Adding support for json-like output

Author: yazgazan

config.go

@@ -29,6 +29,7 @@ type output struct {
 	Indent    string `long:"indent" description:"indent string" default:"\t"`
 	ShowTypes bool   `long:"show-types" short:"t" description:"show types"`
 	Colorized bool
+	JSON      bool `long:"json" description:"json-style output"`
 }
 
 func readConfig() config {
@@ -47,6 +48,15 @@ func readConfig() config {
 		os.Exit(statusUsage)
 	}
 
+	if c.JSON && c.ShowTypes {
+		fmt.Fprintf(os.Stderr, "Incompatible options --json and --show-types\n")
+		os.Exit(statusUsage)
+	}
+	if c.JSON && c.OutputReport {
+		fmt.Fprintf(os.Stderr, "Incompatible options --json and --report\n")
+		os.Exit(statusUsage)
+	}
+
 	c.output.Colorized = terminal.IsTerminal(int(os.Stdout.Fd()))
 
 	return c

diff/map.go

@@ -147,10 +147,10 @@ func (m mapDiff) StringIndent(keyprefix, prefix string, conf Output) string {
 	case Identical:
 		return "  " + prefix + keyprefix + conf.white(m.lhs)
 	case TypesDiffer:
-		return "-" + prefix + keyprefix + conf.red(m.lhs) + "\n" +
+		return "-" + prefix + keyprefix + conf.red(m.lhs) + newLineSeparatorString(conf) +
 			"+" + prefix + keyprefix + conf.green(m.rhs)
 	case ContentDiffer:
-		var ss = []string{" " + prefix + keyprefix + conf.typ(m.lhs) + "map["}
+		var ss = []string{}
 		var keys []interface{}
 
 		for key := range m.diffs {
@@ -164,19 +164,45 @@ func (m mapDiff) StringIndent(keyprefix, prefix string, conf Output) string {
 		for _, key := range keys {
 			d := m.diffs[key]
 
-			keyStr := fmt.Sprintf("%v: ", key)
+			keyStr := m.mapKeyString(key, conf)
 			s := d.StringIndent(keyStr, prefix+conf.Indent, conf)
 			if s != "" {
 				ss = append(ss, s)
 			}
 		}
 
-		return strings.Join(append(ss, " "+prefix+"]"), "\n")
+		return strings.Join([]string{
+			m.openString(keyprefix, prefix, conf),
+			strings.Join(ss, newLineSeparatorString(conf)),
+			m.closeString(prefix, conf),
+		}, "\n")
 	}
 
 	return ""
 }
 
+func (m mapDiff) openString(keyprefix, prefix string, conf Output) string {
+	if conf.JSON {
+		return " " + prefix + keyprefix + "{"
+	}
+	return " " + prefix + keyprefix + conf.typ(m.lhs) + "map["
+}
+
+func (m mapDiff) closeString(prefix string, conf Output) string {
+	if conf.JSON {
+		return " " + prefix + "}"
+	}
+	return " " + prefix + "]"
+}
+
+func (m mapDiff) mapKeyString(key interface{}, conf Output) string {
+	if conf.JSON {
+		return fmt.Sprintf("%q: ", key)
+	}
+
+	return fmt.Sprintf("%v: ", key)
+}
+
 func (m mapDiff) Walk(path string, fn WalkFn) error {
 	var keys []interface{}
 

diff/output.go

@@ -1,6 +1,7 @@
 package diff
 
 import (
+	"encoding/json"
 	"fmt"
 
 	"github.com/fatih/color"
@@ -11,13 +12,16 @@ type Output struct {
 	Indent    string
 	ShowTypes bool
 	Colorized bool
+	JSON      bool
 }
 
 func (o Output) red(v interface{}) string {
 	var s string
 
 	if o.ShowTypes {
 		s = fmt.Sprintf("%T %v", v, v)
+	} else if o.JSON {
+		s = jsonString(v)
 	} else {
 		s = fmt.Sprintf("%v", v)
 	}
@@ -34,6 +38,8 @@ func (o Output) green(v interface{}) string {
 
 	if o.ShowTypes {
 		s = fmt.Sprintf("%T %v", v, v)
+	} else if o.JSON {
+		s = jsonString(v)
 	} else {
 		s = fmt.Sprintf("%v", v)
 	}
@@ -50,6 +56,8 @@ func (o Output) white(v interface{}) string {
 
 	if o.ShowTypes {
 		s = fmt.Sprintf("%T %v", v, v)
+	} else if o.JSON {
+		s = jsonString(v)
 	} else {
 		s = fmt.Sprintf("%v", v)
 	}
@@ -64,3 +72,20 @@ func (o Output) typ(v interface{}) string {
 
 	return ""
 }
+
+func newLineSeparatorString(conf Output) string {
+	if conf.JSON {
+		return ",\n"
+	}
+
+	return "\n"
+}
+
+func jsonString(v interface{}) string {
+	b, err := json.Marshal(v)
+	if err != nil {
+		panic(fmt.Errorf("unexpected error marshaling value: %s", err))
+	}
+
+	return string(b)
+}

diff/scalar.go

@@ -42,7 +42,7 @@ func (s scalar) StringIndent(key, prefix string, conf Output) string {
 		return " " + prefix + key + conf.white(s.lhs)
 	}
 
-	return "-" + prefix + key + conf.red(s.lhs) + "\n" +
+	return "-" + prefix + key + conf.red(s.lhs) + newLineSeparatorString(conf) +
 		"+" + prefix + key + conf.green(s.rhs)
 }
 

diff/slice.go

@@ -213,10 +213,10 @@ func (s slice) StringIndent(key, prefix string, conf Output) string {
 	case Identical:
 		return " " + prefix + key + conf.white(s.lhs)
 	case TypesDiffer:
-		return "-" + prefix + key + conf.red(s.lhs) + "\n" +
+		return "-" + prefix + key + conf.red(s.lhs) + newLineSeparatorString(conf) +
 			"+" + prefix + key + conf.green(s.rhs)
 	case ContentDiffer:
-		var ss = []string{" " + prefix + key + conf.typ(s.lhs) + "["}
+		var ss = []string{}
 
 		for _, d := range s.diffs {
 			s := d.StringIndent("", prefix+conf.Indent, conf)
@@ -225,12 +225,26 @@ func (s slice) StringIndent(key, prefix string, conf Output) string {
 			}
 		}
 
-		return strings.Join(append(ss, " "+prefix+"]"), "\n")
+		return strings.Join(
+			[]string{
+				s.openString(key, prefix, conf),
+				strings.Join(ss, newLineSeparatorString(conf)),
+				" " + prefix + "]",
+			}, "\n",
+		)
 	}
 
 	return ""
 }
 
+func (s slice) openString(key, prefix string, conf Output) string {
+	if conf.JSON {
+		return " " + prefix + key + "["
+	}
+
+	return " " + prefix + key + conf.typ(s.lhs) + "["
+}
+
 func (s slice) Walk(path string, fn WalkFn) error {
 	for i, diff := range s.diffs {
 		d, err := walk(s, diff, path+"[]", fn)

diff/types.go

@@ -21,7 +21,7 @@ func (t types) Strings() []string {
 }
 
 func (t types) StringIndent(key, prefix string, conf Output) string {
-	return "-" + prefix + key + conf.red(t.lhs) + "\n" +
+	return "-" + prefix + key + conf.red(t.lhs) + newLineSeparatorString(conf) +
 		"+" + prefix + key + conf.green(t.rhs)
 }