[PATCH] Add support for polymorphic matchers.

[Manuel Klimek]

On Tue, May 14, 2013 at 9:35 PM, Samuel Benzaquen <sbenza at google.com> wrote:

>
>
> ================
> Comment at: lib/ASTMatchers/Dynamic/DynMatchers.cpp:35
> @@ +34,3 @@
> +          ast_matchers::internal::BoundNodesTreeBuilder *Builder) const {
> +    return M1->matches(DynNode, Finder, Builder) ||
> +        M2->matches(DynNode, Finder, Builder);
> ----------------
> Manuel Klimek wrote:
> > How much harder would it be to not re-implement the matchers? I'd like
> to keep matcher implementations as cohesive as possible, as we want to be
> able to change the implementations when we introduce new features.
> The ones that are easier to reimplement are the ones that are way too
> generic, like anything() or equals().
>
> anything() returns a polymorphic matcher which is not a DynTypedMatcher.
> I don't have specific Ts to create a Matcher<T> from anything(). I could
> list all possible types (the ones that DynTypedNode supports) and merge
> them, but it seemed to me that a reimplementation of it would be simpler.
>

I agree it's easier to implement. I don't agree it'll be easier to
maintain. The problem is that some matchers (forEach*, has, etc) have
specific ways in which they affect binding of nodes. I definitely don't
want to duplicate that logic anywhere. Thus, I'd prefer if we'd find a way
to support those fully polymorphic matchers by generating the dynamic ones
for all types they can possibly match on (perhaps we can just wrap them
with something that works on DynTypedMatcher?)
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