public static void Rewriter_Usage()
{
//this example shows how to create/use rewriter
//create rewriter
var rewriter = new ExpressionRewriter();
//use rewriter.AppendRule(from,to) to set rule
//below is to distribute the multiplication
rewriter.AppendRule <Func <int, int, int, int> >(
(a, b, c) => a * (b + c),
(a, b, c) => (a * b) + (a * c));
//create expression
Expression <Func <int, int, int> > exp = (a, b) => a * (b + 1);
//use rewriter.Rewrite() to rewrite expression
Console.WriteLine("Before rewrite: {0}", exp.Body);
Console.WriteLine("After rewrite: {0}", rewriter.Rewrite(exp.Body));
}
public static void Rewriter_AppendRule_With_Condition()
{
//this example shows how to append rule with condition
//create rewriter
var rewriter = new ExpressionRewriter();
//use rewriter.AppendRule(condition,from,to) to set rule with condition
//below is to swap is 'a' is parameter and 'b' is constant
rewriter.AppendRule <Func <int, int, int> >(
param => param["a"].NodeType == ExpressionType.Parameter && param["b"].NodeType == ExpressionType.Constant,
(a, b) => a * b,
(a, b) => b * a);
//create expression
Expression <Func <int, int> > exp = x => x * 5;
//use rewriter.Rewrite() to rewrite expression
Console.WriteLine("Before rewrite: {0}", exp.Body);
Console.WriteLine("After rewrite: {0}", rewriter.Rewrite(exp.Body));
}