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