生活随笔
收集整理的這篇文章主要介紹了
递归下降分析法（编译原理）
小編覺得挺不錯的,現在分享給大家,幫大家做個參考.
遞歸下降分析法的實現方案
遞歸下降分析法的原理是利用函數之間的遞歸調用模擬語法樹自上而下的構造過程，具體實現方法概述如下：
1）每個非終結符對應一個解析函數；
2）產生式右側為該產生式左側非終結符所對應解析函數的“函數體”；
3）產生式右側終結符對應從輸入串中“消耗”該終結符的操作；
4）產生式中的‘|’對應函數體中的“if-else”語句；
5）對于擴展的BNF文法，產生式中的‘{}’對應函數體中的“while”語句。
說明：
此部分中的數據來源為前一篇（詞法分析）的結果
[cpp] view plain
copy #include?<stdio.h>??#include?<string.h>??#include?<stdlib.h>????#define?MAX_ID_LENGTH???256??#define?MAX_TABLE_SIZE?2048??#define?SUCCESS?????????1????typedef?enum?token??{????????T_0=0,??????????T_1=1,??????????T_2=2,??????????T_INT=3,????????????T_IF=4,?????????T_ELSE=5,??????T_WHILE=6,??????T_FOR=7,????????T_READ=8,???????T_WRITE=9,??????????T_BEGIN=10,?????T_FOUNCTION=11,??????T_END=12,???????T_THEN=13,??????T_ADD=14,???????T_SUB=15,???????????T_MUL=16,???????T_DIV=17,??????T_L=18,?????????T_LE=19,????????T_G=20,?????????T_GE=21,????????????T_NE=22,????????T_E=23,??????T_ASSIGN=24,????T_LPAR=25,??????T_RPAR=26,??????T_COM=27,???????????T_SEM=28,???????T_RETURN=29,??????T_ERROR=30,?????T_SYMBOL=31,????T_CONSTANT=32??}?Token;????typedef?struct?LEX??{??????Token?read;??????struct?LEX?*next;??????size_t?line;??}?MYLEX;??????MYLEX?lex_head,error_temp;??MYLEX*?current;??Token?error_TOKEN=T_0;????????int?item(void);??int?Block(void);??int?Factor(void);??int?Variable(void);??int?Function(void);??int?Constant(void);??int?Parameter?(void?);??int?Identifier?(void);??int?Main_Program(void);??int?Function_call(void);??void?emergency_exit(void);??int?Read_statement(void);??int?Write_statement(void);??int?Execute_statement(void);??MYLEX*?Advance(MYLEX*?read);??MYLEX*?Read_file(MYLEX*?read);??int?Relational_operators(void);??int?Assignment_statement(void);??int?Variable_declaration(void);??int?Function_declaration(void);??int?match(Token?read,Token?aim);??int?Conditional_statement(void);??int?Arithmetic_expression(void);??int?Declarative_statement(void);??int?Conditional_expression(void);??int?Execute_statement_table(void);??int?error(MYLEX?*current,Token?aim);??int?Declarative_statement_table(void);????????void?emergency_exit(void)??{??????MYLEX*?EXIT_TEEMP=lex_head.next;??????current=EXIT_TEEMP;??????while(!current)??????{??????????current=EXIT_TEEMP->next;??????????free(EXIT_TEEMP);??????}??????exit(0);??}??????int?error(MYLEX?*current,Token?aim)??{??????FILE?*error_file=fopen("error.txt","a");??????if(!error_file)??????{??????????perror("can`t?open?file?\n");??????}??????if(error_temp.line<current->line)??????{??????????error_temp=*current;??????????error_TOKEN=aim;??????????fprintf(error_file,"error?in?line:%d\tTOKEN:%d\texpeced?Token?is?:%d\n",??????????????????error_temp.line,error_temp.read,error_TOKEN);??????}??????fclose(error_file);??????return?SUCCESS;??}??????????????????MYLEX*?Read_file(MYLEX*?current)??{??????current->line=0;??????current->next=NULL;??????current->read=T_0;????????MYLEX*?Temp;??????Temp=current;??????FILE*?READ_FILE=fopen("GRAMER.txt","r");??????if(!READ_FILE)??????{??????????printf("can`t?load?file?GRAMER.txt,?a?file?like?GRAMER.txt?is?expectd?here?\n");??????????exit(0);??????}??????while(!feof(READ_FILE))??????{??????????Temp->next=(MYLEX*)malloc(sizeof(MYLEX));??????????Temp=Temp->next;??????????if(!Temp)??????????{??????????????printf("can`t?malloc?a?space?for?this?program!\n");??????????????emergency_exit();??????????}??????????Temp->line=0;??????????Temp->next=NULL;??????????Temp->read=T_0;??????????fscanf(READ_FILE,"%d\t%d\n",&(Temp->line),&(Temp->read));??????}??????fclose(READ_FILE);??????return?current->next;??}????????????????????MYLEX*?Advance(MYLEX*?current)??{??????FILE*EAT_FILE=fopen("symtab2.txt","a");??????FILE*?LEFT_FILE=fopen("detail.txt","a");??????if((!EAT_FILE)||(!LEFT_FILE))??????{??????????perror("can`t?open?file");??????????emergency_exit();??????}??????MYLEX*?Temp=current->next;??????printf("you?have?eat?the?one?is?:%3d\n\n?follow?is?\n",current->read);??????fprintf(EAT_FILE,??????????????"\nyou?have?eat?the?one?is?line:%3d\tToken:%3d\n",??????????????current->line,current->read);??????fprintf(LEFT_FILE,??????????????"\n\ncurrent?eat?the?one?is?line:%3d\tToken:%3d\nfollow?is\n",??????????????current->line,current->read);??????for(Temp;?Temp!=NULL;?Temp=Temp->next)??????{??????????printf("line:%3d?\t?token=%3d\n",?????????????????Temp->line,Temp->read);??????????fprintf(LEFT_FILE,"line:%3d?\t?token=%3d\n",??????????????????Temp->line,Temp->read);??????}??????fclose(EAT_FILE);??????fclose(LEFT_FILE);??????if(current==NULL)??????{??????????printf("all?work?is?to?be?done!,there?is?an?error?in?your?project!\n?");??????????emergency_exit();??????}??????return?current->next;??}??????????????????????int?main(int?agrc,?char*agrv[])??{??????error_temp.line=0;??????error_temp.next=NULL;??????error_temp.read=T_0;????????printf("\t編譯原理實驗二\n\tXXXXXXXXX\n\t\t—NEWPLAN\n");??????current=Read_file(&lex_head);??????system("pause");????????if(Main_Program())??????{??????????printf("\n\ncongratulation\tsuccessfully!\n\n");??????????system("del?error.txt");??????}??????else??????{??????????printf("?sorry?you?have?failed!\n");??????????printf("error?in?line:%d\tTOKEN:%d\texpeced?Token?is?:%d\n",?????????????????error_temp.line,error_temp.read,error_TOKEN);??????}??????system("pause");??????emergency_exit();/*釋放空間，函數返回*/??????return?0;??}??????????????????????int?match(Token?read?,Token?aim)??{??????return?(read==aim)??(current=Advance(current),SUCCESS):?(error(current,aim),!SUCCESS);??}????????????????????int?Main_Program(void)??{??????return?Block()??SUCCESS:?!SUCCESS;??}????????????????????int?Block(void)??{??????MYLEX*?Temp=current;??????return?(match(current->read,T_BEGIN)&&Declarative_statement_table()&&match(current->read,T_SEM)&&??????????????Execute_statement_table()&&match(current->read,T_END))?SUCCESS:(current=Temp,!SUCCESS);??}??????????????????????int?Declarative_statement_table()??{??????MYLEX*?Temp=current;??????if(!Declarative_statement())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????/*采用擴展的BNF方法消除左遞歸*/??????for(;;)??????{??????????Temp=current;??????????if(!match(current->read,T_SEM))??????????????break;??????????if(!Declarative_statement())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}??????????????????????int?Declarative_statement(void)??{??????MYLEX*?Temp=current;??????return?Variable_declaration()??SUCCESS?:?????????????(current=Temp,Function_declaration()??SUCCESS:!SUCCESS);??}??????????????????????int?Execute_statement_table(void)??{??????MYLEX*?Temp=current;??????if(!Execute_statement())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????for(;;)??????{??????????Temp=current;??????????if(!match(current->read,T_SEM))??????????????break;??????????if(!Execute_statement())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}??????????????????????int?Execute_statement(void)??{??????MYLEX*?Temp=current;??????if(Read_statement())??????????return?SUCCESS;??????current=Temp;??????if(Write_statement())??????????return?SUCCESS;??????current=Temp;??????if(Conditional_statement())??????????return?SUCCESS;??????current=Temp;??????if(Assignment_statement())??????????return?SUCCESS;??????current=Temp;??????return?!SUCCESS;??}??????????????????????int?Variable_declaration(void)??{??????MYLEX*?Temp=current;??????return?(match(current->read?,?T_INT)&&Variable())?SUCCESS:(current=Temp,!SUCCESS);??}??????????????????????int?Function_declaration(void)??{??????MYLEX*?Temp=current;??????return?(match(current->read,?T_INT)&&match(current->read,?T_FOUNCTION)&&Identifier()&&??????????????match(current->read,?T_LPAR)&&Parameter()&&match(current->read,?T_RPAR)&&??????????????match(current->read,T_SEM)&&Function())??SUCCESS:(current=Temp,!SUCCESS);??}??????????????????????int?Variable(void)??{??????return?match(current->read,T_SYMBOL)?SUCCESS:!SUCCESS;??}????????????????????int?Identifier??(void)??{??????return?match(current->read,T_SYMBOL)?SUCCESS:!SUCCESS;??}??????????????????????int?Parameter??(void)??{??????MYLEX*?Temp=current;??????return?Variable()?SUCCESS:(current=Temp,!SUCCESS);??}??????????????????????int?Function(void)??{??????MYLEX*?Temp=current;??????return?(match(current->read,?T_BEGIN)&&Declarative_statement_table()&&match(current->read,?T_SEM)&&??????????????Execute_statement_table()&&match(current->read,T_END))?SUCCESS:(current=Temp,!SUCCESS);??}??????????????????????int?Read_statement(void)??{??????MYLEX*?Temp=current;??????return?(match(current->read,T_READ)&&match(current->read,T_LPAR)&&Variable()&&??????????????match(current->read,T_RPAR))?SUCCESS:(current=Temp,!SUCCESS);??}??????????????????????int?Write_statement(void)??{??????MYLEX*?Temp=current;??????return?(match(current->read,T_WRITE)&&match(current->read,T_LPAR)&&Variable()&&??????????????match(current->read,T_RPAR))?SUCCESS:(current=Temp,!SUCCESS);??}??????????????????????int?Assignment_statement(void)??{??????MYLEX*?Temp=current;??????return?(Variable()&&match(current->read,T_ASSIGN)&&??????????????Arithmetic_expression())??SUCCESS:(current=Temp,!SUCCESS);??}????????????????????int?Conditional_statement(void)??{??????MYLEX*?Temp=current;??????return?(match(current->read,T_IF)&&Conditional_expression()&&??????????????match(current->read,T_THEN)&&Execute_statement()&&??????????????match(current->read,T_ELSE)&&Execute_statement()?????????????)?SUCCESS:(current=Temp,!SUCCESS);??}????????????????????int?Arithmetic_expression(void)??{??????MYLEX*?Temp=current;??????if(!item())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????for(;;)??????{??????????Temp=current;??????????if(!match(current->read,T_SUB))??????????????break;??????????if(!item())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}????????????????????int?item(void)??{??????MYLEX*?Temp=current;??????if(!Factor())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????for(;;)??????{??????????Temp=current;??????????if(!match(current->read,T_MUL))??????????????break;??????????if(!Factor())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}????????????????????int?Constant(void)??{??????return?match(current->read,T_CONSTANT)?SUCCESS:?!SUCCESS;??}????????????????????int?Conditional_expression(void)??{??????MYLEX*?Temp=current;??????return?(Arithmetic_expression()&&Relational_operators()&&??????????????Arithmetic_expression())??SUCCESS:(current=Temp,!SUCCESS);??}????????????????????int?Relational_operators(void)??{??????return?(?match(current->read,T_L)||match(current->read,T_LE)||match(current->read,T_G)||???????????????match(current->read,T_GE)||match(current->read,T_E)||match(current->read,T_NE)?????????????)?SUCCESS:!SUCCESS;????}??????????????????????int?Factor(void)??{??????MYLEX*?Temp=current;??????if(Function_call())??????????return?SUCCESS;??????current=Temp;??????if(Variable())??????????return?SUCCESS;??????current=Temp;??????if(Constant())??????????return?SUCCESS;??????current=Temp;??????return?!SUCCESS;??}????????????????????int?Function_call(void)??{??????MYLEX*?Temp=current;??????return?(Identifier()&&match(current->read,T_LPAR)&&Arithmetic_expression()&&??????????????match(current->read,T_RPAR))?SUCCESS:(current=Temp,!SUCCESS);??}??
源碼版本2（更容易理解）
[cpp] view plain
copy #include?<stdio.h>??#include?<string.h>??#include?<stdlib.h>????#define?MAX_ID_LENGTH???256??#define?MAX_TABLE_SIZE?2048??#define?SUCCESS?????????1????typedef?enum?token??{????????T_0=0,??????T_1=1,??????T_2=2,????????T_INT=3,??????T_IF=4,??????T_ELSE=5,??????T_WHILE=6,??????T_FOR=7,??????T_READ=8,??????T_WRITE=9,??????T_BEGIN=10,??????T_FOUNCTION=11,??????T_END=12,??????T_THEN=13,????????T_ADD=14,??????T_SUB=15,??????T_MUL=16,??????T_DIV=17,??????T_L=18,??????T_LE=19,??????T_G=20,??????T_GE=21,??????T_NE=22,??????T_E=23,??????T_ASSIGN=24,??????T_LPAR=25,??????T_RPAR=26,??????T_COM=27,??????T_SEM=28,????????T_RETURN=29,??????T_ERROR=30,??????T_SYMBOL=31,??????T_CONSTANT=32??}?Token;????typedef?struct?LEX??{??????Token?read;??????struct?LEX?*next;??????size_t?line;??}MYLEX;??????#ifndef?SUCCESS??#define?SUCCESS???1??#endif????MYLEX?lex_head,error_temp;??MYLEX*?current;??Token?error_TOKEN=T_0;????????int?item(void);??int?Block(void);??int?Factor(void);??int?Variable(void);??int?Function(void);??int?Constant(void);??int?Parameter?(void?);??int?Identifier?(void);??int?Main_Program(void);??int?Function_call(void);??void?emergency_exit(void);??int?Read_statement(void);??int?Write_statement(void);??int?Execute_statement(void);??MYLEX*?Advance(MYLEX*?read);??MYLEX*?Read_file(MYLEX*?read);??int?Relational_operators(void);??int?Assignment_statement(void);??int?Variable_declaration(void);??int?Function_declaration(void);??int?match(Token?read,Token?aim);??int?Conditional_statement(void);??int?Arithmetic_expression(void);??int?Declarative_statement(void);??int?Conditional_expression(void);??int?Execute_statement_table(void);??int?error(MYLEX?*current,Token?aim);??int?Declarative_statement_table(void);????????void?emergency_exit(void)??{??????MYLEX*?EXIT_TEEMP=lex_head.next;??????current=EXIT_TEEMP;??????while(!current)??????{??????????current=EXIT_TEEMP->next;??????????free(EXIT_TEEMP);??????}??????exit(0);??}????int?error(MYLEX?*current,Token?aim)??{??????FILE?*error_file=fopen("error.txt","a");??????if(!error_file)??????{??????????perror("can`t?open?file?\n");??????}??????if(error_temp.line<current->line)??????{??????????error_temp=*current;??????????error_TOKEN=aim;??????????fprintf(error_file,"error?in?line:%d\tTOKEN:%d\texpeced?Token?is?:%d\n",??????????????????error_temp.line,error_temp.read,error_TOKEN);????????}??????fclose(error_file);????????return?SUCCESS;??}??????????????????MYLEX*?Read_file(MYLEX*?current)??{??????current->line=0;??????current->next=NULL;??????current->read=T_0;????????MYLEX*?Temp;??????Temp=current;??????FILE*?READ_FILE=fopen("GRAMER.txt","r");??????if(!READ_FILE)??????{??????????printf("can`t?load?file?GRAMER.txt,?a?file?like?GRAMER.txt?is?expectd?here?\n");??????????exit(0);??????}????????while(!feof(READ_FILE))??????{??????????Temp->next=(MYLEX*)malloc(sizeof(MYLEX));??????????Temp=Temp->next;??????????if(!Temp)??????????{??????????????printf("can`t?malloc?a?space?for?this?program!\n");??????????????emergency_exit();??????????}??????????Temp->line=0;??????????Temp->next=NULL;??????????Temp->read=T_0;??????????fscanf(READ_FILE,"%d\t%d\n",&(Temp->line),&(Temp->read));????????}??????fclose(READ_FILE);??????return?current->next;??}????????????????????MYLEX*?Advance(MYLEX*?current)??{??????FILE*EAT_FILE=fopen("symtab2.txt","a");??????FILE*?LEFT_FILE=fopen("detail.txt","a");??????if((!EAT_FILE)||(!LEFT_FILE))??????{??????????perror("can`t?open?file");??????????emergency_exit();??????}??????MYLEX*?Temp=current->next;??????printf("you?have?eat?the?one?is?:%3d\n\n?follow?is?\n",current->read);??????fprintf(EAT_FILE,??????????????"\nyou?have?eat?the?one?is?line:%3d\tToken:%3d\n",??????????????current->line,??????????????current->read);??????fprintf(LEFT_FILE,??????????????"\n\ncurrent?eat?the?one?is?line:%3d\tToken:%3d\nfollow?is\n",??????????????current->line,??????????????current->read);??????for(Temp;?Temp!=NULL;?Temp=Temp->next)??????{??????????printf("line:%3d?\t?token=%3d\n",?????????????????Temp->line,Temp->read);??????????fprintf(LEFT_FILE,"line:%3d?\t?token=%3d\n",??????????????????Temp->line,Temp->read);??????}??????fclose(EAT_FILE);??????fclose(LEFT_FILE);??????if(current==NULL)??????{??????????printf("all?work?is?to?be?done!,there?is?an?error?in?your?project!\n?");??????????emergency_exit();??????}??????return?current->next;??}??????????????????????int?main(int?agrc,?char*agrv[])??{??????error_temp.line=0;??????error_temp.next=NULL;??????error_temp.read=T_0;????????printf("\t編譯原理實驗二\n\tXXXXXXXXX\n\tNEWPLAN\n");??????current=Read_file(&lex_head);??????system("pause");????????if(Main_Program())??????{??????????printf("\n\ncongratulation\tsuccessfully!\n\n");??????????system("del?error.txt");??????}??????else??????{??????????printf("?sorry?you?have?failed!\n");??????????printf("error?in?line:%d\tTOKEN:%d\texpeced?Token?is?:%d\n",?????????????????error_temp.line,error_temp.read,error_TOKEN);??????}????????system("pause");??????emergency_exit();/*釋放空間，函數返回*/??????return?0;??}??????????????????????int?match(Token?read?,Token?aim)??{??????if(read==aim)??????????return?SUCCESS;??????error(current,aim);??????return?!SUCCESS;????????}????????????????????int?Main_Program(void)??{??????if(!Block())??????????return?!SUCCESS;??????return?SUCCESS;??}????????????????????int?Block(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read,T_BEGIN))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=?Advance(current);??????if(!Declarative_statement_table())??????{????????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,T_SEM))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????????if(!Execute_statement_table())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????if(!match(current->read,T_END))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????return?SUCCESS;??}??????????????????????int?Declarative_statement_table()??{??????MYLEX*?Temp=current;??????if(!Declarative_statement())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????/*采用擴展的BNF方法消除左遞歸*/??????for(;;)??????{??????????if(!match(current->read,T_SEM))??????????????break;????????????Temp=current;??????????current?=Advance(current);????????????if(!Declarative_statement())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}??????????????????????int?Declarative_statement(void)??{??????MYLEX*?Temp=current;??????if(Variable_declaration())??????{??????????return?SUCCESS;??????}??????else??????{??????????current=Temp;??????}??????if(Function_declaration())??????????return?SUCCESS;??????????current=Temp;??????return?!SUCCESS;????}??????????????????????int?Execute_statement_table(void)??{??????MYLEX*?Temp=current;??????if(!Execute_statement())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????for(;;)??????{??????????if(!match(current->read,T_SEM))??????????????break;??????????Temp=current;??????????current=Advance(current);????????????if(!Execute_statement())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}??????????????????????int?Execute_statement(void)??{??????MYLEX*?Temp=current;????????if(Read_statement())??????{??????????return?SUCCESS;??????}??????else??????{??????????current=Temp;??????}??????if(Write_statement())??????{??????????return?SUCCESS;??????}??????else??????{??????????current=Temp;??????}????????if(Conditional_statement())??????{??????????return?SUCCESS;??????}??????else??????{??????????current=Temp;??????}??????if(Assignment_statement())??????{??????????return?SUCCESS;??????}??????????current=Temp;??????return?!SUCCESS;??}??????????????????????int?Variable_declaration(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read?,?T_INT))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current?=Advance(current);??????if(Variable())??????????return?SUCCESS;??????current=Temp;??????return?!SUCCESS;??}??????????????????????int?Function_declaration(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read,?T_INT))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!match(current->read,?T_FOUNCTION))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Identifier())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????if(!match(current->read,?T_LPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Parameter())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????if(!match(current->read,?T_RPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????if(!match(current->read,T_SEM))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current?=Advance(current);????????if(!Function())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????return?SUCCESS;??}??????????????????????int?Variable(void)??{??????MYLEX*?Temp=current;??????if(!?match(current->read,T_SYMBOL))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????return?SUCCESS;??}????????????????????????int?Identifier??(void)??{??????MYLEX*?Temp=current;??????if(!?match(current->read,T_SYMBOL))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????return?SUCCESS;??}??????????????????????int?Parameter??(void)??{??????MYLEX*?Temp=current;??????if(!Variable())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????return?SUCCESS;??}??????????????????????int?Function(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read,?T_BEGIN))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Declarative_statement_table())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,?T_SEM))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Execute_statement_table())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,T_END))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????return?SUCCESS;??}??????????????????????int?Read_statement(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read,T_READ))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????if(!match(current->read,T_LPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Variable())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,T_RPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????return?SUCCESS;??}??????????????????????int?Write_statement(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read,T_WRITE))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!match(current->read,T_LPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Variable())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,T_RPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????printf("current?to?be?got?is:line=%d\t?%d\n",current->line,current->read);??????return?SUCCESS;??}??????????????????????int?Assignment_statement(void)??{??????MYLEX*?Temp=current;??????if(!Variable())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,T_ASSIGN))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current?=Advance(current);????????if(Arithmetic_expression())??????????return?SUCCESS;??????current=Temp;??????return?!SUCCESS;??}????????????????????int?Conditional_statement(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read,T_IF))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Conditional_expression())??????{????????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,T_THEN))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(!Execute_statement())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????if(!match(current->read,T_ELSE))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);??????if(Execute_statement())??????????return?SUCCESS;??????current=Temp;??????return?!SUCCESS;??}????????????????????int?Arithmetic_expression(void)??{??????MYLEX*?Temp=current;??????if(!item())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????for(;;)??????{??????????if(!match(current->read,T_SUB))??????????????break;????????????Temp=current;??????????current=Advance(current);??????????if(!item())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}????????????????????int?item(void)??{??????MYLEX*?Temp=current;??????if(!Factor())??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????for(;;)??????{??????????if(!match(current->read,T_MUL))??????????????break;??????????Temp=current;??????????current=Advance(current);??????????if(!Factor())??????????{??????????????current=Temp;??????????????break;??????????}??????}??????return?SUCCESS;??}????????????????????int?Constant(void)??{??????MYLEX*?Temp=current;??????if(!match(current->read,T_CONSTANT))??????{??????????return?!SUCCESS;??????}??????current=Advance(current);??????return?SUCCESS;??}????????????????????int?Conditional_expression(void)??{??????MYLEX*?Temp=current;??????if(!Arithmetic_expression())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????printf("line?=?%d,token=%d\n");??????if(!Relational_operators())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????if(!Arithmetic_expression())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????return?SUCCESS;??}????????????????????int?Relational_operators(void)??{??????if(match(current->read,T_L))??????{??????????current=Advance(current);??????????return?SUCCESS;??????}??????if(match(current->read,T_LE))??????{??????????current=Advance(current);??????????return?SUCCESS;??????}??????if(match(current->read,T_G))??????{??????????current=Advance(current);??????????return?SUCCESS;??????}??????if(match(current->read,T_GE))??????{??????????current=Advance(current);??????????return?SUCCESS;??????}??????if(match(current->read,T_E))??????{??????????current=Advance(current);??????????return?SUCCESS;??????}??????if(match(current->read,T_NE))??????{??????????current=Advance(current);??????????return?SUCCESS;??????}??????return?!SUCCESS;????}??????????????????????int?Factor(void)??{??????MYLEX*?Temp=current;??????if(Function_call())??????{??????????return?SUCCESS;??????}??????else??????{??????????current=Temp;??????}??????if(Variable())??????{??????????return?SUCCESS;??????}??????else??????{??????????current=Temp;??????}??????if(Constant())??????{??????????return?SUCCESS;??????}????????current=Temp;??????return?!SUCCESS;??}????????????????????int?Function_call(void)??{??????MYLEX*?Temp=current;??????if(!Identifier())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????if(!match(current->read,T_LPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????current=Advance(current);????????if(?!Arithmetic_expression())??????{??????????current=Temp;??????????return?!SUCCESS;??????}??????if(!match(current->read,T_RPAR))??????{??????????current=Temp;??????????return?!SUCCESS;??????}????????current=Advance(current);??????return?SUCCESS;????}??
結果分析
成功結果
失敗結果：
總結
以上是生活随笔為你收集整理的递归下降分析法（编译原理）的全部內容，希望文章能夠幫你解決所遇到的問題。
如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。
