ytab.c

一个小型的c语言编译器,做的非常好,不过不是我做的.

			register int yy_i;

			printf( "State %d, token ", yy_state );
			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_ps >= &yys[ YYMAXDEPTH ] )	/* room on stack? */
		{
			yyerror( "yacc stack overflow" );
			YYABORT;
		}
		*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( "syntax error" );
				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:
# line 203 "c.y"
{
				PARSE_INFO("translation_unit :external_declaration")
			} break;
case 2:
# line 207 "c.y"
{
				PARSE_INFO("translation_unit :translation_unit external_declaration")
			} break;
case 3:
# line 214 "c.y"
{
				PARSE_INFO("external_declaration :function_definition")
			} break;
case 4:
# line 218 "c.y"
{
				PARSE_INFO("external_declaration :declaration")
				// gen globe value
				gen_globe_var_list(yypvt[-0].p_symbol);
			} break;
case 5:
# line 224 "c.y"
{
				PARSE_INFO("external_declaration :control_line")
			} break;
case 6:
# line 231 "c.y"
{
				PARSE_INFO("function_definition :declaration_specifiers declarator ")
				assert( IS_FUNCTION(yypvt[-0].p_symbol) );
				unoin_specifier_to_declarator(yypvt[-1].p_symbol, yypvt[-0].p_symbol);
				del_symbol( yypvt[-1].p_symbol );
				check_function_retval(yypvt[-0].p_symbol);
				// yypvt[-0].p_symbol->args point to parameter list
				// so we can tell the compound statement to link the parameters
				// assign yypvt[-0].p_symbol->args to sg_parameter_list to tell compound statement
				sg_parameter_list = yypvt[-0].p_symbol->args;
				// add function definition to sg_function_symtab
				// for function call itself
				// can search in function definition table
				yypvt[-0].p_symbol = add_function_def_to_functab(yypvt[-0].p_symbol);
				// for compound statement code genc in code2 files
				open_code2();
				
				// set return label
				set_return_label(get_a_label());
				// create goto label symtab
				create_goto_label_symtab();
			} break;
case 7:
# line 254 "c.y"
{
				PARSE_INFO("compound_statement")

				// destory the goto label
				destory_goto_label_symtab();
				// gen return label
				gen_return_label();

				// set func offset
				set_func_offset(yypvt[-2].p_symbol);
				// gen function head
				gen_func_head(yypvt[-2].p_symbol);
				// copy compound statement in code2 to code
				copy_code2_code();
				// add function end
				gen_func_end(yypvt[-2].p_symbol);
				// since compound statement code has copy to code file,
				// then close code2 for next function
				close_code2();
				yyval.p_symbol = yypvt[-2].p_symbol;
			} break;
case 8:
# line 276 "c.y"
{
				PARSE_INFO("function_definition :declarator ")
				assert( IS_FUNCTION(yypvt[-0].p_symbol) );
				// default the function return value is int
				yypvt[-0].p_symbol->NOUN = SPEC_INT;
				// yypvt[-0].p_symbol->args point to parameter list
				// so we can tell the compound statement to link the parameters
				// assign yypvt[-0].p_symbol->args to sg_parameter_list to tell compound statement
				sg_parameter_list = yypvt[-0].p_symbol->args;
				// add function definition to sg_function_symtab
				// for function call itself
				// can search in function definition table
				yypvt[-0].p_symbol = add_function_def_to_functab(yypvt[-0].p_symbol);
				// for compound statement code genc in code2 files
				open_code2();

				// set return label
				set_return_label(get_a_label());
				// create goto label symtab
				create_goto_label_symtab();
			} break;
case 9:
# line 298 "c.y"
{
				PARSE_INFO("compound_statement")

				// destory the goto label
				destory_goto_label_symtab();
				// gen return label
				gen_return_label();

				// set func offset
				set_func_offset(yypvt[-2].p_symbol);
				// gen function head
				gen_func_head(yypvt[-2].p_symbol);
				// copy compound statement in code2 to code
				copy_code2_code();
				// add function end
				gen_func_end(yypvt[-2].p_symbol);
				// since compound statement code has copy to code file,
				// then close code2 for next function
				close_code2();
			} break;