Function oper

src/backend/parser/parse_oper.c:381–452

oper() -- search for a binary operator * Given operator name, types of arg1 and arg2, return oper struct. * * IMPORTANT: the returned operator (if any) is only promised to be * coercion-compatible with the input datatypes. Do not use this if * you need an exact- or binary-compatible match; see compatible_oper. * * If no matching operator found, return NULL if noError is true, * raise an e

 * must ReleaseSysCache() the entry when done with it.
 */
Operator
oper(ParseState *pstate, List *opname, Oid ltypeId, Oid rtypeId,
	 bool noError, int location)
{
	Oid			operOid;
	OprCacheKey key;
	bool		key_ok;
	FuncDetailCode fdresult = FUNCDETAIL_NOTFOUND;
	HeapTuple	tup = NULL;

	/*
	 * Try to find the mapping in the lookaside cache.
	 */
	key_ok = make_oper_cache_key(pstate, &key, opname, ltypeId, rtypeId, location);

	if (key_ok)
	{
		operOid = find_oper_cache_entry(&key);
		if (OidIsValid(operOid))
		{
			tup = SearchSysCache1(OPEROID, ObjectIdGetDatum(operOid));
			if (HeapTupleIsValid(tup))
				return (Operator) tup;
		}
	}

	/*
	 * First try for an "exact" match.
	 */
	operOid = binary_oper_exact(opname, ltypeId, rtypeId);
	if (!OidIsValid(operOid))
	{
		/*
		 * Otherwise, search for the most suitable candidate.
		 */
		FuncCandidateList clist;

		/* Get binary operators of given name */
		clist = OpernameGetCandidates(opname, 'b', false);

		/* No operators found? Then fail... */
		if (clist != NULL)
		{
			/*
			 * Unspecified type for one of the arguments? then use the other
			 * (XXX this is probably dead code?)
			 */
			Oid			inputOids[2];

			if (rtypeId == InvalidOid)
				rtypeId = ltypeId;
			else if (ltypeId == InvalidOid)
				ltypeId = rtypeId;
			inputOids[0] = ltypeId;
			inputOids[1] = rtypeId;
			fdresult = oper_select_candidate(2, inputOids, clist, &operOid);
		}
	}