mirror of
https://github.com/httpjamesm/AnonymousOverflow.git
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Solomon
23b8ed8899
* improvement: use lang-* classes declared in snippet markup * fix: don't require snippet lang classes in code blocks * fix: constrain greedy code block match
99 lines
2.6 KiB
Go
99 lines
2.6 KiB
Go
package utils
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import (
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"bytes"
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"html"
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"io"
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"regexp"
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"strings"
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html_formatter "github.com/alecthomas/chroma/formatters/html"
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"github.com/alecthomas/chroma/lexers"
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"github.com/alecthomas/chroma/styles"
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)
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// highlightSyntaxViaContent uses Chroma to lex code content and apply the appropriate tokenizer engine.
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// If it can't find one, it defaults to JavaScript syntax highlighting.
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func highlightSyntaxViaContent(content string, lang string) (htmlOut string) {
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content = html.UnescapeString(content)
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fallbackOut := html.EscapeString(content)
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lexer := lexers.Get(lang)
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if lexer == nil {
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lexer = lexers.Analyse(content)
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}
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if lexer == nil {
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lexer = lexers.Get(".js")
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}
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style := styles.Get("xcode")
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if style == nil {
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style = styles.Fallback
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}
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formatter := html_formatter.New(html_formatter.PreventSurroundingPre(true), html_formatter.WithClasses(true))
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iterator, err := lexer.Tokenise(nil, content)
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if err != nil {
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htmlOut = fallbackOut
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return
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}
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b := bytes.NewBufferString("")
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w := io.Writer(b)
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err = formatter.Format(w, style, iterator)
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if err != nil {
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htmlOut = fallbackOut
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return
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}
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htmlOut = b.String()
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return
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}
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var preClassRegex = regexp.MustCompile(`(?s)<pre class=".+">`)
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// stripBlockTags takes an extracted code block from HTML and strips it of its pre and code tags.
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// What's returned is just the code.
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func stripBlockTags(content string) (result string) {
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// strip all "<code>" tags
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content = strings.Replace(content, "<code>", "", -1)
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content = strings.Replace(content, "</code>", "", -1)
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// and the <pre>
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content = strings.Replace(content, "<pre>", "", -1)
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content = strings.Replace(content, "</pre>", "", -1)
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content = preClassRegex.ReplaceAllString(content, "")
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result = content
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return
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}
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var codeBlockRegex = regexp.MustCompile(`(?s)<pre(?:[^>]+?lang-(.+?)[\s"'])?.*?><code>(.*?)<\/code><\/pre>`)
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// HighlightCodeBlocks uses both highlightSyntaxViaContent stripCodeBlocks and returns the newly highlighted code HTML.
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func HighlightCodeBlocks(html string) string {
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// Replace each code block with the highlighted version
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highlightedHTML := codeBlockRegex.ReplaceAllStringFunc(html, func(codeBlock string) string {
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// Extract the code content from the code block
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matches := codeBlockRegex.FindStringSubmatch(codeBlock)
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lang, codeContent := matches[1], matches[2]
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codeContent = stripBlockTags(codeContent)
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// Highlight the code content
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highlightedCode := highlightSyntaxViaContent(codeContent, lang)
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// Replace the original code block with the highlighted version
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highlightedCodeBlock := "<pre>" + highlightedCode + "</pre>"
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return highlightedCodeBlock
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})
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return highlightedHTML
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}
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