[LibTooling] Add `before` and `after` selectors for selecting point-ranges relative to nodes.

Summary:
The `before` and `after` selectors allow users to specify a zero-length range --
a point -- at the relevant location in an AST-node's source.  Point ranges can
be useful, for example, to insert a change using an API that takes a range to be
modified (e.g. `tooling::change()`).

Reviewers: ilya-biryukov

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62419

llvm-svn: 361955

1 files changed, 22 insertions, 0 deletions

diff --git a/clang/lib/Tooling/Refactoring/RangeSelector.cpp b/clang/lib/Tooling/Refactoring/RangeSelector.cpp
index d5f82d4262b..768c02e2277 100644
--- a/clang/lib/Tooling/Refactoring/RangeSelector.cpp
+++ b/clang/lib/Tooling/Refactoring/RangeSelector.cpp
@@ -104,6 +104,28 @@ static SourceLocation findOpenParen(const CallExpr &E, const SourceManager &SM,
   return findPreviousTokenKind(EndLoc, SM, LangOpts, tok::TokenKind::l_paren);
 }
 
+RangeSelector tooling::before(RangeSelector Selector) {
+  return [Selector](const MatchResult &Result) -> Expected<CharSourceRange> {
+    Expected<CharSourceRange> SelectedRange = Selector(Result);
+    if (!SelectedRange)
+      return SelectedRange.takeError();
+    return CharSourceRange::getCharRange(SelectedRange->getBegin());
+  };
+}
+
+RangeSelector tooling::after(RangeSelector Selector) {
+  return [Selector](const MatchResult &Result) -> Expected<CharSourceRange> {
+    Expected<CharSourceRange> SelectedRange = Selector(Result);
+    if (!SelectedRange)
+      return SelectedRange.takeError();
+    if (SelectedRange->isCharRange())
+      return CharSourceRange::getCharRange(SelectedRange->getEnd());
+    return CharSourceRange::getCharRange(Lexer::getLocForEndOfToken(
+        SelectedRange->getEnd(), 0, Result.Context->getSourceManager(),
+        Result.Context->getLangOpts()));
+  };
+}
+
 RangeSelector tooling::node(std::string ID) {
   return [ID](const MatchResult &Result) -> Expected<CharSourceRange> {
     Expected<DynTypedNode> Node = getNode(Result.Nodes, ID);