[libTooling] Further simplify `Stencil` type and introduce `MatchComputation`.

Summary:
This revision introduces a new interface `MatchComputation` which generalizes
the `Stencil` interface and replaces the `std::function` interface of
`MatchConsumer`. With this revision, `Stencil` (as an abstraction) becomes just
one collection of implementations of
`MatchComputation<std::string>`. Correspondingly, we remove the `Stencil` class
entirely in favor of a simple type alias, deprecate `MatchConsumer` and change
all functions that accepted `MatchConsumer<std::string>` to use
`MatchComputation<std::string>` instead.

Reviewers: gribozavr

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69802

2 files changed, 9 insertions, 27 deletions

diff --git a/clang/unittests/Tooling/StencilTest.cpp b/clang/unittests/Tooling/StencilTest.cpp
index 5bbdfea3..7f530fe 100644
--- a/clang/unittests/Tooling/StencilTest.cpp
+++ b/clang/unittests/Tooling/StencilTest.cpp
@@ -24,7 +24,6 @@ using ::llvm::Failed;
 using ::llvm::HasValue;
 using ::llvm::StringError;
 using ::testing::AllOf;
-using ::testing::Eq;
 using ::testing::HasSubstr;
 using MatchResult = MatchFinder::MatchResult;
 
@@ -135,26 +134,6 @@ TEST_F(StencilTest, SingleStatement) {
                        HasValue("if (!true) return 0; else return 1;"));
 }
 
-// Tests `stencil`.
-TEST_F(StencilTest, StencilFactoryFunction) {
-  StringRef Condition("C"), Then("T"), Else("E");
-  const std::string Snippet = R"cc(
-    if (true)
-      return 1;
-    else
-      return 0;
-  )cc";
-  auto StmtMatch = matchStmt(
-      Snippet, ifStmt(hasCondition(expr().bind(Condition)),
-                      hasThen(stmt().bind(Then)), hasElse(stmt().bind(Else))));
-  ASSERT_TRUE(StmtMatch);
-  // Invert the if-then-else.
-  auto Consumer = cat("if (!", node(Condition), ") ", statement(Else), " else ",
-                      statement(Then));
-  EXPECT_THAT_EXPECTED(Consumer(StmtMatch->Result),
-                       HasValue("if (!true) return 0; else return 1;"));
-}
-
 TEST_F(StencilTest, UnboundNode) {
   const std::string Snippet = R"cc(
     if (true)
diff --git a/clang/unittests/Tooling/TransformerTest.cpp b/clang/unittests/Tooling/TransformerTest.cpp
index c99bf97..c382783 100644
--- a/clang/unittests/Tooling/TransformerTest.cpp
+++ b/clang/unittests/Tooling/TransformerTest.cpp
@@ -575,13 +575,16 @@ TEST_F(TransformerTest, TextGeneratorFailure) {
   std::string Input = "int conflictOneRule() { return 3 + 7; }";
   // Try to change the whole binary-operator expression AND one its operands:
   StringRef O = "O";
-  auto AlwaysFail = [](const ast_matchers::MatchFinder::MatchResult &)
-      -> llvm::Expected<std::string> {
-    return llvm::createStringError(llvm::errc::invalid_argument, "ERROR");
+  class AlwaysFail : public transformer::MatchComputation<std::string> {
+    llvm::Error eval(const ast_matchers::MatchFinder::MatchResult &,
+                     std::string *) const override {
+      return llvm::createStringError(llvm::errc::invalid_argument, "ERROR");
+    }
+    std::string toString() const override { return "AlwaysFail"; }
   };
-  Transformer T(
-      makeRule(binaryOperator().bind(O), changeTo(node(O), AlwaysFail)),
-      consumer());
+  Transformer T(makeRule(binaryOperator().bind(O),
+                         changeTo(node(O), std::make_shared<AlwaysFail>())),
+                consumer());
   T.registerMatchers(&MatchFinder);
   EXPECT_FALSE(rewrite(Input));
   EXPECT_THAT(Changes, IsEmpty());