text: #define _XOPEN_SOURCE 500
  #include <string.h>
  #include "sway/commands.h"
  #include "sway/criteria.h"
  #include "list.h"
  #include "log.h"
  #include "stringop.h"
  
  struct cmd_results *cmd_for_window(int argc, char **argv) {
  	struct cmd_results *error = NULL;
  	if ((error = checkarg(argc, "for_window", EXPECTED_AT_LEAST, 2))) {
  		return error;
  	}
  	// add command to a criteria/command pair that is run against views when they appear.
  	char *criteria = argv[0], *cmdlist = join_args(argv + 1, argc - 1);
  
  	struct criteria *crit = malloc(sizeof(struct criteria));
  	if (!crit) {
  		return cmd_results_new(CMD_FAILURE, "for_window", "Unable to allocate criteria");
  	}
  	crit->crit_raw = strdup(criteria);
  	crit->cmdlist = cmdlist;
  	crit->tokens = create_list();
  	char *err_str = extract_crit_tokens(crit->tokens, crit->crit_raw);
  
  	if (err_str) {
  		error = cmd_results_new(CMD_INVALID, "for_window", err_str);
  		free(err_str);
  		free_criteria(crit);
  	} else if (crit->tokens->length == 0) {
  		error = cmd_results_new(CMD_INVALID, "for_window", "Found no name/value pairs in criteria");
  		free_criteria(crit);
  	} else if (list_seq_find(config->criteria, criteria_cmp, crit) != -1) {
  		sway_log(L_DEBUG, "for_window: Duplicate, skipping.");
  		free_criteria(crit);
  	} else {
  		sway_log(L_DEBUG, "for_window: '%s' -> '%s' added", crit->crit_raw, crit->cmdlist);
  		list_add(config->criteria, crit);
  	}
  	return error ? error : cmd_results_new(CMD_SUCCESS, NULL, NULL);
  }
  