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f654cdae59
This commit adds a function that tokenizes the string containing the machine instruction. This commit also adds a struct called 'MIToken' which is used to represent the lexer's tokens. Reviewers: Sean Silva Differential Revision: http://reviews.llvm.org/D10521 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240323 91177308-0d34-0410-b5e6-96231b3b80d8
88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
//===- MILexer.cpp - Machine instructions lexer implementation ----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the lexing of machine instructions.
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//
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//===----------------------------------------------------------------------===//
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#include "MILexer.h"
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#include "llvm/ADT/Twine.h"
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#include <cctype>
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using namespace llvm;
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namespace {
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/// This class provides a way to iterate and get characters from the source
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/// string.
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class Cursor {
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const char *Ptr;
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const char *End;
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public:
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explicit Cursor(StringRef Str) {
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Ptr = Str.data();
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End = Ptr + Str.size();
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}
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bool isEOF() const { return Ptr == End; }
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char peek() const { return isEOF() ? 0 : *Ptr; }
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void advance() { ++Ptr; }
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StringRef remaining() const { return StringRef(Ptr, End - Ptr); }
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StringRef upto(Cursor C) const {
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assert(C.Ptr >= Ptr && C.Ptr <= End);
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return StringRef(Ptr, C.Ptr - Ptr);
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}
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StringRef::iterator location() const { return Ptr; }
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};
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} // end anonymous namespace
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/// Skip the leading whitespace characters and return the updated cursor.
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static Cursor skipWhitespace(Cursor C) {
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while (isspace(C.peek()))
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C.advance();
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return C;
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}
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static bool isIdentifierChar(char C) {
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return isalpha(C) || isdigit(C) || C == '_' || C == '-' || C == '.';
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}
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static Cursor lexIdentifier(Cursor C, MIToken &Token) {
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auto Range = C;
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while (isIdentifierChar(C.peek()))
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C.advance();
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Token = MIToken(MIToken::Identifier, Range.upto(C));
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return C;
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}
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StringRef llvm::lexMIToken(
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StringRef Source, MIToken &Token,
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function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
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auto C = skipWhitespace(Cursor(Source));
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if (C.isEOF()) {
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Token = MIToken(MIToken::Eof, C.remaining());
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return C.remaining();
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}
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auto Char = C.peek();
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if (isalpha(Char) || Char == '_')
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return lexIdentifier(C, Token).remaining();
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Token = MIToken(MIToken::Error, C.remaining());
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ErrorCallback(C.location(),
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Twine("unexpected character '") + Twine(Char) + "'");
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return C.remaining();
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}
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