part of dotenv; class DotenvParser { static const _singleQuot = "'"; static const _keyword = 'export'; static final _comment = RegExp(r'''#.*(?:[^'"])$'''); static final _surroundQuotes = RegExp(r'''^(['"])(.*)\1$'''); static final _bashVar = RegExp(r'(?:\\)?(\$)(?:{)?([a-zA-Z_][\w]*)+(?:})?'); // constructor for parser const DotenvParser(); Map parse(Iterable lines) { var out = {}; lines.forEach((line) { var kv = parseOne(line, env: out); if (kv.isEmpty) return; out.putIfAbsent(kv.keys.single, () => kv.values.single); }); return out; } /// Parses a single line into a key-value pair. @visibleForTesting Map parseOne(String line, {Map env: const {}}) { var stripped = strip(line); if (!_isValid(stripped)) return {}; var idx = stripped.indexOf('='); var lhs = stripped.substring(0, idx); var k = swallow(lhs); if (k.isEmpty) return {}; var rhs = stripped.substring(idx + 1, stripped.length).trim(); var quotChar = surroundingQuote(rhs); var v = unquote(rhs); if (quotChar == _singleQuot) { return {k: v}; } return {k: interpolate(v, env)}; } /// Substitutes $bash_vars in [val] with values from [env]. @visibleForTesting String interpolate(String val, Map env) => val.replaceAllMapped(_bashVar, (m) { var k = m.group(2)!; return (!_has(env, k)) ? _tryPlatformEnv(k) ?? '' : env[k] ?? ''; }); /// If [val] is wrapped in single or double quotes, returns the quote character. /// Otherwise, returns the empty string. @visibleForTesting String surroundingQuote(String val) { if (!_surroundQuotes.hasMatch(val)) return ''; return _surroundQuotes.firstMatch(val)!.group(1)!; } /// Removes quotes (single or double) surrounding a value. @visibleForTesting String unquote(String val) => val.replaceFirstMapped(_surroundQuotes, (m) => m[2]!).trim(); /// Strips comments (trailing or whole-line). @visibleForTesting String strip(String line) => line.replaceAll(_comment, '').trim(); /// Omits 'export' keyword. @visibleForTesting String swallow(String line) => line.replaceAll(_keyword, '').trim(); bool _isValid(String s) => s.isNotEmpty && s.contains('='); bool _has(Map map, String key) => map.containsKey(key) && map[key] != null; String? _tryPlatformEnv(String key) { if (!_has(Platform.environment, key)) { return ''; } return Platform.environment[key]; } }