[AsmParser] Allow tokens to be put back in to the token stream.

Differential Revision: http://reviews.llvm.org/D14252

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252432 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/MC/MCParser/MCAsmLexer.h b/include/llvm/MC/MCParser/MCAsmLexer.h
index a9a9357f827b2ff436890216cc825378c3a14ea6..55279f49529af91046f671d337227f69908e3a8f 100644 (file)
--- a/include/llvm/MC/MCParser/MCAsmLexer.h
+++ b/include/llvm/MC/MCParser/MCAsmLexer.h
@@ -118,7 +118,7 @@ public:
 /// lexers.
 class MCAsmLexer {
   /// The current token, stored in the base class for faster access.
-  AsmToken CurTok;
+  SmallVector<AsmToken, 1> CurTok;
 
   /// The location and description of the current error
   SMLoc ErrLoc;
@@ -148,7 +148,15 @@ public:
   /// The lexer will continuosly return the end-of-file token once the end of
   /// the main input file has been reached.
   const AsmToken &Lex() {
-    return CurTok = LexToken();
+    assert(!CurTok.empty());
+    CurTok.erase(CurTok.begin());
+    if (CurTok.empty())
+      CurTok.emplace_back(LexToken());
+    return CurTok.front();
+  }
+
+  void UnLex(AsmToken const &Token) {
+    CurTok.insert(CurTok.begin(), Token);
   }
 
   virtual StringRef LexUntilEndOfStatement() = 0;
@@ -158,7 +166,7 @@ public:
 
   /// Get the current (last) lexed token.
   const AsmToken &getTok() const {
-    return CurTok;
+    return CurTok[0];
   }
 
   /// Look ahead at the next token to be lexed.

diff --git a/lib/MC/MCParser/MCAsmLexer.cpp b/lib/MC/MCParser/MCAsmLexer.cpp
index 795cc85ef5477fd39acb09929a60defb825c6131..e891bd2c6240a06635bae268b7318fd296c0582b 100644 (file)
--- a/lib/MC/MCParser/MCAsmLexer.cpp
+++ b/lib/MC/MCParser/MCAsmLexer.cpp
@@ -12,8 +12,8 @@
 
 using namespace llvm;
 
-MCAsmLexer::MCAsmLexer() : CurTok(AsmToken::Error, StringRef()),
-                           TokStart(nullptr), SkipSpace(true) {
+MCAsmLexer::MCAsmLexer() : TokStart(nullptr), SkipSpace(true) {
+  CurTok.emplace_back(AsmToken::Error, StringRef());
 }
 
 MCAsmLexer::~MCAsmLexer() {