/* Copyright (c) 2003-2004, Roger Dingledine * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. * Copyright (c) 2007-2019, The Tor Project, Inc. */ /* See LICENSE for licensing information */ /** * \file smartlist_foreach.h * \brief Macros for iterating over the elements of a smartlist_t. **/ #ifndef TOR_SMARTLIST_FOREACH_H #define TOR_SMARTLIST_FOREACH_H /** Iterate over the items in a smartlist sl, in order. For each item, * assign it to a new local variable of type type named var, and * execute the statements inside the loop body. Inside the loop, the loop * index can be accessed as var_sl_idx and the length of the list can * be accessed as var_sl_len. * * NOTE: Do not change the length of the list while the loop is in progress, * unless you adjust the _sl_len variable correspondingly. See second example * below. * * Example use: *
* smartlist_t *list = smartlist_split("A:B:C", ":", 0, 0); * SMARTLIST_FOREACH_BEGIN(list, char *, cp) { * printf("%d: %s\n", cp_sl_idx, cp); * tor_free(cp); * } SMARTLIST_FOREACH_END(cp); * smartlist_free(list); ** * Example use (advanced): *
* SMARTLIST_FOREACH_BEGIN(list, char *, cp) { * if (!strcmp(cp, "junk")) { * tor_free(cp); * SMARTLIST_DEL_CURRENT(list, cp); * } * } SMARTLIST_FOREACH_END(cp); **/ /* Note: these macros use token pasting, and reach into smartlist internals. * This can make them a little daunting. Here's the approximate unpacking of * the above examples, for entertainment value: * *
* smartlist_t *list = smartlist_split("A:B:C", ":", 0, 0); * { * int cp_sl_idx, cp_sl_len = smartlist_len(list); * char *cp; * for (cp_sl_idx = 0; cp_sl_idx < cp_sl_len; ++cp_sl_idx) { * cp = smartlist_get(list, cp_sl_idx); * printf("%d: %s\n", cp_sl_idx, cp); * tor_free(cp); * } * } * smartlist_free(list); ** *
* { * int cp_sl_idx, cp_sl_len = smartlist_len(list); * char *cp; * for (cp_sl_idx = 0; cp_sl_idx < cp_sl_len; ++cp_sl_idx) { * cp = smartlist_get(list, cp_sl_idx); * if (!strcmp(cp, "junk")) { * tor_free(cp); * smartlist_del(list, cp_sl_idx); * --cp_sl_idx; * --cp_sl_len; * } * } * } **/ #define SMARTLIST_FOREACH_BEGIN(sl, type, var) \ STMT_BEGIN \ int var ## _sl_idx, var ## _sl_len=(sl)->num_used; \ type var; \ for (var ## _sl_idx = 0; var ## _sl_idx < var ## _sl_len; \ ++var ## _sl_idx) { \ var = (sl)->list[var ## _sl_idx]; #define SMARTLIST_FOREACH_END(var) \ var = NULL; \ (void) var ## _sl_idx; \ } STMT_END /** * An alias for SMARTLIST_FOREACH_BEGIN and SMARTLIST_FOREACH_END, using * cmd as the loop body. This wrapper is here for convenience with * very short loops. * * By convention, we do not use this for loops which nest, or for loops over * 10 lines or so. Use SMARTLIST_FOREACH_{BEGIN,END} for those. */ #define SMARTLIST_FOREACH(sl, type, var, cmd) \ SMARTLIST_FOREACH_BEGIN(sl,type,var) { \ cmd; \ } SMARTLIST_FOREACH_END(var) /** Helper: While in a SMARTLIST_FOREACH loop over the list sl indexed * with the variable var, remove the current element in a way that * won't confuse the loop. */ #define SMARTLIST_DEL_CURRENT(sl, var) \ STMT_BEGIN \ smartlist_del(sl, var ## _sl_idx); \ --var ## _sl_idx; \ --var ## _sl_len; \ STMT_END /** Helper: While in a SMARTLIST_FOREACH loop over the list sl indexed * with the variable var, remove the current element in a way that * won't confuse the loop. */ #define SMARTLIST_DEL_CURRENT_KEEPORDER(sl, var) \ STMT_BEGIN \ smartlist_del_keeporder(sl, var ## _sl_idx); \ --var ## _sl_idx; \ --var ## _sl_len; \ STMT_END /** Helper: While in a SMARTLIST_FOREACH loop over the list sl indexed * with the variable var, replace the current element with val. * Does not deallocate the current value of var. */ #define SMARTLIST_REPLACE_CURRENT(sl, var, val) \ STMT_BEGIN \ smartlist_set(sl, var ## _sl_idx, val); \ STMT_END #endif /* !defined(TOR_SMARTLIST_FOREACH_H) */