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| LEX 程序代码
chunli@ubuntu:~/lab/yacc/lex$ cat 001.l
%{
/*
* 带符号表的单词识别程序
*/
enum
{
LOOKUP = 0, // 默认 -- 查找而不是定义
VERB,
ADJ,
ADV,
NOUN,
PREP,
PRON,
CONJ
};
int state;
int add_word(int type, char *word);
int lookup_word(char *word);
%}
%%
\n {state = LOOKUP;} /* 行结束, 返回到默认状态 */
/* 无论何时, 行都以 保留字的词性名字开始 */
/* 开始定义该类型的单词 */
^verb {state = VERB;}
^adj {state = ADJ; }
^adv {state = ADV; }
^nonu {state = NOUN;}
^prep {state = PREP;}
^pron {state = PRON;}
^conj {state = CONJ;}
[a-zA-Z]+ {
/* 遇到标准的单词, 查找它 或 定义它 */
if(state != LOOKUP)
{
// 定义当前的单词
add_word(state, yytext);
}
else
{
switch(lookup_word(yytext))
{
case VERB: printf("[%s] is verb\n", yytext); break;
case ADJ : printf("[%s] is adj\n", yytext); break;
case ADV: printf("[%s] is adv\n", yytext); break;
case NOUN: printf("[%s] is nonu\n", yytext); break;
case PREP: printf("[%s] is prep\n", yytext); break;
case PRON: printf("[%s] is pron\n", yytext); break;
case CONJ: printf("[%s] is conj\n", yytext); break;
default : printf("[%s] don't recognize\n", yytext);break;
}
}
}
. ; /* 忽略其他所有 */
%%
int
main()
{
yylex();
}
/* 定义一个链接单词的 类型 与列表 */
struct word
{
char *word_name;
int word_type;
struct word *next;
};
struct word *word_list;
extern void *malloc();
int add_word(int type, char *word)
{
struct word *wp;
if(lookup_word(word) != LOOKUP)
{
printf("warn! already define word [%s]\n", word);
return 0;
}
wp = (struct word*)malloc(sizeof(struct word));
wp->next = word_list;
wp->word_name = (char*)malloc(strlen(word) +1);
strcpy(wp->word_name, word);
wp->word_type = type;
word_list = wp;
return 1; // 它被处理过
}
int lookup_word(char *word)
{
struct word * wp = word_list;
for(;wp; wp = wp -> next)
{
if(strcmp(wp->word_name, word) == 0)
{
//找到了
return wp->word_type;
}
}
// 没有找到
return LOOKUP;
}
chunli@ubuntu:~/lab/yacc/lex$
编译 && 运行
chunli@ubuntu:~/lab/yacc/lex$ lex 001.l && gcc lex.yy.c -l l && ./a.out
pron I you he she
verb is am are was be dose
prep to from
conj if then and but or
I is boy
[I] is pron
[is] is verb
[boy] don't recognize
are you ok?
[are] is verb
[you] is pron
[ok] don't recognize
|
