119 lines
2.8 KiB
C
119 lines
2.8 KiB
C
#include "Calculator.h"
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#include <ctype.h>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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static char logic_log[4096];
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typedef struct {
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const char *buffer;
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int pos;
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} Parser;
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static double parse_expression(Parser *p);
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static void skip_ws(Parser *p) {
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while (p->buffer[p->pos] == ' ')
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p->pos++;
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}
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static double parse_factor(Parser *p) {
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skip_ws(p);
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if (p->buffer[p->pos] == '-') {
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p->pos++;
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return -parse_factor(p);
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}
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if (p->buffer[p->pos] == '(') {
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p->pos++;
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double res = parse_expression(p);
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if (p->buffer[p->pos] == ')')
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p->pos++;
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return res;
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}
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char *endptr;
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double val = strtod(&p->buffer[p->pos], &endptr);
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p->pos = (int)(endptr - p->buffer);
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return val;
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}
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static double parse_term(Parser *p) {
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double left = parse_factor(p);
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while (1) {
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skip_ws(p);
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char op = p->buffer[p->pos];
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if (op == '*' || op == '/') {
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p->pos++;
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double right = parse_factor(p);
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double old = left;
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left = (op == '*') ? left * right : left / right;
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char step[256];
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snprintf(step, sizeof(step), "<div>%g %c %g = <b>%g</b></div>", old, op,
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right, left);
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strncat(logic_log, step, sizeof(logic_log) - strlen(logic_log) - 1);
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} else
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break;
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}
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return left;
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}
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static double parse_expression(Parser *p) {
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double left = parse_term(p);
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while (1) {
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skip_ws(p);
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char op = p->buffer[p->pos];
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if (op == '+' || op == '-') {
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p->pos++;
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double right = parse_term(p);
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double old = left;
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left = (op == '+') ? left + right : left - right;
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char step[256];
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snprintf(step, sizeof(step), "<div>%g %c %g = <b>%g</b></div>", old, op,
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right, left);
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strncat(logic_log, step, sizeof(logic_log) - strlen(logic_log) - 1);
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} else
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break;
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}
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return left;
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}
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double evaluate(const char *expr) {
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logic_log[0] = '\0';
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if (!expr || strlen(expr) == 0)
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return 0.0;
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Parser p = {expr, 0};
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return parse_expression(&p);
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}
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InfoBox fetch_calc_data(char *math_input) {
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InfoBox info = {NULL, NULL, NULL, NULL};
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if (!math_input)
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return info;
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double result = evaluate(math_input);
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char html_output[5120];
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snprintf(html_output, sizeof(html_output),
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"<div class='calc-container' style='line-height: 1.6;'>"
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"%s"
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"<div style='margin-top: 8px; border-top: 1px solid #eee; "
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"padding-top: 8px; font-size: 1.2em;'>"
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"<b>%g</b>"
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"</div>"
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"</div>",
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strlen(logic_log) > 0 ? logic_log : "<div>Constant value</div>",
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result);
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info.title = strdup("Calculation");
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info.extract = strdup(html_output);
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info.thumbnail_url = strdup("/static/calculation.svg");
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info.url = strdup("#");
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return info;
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}
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