some baby steps.

llvm-svn: 73848

1 files changed, 87 insertions, 0 deletions

diff --git a/llvm/tools/llvm-mc/AsmLexer.cpp b/llvm/tools/llvm-mc/AsmLexer.cpp
new file mode 100644
index 00000000000..da86465d7fe
--- /dev/null
+++ b/llvm/tools/llvm-mc/AsmLexer.cpp
@@ -0,0 +1,87 @@
+//===- AsmLexer.cpp - Lexer for Assembly Files ----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class implements the lexer for assembly files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AsmLexer.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/MemoryBuffer.h"
+using namespace llvm;
+
+AsmLexer::AsmLexer(SourceMgr &SM) : SrcMgr(SM) {
+  CurBuffer = 0;
+  CurBuf = SrcMgr.getMemoryBuffer(CurBuffer);
+  CurPtr = CurBuf->getBufferStart();
+  TokStart = 0;
+}
+
+void AsmLexer::PrintError(const char *Loc, const std::string &Msg) const {
+  SrcMgr.PrintError(SMLoc::getFromPointer(Loc), Msg);
+}
+
+void AsmLexer::PrintError(SMLoc Loc, const std::string &Msg) const {
+  SrcMgr.PrintError(Loc, Msg);
+}
+
+int AsmLexer::getNextChar() {
+  char CurChar = *CurPtr++;
+  switch (CurChar) {
+  default:
+    return (unsigned char)CurChar;
+  case 0: {
+    // A nul character in the stream is either the end of the current buffer or
+    // a random nul in the file.  Disambiguate that here.
+    if (CurPtr-1 != CurBuf->getBufferEnd())
+      return 0;  // Just whitespace.
+    
+    // If this is the end of an included file, pop the parent file off the
+    // include stack.
+    SMLoc ParentIncludeLoc = SrcMgr.getParentIncludeLoc(CurBuffer);
+    if (ParentIncludeLoc != SMLoc()) {
+      CurBuffer = SrcMgr.FindBufferContainingLoc(ParentIncludeLoc);
+      CurBuf = SrcMgr.getMemoryBuffer(CurBuffer);
+      CurPtr = ParentIncludeLoc.getPointer();
+      return getNextChar();
+    }
+    
+    // Otherwise, return end of file.
+    --CurPtr;  // Another call to lex will return EOF again.  
+    return EOF;
+  }
+  }
+}
+
+asmtok::TokKind AsmLexer::LexToken() {
+  TokStart = CurPtr;
+  // This always consumes at least one character.
+  int CurChar = getNextChar();
+  
+  switch (CurChar) {
+  default:
+    // Handle letters: [a-zA-Z_]
+//    if (isalpha(CurChar) || CurChar == '_' || CurChar == '#')
+//      return LexIdentifier();
+    
+    // Unknown character, emit an error.
+    return asmtok::Error;
+  case EOF: return asmtok::Eof;
+  case 0:
+  case ' ':
+  case '\t':
+  case '\n':
+  case '\r':
+    // Ignore whitespace.
+    return LexToken();
+  case ':': return asmtok::Colon;
+  case '+': return asmtok::Plus;
+  case '-': return asmtok::Minus;
+  }
+}
\ No newline at end of file