Function scan

mini-code-editor/cm/lib/codemirror.js:1740–1755

(line, from, to)

      var stack = [line.text.charAt(pos)], re = /[(){}[\]]/;
      function scan(line, from, to) {
        if (!line.text) return;
        var st = line.styles, pos = forward ? 0 : line.text.length - 1, cur;
        for (var i = forward ? 0 : st.length - 2, e = forward ? st.length : -2; i != e; i += 2*d) {
          var text = st[i];
          if (st[i+1] != null && st[i+1] != style) {pos += d * text.length; continue;}
          for (var j = forward ? 0 : text.length - 1, te = forward ? text.length : -1; j != te; j += d, pos+=d) {
            if (pos >= from && pos < to && re.test(cur = text.charAt(j))) {
              var match = matching[cur];
              if (match.charAt(1) == ">" == forward) stack.push(cur);
              else if (stack.pop() != match.charAt(0)) return {pos: pos, match: false};
              else if (!stack.length) return {pos: pos, match: true};
            }
          }
        }
      }
      for (var i = head.line, e = forward ? Math.min(i + 100, doc.size) : Math.max(-1, i - 100); i != e; i+=d) {
        var line = getLine(i), first = i == head.line;
        var found = scan(line, first && forward ? pos + 1 : 0, first && !forward ? pos : line.text.length);