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scanner.cpp
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scanner.cpp
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// scanner.cpp: Ä¿±êµÄÔ´Îļþ¡£
//
#include <cstdio>
#include <iostream>
#include <cstring>
#include "scanner.h"
#define __BASE_FILE__ "scanner.cpp"
#define MAX_TOKEN_LEN 0x40
char TokenBufStream[MAX_TOKEN_LEN + 8];
FILE* srcFile;
unsigned int LineCount = 1;
unsigned int LinePos = 0;
int InitScanner(const char* filename) {
srcFile = fopen(filename, "r");
if (srcFile == NULL) {
fprintf(stderr, "[%s, %d, %s()] Can not open file '%s'!\n", __BASE_FILE__, __LINE__, __func__, filename);
return -1;
}
return 0;
}
static fpos_t GetFilePos() {
fpos_t pos;
fgetpos(srcFile, &pos);
return pos;
}
static char FetchChar() {
// Read one char from srcFile stream;
char ch = fgetc(srcFile);
if (ch != EOF) {
LinePos++;
}
return ch;
}
static void IgnoreChar(const char ch) {
// Put ch back to the srcFile stream
// It will be fetched again next turn;
if (ch != EOF) {
ungetc(ch, srcFile);
LinePos--;
}
}
static void EmptyTokenBuf() {
memset(TokenBufStream, 0, sizeof(TokenBufStream));
}
static int TokenBufPush(const char ch) {
if (strlen(TokenBufStream) >= MAX_TOKEN_LEN) {
fprintf(stderr, "[%s, %d, %s()] Token too long! - '%s'\n", __BASE_FILE__, __LINE__, __func__, TokenBufStream);
exit(-1);
}
TokenBufStream[strlen(TokenBufStream)] = ch;
TokenBufStream[strlen(TokenBufStream) + 1] = '\0';
return 0;
}
static Token GetErrorToken() {
Token errtoken;
memset(&errtoken, 0, sizeof(errtoken));
return errtoken;
}
static Token KeyTokenMatch() {
int TokenTabSize = sizeof(TokenTab) / sizeof(Token);
// Traverse the entire TokenTab
for (int i = 0; i < TokenTabSize; i++) {
Token* item = &TokenTab[i];
#if _WIN32
if(!stricmp(TokenBufStream, item->lexeme))
#else
if(!strcasecmp(TokenBufStream, item->lexeme))
#endif
{
// Match successful
return TokenTab[i];
}
}
// Matching failed
return GetErrorToken();
}
Token GetToken() {
Token token;
char CurrChar;
int FiniFlag = 0;
// bzero
GET_TOKEN:
memset(&token, 0, sizeof(token));
EmptyTokenBuf();
CurrChar = FetchChar();
token.lexeme = TokenBufStream;
// strip
switch (CurrChar) {
// strip whitespace
case ' ':
case '\\':
case '\r':
case '\t':
goto GET_TOKEN;
case '\n':
// start new line
LineCount++;
LinePos = 0;
goto GET_TOKEN;
default:
break;
}
// Process symbols beginning with alpha letters
if (isalpha(CurrChar)) {
do {
TokenBufPush(CurrChar);
CurrChar = FetchChar();
} while (isalnum(CurrChar));
IgnoreChar(CurrChar);
token = KeyTokenMatch();
return token;
}
// Process symbols beginning with numeric character
if (isdigit(CurrChar)) {
// Integer part
do {
TokenBufPush(CurrChar);
CurrChar = FetchChar();
} while (isdigit(CurrChar));
// Fractional part (if any)
if (CurrChar == '.') {
TokenBufPush(CurrChar);
CurrChar = FetchChar();
// Cannot be empty after decimal point
if (!isdigit(CurrChar)) {
IgnoreChar(CurrChar);
return GetErrorToken();
}
do {
TokenBufPush(CurrChar);
CurrChar = FetchChar();
} while (isdigit(CurrChar));
IgnoreChar(CurrChar);
}
else {
IgnoreChar(CurrChar);
}
token.type = CONST_ID;
token.lexeme = TokenBufStream;
token.value = atof(TokenBufStream);
return token;
}
TokenBufPush(CurrChar);
switch (CurrChar) {
// Separator
case ';':
token.type = SEMICO;
break;
case '(':
token.type = L_BRACKET;
break;
case ')':
token.type = R_BRACKET;
break;
case ',':
token.type = COMMA;
break;
// Operators
case '+':
token.type = PLUS;
break;
case '-':
CurrChar = FetchChar();
if (CurrChar != '-') {
IgnoreChar(CurrChar);
token.type = MINUS;
break;
}
do {
CurrChar = FetchChar();
} while (CurrChar != '\n');
IgnoreChar(CurrChar); // put '\n' back to the stream
goto GET_TOKEN;
case '/':
CurrChar = FetchChar();
if (CurrChar != '/') {
IgnoreChar(CurrChar);
token.type = DIV;
break;
}
do {
CurrChar = FetchChar();
} while (CurrChar != '\n');
IgnoreChar(CurrChar); // put '\n' back to the stream
goto GET_TOKEN;
case '*':
CurrChar = FetchChar();
if (CurrChar == '*') {
token.type = POWER;
break;
}
else {
IgnoreChar(CurrChar);
token.type = MUL;
break;
}
case EOF:
token.type = NONTOKEN;
break;
default:
fprintf(stderr, "[%s, %d, %s()] Invalid char '%c' at line %u column %u!\n",
__BASE_FILE__, __LINE__, __func__,
CurrChar, LineCount, LinePos);
token.type = ERRTOKEN;
break;
}
return token;
}
int CloseScanner() {
return fclose(srcFile);
}