1 files changed, 143 insertions, 0 deletions
diff --git a/src/encoding/json/indent.go b/src/encoding/json/indent.go
new file mode 100644
index 0000000..2924d3b
--- /dev/null
+++ b/src/encoding/json/indent.go
@@ -0,0 +1,143 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package json
+
+import (
+	"bytes"
+)
+
+// Compact appends to dst the JSON-encoded src with
+// insignificant space characters elided.
+func Compact(dst *bytes.Buffer, src []byte) error {
+	return compact(dst, src, false)
+}
+
+func compact(dst *bytes.Buffer, src []byte, escape bool) error {
+	origLen := dst.Len()
+	scan := newScanner()
+	defer freeScanner(scan)
+	start := 0
+	for i, c := range src {
+		if escape && (c == '<' || c == '>' || c == '&') {
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			dst.WriteString(`\u00`)
+			dst.WriteByte(hex[c>>4])
+			dst.WriteByte(hex[c&0xF])
+			start = i + 1
+		}
+		// Convert U+2028 and U+2029 (E2 80 A8 and E2 80 A9).
+		if escape && c == 0xE2 && i+2 < len(src) && src[i+1] == 0x80 && src[i+2]&^1 == 0xA8 {
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			dst.WriteString(`\u202`)
+			dst.WriteByte(hex[src[i+2]&0xF])
+			start = i + 3
+		}
+		v := scan.step(scan, c)
+		if v >= scanSkipSpace {
+			if v == scanError {
+				break
+			}
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			start = i + 1
+		}
+	}
+	if scan.eof() == scanError {
+		dst.Truncate(origLen)
+		return scan.err
+	}
+	if start < len(src) {
+		dst.Write(src[start:])
+	}
+	return nil
+}
+
+func newline(dst *bytes.Buffer, prefix, indent string, depth int) {
+	dst.WriteByte('\n')
+	dst.WriteString(prefix)
+	for i := 0; i < depth; i++ {
+		dst.WriteString(indent)
+	}
+}
+
+// Indent appends to dst an indented form of the JSON-encoded src.
+// Each element in a JSON object or array begins on a new,
+// indented line beginning with prefix followed by one or more
+// copies of indent according to the indentation nesting.
+// The data appended to dst does not begin with the prefix nor
+// any indentation, to make it easier to embed inside other formatted JSON data.
+// Although leading space characters (space, tab, carriage return, newline)
+// at the beginning of src are dropped, trailing space characters
+// at the end of src are preserved and copied to dst.
+// For example, if src has no trailing spaces, neither will dst;
+// if src ends in a trailing newline, so will dst.
+func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
+	origLen := dst.Len()
+	scan := newScanner()
+	defer freeScanner(scan)
+	needIndent := false
+	depth := 0
+	for _, c := range src {
+		scan.bytes++
+		v := scan.step(scan, c)
+		if v == scanSkipSpace {
+			continue
+		}
+		if v == scanError {
+			break
+		}
+		if needIndent && v != scanEndObject && v != scanEndArray {
+			needIndent = false
+			depth++
+			newline(dst, prefix, indent, depth)
+		}
+
+		// Emit semantically uninteresting bytes
+		// (in particular, punctuation in strings) unmodified.
+		if v == scanContinue {
+			dst.WriteByte(c)
+			continue
+		}
+
+		// Add spacing around real punctuation.
+		switch c {
+		case '{', '[':
+			// delay indent so that empty object and array are formatted as {} and [].
+			needIndent = true
+			dst.WriteByte(c)
+
+		case ',':
+			dst.WriteByte(c)
+			newline(dst, prefix, indent, depth)
+
+		case ':':
+			dst.WriteByte(c)
+			dst.WriteByte(' ')
+
+		case '}', ']':
+			if needIndent {
+				// suppress indent in empty object/array
+				needIndent = false
+			} else {
+				depth--
+				newline(dst, prefix, indent, depth)
+			}
+			dst.WriteByte(c)
+
+		default:
+			dst.WriteByte(c)
+		}
+	}
+	if scan.eof() == scanError {
+		dst.Truncate(origLen)
+		return scan.err
+	}
+	return nil
+}