AST Pattern matching

ast-matching.groovy

// "macro" builds the AST of the corresponding block
def ast1 = macro { foo(a) + foo(a) }
def ast2 = macro { foo(a) + foo(foo(a)) }

// we build another AST which will be used as a pattern
def pattern = macro {
    x + foo(x)
}.withConstraints {
    // declare that x is not a variable, but a placeholder
    placeholder x
}

assert !ast1.matches(pattern) // then the first AST doesn't match the pattern
assert ast2.matches(pattern) // but the second one does!

It's awesome!