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#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
enum tToken
{
PLUS, MINUS, MUL, DIV, LPAR, RPAR, NUMBER, END, ERROR
};
tToken Token;
double TokenValue;
char *srcPos; // Program position
tToken searchToken() {
Token = ERROR;
if (srcPos==0) {
Token = END;
} else {
switch (*srcPos)
{
case '(': Token=LPAR; break;
case ')': Token=RPAR; break;
case '*': Token=MUL; break;
case '/': Token=DIV; break;
case '+': Token=PLUS; break;
case '-': Token=MINUS; break;
}
if (*srcPos>='0' && *srcPos<'9') {
Token=NUMBER;
TokenValue = 0.0;
}
while (*srcPos>='0' && *srcPos<'9') {
TokenValue *= 10;
TokenValue += *srcPos-'0';
srcPos++;
}
if (Token != NUMBER) {
srcPos++;
}
}
return Token;
}
tToken Error(char *s){
cout << s << endl;
return ERROR;
}
double PlusMinus();
double tal() {
double Value;
switch(Token) {
case NUMBER:
searchToken();
return TokenValue;
case MINUS:
searchToken();
return -tal();
case LPAR:
searchToken();
Value = PlusMinus();
if (Token != RPAR) {
return Error(") expected");}
{
searchToken();
return Value;
case END:
return 1;
}
}
return Error("Primary expected");
}
double MulDiv() {
double Value;
Value = tal();
while (Token==MUL || Token==DIV) {
if (Token==MUL)
{
searchToken();
Value *= tal();
} else if (Token==DIV) {
searchToken();
Value /= tal();
}
}
return Value;
}
double PlusMinus() {
double Value;
Value = MulDiv();
while (Token==PLUS || Token==MINUS) {
if (Token==PLUS) {
searchToken();
Value += MulDiv();
} else if (Token==MINUS) {
searchToken();
Value -= MulDiv();
}
}
return Value;
}
double Utvardering(char *s) {
srcPos = s;
searchToken(); // Determines the first token in advance
return PlusMinus();
}
int main(int argc, char* argv[]) {
// Display the application information
cout << "CERES Interpreter 0.1 ALPHA" << endl;
cout << "Written by James Brooks 2009" << endl;
cout << "Based on code by ogranatw" << endl;
if (argc > 1) {
const int MAX_SIZE = 1024;
char buf[MAX_SIZE];
FILE* fFile = fopen(argv[1], "r");
if (!fgets(buf, MAX_SIZE, fFile)) {
Error("Script file could not be executed!");
exit(1);
}else{
printf("%s\n", buf);
double Value = Utvardering(buf);
cout << Value << endl;
}
}else{
// Woops the user made a mistake
cout << "Usage: " << argv[0] << " -scriptfile" << endl;
}
cin.get();
return 0;
}
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