[libTooling] Add `run` combinator to Stencils.

Summary:
This revision adds `run`, a StencilPart that runs a user-defined function that
computes a result over `MatchFinder::MatchResult`.

Reviewers: gribozavr

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67969

llvm-svn: 372936

1 files changed, 22 insertions, 0 deletions

diff --git a/clang/lib/Tooling/Refactoring/Stencil.cpp b/clang/lib/Tooling/Refactoring/Stencil.cpp
index 0e5eaccc7b7..78239b96d3c 100644
--- a/clang/lib/Tooling/Refactoring/Stencil.cpp
+++ b/clang/lib/Tooling/Refactoring/Stencil.cpp
@@ -26,6 +26,7 @@ using namespace tooling;
 using ast_matchers::MatchFinder;
 using llvm::errc;
 using llvm::Error;
+using llvm::Expected;
 using llvm::StringError;
 
 // A down_cast function to safely down cast a StencilPartInterface to a subclass
@@ -102,6 +103,12 @@ bool isEqualData(const IfBoundData &A, const IfBoundData &B) {
   return A.Id == B.Id && A.TruePart == B.TruePart && A.FalsePart == B.FalsePart;
 }
 
+// Equality is not defined over MatchConsumers, which are opaque.
+bool isEqualData(const MatchConsumer<std::string> &A,
+                 const MatchConsumer<std::string> &B) {
+  return false;
+}
+
 // The `evalData()` overloads evaluate the given stencil data to a string, given
 // the match result, and append it to `Result`. We define an overload for each
 // type of stencil data.
@@ -159,6 +166,15 @@ Error evalData(const IfBoundData &Data, const MatchFinder::MatchResult &Match,
       .eval(Match, Result);
 }
 
+Error evalData(const MatchConsumer<std::string> &Fn,
+               const MatchFinder::MatchResult &Match, std::string *Result) {
+  Expected<std::string> Value = Fn(Match);
+  if (!Value)
+    return Value.takeError();
+  *Result += *Value;
+  return Error::success();
+}
+
 template <typename T>
 class StencilPartImpl : public StencilPartInterface {
   T Data;
@@ -233,3 +249,9 @@ StencilPart stencil::ifBound(StringRef Id, StencilPart TruePart,
   return StencilPart(std::make_shared<StencilPartImpl<IfBoundData>>(
       Id, std::move(TruePart), std::move(FalsePart)));
 }
+
+StencilPart stencil::run(MatchConsumer<std::string> Fn) {
+  return StencilPart(
+      std::make_shared<StencilPartImpl<MatchConsumer<std::string>>>(
+          std::move(Fn)));
+}