public void Evaluate_SymbolExpression_Correctly()
{
//Demonstrates how to evaluate a general expression by deferring the loading of values from a data source.
//Arrange
string expression = "a +- (b + c) --d";
var dataSource = new Dictionary <string, int>
{
{ "a", 2 }, { "b", 3 }, { "c", -4 }, { "d", 5 }
};
var evaluator = new IntEvaluator();
evaluator.ValueForToken = token =>
{
if (dataSource.ContainsKey(token.Value))
{
return(dataSource[token.Value]);
}
else
{
return(evaluator.GetValueDefaultAccessor()(token)); //In successive token evaluations, the symbol is already replaced so we should use the default accessor
}
};
//Act
var result = evaluator.Evaluate(new Parser(expression).Parse());
//Assert
Assert.Equal("8", result.Value);
}
public void Evaluate_IntExpressions_Correctly(string expression, int expected)
{
//Arrange
var parser = new Parser(expression);
var evaluator = new IntEvaluator();
//Act
Token t = evaluator.Evaluate(parser.Parse());
//Assert
Assert.Equal(expected, int.Parse(t.Value));
}
