Function fmtIdEnc

src/fe_utils/string_utils.c:100–246

* Quotes input string if it's not a legitimate SQL identifier as-is. * * Note that the returned string must be used before calling fmtIdEnc again, * since we re-use the same return buffer each time. */

 *	since we re-use the same return buffer each time.
 */
const char *
fmtIdEnc(const char *rawid, int encoding)
{
	PQExpBuffer id_return = getLocalPQExpBuffer();

	const char *cp;
	bool		need_quotes = false;
	size_t		remaining = strlen(rawid);

	/*
	 * These checks need to match the identifier production in scan.l. Don't
	 * use islower() etc.
	 */
	if (quote_all_identifiers)
		need_quotes = true;
	/* slightly different rules for first character */
	else if (!((rawid[0] >= 'a' && rawid[0] <= 'z') || rawid[0] == '_'))
		need_quotes = true;
	else
	{
		/* otherwise check the entire string */
		cp = rawid;
		for (size_t i = 0; i < remaining; i++, cp++)
		{
			if (!((*cp >= 'a' && *cp <= 'z')
				  || (*cp >= '0' && *cp <= '9')
				  || (*cp == '_')))
			{
				need_quotes = true;
				break;
			}
		}
	}

	if (!need_quotes)
	{
		/*
		 * Check for keyword.  We quote keywords except for unreserved ones.
		 * (In some cases we could avoid quoting a col_name or type_func_name
		 * keyword, but it seems much harder than it's worth to tell that.)
		 *
		 * Note: ScanKeywordLookup() does case-insensitive comparison, but
		 * that's fine, since we already know we have all-lower-case.
		 */
		int			kwnum = ScanKeywordLookup(rawid, &ScanKeywords);

		if (kwnum >= 0 && ScanKeywordCategories[kwnum] != UNRESERVED_KEYWORD)
			need_quotes = true;
	}

	if (!need_quotes)
	{
		/* no quoting needed */
		appendPQExpBufferStr(id_return, rawid);
	}
	else
	{
		appendPQExpBufferChar(id_return, '"');