forgejo-federation/modules/highlight/highlight.go
Mura Li 19dedc3fa5
Speed up git diff highlight generation (#16180)
Co-authored-by: Mura Li <typeless@users.noreply.github.com>
Co-authored-by: 6543 <6543@obermui.de>
2021-06-17 10:55:16 -04:00

195 lines
4.7 KiB
Go

// Copyright 2015 The Gogs Authors. All rights reserved.
// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package highlight
import (
"bufio"
"bytes"
"fmt"
gohtml "html"
"path/filepath"
"strings"
"sync"
"code.gitea.io/gitea/modules/analyze"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"github.com/alecthomas/chroma"
"github.com/alecthomas/chroma/formatters/html"
"github.com/alecthomas/chroma/lexers"
"github.com/alecthomas/chroma/styles"
lru "github.com/hashicorp/golang-lru"
)
// don't index files larger than this many bytes for performance purposes
const sizeLimit = 1000000
var (
// For custom user mapping
highlightMapping = map[string]string{}
once sync.Once
cache *lru.ARCCache
)
// NewContext loads custom highlight map from local config
func NewContext() {
once.Do(func() {
keys := setting.Cfg.Section("highlight.mapping").Keys()
for i := range keys {
highlightMapping[keys[i].Name()] = keys[i].Value()
}
// The size 512 is simply a conservative rule of thumb
c, err := lru.NewARC(512)
if err != nil {
panic(fmt.Sprintf("failed to initialize LRU cache for highlighter: %s", err))
}
cache = c
})
}
// Code returns a HTML version of code string with chroma syntax highlighting classes
func Code(fileName, code string) string {
NewContext()
// diff view newline will be passed as empty, change to literal \n so it can be copied
// preserve literal newline in blame view
if code == "" || code == "\n" {
return "\n"
}
if len(code) > sizeLimit {
return code
}
formatter := html.New(html.WithClasses(true),
html.WithLineNumbers(false),
html.PreventSurroundingPre(true),
)
if formatter == nil {
log.Error("Couldn't create chroma formatter")
return code
}
htmlbuf := bytes.Buffer{}
htmlw := bufio.NewWriter(&htmlbuf)
var lexer chroma.Lexer
if val, ok := highlightMapping[filepath.Ext(fileName)]; ok {
//use mapped value to find lexer
lexer = lexers.Get(val)
}
if lexer == nil {
if l, ok := cache.Get(fileName); ok {
lexer = l.(chroma.Lexer)
}
}
if lexer == nil {
lexer = lexers.Match(fileName)
if lexer == nil {
lexer = lexers.Fallback
}
cache.Add(fileName, lexer)
}
iterator, err := lexer.Tokenise(nil, string(code))
if err != nil {
log.Error("Can't tokenize code: %v", err)
return code
}
// style not used for live site but need to pass something
err = formatter.Format(htmlw, styles.GitHub, iterator)
if err != nil {
log.Error("Can't format code: %v", err)
return code
}
htmlw.Flush()
// Chroma will add newlines for certain lexers in order to highlight them properly
// Once highlighted, strip them here so they don't cause copy/paste trouble in HTML output
return strings.TrimSuffix(htmlbuf.String(), "\n")
}
// File returns map with line lumbers and HTML version of code with chroma syntax highlighting classes
func File(numLines int, fileName string, code []byte) map[int]string {
NewContext()
if len(code) > sizeLimit {
return plainText(string(code), numLines)
}
formatter := html.New(html.WithClasses(true),
html.WithLineNumbers(false),
html.PreventSurroundingPre(true),
)
if formatter == nil {
log.Error("Couldn't create chroma formatter")
return plainText(string(code), numLines)
}
htmlbuf := bytes.Buffer{}
htmlw := bufio.NewWriter(&htmlbuf)
var lexer chroma.Lexer
if val, ok := highlightMapping[filepath.Ext(fileName)]; ok {
lexer = lexers.Get(val)
}
if lexer == nil {
language := analyze.GetCodeLanguage(fileName, code)
lexer = lexers.Get(language)
if lexer == nil {
lexer = lexers.Match(fileName)
if lexer == nil {
lexer = lexers.Fallback
}
}
}
iterator, err := lexer.Tokenise(nil, string(code))
if err != nil {
log.Error("Can't tokenize code: %v", err)
return plainText(string(code), numLines)
}
err = formatter.Format(htmlw, styles.GitHub, iterator)
if err != nil {
log.Error("Can't format code: %v", err)
return plainText(string(code), numLines)
}
htmlw.Flush()
m := make(map[int]string, numLines)
for k, v := range strings.SplitN(htmlbuf.String(), "\n", numLines) {
line := k + 1
content := string(v)
//need to keep lines that are only \n so copy/paste works properly in browser
if content == "" {
content = "\n"
}
m[line] = content
}
return m
}
// return unhiglighted map
func plainText(code string, numLines int) map[int]string {
m := make(map[int]string, numLines)
for k, v := range strings.SplitN(string(code), "\n", numLines) {
line := k + 1
content := string(v)
//need to keep lines that are only \n so copy/paste works properly in browser
if content == "" {
content = "\n"
}
m[line] = gohtml.EscapeString(content)
}
return m
}