Initial commit

highlighter.go

@@ -0,0 +1,153 @@
+package highlight
+
+import (
+	"regexp"
+	"strings"
+)
+
+func combineLineMatch(src, dst LineMatch) LineMatch {
+	for k, v := range src {
+		dst[k] = v
+	}
+	return dst
+}
+
+type Highlighter struct {
+	states []*Region
+	def    *Def
+}
+
+func NewHighlighter(def *Def) *Highlighter {
+	h := new(Highlighter)
+	h.def = def
+	return h
+}
+
+type LineMatch map[int]string
+
+func FindIndex(regex *regexp.Regexp, str []byte, canMatchStart, canMatchEnd bool) []int {
+	regexStr := regex.String()
+	if strings.Contains(regexStr, "^") {
+		if !canMatchStart {
+			return nil
+		}
+	}
+	if strings.Contains(regexStr, "$") {
+		if !canMatchEnd {
+			return nil
+		}
+	}
+	return regex.FindIndex(str)
+}
+
+func FindAllIndex(regex *regexp.Regexp, str []byte, canMatchStart, canMatchEnd bool) [][]int {
+	regexStr := regex.String()
+	if strings.Contains(regexStr, "^") {
+		if !canMatchStart {
+			return nil
+		}
+	}
+	if strings.Contains(regexStr, "$") {
+		if !canMatchEnd {
+			return nil
+		}
+	}
+	return regex.FindAllIndex(str, -1)
+}
+
+func (h *Highlighter) highlightRegion(start int, canMatchEnd bool, lineNum int, line []byte, region *Region) LineMatch {
+	highlights := make(LineMatch)
+
+	if len(line) == 0 {
+		if canMatchEnd {
+			h.states[lineNum] = region
+		}
+
+		return highlights
+	}
+
+	loc := FindIndex(region.end, line, start == 0, canMatchEnd)
+	if loc != nil {
+		if region.parent == nil {
+			highlights[start+loc[1]] = ""
+			return combineLineMatch(highlights, combineLineMatch(h.highlightRegion(start, false, lineNum, line[:loc[0]], region), h.highlightEmptyRegion(start+loc[1], canMatchEnd, lineNum, line[loc[1]:])))
+		} else {
+			highlights[start+loc[1]] = region.parent.group
+			return combineLineMatch(highlights, combineLineMatch(h.highlightRegion(start, false, lineNum, line[:loc[0]], region), h.highlightRegion(start+loc[1], canMatchEnd, lineNum, line[loc[1]:], region.parent)))
+		}
+	}
+
+	for _, r := range region.rules.regions {
+		loc = FindIndex(r.start, line, start == 0, canMatchEnd)
+		if loc != nil {
+			highlights[start+loc[0]] = r.group
+			return combineLineMatch(highlights, combineLineMatch(h.highlightRegion(start, false, lineNum, line[:loc[0]], region), h.highlightRegion(start+loc[1], canMatchEnd, lineNum, line[loc[1]:], r)))
+		}
+	}
+
+	for _, p := range region.rules.patterns {
+		matches := FindAllIndex(p.regex, line, start == 0, canMatchEnd)
+		for _, m := range matches {
+			highlights[start+m[0]] = p.group
+			if _, ok := highlights[start+m[1]]; !ok {
+				highlights[start+m[1]] = region.group
+			}
+		}
+	}
+
+	if canMatchEnd {
+		h.states[lineNum] = region
+	}
+
+	return highlights
+}
+
+func (h *Highlighter) highlightEmptyRegion(start int, canMatchEnd bool, lineNum int, line []byte) LineMatch {
+	highlights := make(LineMatch)
+	if len(line) == 0 {
+		if canMatchEnd {
+			h.states[lineNum] = nil
+		}
+		return highlights
+	}
+
+	for _, r := range h.def.rules.regions {
+		loc := FindIndex(r.start, line, start == 0, canMatchEnd)
+		if loc != nil {
+			highlights[start+loc[0]] = r.group
+			return combineLineMatch(highlights, combineLineMatch(h.highlightEmptyRegion(start, false, lineNum, line[:loc[0]]), h.highlightRegion(start+loc[1], canMatchEnd, lineNum, line[loc[1]:], r)))
+		}
+	}
+
+	for _, p := range h.def.rules.patterns {
+		matches := FindAllIndex(p.regex, line, start == 0, canMatchEnd)
+		for _, m := range matches {
+			highlights[start+m[0]] = p.group
+			highlights[start+m[1]] = ""
+		}
+	}
+
+	if canMatchEnd {
+		h.states[lineNum] = nil
+	}
+
+	return highlights
+}
+
+func (h *Highlighter) Highlight(input string, startline int) []LineMatch {
+	lines := strings.Split(input, "\n")
+	var lineMatches []LineMatch
+
+	h.states = make([]*Region, len(lines))
+
+	for i := startline; i < len(lines); i++ {
+		line := []byte(lines[i])
+		if i == 0 || h.states[i-1] == nil {
+			lineMatches = append(lineMatches, h.highlightEmptyRegion(0, true, i, line))
+		} else {
+			lineMatches = append(lineMatches, h.highlightRegion(0, true, i, line, h.states[i-1]))
+		}
+	}
+
+	return lineMatches
+}