add1.y.c

yacc和lex的一个例子代码,完全原创

		}
#endif /* YYDEBUG */
		if ( ++yy_ps >= &yys[ yymaxdepth ] )	/* room on stack? */
		{
# ifndef __RUNTIME_YYMAXDEPTH
			yyerror( (nl_msg(30002,"yacc stack overflow")) );
			YYABORT;
# else
			/* save old stack bases to recalculate pointers */
			YYSTYPE * yyv_old = yyv;
			int * yys_old = yys;
			yymaxdepth += YYINCREMENT;
			yys = (int *) realloc(yys, yymaxdepth * sizeof(int));
			yyv = (YYSTYPE *) realloc(yyv, yymaxdepth * sizeof(YYSTYPE));
			if (yys==0 || yyv==0) {
			    yyerror( (nl_msg(30002,"yacc stack overflow")) );
			    YYABORT;
			    }
			/* Reset pointers into stack */
			yy_ps = (yy_ps - yys_old) + yys;
			yyps = (yyps - yys_old) + yys;
			yy_pv = (yy_pv - yyv_old) + yyv;
			yypv = (yypv - yyv_old) + yyv;
# endif

		}
		*yy_ps = yy_state;
		*++yy_pv = yyval;

		/*
		** we have a new state - find out what to do
		*/
	yy_newstate:
		if ( ( yy_n = yypact[ yy_state ] ) <= YYFLAG )
			goto yydefault;		/* simple state */
#if YYDEBUG
		/*
		** if debugging, need to mark whether new token grabbed
		*/
		yytmp = yychar < 0;
#endif
		if ( ( yychar < 0 ) && ( ( yychar = yylex() ) < 0 ) )
			yychar = 0;		/* reached EOF */
#if YYDEBUG
		if ( yydebug && yytmp )
		{
			register int yy_i;

			printf( "Received token " );
			if ( yychar == 0 )
				printf( "end-of-file\n" );
			else if ( yychar < 0 )
				printf( "-none-\n" );
			else
			{
				for ( yy_i = 0; yytoks[yy_i].t_val >= 0;
					yy_i++ )
				{
					if ( yytoks[yy_i].t_val == yychar )
						break;
				}
				printf( "%s\n", yytoks[yy_i].t_name );
			}
		}
#endif /* YYDEBUG */
		if ( ( ( yy_n += yychar ) < 0 ) || ( yy_n >= YYLAST ) )
			goto yydefault;
		if ( yychk[ yy_n = yyact[ yy_n ] ] == yychar )	/*valid shift*/
		{
			yychar = -1;
			yyval = yylval;
			yy_state = yy_n;
			if ( yyerrflag > 0 )
				yyerrflag--;
			goto yy_stack;
		}

	yydefault:
		if ( ( yy_n = yydef[ yy_state ] ) == -2 )
		{
#if YYDEBUG
			yytmp = yychar < 0;
#endif
			if ( ( yychar < 0 ) && ( ( yychar = yylex() ) < 0 ) )
				yychar = 0;		/* reached EOF */
#if YYDEBUG
			if ( yydebug && yytmp )
			{
				register int yy_i;

				printf( "Received token " );
				if ( yychar == 0 )
					printf( "end-of-file\n" );
				else if ( yychar < 0 )
					printf( "-none-\n" );
				else
				{
					for ( yy_i = 0;
						yytoks[yy_i].t_val >= 0;
						yy_i++ )
					{
						if ( yytoks[yy_i].t_val
							== yychar )
						{
							break;
						}
					}
					printf( "%s\n", yytoks[yy_i].t_name );
				}
			}
#endif /* YYDEBUG */
			/*
			** look through exception table
			*/
			{
				register int *yyxi = yyexca;

				while ( ( *yyxi != -1 ) ||
					( yyxi[1] != yy_state ) )
				{
					yyxi += 2;
				}
				while ( ( *(yyxi += 2) >= 0 ) &&
					( *yyxi != yychar ) )
					;
				if ( ( yy_n = yyxi[1] ) < 0 )
					YYACCEPT;
			}
		}

		/*
		** check for syntax error
		*/
		if ( yy_n == 0 )	/* have an error */
		{
			/* no worry about speed here! */
			switch ( yyerrflag )
			{
			case 0:		/* new error */
				yyerror( (nl_msg(30003,"syntax error")) );
				yynerrs++;
				goto skip_init;
			yyerrlab:
				/*
				** get globals into registers.
				** we have a user generated syntax type error
				*/
				yy_pv = yypv;
				yy_ps = yyps;
				yy_state = yystate;
				yynerrs++;
			skip_init:
			case 1:
			case 2:		/* incompletely recovered error */
					/* try again... */
				yyerrflag = 3;
				/*
				** find state where "error" is a legal
				** shift action
				*/
				while ( yy_ps >= yys )
				{
					yy_n = yypact[ *yy_ps ] + YYERRCODE;
					if ( yy_n >= 0 && yy_n < YYLAST &&
						yychk[yyact[yy_n]] == YYERRCODE)					{
						/*
						** simulate shift of "error"
						*/
						yy_state = yyact[ yy_n ];
						goto yy_stack;
					}
					/*
					** current state has no shift on
					** "error", pop stack
					*/
#if YYDEBUG
#	define _POP_ "Error recovery pops state %d, uncovers state %d\n"
					if ( yydebug )
						printf( _POP_, *yy_ps,
							yy_ps[-1] );
#	undef _POP_
#endif
					yy_ps--;
					yy_pv--;
				}
				/*
				** there is no state on stack with "error" as
				** a valid shift.  give up.
				*/
				YYABORT;
			case 3:		/* no shift yet; eat a token */
#if YYDEBUG
				/*
				** if debugging, look up token in list of
				** pairs.  0 and negative shouldn't occur,
				** but since timing doesn't matter when
				** debugging, it doesn't hurt to leave the
				** tests here.
				*/
				if ( yydebug )
				{
					register int yy_i;

					printf( "Error recovery discards " );
					if ( yychar == 0 )
						printf( "token end-of-file\n" );
					else if ( yychar < 0 )
						printf( "token -none-\n" );
					else
					{
						for ( yy_i = 0;
							yytoks[yy_i].t_val >= 0;
							yy_i++ )
						{
							if ( yytoks[yy_i].t_val
								== yychar )
							{
								break;
							}
						}
						printf( "token %s\n",
							yytoks[yy_i].t_name );
					}
				}
#endif /* YYDEBUG */
				if ( yychar == 0 )	/* reached EOF. quit */
					YYABORT;
				yychar = -1;
				goto yy_newstate;
			}
		}/* end if ( yy_n == 0 ) */
		/*
		** reduction by production yy_n
		** put stack tops, etc. so things right after switch
		*/
#if YYDEBUG
		/*
		** if debugging, print the string that is the user's
		** specification of the reduction which is just about
		** to be done.
		*/
		if ( yydebug )
			printf( "Reduce by (%d) \"%s\"\n",
				yy_n, yyreds[ yy_n ] );
#endif
		yytmp = yy_n;			/* value to switch over */
		yypvt = yy_pv;			/* $vars top of value stack */
		/*
		** Look in goto table for next state
		** Sorry about using yy_state here as temporary
		** register variable, but why not, if it works...
		** If yyr2[ yy_n ] doesn't have the low order bit
		** set, then there is no action to be done for
		** this reduction.  So, no saving & unsaving of
		** registers done.  The only difference between the
		** code just after the if and the body of the if is
		** the goto yy_stack in the body.  This way the test
		** can be made before the choice of what to do is needed.
		*/
		{
			/* length of production doubled with extra bit */
			register int yy_len = yyr2[ yy_n ];

			if ( !( yy_len & 01 ) )
			{
				yy_len >>= 1;
				yyval = ( yy_pv -= yy_len )[1];	/* $$ = $1 */
				yy_state = yypgo[ yy_n = yyr1[ yy_n ] ] +
					*( yy_ps -= yy_len ) + 1;
				if ( yy_state >= YYLAST ||
					yychk[ yy_state =
					yyact[ yy_state ] ] != -yy_n )
				{
					yy_state = yyact[ yypgo[ yy_n ] ];
				}
				goto yy_stack;
			}
			yy_len >>= 1;
			yyval = ( yy_pv -= yy_len )[1];	/* $$ = $1 */
			yy_state = yypgo[ yy_n = yyr1[ yy_n ] ] +
				*( yy_ps -= yy_len ) + 1;
			if ( yy_state >= YYLAST ||
				yychk[ yy_state = yyact[ yy_state ] ] != -yy_n )
			{
				yy_state = yyact[ yypgo[ yy_n ] ];
			}
		}
					/* save until reenter driver code */
		yystate = yy_state;
		yyps = yy_ps;
		yypv = yy_pv;
	}
	/*
	** code supplied by user is placed in this switch
	*/
	switch( yytmp )
	{
		
case 1:{printf("%d\n", yypvt[-1]);} break;
case 3:{yyval=yypvt[-1];} break;
case 4:{yyval=yypvt[-1];} break;
case 5:{yyval=yypvt[-0];} break;
case 6:{yyval = yyval + yypvt[-0];} break;
case 7:{yyval = yyval - yypvt[-0];} break;
	}
	goto yystack;		/* reset registers in driver code */
}

# ifdef __RUNTIME_YYMAXDEPTH

static int allocate_stacks() {
	/* allocate the yys and yyv stacks */
	yys = (int *) malloc(yymaxdepth * sizeof(int));
	yyv = (YYSTYPE *) malloc(yymaxdepth * sizeof(YYSTYPE));

	if (yys==0 || yyv==0) {
	   yyerror( (nl_msg(30004,"unable to allocate space for yacc stacks")) );
	   return(1);
	   }
	else return(0);

}


static void free_stacks() {
	if (yys!=0) free((char *) yys);
	if (yyv!=0) free((char *) yyv);
}

# endif  /* defined(__RUNTIME_YYMAXDEPTH) */