From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Wed, 12 Oct 2011 00:37:51 +0000 (+0000)
Subject: Handle Perforce-style conflict markers like normal conflict markers. Perforce
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d5e1d606f8c22ebda17c6fbf952f8c1696428758;p=clang

Handle Perforce-style conflict markers like normal conflict markers. Perforce
swaps over the <<<< and >>>> markers, and uses shorter markers than traditional
tools.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141751 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Lex/Lexer.h b/include/clang/Lex/Lexer.h
index e67013c10e..e01427f574 100644
--- a/include/clang/Lex/Lexer.h
+++ b/include/clang/Lex/Lexer.h
@@ -26,6 +26,19 @@ class SourceManager;
 class Preprocessor;
 class DiagnosticBuilder;
 
+/// ConflictMarkerKind - Kinds of conflict marker which the lexer might be
+/// recovering from.
+enum ConflictMarkerKind {
+  /// Not within a conflict marker.
+  CMK_None,
+  /// A normal or diff3 conflict marker, initiated by at least 7 <s,
+  /// separated by at least 7 =s or |s, and terminated by at least 7 >s.
+  CMK_Normal,
+  /// A Perforce-style conflict marker, initiated by 4 >s, separated by 4 =s,
+  /// and terminated by 4 <s.
+  CMK_Perforce
+};
+
 /// Lexer - This provides a simple interface that turns a text buffer into a
 /// stream of tokens.  This provides no support for file reading or buffering,
 /// or buffering/seeking of tokens, only forward lexing is supported.  It relies
@@ -37,8 +50,7 @@ class Lexer : public PreprocessorLexer {
   const char *BufferEnd;         // End of the buffer.
   SourceLocation FileLoc;        // Location for start of file.
   LangOptions Features;          // Features enabled by this language (cache).
-  bool Is_PragmaLexer : 1;       // True if lexer for _Pragma handling.
-  bool IsInConflictMarker : 1;   // True if in a VCS conflict marker '<<<<<<<'
+  bool Is_PragmaLexer;           // True if lexer for _Pragma handling.
   
   //===--------------------------------------------------------------------===//
   // Context-specific lexing flags set by the preprocessor.
@@ -66,6 +78,9 @@ class Lexer : public PreprocessorLexer {
   // line" flag set on it.
   bool IsAtStartOfLine;
 
+  // CurrentConflictMarkerState - The kind of conflict marker we are handling.
+  ConflictMarkerKind CurrentConflictMarkerState;
+
   Lexer(const Lexer&);          // DO NOT IMPLEMENT
   void operator=(const Lexer&); // DO NOT IMPLEMENT
   friend class Preprocessor;
diff --git a/lib/Lex/Lexer.cpp b/lib/Lex/Lexer.cpp
index 6b69e57074..c7a3df50bc 100644
--- a/lib/Lex/Lexer.cpp
+++ b/lib/Lex/Lexer.cpp
@@ -86,7 +86,7 @@ void Lexer::InitLexer(const char *BufStart, const char *BufPtr,
   }
 
   Is_PragmaLexer = false;
-  IsInConflictMarker = false;
+  CurrentConflictMarkerState = CMK_None;
 
   // Start of the file is a start of line.
   IsAtStartOfLine = true;
@@ -2149,15 +2149,18 @@ unsigned Lexer::isNextPPTokenLParen() {
 }
 
 /// FindConflictEnd - Find the end of a version control conflict marker.
-static const char *FindConflictEnd(const char *CurPtr, const char *BufferEnd) {
-  StringRef RestOfBuffer(CurPtr+7, BufferEnd-CurPtr-7);
-  size_t Pos = RestOfBuffer.find(">>>>>>>");
+static const char *FindConflictEnd(const char *CurPtr, const char *BufferEnd,
+                                   ConflictMarkerKind CMK) {
+  const char *Terminator = CMK == CMK_Perforce ? "<<<<\n" : ">>>>>>>";
+  size_t TermLen = CMK == CMK_Perforce ? 5 : 7;
+  StringRef RestOfBuffer(CurPtr+TermLen, BufferEnd-CurPtr-TermLen);
+  size_t Pos = RestOfBuffer.find(Terminator);
   while (Pos != StringRef::npos) {
     // Must occur at start of line.
     if (RestOfBuffer[Pos-1] != '\r' &&
         RestOfBuffer[Pos-1] != '\n') {
-      RestOfBuffer = RestOfBuffer.substr(Pos+7);
-      Pos = RestOfBuffer.find(">>>>>>>");
+      RestOfBuffer = RestOfBuffer.substr(Pos+TermLen);
+      Pos = RestOfBuffer.find(Terminator);
       continue;
     }
     return RestOfBuffer.data()+Pos;
@@ -2175,23 +2178,25 @@ bool Lexer::IsStartOfConflictMarker(const char *CurPtr) {
       CurPtr[-1] != '\n' && CurPtr[-1] != '\r')
     return false;
   
-  // Check to see if we have <<<<<<<.
-  if (BufferEnd-CurPtr < 8 ||
-      StringRef(CurPtr, 7) != "<<<<<<<")
+  // Check to see if we have <<<<<<< or >>>>.
+  if ((BufferEnd-CurPtr < 8 || StringRef(CurPtr, 7) != "<<<<<<<") &&
+      (BufferEnd-CurPtr < 6 || StringRef(CurPtr, 5) != ">>>> "))
     return false;
 
   // If we have a situation where we don't care about conflict markers, ignore
   // it.
-  if (IsInConflictMarker || isLexingRawMode())
+  if (CurrentConflictMarkerState || isLexingRawMode())
     return false;
   
-  // Check to see if there is a >>>>>>> somewhere in the buffer at the start of
-  // a line to terminate this conflict marker.
-  if (FindConflictEnd(CurPtr, BufferEnd)) {
+  ConflictMarkerKind Kind = *CurPtr == '<' ? CMK_Normal : CMK_Perforce;
+
+  // Check to see if there is an ending marker somewhere in the buffer at the
+  // start of a line to terminate this conflict marker.
+  if (FindConflictEnd(CurPtr, BufferEnd, Kind)) {
     // We found a match.  We are really in a conflict marker.
     // Diagnose this, and ignore to the end of line.
     Diag(CurPtr, diag::err_conflict_marker);
-    IsInConflictMarker = true;
+    CurrentConflictMarkerState = Kind;
     
     // Skip ahead to the end of line.  We know this exists because the
     // end-of-conflict marker starts with \r or \n.
@@ -2208,10 +2213,10 @@ bool Lexer::IsStartOfConflictMarker(const char *CurPtr) {
 }
 
 
-/// HandleEndOfConflictMarker - If this is a '=======' or '|||||||' or '>>>>>>>'
-/// marker, then it is the end of a conflict marker.  Handle it by ignoring up
-/// until the end of the line.  This returns true if it is a conflict marker and
-/// false if not.
+/// HandleEndOfConflictMarker - If this is a '====' or '||||' or '>>>>', or if
+/// it is '<<<<' and the conflict marker started with a '>>>>' marker, then it
+/// is the end of a conflict marker.  Handle it by ignoring up until the end of
+/// the line.  This returns true if it is a conflict marker and false if not.
 bool Lexer::HandleEndOfConflictMarker(const char *CurPtr) {
   // Only a conflict marker if it starts at the beginning of a line.
   if (CurPtr != BufferStart &&
@@ -2220,18 +2225,19 @@ bool Lexer::HandleEndOfConflictMarker(const char *CurPtr) {
   
   // If we have a situation where we don't care about conflict markers, ignore
   // it.
-  if (!IsInConflictMarker || isLexingRawMode())
+  if (!CurrentConflictMarkerState || isLexingRawMode())
     return false;
   
-  // Check to see if we have the marker (7 characters in a row).
-  for (unsigned i = 1; i != 7; ++i)
+  // Check to see if we have the marker (4 characters in a row).
+  for (unsigned i = 1; i != 4; ++i)
     if (CurPtr[i] != CurPtr[0])
       return false;
   
   // If we do have it, search for the end of the conflict marker.  This could
   // fail if it got skipped with a '#if 0' or something.  Note that CurPtr might
   // be the end of conflict marker.
-  if (const char *End = FindConflictEnd(CurPtr, BufferEnd)) {
+  if (const char *End = FindConflictEnd(CurPtr, BufferEnd,
+                                        CurrentConflictMarkerState)) {
     CurPtr = End;
     
     // Skip ahead to the end of line.
@@ -2241,7 +2247,7 @@ bool Lexer::HandleEndOfConflictMarker(const char *CurPtr) {
     BufferPtr = CurPtr;
     
     // No longer in the conflict marker.
-    IsInConflictMarker = false;
+    CurrentConflictMarkerState = CMK_None;
     return true;
   }
   
@@ -2767,6 +2773,10 @@ LexNextToken:
         // If this is actually a '<<<<<<<' version control conflict marker,
         // recognize it as such and recover nicely.
         goto LexNextToken;
+      } else if (After == '<' && HandleEndOfConflictMarker(CurPtr-1)) {
+        // If this is '<<<<' and we're in a Perforce-style conflict marker,
+        // ignore it.
+        goto LexNextToken;
       } else if (Features.CUDA && After == '<') {
         Kind = tok::lesslessless;
         CurPtr = ConsumeChar(ConsumeChar(CurPtr, SizeTmp, Result),
@@ -2814,6 +2824,10 @@ LexNextToken:
         CurPtr = ConsumeChar(ConsumeChar(CurPtr, SizeTmp, Result),
                              SizeTmp2, Result);
         Kind = tok::greatergreaterequal;
+      } else if (After == '>' && IsStartOfConflictMarker(CurPtr-1)) {
+        // If this is actually a '>>>>' conflict marker, recognize it as such
+        // and recover nicely.
+        goto LexNextToken;
       } else if (After == '>' && HandleEndOfConflictMarker(CurPtr-1)) {
         // If this is '>>>>>>>' and we're in a conflict marker, ignore it.
         goto LexNextToken;
@@ -2872,7 +2886,7 @@ LexNextToken:
   case '=':
     Char = getCharAndSize(CurPtr, SizeTmp);
     if (Char == '=') {
-      // If this is '=======' and we're in a conflict marker, ignore it.
+      // If this is '====' and we're in a conflict marker, ignore it.
       if (CurPtr[1] == '=' && HandleEndOfConflictMarker(CurPtr-1))
         goto LexNextToken;
       
diff --git a/test/Lexer/conflict-marker.c b/test/Lexer/conflict-marker.c
index 45efdec826..2a8e43b0cb 100644
--- a/test/Lexer/conflict-marker.c
+++ b/test/Lexer/conflict-marker.c
@@ -19,12 +19,20 @@ typedef int y;
 typedef struct foo *y;
 >>>>>>> .r91107
 
+// Perforce style.
+>>>> ORIGINAL conflict-marker.c#6 // expected-error {{version control conflict marker in file}}
+int z = 1;
+==== THEIRS conflict-marker.c#7
+int z = 0;
+==== YOURS conflict-marker.c
+int z = 2;
+<<<<
+
 ;
 y b;
 
 
 int foo() {
   y a = x;
-  return x + a;
+  return x + a - z;
 }
-