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lexical.c
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lexical.c
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/*
Nothing but a very simple lexicon analyzer .
The whole expression shuld be preprocessed first , and then check
error . After that , copy them into the high speed buffer , and pass
the control to this function .
*/
#include <ctype.h>
#include "types.h"
#include "lexical.h"
#include "sys_ds.h"
#include "buf.h"
#include "err.h"
char rt_token[MAX_TOKEN_NAME+1];
/* I will read the character one by one until a semicolon appeared .
During the process , I will remove all the spaces and newline ,
and combine them into one sentence .
*/
/*
Input : statement="(dfdf,gf,A,(mmn,df));" */
int lexical()
{
int i=0;
char t=0;
while (1)
{
t=buffer_getchar();
if(t==' ' || t=='\t' || t=='\n')
;
else if(t=='(' || t==')' || t==',' || t==';')
{
rt_token[0]=t;
rt_token[1]='\0';
break;
}
/* It is a list name */
else if(isupper(t)!=0)
{
rt_token[0]=t;
t=buffer_getchar();
i=1;
while (isupper(t)!=0)
{
if (i==MAX_LIST_NAME)
{
err_set(E_LSTNAME_LONG);
err_attach(RP_LINE);
return FALSE;
}
rt_token[i++]=t;
t=buffer_getchar();
}
/* Read one more character */
/* At the end of the name , there must
exist a comma or a parenthesis , or it
gets error .
For example:
ABDrt is not a illegal name */
if (t!=',' && t!=')')
{
err_set(E_MISS_SEPARATOR);
err_attach(RP_LINE);
return FALSE;
}
buffer_ungetchar();
MAKE_STRING(rt_token,i);
break;
}
/* It is a element name */
else if (islower(t)!=0)
{
rt_token[0]=t;
t=buffer_getchar();
i=1;
while (islower(t)!=0)
{
if (i==MAX_ELEM_NAME)
{
err_set(E_ELMNAME_LONG);
err_attach(RP_LINE);
return FALSE;
}
rt_token[i++]=t;
t=buffer_getchar();
}
if (t!=',' && t!=')')
{
err_set(E_MISS_SEPARATOR);
err_attach(RP_LINE);
return FALSE;
}
buffer_ungetchar();
MAKE_STRING(rt_token,i);
break;
}
/* Unexpected characters */
else if (isdigit(t)!=0)
{
err_set(E_NODIGIT);
err_attach(RP_LINE);
return FALSE;
}
else if (isascii(t)!=0 || iscntrl(t)!=0)
{
err_set(E_WRONG_SYMBOL);
err_attach(RP_LINE);
return FALSE;
}
else
{
err_set(E_UNCAUGHT_SYMBL);
err_attach(RP_LINE);
return FALSE;
}
}
return TRUE;
}
char* sys_token_get()
{
if (lexical()==FALSE)
return NULL;
return rt_token;
}
void sys_token_clean()
{
buffer_ungetchar();
}