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LibSQL: Parse EXISTS expressions
The EXISTS expression is a bit of an odd-man-out because it can appear as any of the following forms: EXISTS (select-stmt) NOT EXISTS (select-stmt) (select-stmt) Which makes it the only keyword expression that doesn't require its keyword to actually be used. The consequence is that we might come across an EXISTS expression while parsing another expression type; NOT would have triggered a unary operator expression, and an opening parentheses would have triggered an expression chain.
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4 changed files with 80 additions and 5 deletions
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@ -215,7 +215,6 @@ NonnullRefPtr<Expression> Parser::parse_expression()
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// FIXME: Parse 'bind-parameter'.
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// FIXME: Parse 'function-name'.
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// FIXME: Parse 'exists'.
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// FIXME: Parse 'raise-function'.
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return expression;
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@ -241,6 +240,9 @@ NonnullRefPtr<Expression> Parser::parse_primary_expression()
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if (auto expression = parse_case_expression(); expression.has_value())
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return move(expression.value());
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if (auto expression = parse_exists_expression(false); expression.has_value())
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return move(expression.value());
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expected("Primary Expression");
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consume();
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@ -381,8 +383,12 @@ Optional<NonnullRefPtr<Expression>> Parser::parse_unary_operator_expression()
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if (consume_if(TokenType::Tilde))
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return create_ast_node<UnaryOperatorExpression>(UnaryOperator::BitwiseNot, parse_expression());
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if (consume_if(TokenType::Not))
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return create_ast_node<UnaryOperatorExpression>(UnaryOperator::Not, parse_expression());
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if (consume_if(TokenType::Not)) {
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if (match(TokenType::Exists))
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return parse_exists_expression(true);
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else
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return create_ast_node<UnaryOperatorExpression>(UnaryOperator::Not, parse_expression());
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}
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return {};
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}
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@ -448,11 +454,15 @@ Optional<NonnullRefPtr<Expression>> Parser::parse_binary_operator_expression(Non
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Optional<NonnullRefPtr<Expression>> Parser::parse_chained_expression()
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{
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if (!match(TokenType::ParenOpen))
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if (!consume_if(TokenType::ParenOpen))
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return {};
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if (match(TokenType::Select))
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return parse_exists_expression(false, TokenType::Select);
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NonnullRefPtrVector<Expression> expressions;
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parse_comma_separated_list(true, [&]() { expressions.append(parse_expression()); });
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parse_comma_separated_list(false, [&]() { expressions.append(parse_expression()); });
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consume(TokenType::ParenClose);
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return create_ast_node<ChainedExpression>(move(expressions));
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}
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@ -506,6 +516,21 @@ Optional<NonnullRefPtr<Expression>> Parser::parse_case_expression()
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return create_ast_node<CaseExpression>(move(case_expression), move(when_then_clauses), move(else_expression));
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}
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Optional<NonnullRefPtr<Expression>> Parser::parse_exists_expression(bool invert_expression, TokenType opening_token)
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{
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VERIFY((opening_token == TokenType::Exists) || (opening_token == TokenType::Select));
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if ((opening_token == TokenType::Exists) && !consume_if(TokenType::Exists))
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return {};
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if (opening_token == TokenType::Exists)
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consume(TokenType::ParenOpen);
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auto select_statement = parse_select_statement({});
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consume(TokenType::ParenClose);
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return create_ast_node<ExistsExpression>(move(select_statement), invert_expression);
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}
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Optional<NonnullRefPtr<Expression>> Parser::parse_collate_expression(NonnullRefPtr<Expression> expression)
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{
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if (!match(TokenType::Collate))
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