Method buildColumnTransformers

src/Analyzer/QueryTreeBuilder.cpp:1219–1282

ColumnTransformersNodes QueryTreeBuilder::buildColumnTransformers(const ASTPtr & matcher_expression, const ContextPtr & context) const
{
    ColumnTransformersNodes column_transformers;

    if (!matcher_expression)
        return column_transformers;

    for (const auto & child : matcher_expression->children)
    {
        if (auto * apply_transformer = child->as<ASTColumnsApplyTransformer>())
        {
            if (apply_transformer->lambda)
            {
                auto lambda_query_tree_node = buildExpression(apply_transformer->lambda, context);
                column_transformers.emplace_back(std::make_shared<ApplyColumnTransformerNode>(std::move(lambda_query_tree_node)));
            }
            else
            {
                auto function_node = std::make_shared<FunctionNode>(apply_transformer->func_name);
                if (apply_transformer->parameters)
                    function_node->getParametersNode() = buildExpressionList(apply_transformer->parameters, context);

                column_transformers.emplace_back(std::make_shared<ApplyColumnTransformerNode>(std::move(function_node)));
            }
        }
        else if (auto * except_transformer = child->as<ASTColumnsExceptTransformer>())
        {
            auto matcher = except_transformer->getMatcher();
            if (matcher)
            {
                column_transformers.emplace_back(std::make_shared<ExceptColumnTransformerNode>(std::move(matcher)));
            }
            else
            {
                Names except_column_names;
                except_column_names.reserve(except_transformer->children.size());

                for (auto & except_transformer_child : except_transformer->children)
                    except_column_names.push_back(except_transformer_child->as<ASTIdentifier &>().full_name);

                column_transformers.emplace_back(std::make_shared<ExceptColumnTransformerNode>(std::move(except_column_names), except_transformer->is_strict));
            }
        }
        else if (auto * replace_transformer = child->as<ASTColumnsReplaceTransformer>())
        {
            std::vector<ReplaceColumnTransformerNode::Replacement> replacements;
            replacements.reserve(replace_transformer->children.size());

            for (const auto & replace_transformer_child : replace_transformer->children)
            {
                auto & replacement = replace_transformer_child->as<ASTColumnsReplaceTransformer::Replacement &>();
                replacements.emplace_back(ReplaceColumnTransformerNode::Replacement{replacement.name, buildExpression(replacement.children[0], context)});
            }

            column_transformers.emplace_back(std::make_shared<ReplaceColumnTransformerNode>(replacements, replace_transformer->is_strict));
        }
        else
        {