fooparser.cpp

来自「用于词法分析的词法分析器」· C++ 代码 · 共 118 行

/*
  $Id: FooParser.cpp,v 1.3 1997/02/02 01:31:01 matt Exp $

  FooParser class.
  
  (c) 1996 Matt Phillips.
  */

#include <util/checks.h>

#include "FooParser.h"

#define ArraySize(a) (sizeof (a) / sizeof (*(a)))

FooParser::FooParser (BufferedInputStream &i) :
  scanner (i, errors), baseObject (0)
{
  scanner.getNext ();		// cue scanner
   
  baseObject = parseObject ();
}

FooObject *FooParser::parseObject ()
{
  FooObject *object;

  if (scanner.getSymbol () == FooScanner::SymString)
  {
    object = new FooObject (scanner.getText ());
    scanner.getNext ();
  } else
  {
    mustbe (FooScanner::SymLBracket);
    object = new FooObject;
    parseAttrs (*object);
    mustbe (FooScanner::SymRBracket);
  }

  return object;
}

void FooParser::parseAttrs (FooObject &object)
{
  while (scanner.getSymbol () == FooScanner::SymIdent && !scanner.eof ())
  {
    string attr (scanner.getText ());
    scanner.getNext ();
    
    if (have (FooScanner::SymLSBracket))
    {
      FooObject::Objects &values = object.getOrCreateAttrs (attr);
      while (!scanner.eof () &&
	     (scanner.getSymbol () == FooScanner::SymLBracket || 
	      scanner.getSymbol () == FooScanner::SymString))
      {
	values.addTail (*parseObject ());
      }
      mustbe (FooScanner::SymRSBracket);
    } else
    {
      object.addAttr (attr, *parseObject ());
    }
  }
}

void FooParser::mustbeError (int sym)
{
  static char *errStrs [] =
  {
    "(", "missing ')'", "[", "missing ']'", "identfier expected"
  };

  CHECK (sym >= 0 && sym < ArraySize (errStrs),
	 "mustbeError symbol out of range");

  error (errStrs [sym]);
}

int FooParser::mustbe (int sym)
{
  if (scanner.getSymbol () != sym)
  {
    mustbeError (sym);
    return 0;
  } else
  {
    scanner.getNext ();
    return 1;
  }
}

int FooParser::have (int sym)
{
  if (scanner.getSymbol () != sym)
    return 0;
  else
  {
    scanner.getNext ();
    return 1;
  }
}

void FooParser::error (const char *msg)
{
  errors.error (string (msg),
		scanner.getInput ().getFilename (),
		scanner.getSymbolLine (),
		scanner.getSymbolColumn ());
}

void FooParser::warning (const char *msg)
{
  errors.warning (string (msg),
		  scanner.getInput ().getFilename (),
		  scanner.getSymbolLine (),
		  scanner.getSymbolColumn ());
}