dart 匹配基本map

var map_start = RegExp(r'^\s*\{\s*');
var map_end = RegExp(r'^\}\s*(,)?\s*');

var hasComma = true;
Map evalMap(String text, [Function endCB]) {
  var r = {};
  String k;

  void parseStart() {
    var m = map_start.firstMatch(text);
    while (m != null) {
      text = text.substring(m.end);
      m = map_start.firstMatch(text);
    }
  }

  void parseEnd() {
    var m = map_end.firstMatch(text);

    if (m == null && !hasComma) {
      throw '逗号匹配错误。';
    }

    while (m != null) {
      hasComma = m.group(1) != null;
      text = text.substring(m.end);
      if (endCB != null) {
        endCB({
          'map': r,
          'text': text,
        });
        text = '';
      }
      m = map_end.firstMatch(text);
    }
  }

  // 匹配开头
  parseStart();
  while (text.isNotEmpty) {
    // 匹配结束
    parseEnd();

    var m_k = RegExp(r'([^]+?)\s*:\s*').firstMatch(text);
    if (m_k != null) {
      k = m_k.group(1);
      text = text.substring(m_k.end);
    } else {
      k = null;
    }

    // 匹配value前，先查看是否为{}
    if (map_start.hasMatch(text)) {
      evalMap(text, (_r) {
        r[k.trim()] = _r['map'];
        text = _r['text'];
      });
    } else {
      var m_v = RegExp(
              r'''((?:true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?|"[^"\\\n\r]*"|'[^'\\\n\r]*')+)\s*(,)?\s*''')
          .firstMatch(text);
      if (m_v != null && k != null) {
        var v = m_v.group(1);
        hasComma = m_v.group(2) != null;
        r[k.trim()] = v.trim();
        k = null;
        text = text.substring(m_v.end);
      }
    }
  }
  return r;
}

void main() {
  var text = '''

{
  k: 'v',
  k2: {},
  k3: {name: 'a', x: {a: 1}}
}

''';
  var map = evalMap(text);
  print(map);
  print(map['k3']);
  print(map['k3']['x']);
  print(map['k3']['x']['a']);
}

λ dart bin/main.dart
{k: 'v', k2: {}, k3: {name: 'a', x: {a: 1}}}
{name: 'a', x: {a: 1}}
{a: 1}
1