public override void VisitBinaryOperatorExpression(BinaryOperatorExpression binaryOperatorExpression)
{
base.VisitBinaryOperatorExpression(binaryOperatorExpression);
// Looking for patterns like:
//
// (x - 2) - 2
// (x / 2) / 2
// (x - 2) + 4
// (x * 2) / 3
var pattern = new BinaryOperatorExpression
{
Left = new ParenthesizedExpression
{
Expression = new BinaryOperatorExpression
{
Left = new AnyNode("left"),
Operator = BinaryOperatorType.Any,
Right = new AnyNode("rightA")
}
},
Operator = BinaryOperatorType.Any,
Right = new AnyNode("rightB")
};
if (binaryOperatorExpression.Operator != BinaryOperatorType.Add &&
binaryOperatorExpression.Operator != BinaryOperatorType.Subtract &&
binaryOperatorExpression.Operator != BinaryOperatorType.Multiply &&
binaryOperatorExpression.Operator != BinaryOperatorType.Divide)
{
return;
}
if (pattern.IsMatch(binaryOperatorExpression))
{
var match = pattern.Match(binaryOperatorExpression);
var outerOperator = binaryOperatorExpression.Operator;
var innerOperator = (BinaryOperatorType)((dynamic)binaryOperatorExpression.Left).Expression.Operator;
var innerValue = AstHelpers.GetValueFromExpression((Expression)match.Get("rightA").First());
var outerValue = AstHelpers.GetValueFromExpression((Expression)match.Get("rightB").First());
if (innerValue == null && outerValue == null)
return;
// If the operators are equal, then we handle expression like (x - 2) - 4.
if (innerOperator == outerOperator)
{
dynamic resultValue;
switch (binaryOperatorExpression.Operator)
{
case BinaryOperatorType.Add:
case BinaryOperatorType.Subtract:
resultValue = innerValue + outerValue;
break;
case BinaryOperatorType.Multiply:
case BinaryOperatorType.Divide:
resultValue = innerValue * outerValue;
break;
default:
return;
}
binaryOperatorExpression.ReplaceWith(new BinaryOperatorExpression(
(match.Get("left").First() as Expression).Clone(),
binaryOperatorExpression.Operator,
new PrimitiveExpression(resultValue)));
return;
}
// Otherwise handle the slightly more complex cases.
PrimitiveExpression result = null;
switch (innerOperator)
{
case BinaryOperatorType.Add:
switch (outerOperator)
{
case BinaryOperatorType.Subtract:
result = new PrimitiveExpression(innerValue - outerValue);
break;
}
break;
case BinaryOperatorType.Subtract:
switch (outerOperator)
{
case BinaryOperatorType.Add:
result = new PrimitiveExpression(innerValue - outerValue);
break;
}
break;
}
if (result != null)
{
binaryOperatorExpression.ReplaceWith(new BinaryOperatorExpression(
(match.Get("left").First() as Expression).Clone(),
binaryOperatorExpression.Operator,
result));
}
}
}
public override void VisitBinaryOperatorExpression(BinaryOperatorExpression binaryOperatorExpression)
{
base.VisitBinaryOperatorExpression(binaryOperatorExpression);
// Looking for patterns like:
//
// (x - 2) - x
var pattern = new BinaryOperatorExpression
{
Left = new ParenthesizedExpression
{
Expression = new BinaryOperatorExpression
{
Left = new NamedNode(
"ident",
new IdentifierExpression
{
Identifier = Pattern.AnyString
}),
Operator = BinaryOperatorType.Any,
Right = new AnyNode("other")
}
},
Operator = BinaryOperatorType.Any,
Right = new IdentifierExpressionBackreference("ident")
};
if (pattern.IsMatch(binaryOperatorExpression))
{
var match = pattern.Match(binaryOperatorExpression);
var innerOperator = (BinaryOperatorType)((dynamic)binaryOperatorExpression).Left.Expression.Operator;
var outerOperator = binaryOperatorExpression.Operator;
switch (outerOperator)
{
case BinaryOperatorType.Subtract:
switch (innerOperator)
{
case BinaryOperatorType.Add:
binaryOperatorExpression.ReplaceWith(((AstNode)match.Get("other").First()).Clone());
return;
case BinaryOperatorType.Subtract:
binaryOperatorExpression.ReplaceWith(new UnaryOperatorExpression(
UnaryOperatorType.Minus,
((Expression)match.Get("other").First()).Clone()));
return;
}
break;
}
}
// Looking for patterns like:
//
// (2 - x) + x
pattern = new BinaryOperatorExpression
{
Left = new ParenthesizedExpression
{
Expression = new BinaryOperatorExpression
{
Left = new AnyNode("other"),
Operator = BinaryOperatorType.Any,
Right = new NamedNode(
"ident",
new IdentifierExpression
{
Identifier = Pattern.AnyString
})
}
},
Operator = BinaryOperatorType.Any,
Right = new IdentifierExpressionBackreference("ident")
};
if (pattern.IsMatch(binaryOperatorExpression))
{
var match = pattern.Match(binaryOperatorExpression);
var innerOperator = (BinaryOperatorType)((dynamic) binaryOperatorExpression).Left.Expression.Operator;
var outerOperator = binaryOperatorExpression.Operator;
switch (outerOperator)
{
case BinaryOperatorType.Add:
switch (innerOperator)
{
case BinaryOperatorType.Subtract:
binaryOperatorExpression.ReplaceWith(((AstNode)match.Get("other").First()).Clone());
return;
}
break;
case BinaryOperatorType.Subtract:
switch (innerOperator)
{
case BinaryOperatorType.Add:
binaryOperatorExpression.ReplaceWith(((AstNode)match.Get("other").First()).Clone());
return;
}
break;
}
}
// Looking for patterns like:
//
// (x - (2 + x))
pattern = new BinaryOperatorExpression
{
Left = new NamedNode("ident", new IdentifierExpression
{
Identifier = Pattern.AnyString
}),
Operator = BinaryOperatorType.Any,
Right = new ParenthesizedExpression
{
Expression = new BinaryOperatorExpression
{
Left = new AnyNode("other"),
Operator = BinaryOperatorType.Any,
Right = new IdentifierExpressionBackreference("ident")
}
}
};
if (pattern.IsMatch(binaryOperatorExpression))
{
var match = pattern.Match(binaryOperatorExpression);
var innerOperator = (BinaryOperatorType)((dynamic)binaryOperatorExpression).Right.Expression.Operator;
var outerOperator = binaryOperatorExpression.Operator;
switch (outerOperator)
{
case BinaryOperatorType.Subtract:
switch (innerOperator)
{
case BinaryOperatorType.Add:
binaryOperatorExpression.ReplaceWith(((AstNode)match.Get("other").First()).Clone());
return;
}
break;
}
}
// Looking for patterns like:
//
// (x - (x - 2))
pattern = new BinaryOperatorExpression
{
Left = new NamedNode(
"ident",
new IdentifierExpression
{
Identifier = Pattern.AnyString
}),
Operator = BinaryOperatorType.Any,
Right = new ParenthesizedExpression
{
Expression = new BinaryOperatorExpression
{
Left = new IdentifierExpressionBackreference("ident"),
Operator = BinaryOperatorType.Any,
Right = new AnyNode("other")
}
}
};
if (pattern.IsMatch(binaryOperatorExpression))
{
var match = pattern.Match(binaryOperatorExpression);
var innerOperator = (BinaryOperatorType)((dynamic) binaryOperatorExpression).Right.Expression.Operator;
var outerOperator = binaryOperatorExpression.Operator;
switch (outerOperator)
{
case BinaryOperatorType.Subtract:
switch (innerOperator)
{
case BinaryOperatorType.Subtract:
binaryOperatorExpression.ReplaceWith(((AstNode)match.Get("other").First()).Clone());
return;
}
break;
}
}
}
