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lexical_analysis.c
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#include "myhead.h"
/*判断是否在for中*/
int forFlag = 0;
char * keywords[MAX_KEYWORLD] = { "int","printf","if","else","do","while","break","for" };
int lexical_analysis(void)/*词法分析*/
{
/*
共分为四大块，分别是空格、注释、标示符、数字、符号，对应下面的 if else if 和 else
*/
int n = 0, m = 0;
sum = 0;
for (n = 0; n < 20; n++)
token[n] = '\0';
while (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == '\"')
{
while (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n')
{
if (ch == '\n')
current_row++;
ch = progrem[index++];
}
if (ch == '\"')
{
ch = progrem[index++];
while (ch != '\"')
ch = progrem[index++];
ch = progrem[index++];
}
}
if (ch == '/')/*判断是否为注释*/
{
ch = progrem[index++];
if (ch == '*')
{
ch = progrem[index++];
while ((ch != '*') && (progrem[index] != '/'))
{
if (ch == '\n')
current_row++;
ch = progrem[index++];
}
index += 2;
ch = progrem[index - 1];
syn = -1;
return 0;
}
else if (ch == '/')
{
ch = progrem[index++];
while (ch != '\n'&&ch != EOF)
{
ch = progrem[index++];
}
if (ch == '\n')
current_row++;
ch = progrem[index++];
}
else
{
index--,ch = progrem[index - 1];
}
}
if ((ch >= 'a'&&ch <= 'z') || (ch >= 'A'&&ch <= 'Z') || ch == '_') //可能是标示符或者变量名
{
while ((ch >= '0'&&ch <= '9') || (ch >= 'a'&&ch <= 'z') || (ch >= 'A'&&ch <= 'Z') || ch == '_')
{
token[m++] = ch;
ch = progrem[index++];
}
token[m++] = '\0';
syn = 10;
for (n = 0; n<MAX_KEYWORLD; n++) //将识别出来的字符和已定义的标示符作比较，
if (strcmp(token, keywords[n]) == 0)
{
syn = n + 1;
break;
}
if (strcmp(token, "for") == 0)
forFlag = 1,currentFloor++;
}
else if ((ch >= '0'&&ch <= '9')) //数字
{
sum = 0;
while ((ch >= '0'&&ch <= '9'))
{
sum = sum * 10 + ch - '0';
ch = progrem[index++];
}
syn = 11;
}
else switch (ch) //其他字符
{
case'<':m = 0; token[m++] = ch;
ch = progrem[index++];
if (ch == '=')
{
syn = 23;
token[m++] = ch;
ch = progrem[index++];
}
else
{
syn = 19;
}
break;
case'>':m = 0; token[m++] = ch;
ch = progrem[index++];
if (ch == '=')
{
syn = 22;
token[m++] = ch;
ch = progrem[index++];
}
else
{
syn = 18;
}
break;
case'!':m = 0; token[m++] = ch;
ch = progrem[index++];
if (ch == '=')
{
syn = 21;
token[m++] = ch;
ch = progrem[index++];
}
else
{
syn = 17;
}
break;
case'+':m = 0; token[m++] = ch;
ch = progrem[index++];
if (ch == '+')
{
syn = 16;
token[m++] = ch;
ch = progrem[index++];
}
else
{
syn = 12;
}
break;
case'-':m = 0; token[m++] = ch;
ch = progrem[index++];
if (ch == '-')
{
syn = 17;
token[m++] = ch;
ch = progrem[index++];
}
else
{
syn = 13;
}
break;
case '=':m = 0; token[m++] = ch;
ch = progrem[index++];
if (ch == '=')
{
syn = 20;
token[m++] = ch;
ch = progrem[index++];
}
else
{
syn = 29;
}
break;
case'*':syn = 14; token[0] = ch; ch = progrem[index++]; break;
case'/':syn = 15; token[0] = ch; ch = progrem[index++]; break;
case'(':syn = 24; token[0] = ch; ch = progrem[index++]; break;
case')':syn = 25; token[0] = ch; ch = progrem[index++];
if (forFlag)
forFlag = 0,currentFloor--;
break;
case'{':syn = 26; token[0] = ch; ch = progrem[index++]; currentFloor++; break;
case'}':syn = 27; token[0] = ch; ch = progrem[index++]; currentFloor--; break;
case';':syn = 28; token[0] = ch; ch = progrem[index++]; break;
case',':syn = 30; token[0] = ch; ch = progrem[index++]; break;
case'\0':syn = 0; token[0] = ch; ch = progrem[index++]; break;
case'\n':syn = -1; ch = progrem[index++]; current_row++; break;
default: syn = -1; break;
}
return 0;
}