From c7652b708852cfb7091791085b6836115ea8c69b Mon Sep 17 00:00:00 2001
From: Daniel Jasper <djasper@google.com>
Date: Mon, 23 Nov 2015 08:33:48 +0000
Subject: [PATCH] Fix calculation of shifted cursor/code positions.
 Specifically support the case where a specific range is replaced by new text.
 Previously, the calculation would shift any position from within a replaced
 region to the first character after the region. This is undersirable, e.g.
 for clang-format's include sorting.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@253859 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Tooling/Core/Replacement.cpp      | 40 +++++++++++++--------------
 unittests/Tooling/RefactoringTest.cpp | 21 ++++++++++----
 2 files changed, 34 insertions(+), 27 deletions(-)

diff --git a/lib/Tooling/Core/Replacement.cpp b/lib/Tooling/Core/Replacement.cpp
index 301c7b71ca..47bbdeb470 100644
--- a/lib/Tooling/Core/Replacement.cpp
+++ b/lib/Tooling/Core/Replacement.cpp
@@ -143,34 +143,32 @@ void Replacement::setFromSourceRange(const SourceManager &Sources,
                         ReplacementText);
 }
 
-unsigned shiftedCodePosition(const Replacements &Replaces, unsigned Position) {
-  unsigned NewPosition = Position;
-  for (Replacements::iterator I = Replaces.begin(), E = Replaces.end(); I != E;
-       ++I) {
-    if (I->getOffset() >= Position)
-      break;
-    if (I->getOffset() + I->getLength() > Position)
-      NewPosition += I->getOffset() + I->getLength() - Position;
-    NewPosition += I->getReplacementText().size() - I->getLength();
+template <typename T>
+unsigned shiftedCodePositionInternal(const T &Replaces, unsigned Position) {
+  unsigned Offset = 0;
+  for (const auto& R : Replaces) {
+    if (R.getOffset() + R.getLength() <= Position) {
+      Offset += R.getReplacementText().size() - R.getLength();
+      continue;
+    }
+    if (R.getOffset() < Position &&
+        R.getOffset() + R.getReplacementText().size() <= Position) {
+      Position = R.getOffset() + R.getReplacementText().size() - 1;
+    }
+    break;
   }
-  return NewPosition;
+  return Position + Offset;
+}
+
+unsigned shiftedCodePosition(const Replacements &Replaces, unsigned Position) {
+  return shiftedCodePositionInternal(Replaces, Position);
 }
 
 // FIXME: Remove this function when Replacements is implemented as std::vector
 // instead of std::set.
 unsigned shiftedCodePosition(const std::vector<Replacement> &Replaces,
                              unsigned Position) {
-  unsigned NewPosition = Position;
-  for (std::vector<Replacement>::const_iterator I = Replaces.begin(),
-                                                E = Replaces.end();
-       I != E; ++I) {
-    if (I->getOffset() >= Position)
-      break;
-    if (I->getOffset() + I->getLength() > Position)
-      NewPosition += I->getOffset() + I->getLength() - Position;
-    NewPosition += I->getReplacementText().size() - I->getLength();
-  }
-  return NewPosition;
+  return shiftedCodePositionInternal(Replaces, Position);
 }
 
 void deduplicate(std::vector<Replacement> &Replaces,
diff --git a/unittests/Tooling/RefactoringTest.cpp b/unittests/Tooling/RefactoringTest.cpp
index d9a87a5690..ff11aeae11 100644
--- a/unittests/Tooling/RefactoringTest.cpp
+++ b/unittests/Tooling/RefactoringTest.cpp
@@ -176,8 +176,8 @@ TEST(ShiftedCodePositionTest, FindsNewCodePosition) {
   EXPECT_EQ(1u, shiftedCodePosition(Replaces, 2)); //  i|t   i;
   EXPECT_EQ(2u, shiftedCodePosition(Replaces, 3)); //  in|   i;
   EXPECT_EQ(3u, shiftedCodePosition(Replaces, 4)); //  int|  i;
-  EXPECT_EQ(4u, shiftedCodePosition(Replaces, 5)); //  int | i;
-  EXPECT_EQ(4u, shiftedCodePosition(Replaces, 6)); //  int  |i;
+  EXPECT_EQ(3u, shiftedCodePosition(Replaces, 5)); //  int | i;
+  EXPECT_EQ(3u, shiftedCodePosition(Replaces, 6)); //  int  |i;
   EXPECT_EQ(4u, shiftedCodePosition(Replaces, 7)); //  int   |;
   EXPECT_EQ(5u, shiftedCodePosition(Replaces, 8)); //  int   i|
 }
@@ -195,8 +195,8 @@ TEST(ShiftedCodePositionTest, VectorFindsNewCodePositionWithInserts) {
   EXPECT_EQ(1u, shiftedCodePosition(Replaces, 2)); //  i|t   i;
   EXPECT_EQ(2u, shiftedCodePosition(Replaces, 3)); //  in|   i;
   EXPECT_EQ(3u, shiftedCodePosition(Replaces, 4)); //  int|  i;
-  EXPECT_EQ(4u, shiftedCodePosition(Replaces, 5)); //  int | i;
-  EXPECT_EQ(4u, shiftedCodePosition(Replaces, 6)); //  int  |i;
+  EXPECT_EQ(3u, shiftedCodePosition(Replaces, 5)); //  int | i;
+  EXPECT_EQ(3u, shiftedCodePosition(Replaces, 6)); //  int  |i;
   EXPECT_EQ(4u, shiftedCodePosition(Replaces, 7)); //  int   |;
   EXPECT_EQ(5u, shiftedCodePosition(Replaces, 8)); //  int   i|
 }
@@ -205,8 +205,17 @@ TEST(ShiftedCodePositionTest, FindsNewCodePositionWithInserts) {
   Replacements Replaces;
   Replaces.insert(Replacement("", 4, 0, "\"\n\""));
   // Assume '"12345678"' is turned into '"1234"\n"5678"'.
-  EXPECT_EQ(4u, shiftedCodePosition(Replaces, 4)); // "123|5678"
-  EXPECT_EQ(8u, shiftedCodePosition(Replaces, 5)); // "1234|678"
+  EXPECT_EQ(3u, shiftedCodePosition(Replaces, 3)); // "123|5678"
+  EXPECT_EQ(7u, shiftedCodePosition(Replaces, 4)); // "1234|678"
+  EXPECT_EQ(8u, shiftedCodePosition(Replaces, 5)); // "12345|78"
+}
+
+TEST(ShiftedCodePositionTest, FindsNewCodePositionInReplacedText) {
+  Replacements Replaces;
+  // Replace the first four characters with "abcd".
+  Replaces.insert(Replacement("", 0, 4, "abcd"));
+  for (unsigned i = 0; i < 3; ++i)
+    EXPECT_EQ(i, shiftedCodePosition(Replaces, i));
 }
 
 class FlushRewrittenFilesTest : public ::testing::Test {
-- 
2.40.0