Method optimizeLikeSimilar

src/jrd/optimizer/Optimizer.cpp:3445–3650

//

ValueExprNode* Optimizer::optimizeLikeSimilar(ComparativeBoolNode* cmpNode)
{
	ValueExprNode* matchNode = cmpNode->arg1;
	ValueExprNode* patternNode = cmpNode->arg2;
	ValueExprNode* escapeNode = cmpNode->arg3;

	// if the pattern string or the escape string can't be
	// evaluated at compile time, forget it
	if (!nodeIs<LiteralNode>(patternNode) || (escapeNode && !nodeIs<LiteralNode>(escapeNode)))
		return nullptr;

	dsc matchDesc;
	matchNode->getDesc(tdbb, csb, &matchDesc);

	dsc* patternDesc = &nodeAs<LiteralNode>(patternNode)->litDesc;
	dsc* escapeDesc = nullptr;

	if (escapeNode)
		escapeDesc = &nodeAs<LiteralNode>(escapeNode)->litDesc;

	// if either is not a character expression, forget it
	if ((matchDesc.dsc_dtype > dtype_any_text) ||
		(patternDesc->dsc_dtype > dtype_any_text) ||
		(escapeNode && escapeDesc->dsc_dtype > dtype_any_text))
	{
		return nullptr;
	}

	TextType* matchTextType = INTL_texttype_lookup(tdbb, INTL_TTYPE(&matchDesc));
	CharSet* matchCharset = matchTextType->getCharSet();
	TextType* patternTextType = INTL_texttype_lookup(tdbb, INTL_TTYPE(patternDesc));
	CharSet* patternCharset = patternTextType->getCharSet();

	if (cmpNode->blrOp == blr_like)
	{
		UCHAR escape_canonic[sizeof(ULONG)];
		UCHAR first_ch[sizeof(ULONG)];
		ULONG first_len;
		UCHAR* p;
		USHORT p_count;
		MoveBuffer escapeBuffer;

		// Get the escape character, if any
		if (escapeNode)
		{
			// Ensure escape string is same character set as match string
			p_count = MOV_make_string2(tdbb, escapeDesc, INTL_TTYPE(&matchDesc), &p, escapeBuffer);

			first_len = matchCharset->substring(p_count, p, sizeof(first_ch), first_ch, 0, 1);
			matchTextType->canonical(first_len, p, sizeof(escape_canonic), escape_canonic);
		}

		MoveBuffer patternBuffer;
		p_count = MOV_make_string2(tdbb, patternDesc, INTL_TTYPE(&matchDesc), &p, patternBuffer);

		first_len = matchCharset->substring(p_count, p, sizeof(first_ch), first_ch, 0, 1);

		UCHAR first_canonic[sizeof(ULONG)];