deno/cli/fmt_errors.rs

// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
//! This mod provides DenoError to unify errors across Deno.
use crate::colors;
use deno_core::error::{AnyError, JsError, JsStackFrame};
use std::error::Error;
use std::fmt;
use std::ops::Deref;

const SOURCE_ABBREV_THRESHOLD: usize = 150;

fn default_color(s: &str, internal: bool) -> String {
  if internal {
    colors::gray(s).to_string()
  } else {
    s.to_string()
  }
}

fn cyan(s: &str, internal: bool) -> String {
  if internal {
    colors::gray(s).to_string()
  } else {
    colors::cyan(s).to_string()
  }
}

fn yellow(s: &str, internal: bool) -> String {
  if internal {
    colors::gray(s).to_string()
  } else {
    colors::yellow(s).to_string()
  }
}

fn italic_bold(s: &str, internal: bool) -> String {
  if internal {
    colors::italic_bold_gray(s).to_string()
  } else {
    colors::italic_bold(s).to_string()
  }
}

// Keep in sync with `runtime/js/40_error_stack.js`.
pub fn format_location(frame: &JsStackFrame) -> String {
  let internal = frame
    .file_name
    .as_ref()
    .map_or(false, |f| f.starts_with("deno:"));
  if frame.is_native {
    return cyan("native", internal);
  }
  let mut result = String::new();
  if let Some(file_name) = &frame.file_name {
    result += &cyan(&file_name, internal);
  } else {
    if frame.is_eval {
      result += &(cyan(&frame.eval_origin.as_ref().unwrap(), internal) + ", ");
    }
    result += &cyan("<anonymous>", internal);
  }
  if let Some(line_number) = frame.line_number {
    result += &format!(
      "{}{}",
      default_color(":", internal),
      yellow(&line_number.to_string(), internal)
    );
    if let Some(column_number) = frame.column_number {
      result += &format!(
        "{}{}",
        default_color(":", internal),
        yellow(&column_number.to_string(), internal)
      );
    }
  }
  result
}

// Keep in sync with `runtime/js/40_error_stack.js`.
fn format_frame(frame: &JsStackFrame) -> String {
  let internal = frame
    .file_name
    .as_ref()
    .map_or(false, |f| f.starts_with("deno:"));
  let is_method_call =
    !(frame.is_top_level.unwrap_or_default() || frame.is_constructor);
  let mut result = String::new();
  if frame.is_async {
    result += &colors::gray("async ").to_string();
  }
  if frame.is_promise_all {
    result += &italic_bold(
      &format!(
        "Promise.all (index {})",
        frame.promise_index.unwrap_or_default().to_string()
      ),
      internal,
    );
    return result;
  }
  if is_method_call {
    let mut formatted_method = String::new();
    if let Some(function_name) = &frame.function_name {
      if let Some(type_name) = &frame.type_name {
        if !function_name.starts_with(type_name) {
          formatted_method += &format!("{}.", type_name);
        }
      }
      formatted_method += &function_name;
      if let Some(method_name) = &frame.method_name {
        if !function_name.ends_with(method_name) {
          formatted_method += &format!(" [as {}]", method_name);
        }
      }
    } else {
      if let Some(type_name) = &frame.type_name {
        formatted_method += &format!("{}.", type_name);
      }
      if let Some(method_name) = &frame.method_name {
        formatted_method += &method_name
      } else {
        formatted_method += "<anonymous>";
      }
    }
    result += &italic_bold(&formatted_method, internal);
  } else if frame.is_constructor {
    result += &colors::gray("new ").to_string();
    if let Some(function_name) = &frame.function_name {
      result += &italic_bold(&function_name, internal);
    } else {
      result += &cyan("<anonymous>", internal);
    }
  } else if let Some(function_name) = &frame.function_name {
    result += &italic_bold(&function_name, internal);
  } else {
    result += &format_location(frame);
    return result;
  }
  result += &format!(
    " {}{}{}",
    default_color("(", internal),
    format_location(frame),
    default_color(")", internal)
  );
  result
}

fn format_stack(
  is_error: bool,
  message_line: &str,
  source_line: Option<&str>,
  start_column: Option<i64>,
  end_column: Option<i64>,
  frames: &[JsStackFrame],
  level: usize,
) -> String {
  let mut s = String::new();
  s.push_str(&format!("{:indent$}{}", "", message_line, indent = level));
  s.push_str(&format_maybe_source_line(
    source_line,
    start_column,
    end_column,
    is_error,
    level,
  ));
  for frame in frames {
    s.push_str(&format!(
      "\n{:indent$}    at {}",
      "",
      format_frame(frame),
      indent = level
    ));
  }
  s
}

/// Take an optional source line and associated information to format it into
/// a pretty printed version of that line.
fn format_maybe_source_line(
  source_line: Option<&str>,
  start_column: Option<i64>,
  end_column: Option<i64>,
  is_error: bool,
  level: usize,
) -> String {
  if source_line.is_none() || start_column.is_none() || end_column.is_none() {
    return "".to_string();
  }

  let source_line = source_line.unwrap();
  // sometimes source_line gets set with an empty string, which then outputs
  // an empty source line when displayed, so need just short circuit here.
  // Also short-circuit on error line too long.
  if source_line.is_empty() || source_line.len() > SOURCE_ABBREV_THRESHOLD {
    return "".to_string();
  }

  assert!(start_column.is_some());
  assert!(end_column.is_some());
  let mut s = String::new();
  let start_column = start_column.unwrap();
  let end_column = end_column.unwrap();
  // TypeScript uses `~` always, but V8 would utilise `^` always, even when
  // doing ranges, so here, if we only have one marker (very common with V8
  // errors) we will use `^` instead.
  let underline_char = if (end_column - start_column) <= 1 {
    '^'
  } else {
    '~'
  };
  for _i in 0..start_column {
    if source_line.chars().nth(_i as usize).unwrap() == '\t' {
      s.push('\t');
    } else {
      s.push(' ');
    }
  }
  for _i in 0..(end_column - start_column) {
    s.push(underline_char);
  }
  let color_underline = if is_error {
    colors::red(&s).to_string()
  } else {
    colors::cyan(&s).to_string()
  };

  let indent = format!("{:indent$}", "", indent = level);

  format!("\n{}{}\n{}{}", indent, source_line, indent, color_underline)
}

/// Wrapper around deno_core::JsError which provides colorful
/// string representation.
#[derive(Debug)]
pub struct PrettyJsError(JsError);

impl PrettyJsError {
  pub fn create(js_error: JsError) -> AnyError {
    let pretty_js_error = Self(js_error);
    pretty_js_error.into()
  }
}

impl Deref for PrettyJsError {
  type Target = JsError;
  fn deref(&self) -> &Self::Target {
    &self.0
  }
}

impl fmt::Display for PrettyJsError {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    let mut frames = self.0.frames.clone();

    // When the stack frame array is empty, but the source location given by
    // (script_resource_name, line_number, start_column + 1) exists, this is
    // likely a syntax error. For the sake of formatting we treat it like it was
    // given as a single stack frame.
    if frames.is_empty()
      && self.0.script_resource_name.is_some()
      && self.0.line_number.is_some()
      && self.0.start_column.is_some()
    {
      frames = vec![JsStackFrame::from_location(
        self.0.script_resource_name.clone(),
        self.0.line_number,
        self.0.start_column.map(|n| n + 1),
      )];
    }

    write!(
      f,
      "{}",
      &format_stack(
        true,
        &self.0.message,
        self.0.source_line.as_deref(),
        self.0.start_column,
        self.0.end_column,
        &frames,
        0
      )
    )?;
    Ok(())
  }
}

impl Error for PrettyJsError {}

#[cfg(test)]
mod tests {
  use super::*;
  use crate::colors::strip_ansi_codes;

  #[test]
  fn test_format_none_source_line() {
    let actual = format_maybe_source_line(None, None, None, false, 0);
    assert_eq!(actual, "");
  }

  #[test]
  fn test_format_some_source_line() {
    let actual = format_maybe_source_line(
      Some("console.log('foo');"),
      Some(8),
      Some(11),
      true,
      0,
    );
    assert_eq!(
      strip_ansi_codes(&actual),
      "\nconsole.log(\'foo\');\n        ~~~"
    );
  }
}