),
+    stack:             empty(),
+    resolved:          empty(),
+    recipes:           recipes,
+  };
+
+  for recipe in recipes.values() {
+    resolver.resolve(recipe)?;
+    resolver.seen = empty();
+  }
+
+  for recipe in recipes.values() {
+    for line in &recipe.lines {
+      for fragment in line {
+        if let Fragment::Expression{ref expression, ..} = *fragment {
+          for variable in expression.variables() {
+            let name = variable.lexeme;
+            let undefined = !assignments.contains_key(name)
+              && !recipe.parameters.iter().any(|p| p.name == name);
+            if undefined {
+              // There's a borrow issue here that seems too difficult to solve.
+              // The error derived from the variable token has too short a lifetime,
+              // so we create a new error from its contents, which do live long
+              // enough.
+              //
+              // I suspect the solution here is to give recipes, pieces, and expressions
+              // two lifetime parameters instead of one, with one being the lifetime
+              // of the struct, and the second being the lifetime of the tokens
+              // that it contains
+              let error = variable.error(CompilationErrorKind::UndefinedVariable{variable: name});
+              return Err(CompilationError {
+                text:   text,
+                index:  error.index,
+                line:   error.line,
+                column: error.column,
+                width:  error.width,
+                kind:   CompilationErrorKind::UndefinedVariable {
+                  variable: &text[error.index..error.index + error.width.unwrap()],
+                }
+              });
+            }
+          }
+        }
+      }
+    }
+  }
+
+  Ok(())
+}
+
+struct RecipeResolver<'a: 'b, 'b> {
+  stack:    Vec<&'a str>,
+  seen:     Set<&'a str>,
+  resolved: Set<&'a str>,
+  recipes:  &'b Map<&'a str, Recipe<'a>>,
+}
+
+impl<'a, 'b> RecipeResolver<'a, 'b> {
+  fn resolve(&mut self, recipe: &Recipe<'a>) -> Result<(), CompilationError<'a>> {
+    if self.resolved.contains(recipe.name) {
+      return Ok(())
+    }
+    self.stack.push(recipe.name);
+    self.seen.insert(recipe.name);
+    for dependency_token in &recipe.dependency_tokens {
+      match self.recipes.get(dependency_token.lexeme) {
+        Some(dependency) => if !self.resolved.contains(dependency.name) {
+          if self.seen.contains(dependency.name) {
+            let first = self.stack[0];
+            self.stack.push(first);
+            return Err(dependency_token.error(CompilationErrorKind::CircularRecipeDependency {
+              recipe: recipe.name,
+              circle: self.stack.iter()
+                .skip_while(|name| **name != dependency.name)
+                .cloned().collect()
+            }));
+          }
+          self.resolve(dependency)?;
+        },
+        None => return Err(dependency_token.error(CompilationErrorKind::UnknownDependency {
+          recipe:  recipe.name,
+          unknown: dependency_token.lexeme
+        })),
+      }
+    }
+    self.resolved.insert(recipe.name);
+    self.stack.pop();
+    Ok(())
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+  use testing::parse_error;
+
+#[test]
+fn circular_recipe_dependency() {
+  let text = "a: b\nb: a";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  8,
+    line:   1,
+    column: 3,
+    width:  Some(1),
+    kind:   CompilationErrorKind::CircularRecipeDependency{recipe: "b", circle: vec!["a", "b", "a"]}
+  });
+}
+
+#[test]
+fn self_recipe_dependency() {
+  let text = "a: a";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  3,
+    line:   0,
+    column: 3,
+    width:  Some(1),
+    kind:   CompilationErrorKind::CircularRecipeDependency{recipe: "a", circle: vec!["a", "a"]}
+  });
+}
+
+
+#[test]
+fn unknown_dependency() {
+  let text = "a: b";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  3,
+    line:   0,
+    column: 3,
+    width:  Some(1),
+    kind:   CompilationErrorKind::UnknownDependency{recipe: "a", unknown: "b"}
+  });
+}
+
+#[test]
+fn unknown_interpolation_variable() {
+  let text = "x:\n {{   hello}}";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  9,
+    line:   1,
+    column: 6,
+    width:  Some(5),
+    kind:   CompilationErrorKind::UndefinedVariable{variable: "hello"},
+  });
+}
+
+#[test]
+fn unknown_second_interpolation_variable() {
+  let text = "wtf=\"x\"\nx:\n echo\n foo {{wtf}} {{ lol }}";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  33,
+    line:   3,
+    column: 16,
+    width:  Some(3),
+    kind:   CompilationErrorKind::UndefinedVariable{variable: "lol"},
+  });
+}
+
+}

src/run.rs

@@ -1,12 +1,10 @@
-extern crate clap;
-extern crate libc;
+use common::*;
 
-use color::Color;
-use prelude::*;
 use std::{convert, ffi};
-use std::collections::BTreeMap;
-use self::clap::{App, Arg, ArgGroup, AppSettings};
-use super::{Slurp, RunOptions, compile, DEFAULT_SHELL, maybe_s};
+use clap::{App, Arg, ArgGroup, AppSettings};
+use compile;
+use misc::maybe_s;
+use configuration::DEFAULT_SHELL;
 
 macro_rules! die {
   ($($arg:tt)*) => {{
@@ -20,7 +18,7 @@ fn edit<P: convert::AsRef<ffi::OsStr>>(path: P) -> ! {
   let editor = env::var_os("EDITOR")
     .unwrap_or_else(|| die!("Error getting EDITOR environment variable"));
 
-  let error = process::Command::new(editor)
+  let error = Command::new(editor)
     .arg(path)
     .status();
 
@@ -30,7 +28,19 @@ fn edit<P: convert::AsRef<ffi::OsStr>>(path: P) -> ! {
   }
 }
 
-pub fn app() {
+trait Slurp {
+  fn slurp(&mut self) -> Result<String, io::Error>;
+}
+
+impl Slurp for fs::File {
+  fn slurp(&mut self) -> io::Result<String> {
+    let mut destination = String::new();
+    self.read_to_string(&mut destination)?;
+    Ok(destination)
+  }
+}
+
+pub fn run() {
   let matches = App::new("just")
     .version(concat!("v", env!("CARGO_PKG_VERSION")))
     .author(env!("CARGO_PKG_AUTHORS"))
@@ -121,7 +131,7 @@ pub fn app() {
   };
 
   let set_count = matches.occurrences_of("SET");
-  let mut overrides = BTreeMap::new();
+  let mut overrides = Map::new();
   if set_count > 0 {
     let mut values = matches.values_of("SET").unwrap();
     for _ in 0..set_count {
@@ -300,13 +310,13 @@ pub fn app() {
     die!("Justfile contains no recipes.");
   };
 
-  let options = RunOptions {
+  let options = Configuration {
     dry_run:   matches.is_present("DRY-RUN"),
     evaluate:  matches.is_present("EVALUATE"),
     highlight: matches.is_present("HIGHLIGHT"),
     overrides: overrides,
     quiet:     matches.is_present("QUIET"),
-    shell:     matches.value_of("SHELL"),
+    shell:     matches.value_of("SHELL").unwrap(),
     color:     color,
     verbose:   matches.is_present("VERBOSE"),
   };
@@ -320,6 +330,6 @@ pub fn app() {
       }
     }
 
-    process::exit(run_error.code().unwrap_or(libc::EXIT_FAILURE));
+    process::exit(run_error.code().unwrap_or(EXIT_FAILURE));
   }
 }

src/runtime_error.rs

@@ -0,0 +1,201 @@
+use common::*;
+
+use brev::OutputError;
+
+use misc::{And, Or, maybe_s, Tick, ticks, write_error_context};
+
+use self::RuntimeError::*;
+
+fn write_token_error_context(f: &mut fmt::Formatter, token: &Token) -> Result<(), fmt::Error> {
+  write_error_context(
+    f,
+    token.text,
+    token.index,
+    token.line,
+    token.column + token.prefix.len(),
+    Some(token.lexeme.len())
+  )
+}
+
+#[derive(Debug)]
+pub enum RuntimeError<'a> {
+  ArgumentCountMismatch{recipe: &'a str, found: usize, min: usize, max: usize},
+  Backtick{token: Token<'a>, output_error: OutputError},
+  Code{recipe: &'a str, line_number: Option<usize>, code: i32},
+  Cygpath{recipe: &'a str, output_error: OutputError},
+  Internal{message: String},
+  IoError{recipe: &'a str, io_error: io::Error},
+  Shebang{recipe: &'a str, command: String, argument: Option<String>, io_error: io::Error},
+  Signal{recipe: &'a str, line_number: Option<usize>, signal: i32},
+  TmpdirIoError{recipe: &'a str, io_error: io::Error},
+  Unknown{recipe: &'a str, line_number: Option<usize>},
+  UnknownOverrides{overrides: Vec<&'a str>},
+  UnknownRecipes{recipes: Vec<&'a str>, suggestion: Option<&'a str>},
+}
+
+impl<'a> RuntimeError<'a> {
+  pub fn code(&self) -> Option<i32> {
+    match *self {
+      Code{code, ..} | Backtick{output_error: OutputError::Code(code), ..} => Some(code),
+      _ => None,
+    }
+  }
+}
+
+impl<'a> Display for RuntimeError<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    use RuntimeError::*;
+    let color = if f.alternate() { Color::always() } else { Color::never() };
+    let error = color.error();
+    let message = color.message();
+    write!(f, "{} {}", error.paint("error:"), message.prefix())?;
+
+    let mut error_token = None;
+
+    match *self {
+      UnknownRecipes{ref recipes, ref suggestion} => {
+        write!(f, "Justfile does not contain recipe{} {}.",
+                  maybe_s(recipes.len()), Or(&ticks(recipes)))?;
+        if let Some(suggestion) = *suggestion {
+          write!(f, "\nDid you mean `{}`?", suggestion)?;
+        }
+      },
+      UnknownOverrides{ref overrides} => {
+        write!(f, "Variable{} {} overridden on the command line but not present in justfile",
+                  maybe_s(overrides.len()),
+                  And(&overrides.iter().map(Tick).collect::<Vec<_>>()))?;
+      },
+      ArgumentCountMismatch{recipe, found, min, max} => {
+        if min == max {
+          let expected = min;
+          write!(f, "Recipe `{}` got {} argument{} but {}takes {}",
+                    recipe, found, maybe_s(found),
+                    if expected < found { "only " } else { "" }, expected)?;
+        } else if found < min {
+          write!(f, "Recipe `{}` got {} argument{} but takes at least {}",
+                    recipe, found, maybe_s(found), min)?;
+        } else if found > max {
+          write!(f, "Recipe `{}` got {} argument{} but takes at most {}",
+                    recipe, found, maybe_s(found), max)?;
+        }
+      },
+      Code{recipe, line_number, code} => {
+        if let Some(n) = line_number {
+          write!(f, "Recipe `{}` failed on line {} with exit code {}", recipe, n, code)?;
+        } else {
+          write!(f, "Recipe `{}` failed with exit code {}", recipe, code)?;
+        }
+      },
+      Cygpath{recipe, ref output_error} => match *output_error {
+        OutputError::Code(code) => {
+          write!(f, "Cygpath failed with exit code {} while translating recipe `{}` \
+                     shebang interpreter path", code, recipe)?;
+        }
+        OutputError::Signal(signal) => {
+          write!(f, "Cygpath terminated by signal {} while translating recipe `{}` \
+                     shebang interpreter path", signal, recipe)?;
+        }
+        OutputError::Unknown => {
+          write!(f, "Cygpath experienced an unknown failure while translating recipe `{}` \
+                     shebang interpreter path", recipe)?;
+        }
+        OutputError::Io(ref io_error) => {
+          match io_error.kind() {
+            io::ErrorKind::NotFound => write!(
+              f, "Could not find `cygpath` executable to translate recipe `{}` \
+                  shebang interpreter path:\n{}", recipe, io_error),
+            io::ErrorKind::PermissionDenied => write!(
+              f, "Could not run `cygpath` executable to translate recipe `{}` \
+                  shebang interpreter path:\n{}", recipe, io_error),
+            _ => write!(f, "Could not run `cygpath` executable:\n{}", io_error),
+          }?;
+        }
+        OutputError::Utf8(ref utf8_error) => {
+          write!(f, "Cygpath successfully translated recipe `{}` shebang interpreter path, \
+                     but output was not utf8: {}", recipe, utf8_error)?;
+        }
+      },
+      Shebang{recipe, ref command, ref argument, ref io_error} => {
+        if let Some(ref argument) = *argument {
+          write!(f, "Recipe `{}` with shebang `#!{} {}` execution error: {}",
+                    recipe, command, argument, io_error)?;
+        } else {
+          write!(f, "Recipe `{}` with shebang `#!{}` execution error: {}",
+                    recipe, command, io_error)?;
+        }
+      }
+      Signal{recipe, line_number, signal} => {
+        if let Some(n) = line_number {
+          write!(f, "Recipe `{}` was terminated on line {} by signal {}", recipe, n, signal)?;
+        } else {
+          write!(f, "Recipe `{}` was terminated by signal {}", recipe, signal)?;
+        }
+      }
+      Unknown{recipe, line_number} => {
+        if let Some(n) = line_number {
+          write!(f, "Recipe `{}` failed on line {} for an unknown reason", recipe, n)?;
+        } else {
+        }
+      },
+      IoError{recipe, ref io_error} => {
+        match io_error.kind() {
+          io::ErrorKind::NotFound => write!(f,
+            "Recipe `{}` could not be run because just could not find `sh`:\n{}",
+            recipe, io_error),
+          io::ErrorKind::PermissionDenied => write!(
+            f, "Recipe `{}` could not be run because just could not run `sh`:\n{}",
+            recipe, io_error),
+          _ => write!(f, "Recipe `{}` could not be run because of an IO error while \
+                      launching `sh`:\n{}", recipe, io_error),
+        }?;
+      },
+      TmpdirIoError{recipe, ref io_error} =>
+        write!(f, "Recipe `{}` could not be run because of an IO error while trying \
+                  to create a temporary directory or write a file to that directory`:\n{}",
+                  recipe, io_error)?,
+      Backtick{ref token, ref output_error} => match *output_error {
+        OutputError::Code(code) => {
+          write!(f, "Backtick failed with exit code {}\n", code)?;
+          error_token = Some(token);
+        }
+        OutputError::Signal(signal) => {
+          write!(f, "Backtick was terminated by signal {}", signal)?;
+          error_token = Some(token);
+        }
+        OutputError::Unknown => {
+          write!(f, "Backtick failed for an unknown reason")?;
+          error_token = Some(token);
+        }
+        OutputError::Io(ref io_error) => {
+          match io_error.kind() {
+            io::ErrorKind::NotFound => write!(
+              f, "Backtick could not be run because just could not find `sh`:\n{}",
+              io_error),
+            io::ErrorKind::PermissionDenied => write!(
+              f, "Backtick could not be run because just could not run `sh`:\n{}", io_error),
+            _ => write!(f, "Backtick could not be run because of an IO \
+                            error while launching `sh`:\n{}", io_error),
+          }?;
+          error_token = Some(token);
+        }
+        OutputError::Utf8(ref utf8_error) => {
+          write!(f, "Backtick succeeded but stdout was not utf8: {}", utf8_error)?;
+          error_token = Some(token);
+        }
+      },
+      Internal{ref message} => {
+        write!(f, "Internal error, this may indicate a bug in just: {} \
+                   consider filing an issue: https://github.com/casey/just/issues/new",
+                   message)?;
+      }
+    }
+
+    write!(f, "{}", message.suffix())?;
+
+    if let Some(token) = error_token {
+      write_token_error_context(f, token)?;
+    }
+
+    Ok(())
+  }
+}

src/shebang.rs

@@ -0,0 +1,60 @@
+pub struct Shebang<'a> {
+  pub interpreter: &'a str,
+  pub argument:    Option<&'a str>,
+}
+
+impl<'a> Shebang<'a> {
+  pub fn new(text: &'a str) -> Option<Shebang<'a>> {
+    if !text.starts_with("#!") {
+      return None;
+    }
+
+    let mut pieces = text[2..]
+      .lines()
+      .nth(0)
+      .unwrap_or("")
+      .trim()
+      .splitn(2, |c| c == ' ' || c == '\t');
+
+    let interpreter = pieces.next().unwrap_or("");
+    let argument    = pieces.next();
+
+    if interpreter == "" {
+      return None;
+    }
+
+    Some(Shebang{interpreter, argument})
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::Shebang;
+
+  #[test]
+  fn split_shebang() {
+    fn check(text: &str, expected_split: Option<(&str, Option<&str>)>) {
+      let shebang = Shebang::new(text);
+      assert_eq!(shebang.map(|shebang| (shebang.interpreter, shebang.argument)), expected_split);
+    }
+
+    check("#!    ",                         None                                       );
+    check("#!",                             None                                       );
+    check("#!/bin/bash",                    Some(("/bin/bash",    None               )));
+    check("#!/bin/bash    ",                Some(("/bin/bash",    None               )));
+    check("#!/usr/bin/env python",          Some(("/usr/bin/env", Some("python"     ))));
+    check("#!/usr/bin/env python   ",       Some(("/usr/bin/env", Some("python"     ))));
+    check("#!/usr/bin/env python -x",       Some(("/usr/bin/env", Some("python -x"  ))));
+    check("#!/usr/bin/env python   -x",     Some(("/usr/bin/env", Some("python   -x"))));
+    check("#!/usr/bin/env python \t-x\t",   Some(("/usr/bin/env", Some("python \t-x"))));
+    check("#/usr/bin/env python \t-x\t",    None                                       );
+    check("#!  /bin/bash",                  Some(("/bin/bash",    None               )));
+    check("#!\t\t/bin/bash    ",            Some(("/bin/bash",    None               )));
+    check("#!  \t\t/usr/bin/env python",    Some(("/usr/bin/env", Some("python"     ))));
+    check("#!  /usr/bin/env python   ",     Some(("/usr/bin/env", Some("python"     ))));
+    check("#!  /usr/bin/env python -x",     Some(("/usr/bin/env", Some("python -x"  ))));
+    check("#!  /usr/bin/env python   -x",   Some(("/usr/bin/env", Some("python   -x"))));
+    check("#!  /usr/bin/env python \t-x\t", Some(("/usr/bin/env", Some("python \t-x"))));
+    check("#  /usr/bin/env python \t-x\t",  None                                       );
+  }
+}

src/testing.rs

@@ -0,0 +1,25 @@
+use common::*;
+
+use compile;
+
+pub fn parse_success(text: &str) -> Justfile {
+  match compile(text) {
+    Ok(justfile) => justfile,
+    Err(error) => panic!("Expected successful parse but got error:\n{}", error),
+  }
+}
+
+pub fn parse_error(text: &str, expected: CompilationError) {
+  if let Err(error) = compile(text) {
+    assert_eq!(error.text,   expected.text);
+    assert_eq!(error.index,  expected.index);
+    assert_eq!(error.line,   expected.line);
+    assert_eq!(error.column, expected.column);
+    assert_eq!(error.kind,   expected.kind);
+    assert_eq!(error.width,  expected.width);
+    assert_eq!(error,        expected);
+  } else {
+    panic!("Expected {:?} but parse succeeded", expected.kind);
+  }
+}
+

src/token.rs

@@ -0,0 +1,71 @@
+use common::*;
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct Token<'a> {
+  pub index:  usize,
+  pub line:   usize,
+  pub column: usize,
+  pub text:   &'a str,
+  pub prefix: &'a str,
+  pub lexeme: &'a str,
+  pub kind:   TokenKind,
+}
+
+impl<'a> Token<'a> {
+  pub fn error(&self, kind: CompilationErrorKind<'a>) -> CompilationError<'a> {
+    CompilationError {
+      text:   self.text,
+      index:  self.index + self.prefix.len(),
+      line:   self.line,
+      column: self.column + self.prefix.len(),
+      width:  Some(self.lexeme.len()),
+      kind:   kind,
+    }
+  }
+}
+
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub enum TokenKind {
+  At,
+  Backtick,
+  Colon,
+  Comment,
+  Dedent,
+  Eof,
+  Eol,
+  Equals,
+  Indent,
+  InterpolationEnd,
+  InterpolationStart,
+  Line,
+  Name,
+  Plus,
+  RawString,
+  StringToken,
+  Text,
+}
+
+impl Display for TokenKind {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    use TokenKind::*;
+    write!(f, "{}", match *self {
+      Backtick           => "backtick",
+      Colon              => "':'",
+      Comment            => "comment",
+      Dedent             => "dedent",
+      Eof                => "end of file",
+      Eol                => "end of line",
+      Equals             => "'='",
+      Indent             => "indent",
+      InterpolationEnd   => "'}}'",
+      InterpolationStart => "'{{'",
+      Line               => "command",
+      Name               => "name",
+      Plus               => "'+'",
+      At                 => "'@'",
+      StringToken        => "string",
+      RawString          => "raw string",
+      Text               => "command text",
+    })
+  }
+}

src/tokenizer.rs

@@ -0,0 +1,585 @@
+use common::*;
+
+use TokenKind::*;
+
+fn re(pattern: &str) -> Regex {
+  Regex::new(pattern).unwrap()
+}
+
+fn token(pattern: &str) -> Regex {
+  let mut s = String::new();
+  s += r"^(?m)([ \t]*)(";
+  s += pattern;
+  s += ")";
+  re(&s)
+}
+
+fn mixed_whitespace(text: &str) -> bool {
+  !(text.chars().all(|c| c == ' ') || text.chars().all(|c| c == '\t'))
+}
+
+pub fn tokenize(text: &str) -> Result<Vec<Token>, CompilationError> {
+  lazy_static! {
+    static ref BACKTICK:                  Regex = token(r"`[^`\n\r]*`"               );
+    static ref COLON:                     Regex = token(r":"                         );
+    static ref AT:                        Regex = token(r"@"                         );
+    static ref COMMENT:                   Regex = token(r"#([^!\n\r].*)?$"           );
+    static ref EOF:                       Regex = token(r"(?-m)$"                    );
+    static ref EOL:                       Regex = token(r"\n|\r\n"                   );
+    static ref EQUALS:                    Regex = token(r"="                         );
+    static ref INTERPOLATION_END:         Regex = token(r"[}][}]"                    );
+    static ref INTERPOLATION_START_TOKEN: Regex = token(r"[{][{]"                    );
+    static ref NAME:                      Regex = token(r"([a-zA-Z_][a-zA-Z0-9_-]*)" );
+    static ref PLUS:                      Regex = token(r"[+]"                       );
+    static ref STRING:                    Regex = token("\""                         );
+    static ref RAW_STRING:                Regex = token(r#"'[^']*'"#                 );
+    static ref UNTERMINATED_RAW_STRING:   Regex = token(r#"'[^']*"#                  );
+    static ref INDENT:                    Regex = re(r"^([ \t]*)[^ \t\n\r]"     );
+    static ref INTERPOLATION_START:       Regex = re(r"^[{][{]"                 );
+    static ref LEADING_TEXT:              Regex = re(r"^(?m)(.+?)[{][{]"        );
+    static ref LINE:                      Regex = re(r"^(?m)[ \t]+[^ \t\n\r].*$");
+    static ref TEXT:                      Regex = re(r"^(?m)(.+)"               );
+  }
+
+  #[derive(PartialEq)]
+  enum State<'a> {
+    Start,
+    Indent(&'a str),
+    Text,
+    Interpolation,
+  }
+
+  fn indentation(text: &str) -> Option<&str> {
+    INDENT.captures(text).map(|captures| captures.get(1).unwrap().as_str())
+  }
+
+  let mut tokens = vec![];
+  let mut rest   = text;
+  let mut index  = 0;
+  let mut line   = 0;
+  let mut column = 0;
+  let mut state  = vec![State::Start];
+
+  macro_rules! error {
+    ($kind:expr) => {{
+      Err(CompilationError {
+        text:   text,
+        index:  index,
+        line:   line,
+        column: column,
+        width:  None,
+        kind:   $kind,
+      })
+    }};
+  }
+
+  loop {
+    if column == 0 {
+      if let Some(kind) = match (state.last().unwrap(), indentation(rest)) {
+        // ignore: was no indentation and there still isn't
+        //         or current line is blank
+        (&State::Start, Some("")) | (_, None) => {
+          None
+        }
+        // indent: was no indentation, now there is
+        (&State::Start, Some(current)) => {
+          if mixed_whitespace(current) {
+            return error!(CompilationErrorKind::MixedLeadingWhitespace{whitespace: current})
+          }
+          //indent = Some(current);
+          state.push(State::Indent(current));
+          Some(Indent)
+        }
+        // dedent: there was indentation and now there isn't
+        (&State::Indent(_), Some("")) => {
+          // indent = None;
+          state.pop();
+          Some(Dedent)
+        }
+        // was indentation and still is, check if the new indentation matches
+        (&State::Indent(previous), Some(current)) => {
+          if !current.starts_with(previous) {
+            return error!(CompilationErrorKind::InconsistentLeadingWhitespace{
+              expected: previous,
+              found: current
+            });
+          }
+          None
+        }
+        // at column 0 in some other state: this should never happen
+        (&State::Text, _) | (&State::Interpolation, _) => {
+          return error!(CompilationErrorKind::Internal {
+            message: "unexpected state at column 0".to_string()
+          });
+        }
+      } {
+        tokens.push(Token {
+          index:  index,
+          line:   line,
+          column: column,
+          text:   text,
+          prefix: "",
+          lexeme: "",
+          kind:   kind,
+        });
+      }
+    }
+
+    // insert a dedent if we're indented and we hit the end of the file
+    if &State::Start != state.last().unwrap() && EOF.is_match(rest) {
+      tokens.push(Token {
+        index:  index,
+        line:   line,
+        column: column,
+        text:   text,
+        prefix: "",
+        lexeme: "",
+        kind:   Dedent,
+      });
+    }
+
+    let (prefix, lexeme, kind) =
+    if let (0, &State::Indent(indent), Some(captures)) =
+      (column, state.last().unwrap(), LINE.captures(rest)) {
+      let line = captures.get(0).unwrap().as_str();
+      if !line.starts_with(indent) {
+        return error!(CompilationErrorKind::Internal{message: "unexpected indent".to_string()});
+      }
+      state.push(State::Text);
+      (&line[0..indent.len()], "", Line)
+    } else if let Some(captures) = EOF.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Eof)
+    } else if let State::Text = *state.last().unwrap() {
+      if let Some(captures) = INTERPOLATION_START.captures(rest) {
+        state.push(State::Interpolation);
+        ("", captures.get(0).unwrap().as_str(), InterpolationStart)
+      } else if let Some(captures) = LEADING_TEXT.captures(rest) {
+        ("", captures.get(1).unwrap().as_str(), Text)
+      } else if let Some(captures) = TEXT.captures(rest) {
+        ("", captures.get(1).unwrap().as_str(), Text)
+      } else if let Some(captures) = EOL.captures(rest) {
+        state.pop();
+        (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Eol)
+      } else {
+        return error!(CompilationErrorKind::Internal {
+          message: format!("Could not match token in text state: \"{}\"", rest)
+        });
+      }
+    } else if let Some(captures) = INTERPOLATION_START_TOKEN.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), InterpolationStart)
+    } else if let Some(captures) = INTERPOLATION_END.captures(rest) {
+      if state.last().unwrap() == &State::Interpolation {
+        state.pop();
+      }
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), InterpolationEnd)
+    } else if let Some(captures) = NAME.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Name)
+    } else if let Some(captures) = EOL.captures(rest) {
+      if state.last().unwrap() == &State::Interpolation {
+        return error!(CompilationErrorKind::Internal {
+          message: "hit EOL while still in interpolation state".to_string()
+        });
+      }
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Eol)
+    } else if let Some(captures) = BACKTICK.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Backtick)
+    } else if let Some(captures) = COLON.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Colon)
+    } else if let Some(captures) = AT.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), At)
+    } else if let Some(captures) = PLUS.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Plus)
+    } else if let Some(captures) = EQUALS.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Equals)
+    } else if let Some(captures) = COMMENT.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), Comment)
+    } else if let Some(captures) = RAW_STRING.captures(rest) {
+      (captures.get(1).unwrap().as_str(), captures.get(2).unwrap().as_str(), RawString)
+    } else if UNTERMINATED_RAW_STRING.is_match(rest) {
+      return error!(CompilationErrorKind::UnterminatedString);
+    } else if let Some(captures) = STRING.captures(rest) {
+      let prefix = captures.get(1).unwrap().as_str();
+      let contents = &rest[prefix.len()+1..];
+      if contents.is_empty() {
+        return error!(CompilationErrorKind::UnterminatedString);
+      }
+      let mut len = 0;
+      let mut escape = false;
+      for c in contents.chars() {
+        if c == '\n' || c == '\r' {
+          return error!(CompilationErrorKind::UnterminatedString);
+        } else if !escape && c == '"' {
+          break;
+        } else if !escape && c == '\\' {
+          escape = true;
+        } else if escape {
+          escape = false;
+        }
+        len += c.len_utf8();
+      }
+      let start = prefix.len();
+      let content_end = start + len + 1;
+      if escape || content_end >= rest.len() {
+        return error!(CompilationErrorKind::UnterminatedString);
+      }
+      (prefix, &rest[start..content_end + 1], StringToken)
+    } else if rest.starts_with("#!") {
+      return error!(CompilationErrorKind::OuterShebang)
+    } else {
+      return error!(CompilationErrorKind::UnknownStartOfToken)
+    };
+
+    tokens.push(Token {
+      index:  index,
+      line:   line,
+      column: column,
+      prefix: prefix,
+      text:   text,
+      lexeme: lexeme,
+      kind:   kind,
+    });
+
+    let len = prefix.len() + lexeme.len();
+
+    if len == 0 {
+      let last = tokens.last().unwrap();
+      match last.kind {
+        Eof => {},
+        _ => return Err(last.error(CompilationErrorKind::Internal {
+          message: format!("zero length token: {:?}", last)
+        })),
+      }
+    }
+
+    match tokens.last().unwrap().kind {
+      Eol => {
+        line += 1;
+        column = 0;
+      }
+      Eof => {
+        break;
+      }
+      RawString => {
+        let lexeme_lines = lexeme.lines().count();
+        line += lexeme_lines - 1;
+        if lexeme_lines == 1 {
+          column += len;
+        } else {
+          column = lexeme.lines().last().unwrap().len();
+        }
+      }
+      _ => {
+        column += len;
+      }
+    }
+
+    rest = &rest[len..];
+    index += len;
+  }
+
+  Ok(tokens)
+}
+
+#[cfg(test)]
+mod test {  
+  use super::*;
+  use testing::parse_error;
+
+  fn tokenize_success(text: &str, expected_summary: &str) {
+    let tokens = tokenize(text).unwrap();
+    let roundtrip = tokens.iter().map(|t| {
+      let mut s = String::new();
+      s += t.prefix;
+      s += t.lexeme;
+      s
+    }).collect::<Vec<_>>().join("");
+    let summary = token_summary(&tokens);
+    if summary != expected_summary {
+      panic!("token summary mismatch:\nexpected: {}\ngot:      {}\n", expected_summary, summary);
+    }
+    assert_eq!(text, roundtrip);
+  }
+
+  fn tokenize_error(text: &str, expected: CompilationError) {
+    if let Err(error) = tokenize(text) {
+      assert_eq!(error.text,   expected.text);
+      assert_eq!(error.index,  expected.index);
+      assert_eq!(error.line,   expected.line);
+      assert_eq!(error.column, expected.column);
+      assert_eq!(error.kind,   expected.kind);
+      assert_eq!(error,        expected);
+    } else {
+      panic!("tokenize() succeeded but expected: {}\n{}", expected, text);
+    }
+  }
+
+  fn token_summary(tokens: &[Token]) -> String {
+    tokens.iter().map(|t| {
+      match t.kind {
+        At                 => "@",
+        Backtick           => "`",
+        Colon              => ":",
+        Comment{..}        => "#",
+        Dedent             => "<",
+        Eof                => ".",
+        Eol                => "$",
+        Equals             => "=",
+        Indent{..}         => ">",
+        InterpolationEnd   => "}",
+        InterpolationStart => "{",
+        Line{..}           => "^",
+        Name               => "N",
+        Plus               => "+",
+        RawString          => "'",
+        StringToken        => "\"",
+        Text               => "_",
+      }
+    }).collect::<Vec<_>>().join("")
+  }
+
+#[test]
+fn tokanize_strings() {
+  tokenize_success(
+    r#"a = "'a'" + '"b"' + "'c'" + '"d"'#echo hello"#,
+    r#"N="+'+"+'#."#
+  );
+}
+
+#[test]
+fn tokenize_recipe_interpolation_eol() {
+  let text = "foo: # some comment
+ {{hello}}
+";
+  tokenize_success(text, "N:#$>^{N}$<.");
+}
+
+#[test]
+fn tokenize_recipe_interpolation_eof() {
+  let text = "foo: # more comments
+ {{hello}}
+# another comment
+";
+  tokenize_success(text, "N:#$>^{N}$<#$.");
+}
+
+#[test]
+fn tokenize_recipe_complex_interpolation_expression() {
+  let text = "foo: #lol\n {{a + b + \"z\" + blarg}}";
+  tokenize_success(text, "N:#$>^{N+N+\"+N}<.");
+}
+
+#[test]
+fn tokenize_recipe_multiple_interpolations() {
+  let text = "foo:#ok\n {{a}}0{{b}}1{{c}}";
+  tokenize_success(text, "N:#$>^{N}_{N}_{N}<.");
+}
+
+#[test]
+fn tokenize_junk() {
+  let text = "bob
+
+hello blah blah blah : a b c #whatever
+";
+  tokenize_success(text, "N$$NNNN:NNN#$.");
+}
+
+#[test]
+fn tokenize_empty_lines() {
+  let text = "
+# this does something
+hello:
+  asdf
+  bsdf
+
+  csdf
+
+  dsdf # whatever
+
+# yolo
+  ";
+
+  tokenize_success(text, "$#$N:$>^_$^_$$^_$$^_$$<#$.");
+}
+
+#[test]
+fn tokenize_comment_before_variable() {
+  let text = "
+#
+A='1'
+echo:
+  echo {{A}}
+  ";
+  tokenize_success(text, "$#$N='$N:$>^_{N}$<.");
+}
+
+#[test]
+fn tokenize_interpolation_backticks() {
+  tokenize_success(
+    "hello:\n echo {{`echo hello` + `echo goodbye`}}",
+    "N:$>^_{`+`}<."
+  );
+}
+
+#[test]
+fn tokenize_assignment_backticks() {
+  tokenize_success(
+    "a = `echo hello` + `echo goodbye`",
+    "N=`+`."
+  );
+}
+
+#[test]
+fn tokenize_multiple() {
+  let text = "
+hello:
+  a
+  b
+
+  c
+
+  d
+
+# hello
+bob:
+  frank
+  ";
+
+  tokenize_success(text, "$N:$>^_$^_$$^_$$^_$$<#$N:$>^_$<.");
+}
+
+
+#[test]
+fn tokenize_comment() {
+  tokenize_success("a:=#", "N:=#.")
+}
+
+#[test]
+fn tokenize_space_then_tab() {
+  let text = "a:
+ 0
+ 1
+\t2
+";
+  tokenize_error(text, CompilationError {
+    text:   text,
+    index:  9,
+    line:   3,
+    column: 0,
+    width:  None,
+    kind:   CompilationErrorKind::InconsistentLeadingWhitespace{expected: " ", found: "\t"},
+  });
+}
+
+#[test]
+fn tokenize_tabs_then_tab_space() {
+  let text = "a:
+\t\t0
+\t\t 1
+\t  2
+";
+  tokenize_error(text, CompilationError {
+    text:   text,
+    index:  12,
+    line:   3,
+    column: 0,
+    width:  None,
+    kind:   CompilationErrorKind::InconsistentLeadingWhitespace{expected: "\t\t", found: "\t  "},
+  });
+}
+
+#[test]
+fn tokenize_outer_shebang() {
+  let text = "#!/usr/bin/env bash";
+  tokenize_error(text, CompilationError {
+    text:   text,
+    index:  0,
+    line:   0,
+    column: 0,
+    width:  None,
+    kind:   CompilationErrorKind::OuterShebang
+  });
+}
+
+#[test]
+fn tokenize_unknown() {
+  let text = "~";
+  tokenize_error(text, CompilationError {
+    text:   text,
+    index:  0,
+    line:   0,
+    column: 0,
+    width:  None,
+    kind:   CompilationErrorKind::UnknownStartOfToken
+  });
+}
+#[test]
+fn tokenize_order() {
+  let text = r"
+b: a
+  @mv a b
+
+a:
+  @touch F
+  @touch a
+
+d: c
+  @rm c
+
+c: b
+  @mv b c";
+  tokenize_success(text, "$N:N$>^_$$<N:$>^_$^_$$<N:N$>^_$$<N:N$>^_<.");
+}
+
+#[test]
+fn unterminated_string() {
+  let text = r#"a = ""#;
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  3,
+    line:   0,
+    column: 3,
+    width:  None,
+    kind:   CompilationErrorKind::UnterminatedString,
+  });
+}
+
+#[test]
+fn unterminated_string_with_escapes() {
+  let text = r#"a = "\n\t\r\"\\"#;
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  3,
+    line:   0,
+    column: 3,
+    width:  None,
+    kind:   CompilationErrorKind::UnterminatedString,
+  });
+}
+#[test]
+fn unterminated_raw_string() {
+  let text = "r a='asdf";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  4,
+    line:   0,
+    column: 4,
+    width:  None,
+    kind:   CompilationErrorKind::UnterminatedString,
+  });
+}
+
+
+#[test]
+fn mixed_leading_whitespace() {
+  let text = "a:\n\t echo hello";
+  parse_error(text, CompilationError {
+    text:   text,
+    index:  3,
+    line:   1,
+    column: 0,
+    width:  None,
+    kind:   CompilationErrorKind::MixedLeadingWhitespace{whitespace: "\t "}
+  });
+}
+
+}

tests/integration.rs

@@ -1,9 +1,14 @@
 extern crate tempdir;
 extern crate brev;
+extern crate libc;
+extern crate utilities;
 
-use ::prelude::*;
-use tempdir::TempDir;
+use libc::{EXIT_FAILURE, EXIT_SUCCESS};
+use std::env;
+use std::process;
 use std::str;
+use tempdir::TempDir;
+use utilities::just_binary_path;
 
 /// Instantiate integration tests for a given test case using
 /// sh, dash, and bash.
@@ -22,8 +27,7 @@ macro_rules! integration_test {
     status:   $status:expr,
   ) => {
     mod $name {
-      use ::prelude::*;
-      use super::integration_test;
+      use super::*;
 
       // silence unused import warnings
       const __: i32 = EXIT_SUCCESS;
@@ -50,7 +54,7 @@ fn integration_test(
   path.push("justfile");
   brev::dump(path, justfile);
 
-  let output = process::Command::new(&super::test_utils::just_binary_path())
+  let output = process::Command::new(&just_binary_path())
     .current_dir(tmp.path())
     .args(&["--shell", shell])
     .args(args)

tests/search.rs

@@ -1,10 +1,13 @@
-use ::prelude::*;
+extern crate utilities;
+extern crate brev;
+extern crate tempdir;
+
+use utilities::just_binary_path;
 use tempdir::TempDir;
-use std::{path, str};
-use super::brev;
+use std::{path, str, fs, process};
 
 fn search_test<P: AsRef<path::Path>>(path: P, args: &[&str]) {
-  let binary = super::test_utils::just_binary_path();
+  let binary = just_binary_path();
 
   let output = process::Command::new(binary)
     .current_dir(path)

utilities/Cargo.toml

@@ -0,0 +1,5 @@
+[package]
+name    = "utilities"
+version = "0.0.0"
+authors = ["Casey Rodarmor <casey@rodarmor.com>"]
+publish = false

utilities/src/lib.rs

@@ -1,4 +1,5 @@
-use ::prelude::*;
+use std::env;
+use std::path::PathBuf;
 
 pub fn just_binary_path() -> PathBuf {
   let mut path = env::current_exe().unwrap();
@@ -10,3 +11,4 @@ pub fn just_binary_path() -> PathBuf {
   path.push(exe);
   path
 }
+