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// 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.TwoQueueCache
)
// 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.New2Q(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, language, 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
}
var lexer chroma.Lexer
if len(language) > 0 {
lexer = lexers.Get(language)
if lexer == nil {
// Attempt stripping off the '?'
if idx := strings.IndexByte(language, '?'); idx > 0 {
lexer = lexers.Get(language[:idx])
}
}
}
if lexer == nil {
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)
}
return CodeFromLexer(lexer, code)
}
// CodeFromLexer returns a HTML version of code string with chroma syntax highlighting classes
func CodeFromLexer(lexer chroma.Lexer, code string) string {
formatter := html.New(html.WithClasses(true),
html.WithLineNumbers(false),
html.PreventSurroundingPre(true),
)
htmlbuf := bytes.Buffer{}
htmlw := bufio.NewWriter(&htmlbuf)
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 a slice of chroma syntax highlighted lines of code
func File(numLines int, fileName, language string, code []byte) []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
// provided language overrides everything
if len(language) > 0 {
lexer = lexers.Get(language)
}
if lexer == nil {
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()
finalNewLine := false
if len(code) > 0 {
finalNewLine = code[len(code)-1] == '\n'
}
m := make([]string, 0, numLines)
for _, v := range strings.SplitN(htmlbuf.String(), "\n", numLines) {
content := string(v)
// need to keep lines that are only \n so copy/paste works properly in browser
if content == "" {
content = "\n"
} else if content == `</span><span class="w">` {
content += "\n</span>"
}
content = strings.TrimSuffix(content, `<span class="w">`)
content = strings.TrimPrefix(content, `</span>`)
m = append(m, content)
}
if finalNewLine {
m = append(m, "<span class=\"w\">\n</span>")
}
return m
}
// return unhiglighted map
func plainText(code string, numLines int) []string {
m := make([]string, 0, numLines)
for _, v := range strings.SplitN(string(code), "\n", numLines) {
content := string(v)
// need to keep lines that are only \n so copy/paste works properly in browser
if content == "" {
content = "\n"
}
m = append(m, gohtml.EscapeString(content))
}
return m
}
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