Refactors ungron main, updates help and readme

README.mkd

@@ -79,6 +79,53 @@ The output of `gron` is valid JavaScript:
   name: 'Tom' }
 ```
 
+## ungronning
+gron can also turn its output back into JSON:
+```
+▶ gron testdata/two.json | gron -u
+{
+  "contact": {
+    "email": "mail@tomnomnom.com",
+    "twitter": "@TomNomNom"
+  },
+  "github": "https://github.com/tomnomnom/",
+  "likes": [
+    "code",
+    "cheese",
+    "meat"
+  ],
+  "name": "Tom"
+}
+```
+
+This means use can use gron with `grep` and other tools to modify JSON:
+```
+▶ gron testdata/two.json | grep likes | gron --ungron
+{
+  "likes": [
+    "code",
+    "cheese",
+    "meat"
+  ]
+}
+```
+
+To preserve array keys, arrays are padded with `null` when values are missing:
+```
+▶ gron testdata/two.json | grep likes | grep -v cheese
+json.likes = [];
+json.likes[0] = "code";
+json.likes[2] = "meat";
+▶ gron testdata/two.json | grep likes | grep -v cheese | gron --ungron
+{
+  "likes": [
+    "code",
+    null,
+    "meat"
+  ]
+}
+```
+
 ## Get Help
 
 ```
@@ -86,20 +133,26 @@ The output of `gron` is valid JavaScript:
 Transform JSON (from a file, URL, or stdin) into discrete assignments to make it greppable
 
 Usage:
-  gron [file|url]
+  gron [OPTIONS] [FILE|URL|-]
+
+Options:
+  -u, --ungron	Reverse the operation (turn assignments back into JSON)
 
 Exit Codes:
   0	OK
   1	Failed to open file
   2	Failed to read input
   3	Failed to decode JSON
-  4	Failed to from statements
+  4	Failed to form statements
   5	Failed to fetch URL
+  6	Failed to parse statements
+  7	Failed to encode JSON
 
 Examples:
   gron /tmp/apiresponse.json
-  gron http://headers.jsontest.com/ 
-  curl -s http://headers.jsontest.com/ | gron
+  gron http://jsonplaceholder.typicode.com/users/1 
+  curl -s http://jsonplaceholder.typicode.com/users/1 | gron
+  gron http://jsonplaceholder.typicode.com/users/1 | grep company | gron --ungron
 ```
 
 ## FAQ

main.go

@@ -18,7 +18,8 @@ const (
 	exitJSONDecode
 	exitFormStatements
 	exitFetchURL
-	exitUnknown
+	exitParseStatements
+	exitJSONEncode
 )
 
 func init() {
@@ -26,28 +27,38 @@ func init() {
 		h := "Transform JSON (from a file, URL, or stdin) into discrete assignments to make it greppable\n\n"
 
 		h += "Usage:\n"
-		h += "  gron [file|url]\n\n"
+		h += "  gron [OPTIONS] [FILE|URL|-]\n\n"
+
+		h += "Options:\n"
+		h += "  -u, --ungron\tReverse the operation (turn assignments back into JSON)\n\n"
 
 		h += "Exit Codes:\n"
 		h += fmt.Sprintf("  %d\t%s\n", exitOK, "OK")
 		h += fmt.Sprintf("  %d\t%s\n", exitOpenFile, "Failed to open file")
 		h += fmt.Sprintf("  %d\t%s\n", exitReadInput, "Failed to read input")
 		h += fmt.Sprintf("  %d\t%s\n", exitJSONDecode, "Failed to decode JSON")
-		h += fmt.Sprintf("  %d\t%s\n", exitFormStatements, "Failed to from statements")
+		h += fmt.Sprintf("  %d\t%s\n", exitFormStatements, "Failed to form statements")
 		h += fmt.Sprintf("  %d\t%s\n", exitFetchURL, "Failed to fetch URL")
+		h += fmt.Sprintf("  %d\t%s\n", exitParseStatements, "Failed to parse statements")
+		h += fmt.Sprintf("  %d\t%s\n", exitJSONEncode, "Failed to encode JSON")
 		h += "\n"
 
 		h += "Examples:\n"
 		h += "  gron /tmp/apiresponse.json\n"
-		h += "  gron http://headers.jsontest.com/ \n"
-		h += "  curl -s http://headers.jsontest.com/ | gron\n"
+		h += "  gron http://jsonplaceholder.typicode.com/users/1 \n"
+		h += "  curl -s http://jsonplaceholder.typicode.com/users/1 | gron\n"
+		h += "  gron http://jsonplaceholder.typicode.com/users/1 | grep company | gron --ungron\n"
 
 		fmt.Fprintf(os.Stderr, h)
 	}
 }
 
+var ungronFlag bool
+
 func main() {
-	ungronFlag := flag.Bool("ungron", false, "Turn statements into JSON instead")
+	flag.BoolVar(&ungronFlag, "ungron", false, "Turn statements into JSON instead")
+	flag.BoolVar(&ungronFlag, "u", false, "Turn statements into JSON instead")
+
 	flag.Parse()
 
 	var raw io.Reader
@@ -73,7 +84,7 @@ func main() {
 
 	var exitCode int
 	var err error
-	if *ungronFlag {
+	if ungronFlag {
 		exitCode, err = ungron(raw, os.Stdout)
 	} else {
 		exitCode, err = gron(raw, os.Stdout)
@@ -121,31 +132,19 @@ func gron(r io.Reader, w io.Writer) (int, error) {
 func ungron(r io.Reader, w io.Writer) (int, error) {
 	scanner := bufio.NewScanner(r)
 
-	// Get all the idividually parsed statements
-	var parsed []interface{}
+	// Make a list of statements from the input
+	var ss statements
 	for scanner.Scan() {
-		l := newLexer(scanner.Text())
-		u, err := ungronTokens(l.lex())
-
-		if err != nil {
-			return exitUnknown, fmt.Errorf("failed to translate tokens into datastructure: %s", err)
-		}
-
-		parsed = append(parsed, u)
+		ss.AddFull(scanner.Text())
 	}
-	// TODO: Handle any scanner errors
-
-	if len(parsed) == 0 {
-		return exitUnknown, fmt.Errorf("no statements were parsed")
+	if err := scanner.Err(); err != nil {
+		return exitReadInput, fmt.Errorf("failed to read input statements")
 	}
 
-	merged := parsed[0]
-	for _, p := range parsed[1:] {
-		m, err := recursiveMerge(merged, p)
-		if err != nil {
-			return exitUnknown, fmt.Errorf("failed to merge statements: %s", err)
-		}
-		merged = m
+	// ungron the statements
+	merged, err := ss.ungron()
+	if err != nil {
+		return exitParseStatements, fmt.Errorf("failed to parse input statements")
 	}
 
 	// If there's only one top level key and it's "json", make that the top level thing
@@ -160,7 +159,7 @@ func ungron(r io.Reader, w io.Writer) (int, error) {
 
 	j, err := json.MarshalIndent(merged, "", "  ")
 	if err != nil {
-		return exitUnknown, fmt.Errorf("failed to convert statements to JSON: %s", err)
+		return exitJSONEncode, fmt.Errorf("failed to convert statements to JSON: %s", err)
 	}
 
 	fmt.Fprintf(w, "%s\n", j)

statements.go

@@ -17,6 +17,11 @@ func (ss *statements) Add(prefix, value string) {
 	*ss = append(*ss, fmt.Sprintf("%s = %s;", prefix, value))
 }
 
+// AddFull adds a new statement to the list given the entire statement
+func (ss *statements) AddFull(s string) {
+	*ss = append(*ss, s)
+}
+
 // AddMulti adds a whole other list of statements
 func (ss *statements) AddMulti(l statements) {
 	*ss = append(*ss, l...)
@@ -32,6 +37,38 @@ func (ss statements) Swap(i, j int) {
 	ss[i], ss[j] = ss[j], ss[i]
 }
 
+// ungron turns statements into a proper datastructur
+func (ss statements) ungron() (interface{}, error) {
+
+	// Get all the idividually parsed statements
+	var parsed []interface{}
+	for _, s := range ss {
+		l := newLexer(s)
+		u, err := ungronTokens(l.lex())
+
+		if err != nil {
+			return nil, fmt.Errorf("failed to translate tokens into datastructure: %s", err)
+		}
+
+		parsed = append(parsed, u)
+	}
+
+	if len(parsed) == 0 {
+		return nil, fmt.Errorf("no statements were parsed")
+	}
+
+	merged := parsed[0]
+	for _, p := range parsed[1:] {
+		m, err := recursiveMerge(merged, p)
+		if err != nil {
+			return nil, fmt.Errorf("failed to merge statements: %s", err)
+		}
+		merged = m
+	}
+	return merged, nil
+
+}
+
 // Less compares two statements for sort.Sort
 // Implements a natural sort to keep array indexes in order
 func (ss statements) Less(a, b int) bool {

statements_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"reflect"
 	"sort"
 	"testing"
 )
@@ -291,3 +292,40 @@ func BenchmarkMakePrefixInt(b *testing.B) {
 		_, _ = makePrefix("json", 212)
 	}
 }
+
+func TestUngronStatements(t *testing.T) {
+	in := statements{
+		`json.contact = {};`,
+		`json.contact["e-mail"][0] = "mail@tomnomnom.com";`,
+		`json.contact["e-mail"][1] = "test@tomnomnom.com";`,
+		`json.contact["e-mail"][3] = "foo@tomnomnom.com";`,
+		`json.contact.twitter = "@TomNomNom";`,
+	}
+
+	want := map[string]interface{}{
+		"json": map[string]interface{}{
+			"contact": map[string]interface{}{
+				"e-mail": []interface{}{
+					0: "mail@tomnomnom.com",
+					1: "test@tomnomnom.com",
+					3: "foo@tomnomnom.com",
+				},
+				"twitter": "@TomNomNom",
+			},
+		},
+	}
+
+	have, err := in.ungron()
+
+	if err != nil {
+		t.Fatalf("want nil error but have: %s", err)
+	}
+
+	t.Logf("Have: %#v", have)
+	t.Logf("Want: %#v", want)
+
+	eq := reflect.DeepEqual(have, want)
+	if !eq {
+		t.Errorf("have and want are not equal")
+	}
+}

url.go

@@ -18,7 +18,7 @@ func getURL(url string) (io.Reader, error) {
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Set("User-Agent", "gron/0.1")
+	req.Header.Set("User-Agent", "gron/0.2")
 	req.Header.Set("Accept", "application/json")
 
 	resp, err := client.Do(req)