Calculates the input while respecting operator precedence, parentheses, etc. Not designed to be useful.
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/* vim: set filetype=c: */
#include "lex.h"
#include "ast.h"
#include <stdlib.h>
#include <stdio.h>
#define INPUT_SIZE 512
static void print_tokens(const Lex* lex) {
const TokenListItem* curr;
for(curr = lex->tokens.front; curr != NULL; curr = curr->next) {
Token_print(&curr->val, stdout);
fputc('\n', stdout);
}
}
static void handle_normal_err(const Result res, const char* domain) {
Result_print_err_or(res, domain, NULL, stderr, stdout);
if(res.has_err)
exit(EXIT_FAILURE);
}
int main() {
size_t i;
Result res;
char in[INPUT_SIZE];
Lex lex;
Lex_init(&lex);
printf("Enter an expression:\n");
for(i = 0;;i++) {
const char c = fgetc(stdin);
if(i >= INPUT_SIZE - 1 || c == '\n' || c == EOF) {
in[i] = '\0'; /* String terminator */
break;
}
in[i] = c;
}
for(i = 0; in[i] != '\0'; i++) {
res = Lex_lex_char(&lex, in[i]);
handle_normal_err(res, "Lexer error: ");
}
res = Lex_finish_lex(&lex);
handle_normal_err(res, "Lexer error: ");
printf("\n**Tokens**\n");
print_tokens(&lex);
res = Lex_apply_op_precedence(&lex, "^", true);
handle_normal_err(res, "Lexer error: ");
res = Lex_apply_op_precedence(&lex, "*/", false);
handle_normal_err(res, "Lexer error: ");
res = Lex_apply_op_precedence(&lex, "+-", false);
handle_normal_err(res, "Lexer error: ");
printf("\n**Tokens (with operator precedence)**\n");
print_tokens(&lex);
AST ast;
AST_init(&ast);
res = AST_parse_from_TokenList(&ast, &lex.tokens);
handle_normal_err(res, "Parser error: ");
printf("\n**AST**\n");
Token_print_as_tree(ast.root, stdout);
long double result = AST_evaluate(&ast);
printf("Result: %Lf\n", result);
AST_uninit(&ast);
Lex_uninit(&lex);
return EXIT_SUCCESS;
}