Make highlight code fully re-useable

tools/highlight/api.go

@@ -0,0 +1,55 @@
+package highlight
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/alecthomas/chroma/v2"
+)
+
+var _ = fmt.Print
+
+var ErrNoLexer = errors.New("No lexer available for this format")
+
+type StyleResolveData interface {
+	StyleName() string
+	UseLightColors() bool
+	SyntaxAliases() map[string]string
+	TextForPath(string) (string, error)
+}
+
+type SanitizeControlCodes struct {
+	r *strings.Replacer
+}
+
+func (s SanitizeControlCodes) Sanitize(x string) string { return s.r.Replace(x) }
+
+func NewSanitizeControlCodes(replace_tab_by string) *SanitizeControlCodes {
+	repls := make([]string, 0, 2*(0x1f+2+(0x9f-0x80+1)))
+	for i := range 0x1f + 1 {
+		var repl string
+		switch i {
+		case '\n', ' ':
+			repl = string(rune(i))
+		case '\t':
+			repl = replace_tab_by
+		default:
+			repl = string(rune(0x2400 + i))
+		}
+		repls = append(repls, string(rune(i)), repl)
+	}
+	return &SanitizeControlCodes{r: strings.NewReplacer(repls...)}
+}
+
+type Highlighter interface {
+	HighlightFile(path string, srd StyleResolveData) (highlighted_string string, err error)
+}
+
+func NewHighlighter(sanitize func(string) string) Highlighter {
+	if sanitize == nil {
+		s := NewSanitizeControlCodes("    ")
+		sanitize = s.Sanitize
+	}
+	return &highlighter{sanitize: sanitize, tokens_map: make(map[string][]chroma.Token)}
+}