Function parseUnifiedDiff

vcs/git/git_diff_lines.go:125–175

parseUnifiedDiff walks `git diff --unified=0` output and emits per-file FileDiff structures with 1-indexed line numbers.

(diff string)

// parseUnifiedDiff walks `git diff --unified=0` output and emits per-file
// FileDiff structures with 1-indexed line numbers.
func parseUnifiedDiff(diff string) map[string]vcs.FileDiff {
	out := make(map[string]vcs.FileDiff)
	var currentPath string
	var current vcs.FileDiff
	var oldLine, newLine int

	flush := func() {
		if currentPath == "" {
			return
		}
		out[currentPath] = current
	}

	lines := strings.Split(diff, "\n")
	for _, line := range lines {
		switch {
		case strings.HasPrefix(line, "diff --git "):
			flush()
			currentPath = ""
			current = vcs.FileDiff{}
			// Path is the `b/...` side; pick it from the trailing token.
			fields := strings.Fields(line)
			if len(fields) >= 4 {
				currentPath = strings.TrimPrefix(fields[3], "b/")
			}
		case strings.HasPrefix(line, "new file mode"):
			current.IsNew = true
		case strings.HasPrefix(line, "deleted file mode"):
			current.IsDeleted = true
		case strings.HasPrefix(line, "rename from"), strings.HasPrefix(line, "rename to"):
			current.IsRenamed = true
		case strings.HasPrefix(line, "@@"):
			oldStart, _, newStart, _, ok := parseHunkHeader(line)
			if !ok {
				continue
			}
			oldLine = oldStart
			newLine = newStart
		case strings.HasPrefix(line, "+++"), strings.HasPrefix(line, "---"):
			// File headers; ignore.
		case strings.HasPrefix(line, "+"):
			current.Additions = append(current.Additions, newLine)
			newLine++
		case strings.HasPrefix(line, "-"):
			current.Deletions = append(current.Deletions, oldLine)
			oldLine++
		}
	}
	flush()
	return out
}

// parseHunkHeader parses a unified-diff hunk header of the form
//