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Simplify parsing comparison expressions

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This commit is contained in:
Jeff 2024-10-01 20:07:57 -04:00
parent 88684f49b6
commit 9d1996c9ec
2 changed files with 36 additions and 25 deletions
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13
dust-lang/src/chunk.rs
View File

@ -87,6 +87,19 @@ impl Chunk {
Ok((instruction, position)) Ok((instruction, position))
} }
pub fn get_last_n_instructions<const N: usize>(&self) -> [Option<&(Instruction, Span)>; N] {
let mut instructions = [None; N];
for i in 0..N {
let index = self.instructions.len().saturating_sub(i + 1);
let instruction = self.instructions.get(index);
instructions[i] = instruction;
}
instructions
}
pub fn find_last_instruction(&mut self, operation: Operation) -> Option<usize> { pub fn find_last_instruction(&mut self, operation: Operation) -> Option<usize> {
self.instructions self.instructions
.iter() .iter()

48
dust-lang/src/parser/mod.rs
View File

@ -477,21 +477,6 @@ impl<'src> Parser<'src> {
} }
fn parse_comparison_binary(&mut self) -> Result<(), ParseError> { fn parse_comparison_binary(&mut self) -> Result<(), ParseError> {
let is_repetition = matches!(
self.chunk.get_last_n_operations(),
[
Some(_),
Some(_),
Some(Operation::Jump),
Some(Operation::Equal | Operation::Less | Operation::LessEqual)
]
);
if is_repetition {
self.decrement_register()?;
self.decrement_register()?;
}
let (left_instruction, left_position) = let (left_instruction, left_position) =
self.chunk.pop_instruction(self.current_position)?; self.chunk.pop_instruction(self.current_position)?;
let (push_back_left, left_is_constant, left) = let (push_back_left, left_is_constant, left) =
@ -551,15 +536,6 @@ impl<'src> Parser<'src> {
self.emit_instruction(instruction, operator_position); self.emit_instruction(instruction, operator_position);
self.emit_instruction(Instruction::jump(1, true), operator_position); self.emit_instruction(Instruction::jump(1, true), operator_position);
self.emit_instruction(
Instruction::load_boolean(self.current_register, true, true),
operator_position,
);
self.emit_instruction(
Instruction::load_boolean(self.current_register, false, false),
operator_position,
);
self.increment_register()?;
Ok(()) Ok(())
} }
@ -837,7 +813,29 @@ impl<'src> Parser<'src> {
} }
fn parse_expression(&mut self) -> Result<(), ParseError> { fn parse_expression(&mut self) -> Result<(), ParseError> {
self.parse(Precedence::None) self.parse(Precedence::None)?;
if let [Some((jump, _)), Some((comparison, comparison_position))] =
self.chunk.get_last_n_instructions()
{
if let (Operation::Jump, Operation::Equal | Operation::Less | Operation::LessEqual) =
(jump.operation(), comparison.operation())
{
let comparison_position = *comparison_position;
self.emit_instruction(
Instruction::load_boolean(self.current_register, true, true),
comparison_position,
);
self.emit_instruction(
Instruction::load_boolean(self.current_register, false, false),
comparison_position,
);
self.increment_register()?;
}
}
Ok(())
} }
fn parse_statement(&mut self, allow_return: bool) -> Result<(), ParseError> { fn parse_statement(&mut self, allow_return: bool) -> Result<(), ParseError> {