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/*
* Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibSQL/AST/AST.h>
#include <LibSQL/Database.h>
#include <LibSQL/Meta.h>
#include <LibSQL/Row.h>
namespace SQL::AST {
RefPtr<SQLResult> Select::execute(ExecutionContext& context) const
{
NonnullRefPtrVector<ResultColumn> columns;
for (auto& table_descriptor : table_or_subquery_list()) {
if (!table_descriptor.is_table())
TODO();
auto table = context.database->get_table(table_descriptor.schema_name(), table_descriptor.table_name());
if (!table) {
return SQLResult::construct(SQL::SQLCommand::Select, SQL::SQLErrorCode::TableDoesNotExist, table_descriptor.table_name());
}
if (result_column_list().size() == 1 && result_column_list()[0].type() == ResultType::All) {
for (auto& col : table->columns()) {
columns.append(
create_ast_node<ResultColumn>(
create_ast_node<ColumnNameExpression>(table->parent()->name(), table->name(), col.name()),
""));
}
}
}
VERIFY(!result_column_list().is_empty());
if (result_column_list().size() != 1 || result_column_list()[0].type() != ResultType::All) {
for (auto& col : result_column_list()) {
if (col.type() == ResultType::All)
// FIXME can have '*' for example in conjunction with computed columns
return SQLResult::construct(SQL::SQLCommand::Select, SQL::SQLErrorCode::SyntaxError, "*");
columns.append(col);
}
}
context.result = SQLResult::construct();
AK::NonnullRefPtr<TupleDescriptor> descriptor = AK::adopt_ref(*new TupleDescriptor);
Tuple tuple(descriptor);
Vector<Tuple> rows;
descriptor->empend("__unity__");
tuple.append(Value(SQLType::Boolean, true));
rows.append(tuple);
for (auto& table_descriptor : table_or_subquery_list()) {
if (!table_descriptor.is_table())
TODO();
auto table = context.database->get_table(table_descriptor.schema_name(), table_descriptor.table_name());
if (table->num_columns() == 0)
continue;
auto old_descriptor_size = descriptor->size();
descriptor->extend(table->to_tuple_descriptor());
for (auto cartesian_row = rows.first(); cartesian_row.size() == old_descriptor_size; cartesian_row = rows.first()) {
rows.remove(0);
for (auto& table_row : context.database->select_all(*table)) {
auto new_row = cartesian_row;
new_row.extend(table_row);
rows.append(new_row);
}
}
}
for (auto& row : rows) {
context.current_row = &row;
if (where_clause()) {
auto where_result = where_clause()->evaluate(context);
if (context.result->has_error())
return context.result;
if (!where_result)
continue;
}
tuple.clear();
for (auto& col : columns) {
auto value = col.expression()->evaluate(context);
if (context.result->has_error())
return context.result;
tuple.append(value);
}
context.result->append(tuple);
}
return context.result;
}
}
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