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(int I = 0) const { return End - Ptr <= I ? 0 : Ptr[I]; }
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 static Cursor lexPercent(Cursor C, MIToken &Token) {
73 C.advance(); // Skip '%'
74 while (isIdentifierChar(C.peek()))
76 Token = MIToken(MIToken::NamedRegister, Range.upto(C));
80 static Cursor lexIntegerLiteral(Cursor C, MIToken &Token) {
83 while (isdigit(C.peek()))
85 StringRef StrVal = Range.upto(C);
86 Token = MIToken(MIToken::IntegerLiteral, StrVal, APSInt(StrVal));
90 static MIToken::TokenKind symbolToken(char C) {
93 return MIToken::comma;
95 return MIToken::equal;
97 return MIToken::Error;
101 static Cursor lexSymbol(Cursor C, MIToken::TokenKind Kind, MIToken &Token) {
104 Token = MIToken(Kind, Range.upto(C));
108 StringRef llvm::lexMIToken(
109 StringRef Source, MIToken &Token,
110 function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
111 auto C = skipWhitespace(Cursor(Source));
113 Token = MIToken(MIToken::Eof, C.remaining());
114 return C.remaining();
117 auto Char = C.peek();
118 if (isalpha(Char) || Char == '_')
119 return lexIdentifier(C, Token).remaining();
121 return lexPercent(C, Token).remaining();
122 if (isdigit(Char) || (Char == '-' && isdigit(C.peek(1))))
123 return lexIntegerLiteral(C, Token).remaining();
124 MIToken::TokenKind Kind = symbolToken(Char);
125 if (Kind != MIToken::Error)
126 return lexSymbol(C, Kind, Token).remaining();
127 Token = MIToken(MIToken::Error, C.remaining());
128 ErrorCallback(C.location(),
129 Twine("unexpected character '") + Twine(Char) + "'");
130 return C.remaining();