编译原理实验二 语法分析
输入：token[40]
tokenstring[40][30]
输出：检查是否符合文法]；
生成语法树。
样例程序已经对符合以下文法的源程序进行语法分析但不能生成抽象语法树。
要求写出能生成抽象语法树的语法分析程序。
maximum是什么意思文法： stmt_q stmt_q ; assign_stmt | assign_stmt
assign_stmt id := exp
expexp + term | exp – term | term
termterm * factor | term / factor | factor
prefer是什么意思 factor ( exp ) | id | num
语法树的数据结构：
typedef enum {stmtk,expk} nodekind;
typedef enum {ifk,assignk,declk} stmtkind;
typedef enum {opk,constk,idk} expkind;
typedef struct treenode
{ struct treenode * child[3];
struct treenode * sibling;
nodekind nodek;
union { stmtkind stmt; expkind exp;} kind;
turnaround union { tokentype op;
int val;
char * name; } attr;
} treenode;
样例程序
#include<stdio.h>
#include<ctype.h>
typedef enum {PLUS,MINUS,TIMES,OVER,LPAREN,RPAREN,SEMI,ASSIGN,NUM,ID,DOLLAR} tokentype;/*记号*/
tokentype token[]={ID,ASSIGN,NUM,PLUS,NUM,TIMES,NUM,SEMI,ID,ASSIGN,NUM,DOLLAR}; /*存记号*/
char tokenstring[][30]={"ab",":=","12","+","5","*","3",";","xy",":=","34","$"};/*存记号串*/熬更守夜
int wordindex=0; /*以上两个数组的索引*/
factor();
term();
exp();
assign_stmt();
stmt_q();
main()
{ stmt_q();
}
stmt_q()
{assign_stmt();
while( (token[wordindex]==SEMI)&& (token[wordindex]!=DOLLAR))
{wordindex++;
assign_stmt();
}
小语种就业
白萝卜英文}
assign_stmt()
{if(token[wordindex]==ID)
wordindex++;
el {printf("error");
exit(1);}
if(token[wordindex]==ASSIGN)
wordindex++;
el {printf("error");
exit(1);}
exp();
}
exp()
{term();
while((token[wordindex]==PLUS)||(token[wordindex]==MINUS))
{wordindex++;
term();}
}
term()
{factor();
while((token[wordindex]==TIMES)||(token[wordindex]==OVER))
{wordindex++;
factor();}
}
factor()
{switch(token[wordindex]){
ca LPAREN :
wordindex++;
exp();
if(token[wordindex]==RPAREN)
wordindex++;
el {printf("error");
exit(1);}
break;
ca NUM :
sar是什么意思 wordindex++;学生厌学怎么办
break;
ca ID :
wordindex++;
break;
default:
printf("error");
jane doe }
teradata}
