Flutter Dart parse advanced expressions

Question

I have string with a lot of expressions, and must return true or false. I tried do it using this library: https://pub.dev/packages/expression_language/example but have some problems with strings.

This is sample of code from library:

import 'package:expression_language/expression_language.dart';

void main() {
var input = '\"Hello 1 + 1 equals: \" +  (1 + 1)'
  var expressionGrammarDefinition = ExpressionGrammarParser({});
  var parser = expressionGrammarDefinition.build();
  var result = parser.parse(input);
  var expression = result.value as Expression;
  var value = expression.evaluate();
  print(value);
}

output is: Hello 1 + 1 equals: 2

But my expressions are more complicated, for example:

input = '(!\"Dog\" == \"Cat\")';
input = '(1+1) || (\"Dog\" == \"Dog\")';
input = '(1+1) + (\"2\" * 2)';

I can parse this using expression_language library? Maybe exist better solution?

Answer 1

expression_language is built with petitparser , which is a very flexible general purpose parser. If you learn petitparser, you'll be able to build anything! (You may never write another regex in Dart as well.)