From ed3fce2b19fa0d28054382093b019967a9a16177 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Tue, 2 Mar 2021 22:26:02 +0200 Subject: feat(tazjin/rlox): Implement expression statements These aren't particularly useful without side effects, but one step at a time. This diverges slightly from the book, in that OpPop retains the last value it "forgot" from the stack in a special field on the interpreter. This makes it possible to return values from expression statements, which helps in cases where Lox is embedded as a scripting language (please don't do this ever) or in tests. Change-Id: Ided0bc04c6e80ddb23ba4693d61ac9e08b002d58 Reviewed-on: https://cl.tvl.fyi/c/depot/+/2584 Reviewed-by: tazjin Tested-by: BuildkiteCI --- users/tazjin/rlox/src/bytecode/compiler.rs | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'users/tazjin/rlox/src/bytecode/compiler.rs') diff --git a/users/tazjin/rlox/src/bytecode/compiler.rs b/users/tazjin/rlox/src/bytecode/compiler.rs index 1408f519bb2d..9a8f80ae2b7d 100644 --- a/users/tazjin/rlox/src/bytecode/compiler.rs +++ b/users/tazjin/rlox/src/bytecode/compiler.rs @@ -179,10 +179,10 @@ impl> Compiler { fn statement(&mut self) -> LoxResult<()> { if self.match_token(&TokenKind::Print) { - return self.print_statement(); + self.print_statement() + } else { + self.expression_statement() } - - Ok(()) } fn print_statement(&mut self) -> LoxResult<()> { @@ -195,6 +195,16 @@ impl> Compiler { Ok(()) } + fn expression_statement(&mut self) -> LoxResult<()> { + self.expression()?; + self.consume( + &TokenKind::Semicolon, + ErrorKind::ExpectedToken("Expected ';' after expression"), + ); + self.emit_op(OpCode::OpPop); + Ok(()) + } + fn number(&mut self) -> LoxResult<()> { if let TokenKind::Number(num) = self.previous().kind { self.emit_constant(Value::Number(num)); -- cgit 1.4.1