[LibTooling] Add insert/remove convenience functions for creating `ASTEdit`s.

Summary: `change()` is an all purpose function; the revision adds simple shortcuts for the specific operations of inserting (before/after) or removing source.

Reviewers: ilya-biryukov

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62621

llvm-svn: 362707

2 files changed, 75 insertions, 0 deletions

diff --git a/clang/include/clang/Tooling/Refactoring/Transformer.h b/clang/include/clang/Tooling/Refactoring/Transformer.h
index e66dd055024..1b71d1541d0 100644
--- a/clang/include/clang/Tooling/Refactoring/Transformer.h
+++ b/clang/include/clang/Tooling/Refactoring/Transformer.h
@@ -193,6 +193,23 @@ inline ASTEdit change(TextGenerator Replacement) {
   return change(node(RewriteRule::RootID), std::move(Replacement));
 }
 
+/// Inserts \p Replacement before \p S, leaving the source selected by \S
+/// unchanged.
+inline ASTEdit insertBefore(RangeSelector S, TextGenerator Replacement) {
+  return change(before(std::move(S)), std::move(Replacement));
+}
+
+/// Inserts \p Replacement after \p S, leaving the source selected by \S
+/// unchanged.
+inline ASTEdit insertAfter(RangeSelector S, TextGenerator Replacement) {
+  return change(after(std::move(S)), std::move(Replacement));
+}
+
+/// Removes the source selected by \p S.
+inline ASTEdit remove(RangeSelector S) {
+  return change(std::move(S), text(""));
+}
+
 /// The following three functions are a low-level part of the RewriteRule
 /// API. We expose them for use in implementing the fixtures that interpret
 /// RewriteRule, like Transformer and TransfomerTidy, or for more advanced
diff --git a/clang/unittests/Tooling/TransformerTest.cpp b/clang/unittests/Tooling/TransformerTest.cpp
index 41c7e7a28bd..e9de00d22a5 100644
--- a/clang/unittests/Tooling/TransformerTest.cpp
+++ b/clang/unittests/Tooling/TransformerTest.cpp
@@ -349,6 +349,64 @@ TEST_F(TransformerTest, NodePartMemberMultiToken) {
            Input, Expected);
 }
 
+TEST_F(TransformerTest, InsertBeforeEdit) {
+  std::string Input = R"cc(
+    int f() {
+      return 7;
+    }
+  )cc";
+  std::string Expected = R"cc(
+    int f() {
+      int y = 3;
+      return 7;
+    }
+  )cc";
+
+  StringRef Ret = "return";
+  testRule(makeRule(returnStmt().bind(Ret),
+                    insertBefore(statement(Ret), text("int y = 3;"))),
+           Input, Expected);
+}
+
+TEST_F(TransformerTest, InsertAfterEdit) {
+  std::string Input = R"cc(
+    int f() {
+      int x = 5;
+      return 7;
+    }
+  )cc";
+  std::string Expected = R"cc(
+    int f() {
+      int x = 5;
+      int y = 3;
+      return 7;
+    }
+  )cc";
+
+  StringRef Decl = "decl";
+  testRule(makeRule(declStmt().bind(Decl),
+                    insertAfter(statement(Decl), text("int y = 3;"))),
+           Input, Expected);
+}
+
+TEST_F(TransformerTest, RemoveEdit) {
+  std::string Input = R"cc(
+    int f() {
+      int x = 5;
+      return 7;
+    }
+  )cc";
+  std::string Expected = R"cc(
+    int f() {
+      return 7;
+    }
+  )cc";
+
+  StringRef Decl = "decl";
+  testRule(makeRule(declStmt().bind(Decl), remove(statement(Decl))), Input,
+           Expected);
+}
+
 TEST_F(TransformerTest, MultiChange) {
   std::string Input = R"cc(
     void foo() {