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82 lines
2.3 KiB
Go
82 lines
2.3 KiB
Go
package m
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import (
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"bytes"
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"os"
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"strings"
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"github.com/alecthomas/chroma"
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"github.com/alecthomas/chroma/lexers"
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log "github.com/sirupsen/logrus"
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)
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// Files larger than this won't be highlighted
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const MAX_HIGHLIGHT_SIZE int64 = 1024 * 1024
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// Read and highlight a file using Chroma: https://github.com/alecthomas/chroma
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//
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// If force is true, file will always be highlighted. If force is false, files
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// larger than MAX_HIGHLIGHT_SIZE will not be highlighted.
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//
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// Returns nil with no error if highlighting would be a no-op.
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func highlight(filename string, force bool, style chroma.Style, formatter chroma.Formatter) (*string, error) {
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// Highlight input file using Chroma:
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// https://github.com/alecthomas/chroma
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fileInfo, err := os.Stat(filename)
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if err != nil {
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return nil, err
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}
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if fileInfo.Size() > MAX_HIGHLIGHT_SIZE {
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log.Debugf("Not highlighting %s because it is %d bytes large, which is larger than moar's built-in highlighting limit of %d bytes",
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filename, fileInfo.Size(), MAX_HIGHLIGHT_SIZE)
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return nil, nil
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}
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lexer := lexers.Match(filename)
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if lexer == nil {
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// No highlighter available for this file type
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return nil, nil
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}
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// FIXME: Can we test for the lexer implementation class instead? That
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// should be more resilient towards this arbitrary string changing if we
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// upgrade Chroma at some point.
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if lexer.Config().Name == "plaintext" {
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// This highlighter doesn't provide any highlighting, but not doing
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// anything at all is cheaper and simpler, so we do that.
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return nil, nil
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}
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// See: https://github.com/alecthomas/chroma#identifying-the-language
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// FIXME: Do we actually need this? We should profile our reader performance
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// with and without.
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lexer = chroma.Coalesce(lexer)
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contents, err := os.ReadFile(filename)
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if err != nil {
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return nil, err
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}
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iterator, err := lexer.Tokenise(nil, string(contents))
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if err != nil {
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return nil, err
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}
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var stringBuffer bytes.Buffer
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err = formatter.Format(&stringBuffer, &style, iterator)
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if err != nil {
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return nil, err
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}
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highlighted := stringBuffer.String()
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// If buffer ends with SGR Reset ("<ESC>[0m"), remove it. Chroma sometimes
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// (always?) puts one of those by itself on the last line, making us believe
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// there is one line too many.
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sgrReset := "\x1b[0m"
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trimmed := strings.TrimSuffix(highlighted, sgrReset)
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return &trimmed, nil
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}
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