#include "globals.h"
#include "util.h"
#include "scan.h"
#define BUFLEN 256
static struct //保留字的结构
{
char* str;
TokenType tok;
}reservedWords[MAXRESERVED] //给保留字结构数组附值
={
{"if",IF},{"int",INT},{"else",ELSE},
{"return",RETURN},{"while",WHILE},{"void",VOID}};
typedef enum
{ START,INNUM,INID,DONE,
INAOE,INASSIGN,
INOOC,INCOMMENT,INOUTCOM,
INLOE,INLT,INLE,
INROE,INRT,INRE,
INNE
} StateType;
char tokenString[MAXTOKENLEN+1];
static char lineBuf[ BUFLEN ] ; //一行的缓冲字符
static int linepos=0; //在一行的具体位置
static int bufsize=0; //缓冲的大小
static TokenType reservedLookup(char * s) //保留字的查找
{
int i;
for(i=0;i<MAXRESERVED;i++)
{
if(!strcmp(s,reservedWords[i].str))
return reservedWords[i].tok ;
}
return ID;
}
static char getNextChar() //得到 下一个字符
{
//sourceFile=fopen("sourceFile.txt","r"); //找不到文件。
if(sourceFile==NULL)
{
printf("sourceFile null");
exit(0);
}
// listOutFile=fopen("listOutFile.txt","w"); //
if(listOutFile==NULL)
{
printf("listOutFile null");
exit(0);
}
EchoSource=1;
if(!(linepos<bufsize))
{
lineNo++;
if(fgets(lineBuf,BUFLEN-1,sourceFile)) //从sourceFile中读取内容
{
if(EchoSource)
fprintf(listOutFile,"%4d:%s",lineNo,lineBuf);
bufsize=strlen(lineBuf);
linepos=0;
return lineBuf[linepos++];
}
else
return EOF;
}
else
return lineBuf[linepos++];
}
static void ungetNextChar() //读字符的位置往回走一个
{
linepos--;
}
TokenType getToken()
{
int tokenStringIndex= 0 ;
TokenType currentToken ;
StateType state = START ;
int save ;
while(state!=DONE)
{
char c=getNextChar();
save=TRUE;
switch(state)
{
case START:
if(isdigit(c))
state=INNUM ;
else if(isalpha(c))
state=INID ;
else if(c==' '||(c=='\t'||(c=='\n')))
save =FALSE ;//false
else if(c=='<')
state=INLOE;
else if(c=='=')
state=INAOE;
else if(c=='>')
state=INROE;
else if(c=='/')
{
save=FALSE;
state=INOOC;
}
else
{
state=DONE;
switch(c)
{
case EOF:
save=FALSE;//false
currentToken=ENDFILE; break;
case '+':
currentToken=PLUS; break;
case '-':
currentToken=MINUS; break;
case '*':
currentToken=TIMES; break;
case '(':
currentToken=LPAREN; break;
case ')':
currentToken=RPAREN; break;
case '[':
currentToken=LBRACK; break;
case ']':
currentToken=RBRACK; break;
case '{':
currentToken=LBRACE; break;
case '}':
currentToken=RBRACE; break;
case ';':
currentToken=SEMI; break;
case ',':
currentToken=COMMA;break;
default:
currentToken=ERROR; break;
}
}
break;
case INID:
if (!isalpha(c))
{
ungetNextChar();
save=FALSE;
state=DONE;
currentToken=ID;
}
break;
case INNUM:
if (!isdigit(c))
{
ungetNextChar();
save=FALSE;
state=DONE;
currentToken=NUM;
}
break;
case INLOE:
if(c=='='){
save=FALSE;
state=DONE;
currentToken=LE;
}else{
ungetNextChar();
save=FALSE;
state=DONE;
currentToken=LT;
}
break;
case INOOC:
save=FALSE;
if(c == '*'){
state=INCOMMENT;
currentToken =LCOMMENT;
}
else
{
ungetNextChar();
save=FALSE;
currentToken=OVER;
state=DONE;
}
break ;
case INCOMMENT:
save=FALSE;
if(c=='*')
state =INOUTCOM;
break;
case INOUTCOM:
if(c=='/'){
save=FALSE;
currentToken=RCOMMENT;
state=START;
}
else{
save=FALSE;
currentToken =INCOMMENT;
}
break;
case INAOE:
state=DONE;
if( c == '=')
currentToken=EQ;
else
{
ungetNextChar();
save=FALSE; //false
currentToken=ASSIGN;
}
break;
case DONE:
default:
fprintf(listOutFile,"scan bug:state=%d\n",state);
state=DONE;
currentToken=ERROR;
break;
} //switch 结束
if((save)&&(tokenStringIndex<=MAXTOKENLEN))
tokenString[tokenStringIndex++]=c;
if(state== DONE)
{
tokenString[tokenStringIndex]='\0';
if(currentToken==ID)
currentToken=reservedLookup(tokenString); //判断当前Token是否为保留字
}
} //while循环结束
if(!TraceScan)
{
fprintf(listOutFile,"\t%d: ",lineNo);
printToken(currentToken,tokenString);
}
return currentToken;
}
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