73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
/**
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* This file is part of the Fun programming language.
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* https://fun-lang.xyz/
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*
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* Copyright 2025 Johannes Findeisen <you@hanez.org>
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* Licensed under the terms of the Apache-2.0 license.
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* https://opensource.org/license/apache-2-0
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*
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* Added: 2025-10-04
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*/
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/**
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* @file date_format.c
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* @brief Implements OP_DATE_FORMAT to format an epoch milliseconds timestamp using strftime.
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*
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* Behavior:
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* - Pops fmt string, then milliseconds since Unix epoch (int).
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* - Formats the local time according to fmt and pushes a string.
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*
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* Errors:
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* - If types are wrong, prints error and pushes empty string to keep stack safe.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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case OP_DATE_FORMAT: {
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Value fmt = pop_value(vm);
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Value ms = pop_value(vm);
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if (ms.type != VAL_INT || fmt.type != VAL_STRING) {
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fprintf(stderr, "DATE_FORMAT expects (fmt:string, ms:int)\n");
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if (ms.type != VAL_NIL) free_value(ms);
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if (fmt.type != VAL_NIL) free_value(fmt);
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push_value(vm, make_string(""));
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break;
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}
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time_t secs = (time_t)(ms.i / 1000);
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struct tm tmv;
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#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 1
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localtime_r(&secs, &tmv);
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#else
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struct tm *ptm = localtime(&secs);
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if (!ptm) {
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free_value(ms);
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free_value(fmt);
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push_value(vm, make_string(""));
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break;
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}
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tmv = *ptm;
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#endif
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/* Determine buffer size by attempting once with a reasonable size and retrying if needed */
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size_t cap = 128;
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char *buf = (char *)malloc(cap);
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size_t n = strftime(buf, cap, fmt.s, &tmv);
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if (n == 0) {
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/* try larger */
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cap = 512;
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buf = (char *)realloc(buf, cap);
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n = strftime(buf, cap, fmt.s, &tmv);
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}
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Value out;
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if (n == 0) {
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out = make_string("");
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} else {
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out = make_string(buf);
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}
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free(buf);
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free_value(ms);
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free_value(fmt);
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push_value(vm, out);
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break;
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}
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