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@byanofsky
Last active April 23, 2023 16:54
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A lexer product by ChatGPT
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#define MAX_TOKEN_LENGTH 100
enum TokenType
{
TOKEN_INTEGER,
TOKEN_VARIABLE,
TOKEN_ADD_OP,
TOKEN_ASSIGN_OP,
TOKEN_PRINT,
TOKEN_LPAREN,
TOKEN_RPAREN,
TOKEN_SEMICOLON,
TOKEN_END,
TOKEN_UNKNOWN
};
struct Token
{
enum TokenType type;
char lexeme[MAX_TOKEN_LENGTH];
};
int is_add_op(char c)
{
return c == '+' || c == '-';
}
int is_digit(char c)
{
return isdigit(c);
}
int is_letter(char c)
{
return isalpha(c);
}
int is_variable_char(char c)
{
return is_letter(c) || is_digit(c);
}
int is_whitespace(char c)
{
return isspace(c);
}
struct Token get_next_token()
{
char c;
struct Token token;
token.type = TOKEN_UNKNOWN;
memset(token.lexeme, '\0', MAX_TOKEN_LENGTH);
while ((c = getchar()) != EOF)
{
if (is_whitespace(c))
{
continue;
}
else if (is_add_op(c))
{
token.type = TOKEN_ADD_OP;
sprintf(token.lexeme, "%c", c);
break;
}
else if (c == '=')
{
token.type = TOKEN_ASSIGN_OP;
sprintf(token.lexeme, "%c", c);
break;
}
else if (c == '(')
{
token.type = TOKEN_LPAREN;
sprintf(token.lexeme, "%c", c);
break;
}
else if (c == ')')
{
token.type = TOKEN_RPAREN;
sprintf(token.lexeme, "%c", c);
break;
}
else if (c == ';')
{
token.type = TOKEN_SEMICOLON;
sprintf(token.lexeme, "%c", c);
break;
}
else if (is_digit(c))
{
token.type = TOKEN_INTEGER;
int i = 0;
while (is_digit(c))
{
token.lexeme[i++] = c;
c = getchar();
}
ungetc(c, stdin);
break;
}
else if (is_letter(c))
{
int i = 0;
while (is_variable_char(c))
{
token.lexeme[i++] = c;
c = getchar();
}
ungetc(c, stdin);
if (strcmp(token.lexeme, "print") == 0)
{
token.type = TOKEN_PRINT;
}
else
{
token.type = TOKEN_VARIABLE;
}
break;
}
else
{
token.type = TOKEN_UNKNOWN;
break;
}
}
if (c == EOF)
{
token.type = TOKEN_END;
}
return token;
}
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