exduckdb

#include "duckdb/main/relation/projection_relation.hpp"
#include "duckdb/main/client_context.hpp"
#include "duckdb/parser/query_node/select_node.hpp"
#include "duckdb/parser/tableref/subqueryref.hpp"

namespace duckdb {

ProjectionRelation::ProjectionRelation(shared_ptr<Relation> child_p,
                                       vector<unique_ptr<ParsedExpression>> parsed_expressions, vector<string> aliases)
    : Relation(child_p->context, RelationType::PROJECTION_RELATION), expressions(move(parsed_expressions)),
      child(move(child_p)) {
	if (!aliases.empty()) {
		if (aliases.size() != expressions.size()) {
			throw ParserException("Aliases list length must match expression list length!");
		}
		for (idx_t i = 0; i < aliases.size(); i++) {
			expressions[i]->alias = aliases[i];
		}
	}
	// bind the expressions
	context.TryBindRelation(*this, this->columns);
}

unique_ptr<QueryNode> ProjectionRelation::GetQueryNode() {
	auto child_ptr = child.get();
	while (child_ptr->InheritsColumnBindings()) {
		child_ptr = child_ptr->ChildRelation();
	}
	unique_ptr<QueryNode> result;
	if (child_ptr->type == RelationType::JOIN_RELATION) {
		// child node is a join: push projection into the child query node
		result = child->GetQueryNode();
	} else {
		// child node is not a join: create a new select node and push the child as a table reference
		auto select = make_unique<SelectNode>();
		select->from_table = child->GetTableRef();
		result = move(select);
	}
	D_ASSERT(result->type == QueryNodeType::SELECT_NODE);
	auto &select_node = (SelectNode &)*result;
	select_node.aggregate_handling = AggregateHandling::NO_AGGREGATES_ALLOWED;
	select_node.select_list.clear();
	for (auto &expr : expressions) {
		select_node.select_list.push_back(expr->Copy());
	}
	return result;
}

string ProjectionRelation::GetAlias() {
	return child->GetAlias();
}

const vector<ColumnDefinition> &ProjectionRelation::Columns() {
	return columns;
}

string ProjectionRelation::ToString(idx_t depth) {
	string str = RenderWhitespace(depth) + "Projection [";
	for (idx_t i = 0; i < expressions.size(); i++) {
		if (i != 0) {
			str += ", ";
		}
		str += expressions[i]->ToString();
	}
	str += "]\n";
	return str + child->ToString(depth + 1);
}

} // namespace duckdb