Fine-tune pratt parsing to support more complexity
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c56a187d05
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@ -126,6 +126,10 @@ impl<'a> Analyzer<'a> {
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actual: right.as_ref().clone(),
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});
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}
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} else {
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return Err(AnalyzerError::ExpectedValue {
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actual: left.as_ref().clone(),
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});
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}
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}
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}
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@ -147,13 +147,19 @@ impl<'src> Parser<'src> {
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Ok(())
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}
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fn parse_statement(&mut self, precedence: u8) -> Result<Node<Statement>, ParseError> {
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fn parse_statement(&mut self, mut precedence: u8) -> Result<Node<Statement>, ParseError> {
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// Parse a statement starting from the current node.
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let mut left = self.parse_prefix()?;
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// While the current token has a higher precedence than the given precedence
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while precedence < self.current.0.precedence() {
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// Give precedence to postfix operations
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if self.current.0.is_postfix() {
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left = self.parse_postfix(left)?;
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// Replace the left-hand side with the postfix operation and use the postfix
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// operator's precedence to determine if the loop should continue
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(left, precedence) = self.parse_postfix(left)?;
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} else {
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// Replace the left-hand side with the infix operation
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left = self.parse_infix(left)?;
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}
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}
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@ -586,7 +592,7 @@ impl<'src> Parser<'src> {
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if let Token::Dot = &self.current.0 {
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self.next_token()?;
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let right = self.parse_statement(Token::Dot.precedence() + 1)?;
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let right = self.parse_statement(0)?;
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let right_end = right.position.1;
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if let Statement::BuiltInFunctionCall {
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@ -688,17 +694,18 @@ impl<'src> Parser<'src> {
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))
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}
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fn parse_postfix(&mut self, left: Node<Statement>) -> Result<Node<Statement>, ParseError> {
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fn parse_postfix(
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&mut self,
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left: Node<Statement>,
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) -> Result<(Node<Statement>, u8), ParseError> {
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if let Token::Semicolon = &self.current.0 {
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self.next_token()?;
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let left_start = left.position.0;
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let operator_end = self.current.1 .1;
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let node = Node::new(Statement::Nil(Box::new(left)), (left_start, operator_end));
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Ok(Node::new(
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Statement::Nil(Box::new(left)),
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(left_start, operator_end),
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))
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Ok((node, self.current.0.precedence()))
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} else {
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Err(ParseError::UnexpectedToken {
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actual: self.current.0.to_owned(),
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@ -843,6 +850,7 @@ mod tests {
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Ok(AbstractSyntaxTree {
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nodes: [
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Node::new(
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Statement::Nil(Box::new(Node::new(
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Statement::BinaryOperation {
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left: Box::new(Node::new(
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Statement::Identifier(Identifier::new("a")),
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@ -854,17 +862,19 @@ mod tests {
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(4, 5)
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)),
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},
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(6, 7)
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(0, 5)
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))),
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(0, 8)
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),
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Node::new(
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Statement::UnaryOperation {
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operator: Node::new(UnaryOperator::Negate, (0, 1)),
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operator: Node::new(UnaryOperator::Negate, (7, 8)),
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operand: Box::new(Node::new(
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Statement::Identifier(Identifier::new("a")),
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(7, 8)
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(8, 9)
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)),
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},
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(4, 8)
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(7, 9)
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)
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]
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.into()
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