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 +++++- users/tazjin/rlox/src/bytecode/opcode.rs | 1 + users/tazjin/rlox/src/bytecode/tests.rs | 92 +++++++++++++++--------------- users/tazjin/rlox/src/bytecode/vm.rs | 22 +++++-- 4 files changed, 78 insertions(+), 53 deletions(-) (limited to 'users/tazjin/rlox') 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)); diff --git a/users/tazjin/rlox/src/bytecode/opcode.rs b/users/tazjin/rlox/src/bytecode/opcode.rs index 7a3355460473..37466b30564c 100644 --- a/users/tazjin/rlox/src/bytecode/opcode.rs +++ b/users/tazjin/rlox/src/bytecode/opcode.rs @@ -28,4 +28,5 @@ pub enum OpCode { // Built in operations OpPrint, + OpPop, } diff --git a/users/tazjin/rlox/src/bytecode/tests.rs b/users/tazjin/rlox/src/bytecode/tests.rs index b29769f460a1..b346da19810d 100644 --- a/users/tazjin/rlox/src/bytecode/tests.rs +++ b/users/tazjin/rlox/src/bytecode/tests.rs @@ -24,87 +24,87 @@ fn expect_str(code: &str, value: &str) { #[test] fn numbers() { - expect_num("1", 1.0); - expect_num("13.37", 13.37); + expect_num("1;", 1.0); + expect_num("13.37;", 13.37); } #[test] fn negative_numbers() { // Note: This technically tests unary operators. - expect_num("-1", -1.0); - expect_num("-13.37", -13.37); + expect_num("-1;", -1.0); + expect_num("-13.37;", -13.37); } #[test] fn terms() { - expect_num("1 + 2", 3.0); - expect_num("3 - 1", 2.0); - expect_num("0.7 + 0.3", 1.0); - expect_num("1 + -3", -2.0); - expect_num("-1 - -1", 0.0); - expect_num("10 - -10 + 10", 30.0); + expect_num("1 + 2;", 3.0); + expect_num("3 - 1;", 2.0); + expect_num("0.7 + 0.3;", 1.0); + expect_num("1 + -3;", -2.0); + expect_num("-1 - -1;", 0.0); + expect_num("10 - -10 + 10;", 30.0); } #[test] fn factors() { - expect_num("1 * 2", 2.0); - expect_num("10 / 5", 2.0); - expect_num("0.7 * 4 / 1.4", 2.0); - expect_num("10 * -10 / 10", -10.0); + expect_num("1 * 2;", 2.0); + expect_num("10 / 5;", 2.0); + expect_num("0.7 * 4 / 1.4;", 2.0); + expect_num("10 * -10 / 10;", -10.0); } #[test] fn arithmetic() { - expect_num("10 - 3 * 2", 4.0); - expect_num("-4 * -4 + (14 - 5)", 25.0); - expect_num("(702 + 408) - ((239 - 734) / -5) + -4", 1007.0); + expect_num("10 - 3 * 2;", 4.0); + expect_num("-4 * -4 + (14 - 5);", 25.0); + expect_num("(702 + 408) - ((239 - 734) / -5) + -4;", 1007.0); } #[test] fn trivial_literals() { - expect("true", Value::Bool(true)); - expect("false", Value::Bool(false)); - expect("nil", Value::Nil); + expect("true;", Value::Bool(true)); + expect("false;", Value::Bool(false)); + expect("nil;", Value::Nil); } #[test] fn negation() { - expect_bool("!true", false); - expect_bool("!false", true); - expect_bool("!nil", true); - expect_bool("!13.5", false); - expect_bool("!-42", false); + expect_bool("!true;", false); + expect_bool("!false;", true); + expect_bool("!nil;", true); + expect_bool("!13.5;", false); + expect_bool("!-42;", false); } #[test] fn equality() { - expect_bool("42 == 42", true); - expect_bool("42 != 42", false); - expect_bool("42 == 42.0", true); - - expect_bool("true == true", true); - expect_bool("true == false", false); - expect_bool("true == !false", true); - expect_bool("true != true", false); - expect_bool("true != false", true); - - expect_bool("42 == false", false); - expect_bool("42 == true", false); - expect_bool("!42 == !true", true); + expect_bool("42 == 42;", true); + expect_bool("42 != 42;", false); + expect_bool("42 == 42.0;", true); + + expect_bool("true == true;", true); + expect_bool("true == false;", false); + expect_bool("true == !false;", true); + expect_bool("true != true;", false); + expect_bool("true != false;", true); + + expect_bool("42 == false;", false); + expect_bool("42 == true;", false); + expect_bool("!42 == !true;", true); } #[test] fn comparisons() { - expect_bool("42 > 23", true); - expect_bool("42 < 23", false); - expect_bool("42 <= 42", true); - expect_bool("42 <= 23", false); - expect_bool("42 >= 42", true); - expect_bool("42 >= 23", true); + expect_bool("42 > 23;", true); + expect_bool("42 < 23;", false); + expect_bool("42 <= 42;", true); + expect_bool("42 <= 23;", false); + expect_bool("42 >= 42;", true); + expect_bool("42 >= 23;", true); } #[test] fn strings() { - expect_str("\"hello\"", "hello"); - expect_str("\"hello\" + \" world\"", "hello world"); + expect_str("\"hello\";", "hello"); + expect_str("\"hello\" + \" world\";", "hello world"); } diff --git a/users/tazjin/rlox/src/bytecode/vm.rs b/users/tazjin/rlox/src/bytecode/vm.rs index c43b197279be..9161bdfe53b8 100644 --- a/users/tazjin/rlox/src/bytecode/vm.rs +++ b/users/tazjin/rlox/src/bytecode/vm.rs @@ -13,6 +13,12 @@ pub struct VM { stack: Vec, strings: Interner, + + // Operations that consume values from the stack without pushing + // anything leave their last value in this slot, which makes it + // possible to return values from interpreters that ran code which + // ended with a statement. + last_drop: Option, } impl VM { @@ -72,12 +78,15 @@ impl VM { match op { OpCode::OpReturn => { - if self.stack.is_empty() { + if !self.stack.is_empty() { + let val = self.pop(); + return Ok(self.return_value(val)); + } else if self.last_drop.is_some() { + let val = self.last_drop.take().unwrap(); + return Ok(self.return_value(val)); + } else { return Ok(Value::Nil); } - - let val = self.pop(); - return Ok(self.return_value(val)); } OpCode::OpConstant(idx) => { @@ -144,6 +153,10 @@ impl VM { let val = self.pop(); println!("{}", self.print_value(val)); } + + OpCode::OpPop => { + self.last_drop = Some(self.pop()); + } } #[cfg(feature = "disassemble")] @@ -186,6 +199,7 @@ pub fn interpret(strings: Interner, chunk: chunk::Chunk) -> LoxResult { strings, ip: 0, stack: vec![], + last_drop: None, }; vm.run() -- cgit 1.4.1