eval function

dynamic eval(String source, { String function = 'main', List args = const [], List<EvalPlugin> plugins = const [], List<Permission> permissions = const [], String? outputFile, })

Evaluate the Dart source code. If the source is a raw expression such as "2 + 2" it will be evaluated directly and the result will be returned; otherwise, the function function will be called with arguments specified by args. You can use plugins to configure bridge classes and permissions to grant permissions to the runtime. You can also specify outputFile to write the generated EVC bytecode to a file.

The eval() function automatically unboxes return values for convenience.

Implementation

dynamic eval(String source,
    {String function = 'main',
    List args = const [],
    List<EvalPlugin> plugins = const [],
    List<Permission> permissions = const [],
    String? outputFile}) {
  final compiler = Compiler();
  for (final plugin in plugins) {
    plugin.configureForCompile(compiler);
  }

  var _source = source;

  if (!RegExp(r'(?:\w* )?' + function + r'\s?\([\s\S]*?\)\s?({|=>)')
      .hasMatch(_source)) {
    if (!_source.contains(';')) {
      _source = '$_source;';
      if (!_source.contains('return')) {
        _source = 'return $_source';
      }
    }
    _source = 'dynamic $function() {$_source}';
  }

  final program = compiler.compile({
    'default': {'main.dart': _source}
  });

  if (outputFile != null) {
    File(outputFile).writeAsBytesSync(program.write());
  }

  final runtime = Runtime.ofProgram(program);
  for (final plugin in plugins) {
    plugin.configureForRuntime(runtime);
  }

  for (final permission in permissions) {
    runtime.grant(permission);
  }

  runtime.args = args;
  final result = runtime.executeLib('package:default/main.dart', function);

  if (result is $Value) {
    return result.$reified;
  }
  return result;
}