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d074a601df
This patch provides very basic, bare bones implementations of the
INSERT and SELECT statements. They are *very* limited:
- The only variant of the INSERT statement that currently works is
SELECT INTO schema.table (column1, column2, ....) VALUES
(value11, value21, ...), (value12, value22, ...), ...
where the values are literals.
- The SELECT statement is even more limited, and is only provided to
allow verification of the INSERT statement. The only form implemented
is: SELECT * FROM schema.table
These statements required a bit of change in the Statement::execute
API. Originally execute only received a Database object as parameter.
This is not enough; we now pass an ExecutionContext object which
contains the Database, the current result set, and the last Tuple read
from the database. This object will undoubtedly evolve over time.
This API change dragged SQLServer::SQLStatement into the patch.
Another API addition is Expression::evaluate. This method is,
unsurprisingly, used to evaluate expressions, like the values in the
INSERT statement.
Finally, a new test file is added: TestSqlStatementExecution, which
tests the currently implemented statements. As the number and flavour of
implemented statements grows, this test file will probably have to be
restructured.
90 lines
2.3 KiB
C++
90 lines
2.3 KiB
C++
/*
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* Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibSQL/AST/AST.h>
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#include <LibSQL/Database.h>
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namespace SQL::AST {
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Value Expression::evaluate(ExecutionContext&) const
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{
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return Value::null();
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}
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Value NumericLiteral::evaluate(ExecutionContext&) const
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{
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Value ret(SQLType::Float);
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ret = value();
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return ret;
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}
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Value StringLiteral::evaluate(ExecutionContext&) const
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{
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Value ret(SQLType::Text);
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ret = value();
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return ret;
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}
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Value NullLiteral::evaluate(ExecutionContext&) const
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{
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return Value::null();
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}
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Value NestedExpression::evaluate(ExecutionContext& context) const
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{
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return expression()->evaluate(context);
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}
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Value ChainedExpression::evaluate(ExecutionContext& context) const
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{
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Value ret(SQLType::Tuple);
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Vector<Value> values;
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for (auto& expression : expressions()) {
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values.append(expression.evaluate(context));
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}
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ret = values;
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return ret;
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}
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Value UnaryOperatorExpression::evaluate(ExecutionContext& context) const
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{
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Value expression_value = NestedExpression::evaluate(context);
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switch (type()) {
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case UnaryOperator::Plus:
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if (expression_value.type() == SQLType::Integer || expression_value.type() == SQLType::Float)
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return expression_value;
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// TODO: Error handling.
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VERIFY_NOT_REACHED();
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case UnaryOperator::Minus:
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if (expression_value.type() == SQLType::Integer) {
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expression_value = -int(expression_value);
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return expression_value;
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}
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if (expression_value.type() == SQLType::Float) {
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expression_value = -double(expression_value);
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return expression_value;
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}
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// TODO: Error handling.
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VERIFY_NOT_REACHED();
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case UnaryOperator::Not:
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if (expression_value.type() == SQLType::Boolean) {
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expression_value = !bool(expression_value);
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return expression_value;
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}
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// TODO: Error handling.
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VERIFY_NOT_REACHED();
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case UnaryOperator::BitwiseNot:
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if (expression_value.type() == SQLType::Integer) {
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expression_value = ~u32(expression_value);
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return expression_value;
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}
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// TODO: Error handling.
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VERIFY_NOT_REACHED();
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}
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VERIFY_NOT_REACHED();
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}
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}
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