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Improve performance by reducing allocations #17

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Improve performance by reducing allocations #17

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187 changes: 120 additions & 67 deletions prettyjson.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,10 @@ import (
"bytes"
"encoding/json"
"fmt"
"io"
"sort"
"strconv"
"strings"
_ "unsafe" // go:linkname

"github.com/fatih/color"
)
Expand Down Expand Up @@ -77,14 +78,23 @@ func (f *Formatter) Format(data []byte) ([]byte, error) {
return nil, err
}

return []byte(f.pretty(v, 1)), nil
buf := newBytesBuffer()
f.pretty(buf, v, 1)
return buf.Bytes(), nil
}

func (f *Formatter) sprintfColor(c *color.Color, format string, args ...interface{}) string {
func (f *Formatter) setColor(buf *bytesBuffer, c *color.Color) {
if f.DisabledColor || c == nil {
return fmt.Sprintf(format, args...)
return
}
return c.SprintfFunc()(format, args...)
setWriter(c, buf)
}

func (f *Formatter) unsetColor(buf *bytesBuffer, c *color.Color) {
if f.DisabledColor || c == nil {
return
}
unsetWriter(c, buf)
}

func (f *Formatter) sprintColor(c *color.Color, s string) string {
Expand All @@ -94,99 +104,119 @@ func (f *Formatter) sprintColor(c *color.Color, s string) string {
return c.SprintFunc()(s)
}

func (f *Formatter) pretty(v interface{}, depth int) string {
//go:linkname setWriter github.com/fatih/color.(*Color).setWriter
func setWriter(*color.Color, io.Writer) *color.Color

//go:linkname unsetWriter github.com/fatih/color.(*Color).unsetWriter
func unsetWriter(*color.Color, io.Writer)

func (f *Formatter) pretty(buf *bytesBuffer, v interface{}, depth int) {
switch val := v.(type) {
case string:
return f.processString(val)
f.setColor(buf, f.StringColor)
f.writeString(buf, val)
f.unsetColor(buf, f.StringColor)
case float64:
return f.sprintColor(f.NumberColor, strconv.FormatFloat(val, 'f', -1, 64))
f.setColor(buf, f.NumberColor)
buf.writeFloat64(val)
f.unsetColor(buf, f.NumberColor)
case json.Number:
return f.sprintColor(f.NumberColor, string(val))
f.setColor(buf, f.NumberColor)
buf.WriteString(val.String())
f.unsetColor(buf, f.NumberColor)
case bool:
return f.sprintColor(f.BoolColor, strconv.FormatBool(val))
f.setColor(buf, f.BoolColor)
if val {
buf.WriteString("true")
} else {
buf.WriteString("false")
}
f.unsetColor(buf, f.BoolColor)
case nil:
return f.sprintColor(f.NullColor, "null")
f.setColor(buf, f.NullColor)
buf.WriteString("null")
f.unsetColor(buf, f.NullColor)
case map[string]interface{}:
return f.processMap(val, depth)
f.writeMap(buf, val, depth)
case []interface{}:
return f.processArray(val, depth)
f.writeArray(buf, val, depth)
}

return ""
}

func (f *Formatter) processString(s string) string {
r := []rune(s)
if f.StringMaxLength != 0 && len(r) >= f.StringMaxLength {
s = string(r[0:f.StringMaxLength]) + "..."
func (f *Formatter) writeString(buf *bytesBuffer, s string) {
if f.StringMaxLength != 0 {
if r := []rune(s); len(r) >= f.StringMaxLength {
s = string(r[0:f.StringMaxLength]) + "..."
}
}

buf := &bytes.Buffer{}
encoder := json.NewEncoder(buf)
encoder.SetEscapeHTML(false)
encoder.Encode(s)
s = string(buf.Bytes())
s = strings.TrimSuffix(s, "\n")

return f.sprintColor(f.StringColor, s)
buf.writeString(s)
}

func (f *Formatter) processMap(m map[string]interface{}, depth int) string {
func (f *Formatter) writeMap(buf *bytesBuffer, m map[string]interface{}, depth int) {
if len(m) == 0 {
return "{}"
buf.WriteString("{}")
return
}

currentIndent := f.generateIndent(depth - 1)
nextIndent := f.generateIndent(depth)
rows := []string{}
keys := []string{}

keys := make([]string, len(m))
var i int
for key := range m {
keys = append(keys, key)
keys[i] = key
i++
}

sort.Strings(keys)

for _, key := range keys {
val := m[key]
buf := &bytes.Buffer{}
encoder := json.NewEncoder(buf)
encoder.SetEscapeHTML(false)
encoder.Encode(key)
s := strings.TrimSuffix(string(buf.Bytes()), "\n")
k := f.sprintColor(f.KeyColor, s)
v := f.pretty(val, depth+1)

valueIndent := " "
if f.Newline == "" {
valueIndent = ""
buf.WriteByte('{')
for i, key := range keys {
if i > 0 {
buf.WriteByte(',')
}
buf.WriteString(f.Newline)
f.appendIndent(buf, depth)
f.setColor(buf, f.KeyColor)
buf.writeString(key)
f.unsetColor(buf, f.KeyColor)
buf.WriteByte(':')
if f.Newline != "" {
buf.WriteByte(' ')
}
row := fmt.Sprintf("%s%s:%s%s", nextIndent, k, valueIndent, v)
rows = append(rows, row)
f.pretty(buf, m[key], depth+1)
}

return fmt.Sprintf("{%s%s%s%s}", f.Newline, strings.Join(rows, ","+f.Newline), f.Newline, currentIndent)
buf.WriteString(f.Newline)
f.appendIndent(buf, depth-1)
buf.WriteByte('}')
}

func (f *Formatter) processArray(a []interface{}, depth int) string {
func (f *Formatter) writeArray(buf *bytesBuffer, a []interface{}, depth int) {
if len(a) == 0 {
return "[]"
buf.WriteString("[]")
return
}

currentIndent := f.generateIndent(depth - 1)
nextIndent := f.generateIndent(depth)
rows := []string{}

for _, val := range a {
c := f.pretty(val, depth+1)
row := nextIndent + c
rows = append(rows, row)
buf.WriteByte('[')
for i, val := range a {
if i > 0 {
buf.WriteByte(',')
}
buf.WriteString(f.Newline)
f.appendIndent(buf, depth)
f.pretty(buf, val, depth+1)
}
return fmt.Sprintf("[%s%s%s%s]", f.Newline, strings.Join(rows, ","+f.Newline), f.Newline, currentIndent)
buf.WriteString(f.Newline)
f.appendIndent(buf, depth-1)
buf.WriteByte(']')
}

func (f *Formatter) generateIndent(depth int) string {
return strings.Repeat(" ", f.Indent*depth)
const spaces = " "

func (f *Formatter) appendIndent(buf *bytesBuffer, depth int) {
if n := f.Indent * depth; n > 0 {
for n > len(spaces) {
buf.Write([]byte(spaces))
n -= len(spaces)
}
buf.Write([]byte(spaces)[:n])
}
}

// Marshal JSON data with default options.
Expand All @@ -198,3 +228,26 @@ func Marshal(v interface{}) ([]byte, error) {
func Format(data []byte) ([]byte, error) {
return NewFormatter().Format(data)
}

type bytesBuffer struct {
bytes.Buffer
enc *json.Encoder
scratch [64]byte
}

func newBytesBuffer() *bytesBuffer {
var buf bytesBuffer
buf.enc = json.NewEncoder(&buf.Buffer)
buf.enc.SetEscapeHTML(false)
return &buf
}

func (buf *bytesBuffer) writeString(str string) {
if buf.enc.Encode(str) == nil {
buf.Truncate(len(buf.Bytes()) - 1)
}
}

func (buf *bytesBuffer) writeFloat64(f float64) {
buf.Write(strconv.AppendFloat(buf.scratch[:0], f, 'f', -1, 64))
}