ladybird/Userland/Libraries/LibSQL/AST/Expression.cpp

/*
 * 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>

namespace SQL::AST {

Value Expression::evaluate(ExecutionContext&) const
{
    return Value::null();
}

Value NumericLiteral::evaluate(ExecutionContext&) const
{
    Value ret(SQLType::Float);
    ret = value();
    return ret;
}

Value StringLiteral::evaluate(ExecutionContext&) const
{
    Value ret(SQLType::Text);
    ret = value();
    return ret;
}

Value NullLiteral::evaluate(ExecutionContext&) const
{
    return Value::null();
}

Value NestedExpression::evaluate(ExecutionContext& context) const
{
    return expression()->evaluate(context);
}

Value ChainedExpression::evaluate(ExecutionContext& context) const
{
    Value ret(SQLType::Tuple);
    Vector<Value> values;
    for (auto& expression : expressions()) {
        values.append(expression.evaluate(context));
    }
    ret = values;
    return ret;
}

Value BinaryOperatorExpression::evaluate(ExecutionContext& context) const
{
    Value lhs_value = lhs()->evaluate(context);
    Value rhs_value = rhs()->evaluate(context);
    switch (type()) {
    case BinaryOperator::Concatenate: {
        if (lhs_value.type() != SQLType::Text) {
            VERIFY_NOT_REACHED();
        }
        AK::StringBuilder builder;
        builder.append(lhs_value.to_string());
        builder.append(rhs_value.to_string());
        return Value(builder.to_string());
    }
    case BinaryOperator::Multiplication:
        return lhs_value.multiply(rhs_value);
    case BinaryOperator::Division:
        return lhs_value.divide(rhs_value);
    case BinaryOperator::Modulo:
        return lhs_value.modulo(rhs_value);
    case BinaryOperator::Plus:
        return lhs_value.add(rhs_value);
    case BinaryOperator::Minus:
        return lhs_value.subtract(rhs_value);
    case BinaryOperator::ShiftLeft:
        return lhs_value.shift_left(rhs_value);
    case BinaryOperator::ShiftRight:
        return lhs_value.shift_right(rhs_value);
    case BinaryOperator::BitwiseAnd:
        return lhs_value.bitwise_and(rhs_value);
    case BinaryOperator::BitwiseOr:
        return lhs_value.bitwise_or(rhs_value);
    case BinaryOperator::LessThan:
        return Value(lhs_value.compare(rhs_value) < 0);
    case BinaryOperator::LessThanEquals:
        return Value(lhs_value.compare(rhs_value) <= 0);
    case BinaryOperator::GreaterThan:
        return Value(lhs_value.compare(rhs_value) > 0);
    case BinaryOperator::GreaterThanEquals:
        return Value(lhs_value.compare(rhs_value) >= 0);
    case BinaryOperator::Equals:
        return Value(lhs_value.compare(rhs_value) == 0);
    case BinaryOperator::NotEquals:
        return Value(lhs_value.compare(rhs_value) != 0);
    case BinaryOperator::And: {
        auto lhs_bool_maybe = lhs_value.to_bool();
        auto rhs_bool_maybe = rhs_value.to_bool();
        if (!lhs_bool_maybe.has_value() || !rhs_bool_maybe.has_value()) {
            // TODO Error handling
            VERIFY_NOT_REACHED();
        }
        return Value(lhs_bool_maybe.value() && rhs_bool_maybe.value());
    }
    case BinaryOperator::Or: {
        auto lhs_bool_maybe = lhs_value.to_bool();
        auto rhs_bool_maybe = rhs_value.to_bool();
        if (!lhs_bool_maybe.has_value() || !rhs_bool_maybe.has_value()) {
            // TODO Error handling
            VERIFY_NOT_REACHED();
        }
        return Value(lhs_bool_maybe.value() || rhs_bool_maybe.value());
    }
    }
    VERIFY_NOT_REACHED();
}

Value UnaryOperatorExpression::evaluate(ExecutionContext& context) const
{
    Value expression_value = NestedExpression::evaluate(context);
    switch (type()) {
    case UnaryOperator::Plus:
        if (expression_value.type() == SQLType::Integer || expression_value.type() == SQLType::Float)
            return expression_value;
        // TODO: Error handling.
        VERIFY_NOT_REACHED();
    case UnaryOperator::Minus:
        if (expression_value.type() == SQLType::Integer) {
            expression_value = -int(expression_value);
            return expression_value;
        }
        if (expression_value.type() == SQLType::Float) {
            expression_value = -double(expression_value);
            return expression_value;
        }
        // TODO: Error handling.
        VERIFY_NOT_REACHED();
    case UnaryOperator::Not:
        if (expression_value.type() == SQLType::Boolean) {
            expression_value = !bool(expression_value);
            return expression_value;
        }
        // TODO: Error handling.
        VERIFY_NOT_REACHED();
    case UnaryOperator::BitwiseNot:
        if (expression_value.type() == SQLType::Integer) {
            expression_value = ~u32(expression_value);
            return expression_value;
        }
        // TODO: Error handling.
        VERIFY_NOT_REACHED();
    }
    VERIFY_NOT_REACHED();
}

Value ColumnNameExpression::evaluate(ExecutionContext& context) const
{
    auto& descriptor = *context.current_row->descriptor();
    VERIFY(context.current_row->size() == descriptor.size());
    for (auto ix = 0u; ix < context.current_row->size(); ix++) {
        auto& column_descriptor = descriptor[ix];
        if (column_descriptor.name == column_name())
            return { (*context.current_row)[ix] };
    }
    // TODO: Error handling.
    VERIFY_NOT_REACHED();
}

}