feat(tazjin/rlox): Add initial support for strings
... including concatenation. This diverges significantly from the book, as I'm using std::String instead of implementing the book's whole heap object management system. It's possible that Lox in Rust actually doesn't need a GC and the ownership model works just fine. Change-Id: I374a0461d627cfafc26b2b54bfefac8b7c574d00 Reviewed-on: https://cl.tvl.fyi/c/depot/+/2577 Tested-by: BuildkiteCI Reviewed-by: tazjin <mail@tazj.in>
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					 3 changed files with 40 additions and 1 deletions
				
			
		|  | @ -144,6 +144,10 @@ fn rule_for<T: Iterator<Item = Token>>(token: &TokenKind) -> ParseRule<T> { | |||
|             ParseRule::new(None, Some(Compiler::binary), Precedence::Comparison) | ||||
|         } | ||||
| 
 | ||||
|         TokenKind::String(_) => { | ||||
|             ParseRule::new(Some(Compiler::string), None, Precedence::None) | ||||
|         }, | ||||
| 
 | ||||
|         _ => ParseRule::new(None, None, Precedence::None), | ||||
|     } | ||||
| } | ||||
|  | @ -255,6 +259,18 @@ impl<T: Iterator<Item = Token>> Compiler<T> { | |||
|         Ok(()) | ||||
|     } | ||||
| 
 | ||||
|     fn string(&mut self) -> LoxResult<()> { | ||||
|         match &self.previous().kind { | ||||
|             TokenKind::String(s) => { | ||||
|                 let s = s.clone(); | ||||
|                 self.emit_constant(Value::String(s)); | ||||
|             } | ||||
|             _ => unreachable!("only called for strings"), | ||||
|         } | ||||
| 
 | ||||
|         Ok(()) | ||||
|     } | ||||
| 
 | ||||
|     fn parse_precedence(&mut self, precedence: Precedence) -> LoxResult<()> { | ||||
|         self.advance(); | ||||
|         let rule: ParseRule<T> = rule_for(&self.previous().kind); | ||||
|  |  | |||
|  | @ -3,6 +3,7 @@ pub enum Value { | |||
|     Nil, | ||||
|     Bool(bool), | ||||
|     Number(f64), | ||||
|     String(String), | ||||
| } | ||||
| 
 | ||||
| impl Value { | ||||
|  |  | |||
|  | @ -104,10 +104,32 @@ impl VM { | |||
|                     ); | ||||
|                 } | ||||
| 
 | ||||
|                 OpCode::OpAdd => binary_op!(self, Number, +), | ||||
|                 OpCode::OpSubtract => binary_op!(self, Number, -), | ||||
|                 OpCode::OpMultiply => binary_op!(self, Number, *), | ||||
|                 OpCode::OpDivide => binary_op!(self, Number, /), | ||||
| 
 | ||||
|                 OpCode::OpAdd => { | ||||
|                     let b = self.pop(); | ||||
|                     let a = self.pop(); | ||||
| 
 | ||||
|                     match (a, b) { | ||||
|                         (Value::String(s_a), Value::String(s_b)) => { | ||||
|                             let mut new_s = s_a.clone(); | ||||
|                             new_s.push_str(&s_b); | ||||
|                             self.push(Value::String(new_s)); | ||||
|                         } | ||||
| 
 | ||||
|                         (Value::Number(n_a), Value::Number(n_b)) => | ||||
|                             self.push(Value::Number(n_a + n_b)), | ||||
| 
 | ||||
|                         _ => return Err(Error { | ||||
|                             line: self.chunk.get_line(self.ip - 1), | ||||
|                             kind: ErrorKind::TypeError( | ||||
|                                 "'+' operator only works on strings and numbers".into() | ||||
|                             ), | ||||
|                         }) | ||||
|                     } | ||||
|                 } | ||||
|             } | ||||
| 
 | ||||
|             #[cfg(feature = "disassemble")] | ||||
|  |  | |||
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