Lexer.h

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//===- Lexer.h - MLIR Lexer Interface ---------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file declares the MLIR Lexer class.
//
//===----------------------------------------------------------------------===//
 
#ifndef MLIR_LIB_ASMPARSER_LEXER_H
#define MLIR_LIB_ASMPARSER_LEXER_H
 
#include "Token.h"
#include "mlir/AsmParser/AsmParser.h"
 
namespace mlir {
class Location;
 
/// This class breaks up the current file into a token stream.
class Lexer {
public:
  explicit Lexer(const llvm::SourceMgr &sourceMgr, MLIRContext *context,
                 AsmParserCodeCompleteContext *codeCompleteContext);
 
  const llvm::SourceMgr &getSourceMgr() { return sourceMgr; }
 
  Token lexToken();
 
  /// Encode the specified source location information into a Location object
  /// for attachment to the IR or error reporting.
  Location getEncodedSourceLocation(SMLoc loc);
 
  /// Change the position of the lexer cursor.  The next token we lex will start
  /// at the designated point in the input.
  void resetPointer(const char *newPointer) { curPtr = newPointer; }
 
  /// Returns the start of the buffer.
  const char *getBufferBegin() { return curBuffer.data(); }
 
  /// Returns the end of the buffer.
  const char *getBufferEnd() { return curBuffer.end(); }
 
  /// Return the code completion location of the lexer, or nullptr if there is
  /// none.
  const char *getCodeCompleteLoc() const { return codeCompleteLoc; }
 
private:
  // Helpers.
  Token formToken(Token::Kind kind, const char *tokStart) {
    return Token(kind, StringRef(tokStart, curPtr - tokStart));
  }
 
  Token emitError(const char *loc, const Twine &message);
 
  /// Returns the character `offset` positions past the cursor, or 0 if that
  /// position is not inside the buffer. The buffer is not required to be
  /// followed by a terminator, so the scanners look ahead through this instead
  /// of dereferencing the cursor.
  char peek(size_t offset = 0) const {
    return offset < static_cast<size_t>(curBuffer.end() - curPtr)
               ? curPtr[offset]
               : 0;
  }
 
  // Lexer implementation methods.
  Token lexAtIdentifier(const char *tokStart);
  Token lexBareIdentifierOrKeyword(const char *tokStart);
  Token lexEllipsis(const char *tokStart);
  Token lexNumber(const char *tokStart);
  Token lexPrefixedIdentifier(const char *tokStart);
  Token lexString(const char *tokStart);
 
  /// Skip a comment line, starting with a '//'.
  void skipComment();
 
  const llvm::SourceMgr &sourceMgr;
  MLIRContext *context;
 
  StringRef curBuffer;
  const char *curPtr;
 
  /// An optional code completion point within the input file, used to indicate
  /// the position of a code completion token.
  const char *codeCompleteLoc;
 
  Lexer(const Lexer &) = delete;
  void operator=(const Lexer &) = delete;
};
 
} // namespace mlir
 
#endif // MLIR_LIB_ASMPARSER_LEXER_H