1 //===- MILexer.cpp - Machine instructions lexer implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the lexing of machine instructions.
12 //===----------------------------------------------------------------------===//
15 #include "llvm/ADT/Twine.h"
22 /// This class provides a way to iterate and get characters from the source
29 explicit Cursor(StringRef Str) {
31 End = Ptr + Str.size();
34 bool isEOF() const { return Ptr == End; }
36 char peek() const { return isEOF() ? 0 : *Ptr; }
38 void advance() { ++Ptr; }
40 StringRef remaining() const { return StringRef(Ptr, End - Ptr); }
42 StringRef upto(Cursor C) const {
43 assert(C.Ptr >= Ptr && C.Ptr <= End);
44 return StringRef(Ptr, C.Ptr - Ptr);
47 StringRef::iterator location() const { return Ptr; }
50 } // end anonymous namespace
52 /// Skip the leading whitespace characters and return the updated cursor.
53 static Cursor skipWhitespace(Cursor C) {
54 while (isspace(C.peek()))
59 static bool isIdentifierChar(char C) {
60 return isalpha(C) || isdigit(C) || C == '_' || C == '-' || C == '.';
63 static Cursor lexIdentifier(Cursor C, MIToken &Token) {
65 while (isIdentifierChar(C.peek()))
67 Token = MIToken(MIToken::Identifier, Range.upto(C));
71 StringRef llvm::lexMIToken(
72 StringRef Source, MIToken &Token,
73 function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
74 auto C = skipWhitespace(Cursor(Source));
76 Token = MIToken(MIToken::Eof, C.remaining());
81 if (isalpha(Char) || Char == '_')
82 return lexIdentifier(C, Token).remaining();
83 Token = MIToken(MIToken::Error, C.remaining());
84 ErrorCallback(C.location(),
85 Twine("unexpected character '") + Twine(Char) + "'");