diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/compiler.rs | 80 |
1 files changed, 43 insertions, 37 deletions
diff --git a/src/compiler.rs b/src/compiler.rs index 40a597f..f36d717 100644 --- a/src/compiler.rs +++ b/src/compiler.rs @@ -6,13 +6,31 @@ struct Compiler { tokens: TokenStream, } -//TODO rustify -const PREC_NO: u64 = 0; -const PREC_ASSERT: u64 = 1; -const PREC_BOOL: u64 = 2; -const PREC_COMP: u64 = 3; -const PREC_TERM: u64 = 4; -const PREC_FACTOR: u64 = 5; +macro_rules! nextable_enum { + ( $name:ident, $( $thing:ident ),* ) => { + #[derive(PartialEq, PartialOrd, Clone, Copy, Debug)] + enum $name { + $( $thing, )* + } + + impl $name { + pub fn next(&self) -> Self { + *[$( $name::$thing, )*].iter() + .find(|x| { x > &self }) + .unwrap_or(self) + } + } + }; +} + +nextable_enum!(Prec, + No, + Assert, + Bool, + Comp, + Term, + Factor +); impl Compiler { pub fn new(tokens: TokenStream) -> Self { @@ -41,11 +59,11 @@ impl Compiler { t } - fn precedence(&self, token: Token) -> u64 { + fn precedence(&self, token: Token) -> Prec { match token { - Token::Star | Token::Slash => PREC_FACTOR, + Token::Star | Token::Slash => Prec::Factor, - Token::Minus | Token::Plus => PREC_TERM, + Token::Minus | Token::Plus => Prec::Term, Token::EqualEqual | Token::Greater @@ -53,13 +71,13 @@ impl Compiler { | Token::Less | Token::LessEqual | Token::NotEqual - => PREC_COMP, + => Prec::Comp, - Token::And | Token::Or => PREC_BOOL, + Token::And | Token::Or => Prec::Bool, - Token::AssertEqual => PREC_ASSERT, + Token::AssertEqual => Prec::Assert, - _ => PREC_NO, + _ => Prec::No, } } @@ -94,15 +112,13 @@ impl Compiler { | Token::Slash | Token::Star | Token::AssertEqual - => self.binary(block), - - Token::EqualEqual + | Token::EqualEqual | Token::Greater | Token::GreaterEqual | Token::Less | Token::LessEqual | Token::NotEqual - => self.comparison(block), + => self.binary(block), _ => { return false; }, } @@ -144,40 +160,30 @@ impl Compiler { fn binary(&mut self, block: &mut Block) { let op = self.eat(); - self.parse_precedence(block, self.precedence(op.clone()) + 1); - - let op = match op { - Token::Plus => Op::Add, - Token::Minus => Op::Sub, - Token::Star => Op::Mul, - Token::Slash => Op::Div, - Token::AssertEqual => Op::AssertEqual, - _ => { self.error("Illegal operator"); } - }; - block.add(op, self.line()); - } - - fn comparison(&mut self, block: &mut Block) { - let op = self.eat(); - self.parse_precedence(block, self.precedence(op.clone()) + 1); + self.parse_precedence(block, self.precedence(op.clone()).next()); let op: &[Op] = match op { + Token::Plus => &[Op::Add], + Token::Minus => &[Op::Sub], + Token::Star => &[Op::Mul], + Token::Slash => &[Op::Div], + Token::AssertEqual => &[Op::AssertEqual], Token::EqualEqual => &[Op::Equal], Token::Less => &[Op::Less], Token::Greater => &[Op::Greater], Token::NotEqual => &[Op::Equal, Op::Not], Token::LessEqual => &[Op::Greater, Op::Not], Token::GreaterEqual => &[Op::Less, Op::Not], - _ => { self.error("Illegal comparison operator"); } + _ => { self.error("Illegal operator"); } }; block.add_from(op, self.line()); } fn expression(&mut self, block: &mut Block) { - self.parse_precedence(block, PREC_NO); + self.parse_precedence(block, Prec::No); } - fn parse_precedence(&mut self, block: &mut Block, precedence: u64) { + fn parse_precedence(&mut self, block: &mut Block, precedence: Prec) { println!("-- {:?}", self.peek()); if !self.prefix(self.peek(), block) { self.error("Expected expression."); |