Method setupComputedFields

src/jrd/ExtEngineManager.cpp:1000–1080

void ExtEngineManager::Trigger::setupComputedFields(thread_db* tdbb, MemoryPool& pool, CompilerScratch* csb)
{
	SET_TDBB(tdbb);

	USHORT varId = 0;

	static_assert(NEW_CONTEXT_VALUE == OLD_CONTEXT_VALUE + 1, "OLD/NEW context assumption.");

	for (unsigned context = OLD_CONTEXT_VALUE; context <= NEW_CONTEXT_VALUE; ++context)	// OLD (0), NEW (1)
	{
		for (FB_SIZE_T i = 0; i < trg->relation->rel_fields->count(); ++i)
		{
			jrd_fld* field = (*trg->relation->rel_fields)[i];
			if (!field || !field->fld_computation)
				continue;

			if (context == OLD_CONTEXT_VALUE)	// count once
				++computedCount;

			DeclareVariableNode* declareNode = FB_NEW_POOL(pool) DeclareVariableNode(pool);
			declareNode->varId = varId;

			declareNode->varDesc = trg->relation->rel_current_format->fmt_desc[i];

			// For CHAR fields, change variable type to VARCHAR to avoid manual INTL adjustments for multi-byte.
			if (declareNode->varDesc.isText())
			{
				declareNode->varDesc.dsc_dtype = dtype_varying;
				declareNode->varDesc.dsc_length += sizeof(USHORT);
			}

			varDecls.push(declareNode);

			csb->csb_variables = vec<DeclareVariableNode*>::newVector(
				*tdbb->getDefaultPool(), csb->csb_variables, varId);

			ValueExprNode* exprNode = FB_NEW_POOL(*tdbb->getDefaultPool()) FieldNode(*tdbb->getDefaultPool(), context, i, true);

			VariableNode* varNode = FB_NEW_POOL(pool) VariableNode(pool);
			varNode->varId = varId;

			AssignmentNode* assignNode = FB_NEW_POOL(pool) AssignmentNode(pool);
			assignNode->asgnFrom = exprNode;
			assignNode->asgnTo = varNode;

			// Do not run the assignment for invalid RPBs (NEW in DELETE, OLD in INSERT).

			SLONG* actionPtr = FB_NEW_POOL(pool) SLONG(INFO_TYPE_TRIGGER_ACTION);

			LiteralNode* actionLiteral = FB_NEW_POOL(pool) LiteralNode(pool);
			actionLiteral->litDesc.dsc_dtype = dtype_long;
			actionLiteral->litDesc.dsc_length = sizeof(SLONG);
			actionLiteral->litDesc.dsc_scale = 0;
			actionLiteral->litDesc.dsc_sub_type = 0;
			actionLiteral->litDesc.dsc_address = reinterpret_cast<UCHAR*>(actionPtr);

			InternalInfoNode* internalInfo = FB_NEW_POOL(pool) InternalInfoNode(pool, actionLiteral);