飞镖扑向高级表达式
我的字符串带有很多表达式，必须返回真或错误。我尝试使用此库进行操作： https:/ https:/pab.dev/packages/packages/ppackages/expression_lagesression_lageage/example/example/example/example 但在字符串方面有一些问题。
这是库中的代码示例：
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);
}
输出为：Hello 1 + 1等于：2，
但是我的表达式更为复杂，例如：
input = '(!\"Dog\" == \"Cat\")';
input = '(1+1) || (\"Dog\" == \"Dog\")';
input = '(1+1) + (\"2\" * 2)';
我可以使用expression_language库来解析此内容？也许有更好的解决方案？
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?
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expression_language是用petitparser构建的，这是一个非常灵活的通用解析器。如果您学习Petitparser，您将能够建造任何东西！ （您可能永远也不会在Dart上写另一个正则。）expression_languageis built withpetitparser, 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.)