Function defGetBoolean

src/backend/commands/define.c:110–160

* Extract a boolean value from a DefElem. */

 * Extract a boolean value from a DefElem.
 */
bool
defGetBoolean(DefElem *def)
{
	/*
	 * If no parameter given, assume "true" is meant.
	 */
	if (def->arg == NULL)
		return true;

	/*
	 * Allow 0, 1, "true", "false", "on", "off"
	 */
	switch (nodeTag(def->arg))
	{
		case T_Integer:
			switch (intVal(def->arg))
			{
				case 0:
					return false;
				case 1:
					return true;
				default:
					/* otherwise, error out below */
					break;
			}
			break;
		default:
			{
				char	   *sval = defGetString(def);

				/*
				 * The set of strings accepted here should match up with the
				 * grammar's opt_boolean_or_string production.
				 */
				if (pg_strcasecmp(sval, "true") == 0)
					return true;
				if (pg_strcasecmp(sval, "false") == 0)
					return false;
				if (pg_strcasecmp(sval, "on") == 0)
					return true;
				if (pg_strcasecmp(sval, "off") == 0)
					return false;
			}
			break;
	}
	ereport(ERROR,
			(errcode(ERRCODE_SYNTAX_ERROR),
			 errmsg("%s requires a Boolean value",
					def->defname)));
	return false;				/* keep compiler quiet */
}

/*
 * Extract an int32 value from a DefElem.