1 files changed, 172 insertions, 0 deletions
diff --git a/lib/bytes/json.go b/lib/bytes/json.go
new file mode 100644
index 00000000..1a296a3b
--- /dev/null
+++ b/lib/bytes/json.go
@@ -0,0 +1,172 @@
+// Copyright 2018, Shulhan <ms@kilabit.info>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bytes
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+)
+
+const (
+	errInvalidSyntax = "%s: invalid syntax at %d"
+)
+
+const (
+	bDoubleQuote = '"'
+	bRevSolidus  = '\\'
+	bSolidus     = '/'
+	bBackspace   = '\b'
+	bFormFeed    = '\f'
+	bLineFeed    = '\n'
+	bCarReturn   = '\r'
+	bTab         = '\t'
+)
+
+//
+// JSONEscape escape the following character: `"` (quotation mark),
+// `\` (reverse solidus), `/` (solidus), `\b` (backspace), `\f` (formfeed),
+// `\n` (newline), `\r` (carriage return`), `\t` (horizontal tab), and control
+// character from 0 - 31.
+//
+// References:
+//
+// * https://tools.ietf.org/html/rfc7159#page-8
+//
+func JSONEscape(in []byte) []byte {
+	var buf bytes.Buffer
+
+	for x := 0; x < len(in); x++ {
+		if in[x] == bDoubleQuote || in[x] == bRevSolidus || in[x] == bSolidus {
+			buf.WriteByte(bRevSolidus)
+			buf.WriteByte(in[x])
+			continue
+		}
+		if in[x] == bBackspace {
+			buf.WriteByte(bRevSolidus)
+			buf.WriteByte('b')
+			continue
+		}
+		if in[x] == bFormFeed {
+			buf.WriteByte(bRevSolidus)
+			buf.WriteByte('f')
+			continue
+		}
+		if in[x] == bLineFeed {
+			buf.WriteByte(bRevSolidus)
+			buf.WriteByte('n')
+			continue
+		}
+		if in[x] == bCarReturn {
+			buf.WriteByte(bRevSolidus)
+			buf.WriteByte('r')
+			continue
+		}
+		if in[x] == bTab {
+			buf.WriteByte(bRevSolidus)
+			buf.WriteByte('t')
+			continue
+		}
+		if in[x] <= 31 {
+			buf.WriteString(fmt.Sprintf("\\u%04X", in[x]))
+			continue
+		}
+
+		buf.WriteByte(in[x])
+	}
+
+	return buf.Bytes()
+}
+
+//
+// JSONUnescape unescape JSON bytes, reversing what BytesJSONEscape do.
+//
+// If strict is true, any unknown control character will be returned as error.
+// For example, in string "\x", "x" is not valid control character, and the
+// function will return empty string and error.
+// If strict is false, it will return "x".
+//
+func JSONUnescape(in []byte, strict bool) ([]byte, error) {
+	var (
+		buf bytes.Buffer
+		uni bytes.Buffer
+		esc bool
+	)
+
+	for x := 0; x < len(in); x++ {
+		if esc {
+			if in[x] == 'u' {
+				uni.Reset()
+				x++
+
+				for y := 0; y < 4 && x < len(in); x++ {
+					uni.WriteByte(in[x])
+					y++
+				}
+
+				dec, err := strconv.ParseUint(uni.String(), 16, 32)
+				if err != nil {
+					return nil, err
+				}
+
+				if dec <= 31 {
+					buf.WriteByte(byte(dec))
+				} else {
+					buf.WriteRune(rune(dec))
+				}
+
+				esc = false
+				x--
+				continue
+			}
+			if in[x] == 't' {
+				buf.WriteByte(bTab)
+				esc = false
+				continue
+			}
+			if in[x] == 'r' {
+				buf.WriteByte(bCarReturn)
+				esc = false
+				continue
+			}
+			if in[x] == 'n' {
+				buf.WriteByte(bLineFeed)
+				esc = false
+				continue
+			}
+			if in[x] == 'f' {
+				buf.WriteByte(bFormFeed)
+				esc = false
+				continue
+			}
+			if in[x] == 'b' {
+				buf.WriteByte(bBackspace)
+				esc = false
+				continue
+			}
+			if in[x] == bDoubleQuote || in[x] == bRevSolidus || in[x] == bSolidus {
+				buf.WriteByte(in[x])
+				esc = false
+				continue
+			}
+
+			if strict {
+				err := fmt.Errorf(errInvalidSyntax, "BytesJSONUnescape", x)
+				return nil, err
+			}
+
+			buf.WriteByte(in[x])
+			esc = false
+			continue
+		}
+		if in[x] == bRevSolidus {
+			esc = true
+			continue
+		}
+		buf.WriteByte(in[x])
+	}
+
+	return buf.Bytes(), nil
+}