diff options
| -rw-r--r-- | tvix/eval/src/compiler.rs | 58 | ||||
| -rw-r--r-- | tvix/eval/src/opcode.rs | 9 | ||||
| -rw-r--r-- | tvix/eval/src/value/mod.rs | 4 | ||||
| -rw-r--r-- | tvix/eval/src/vm.rs | 18 |
4 files changed, 84 insertions, 5 deletions
diff --git a/tvix/eval/src/compiler.rs b/tvix/eval/src/compiler.rs index 4a3a652af5c5..3df0ea4c9810 100644 --- a/tvix/eval/src/compiler.rs +++ b/tvix/eval/src/compiler.rs @@ -3,7 +3,7 @@ use crate::chunk::Chunk; use crate::errors::EvalResult; -use crate::opcode::OpCode; +use crate::opcode::{CodeIdx, OpCode}; use crate::value::Value; use rnix; @@ -68,6 +68,11 @@ impl Compiler { self.compile_list(node) } + rnix::SyntaxKind::NODE_IF_ELSE => { + let node = rnix::types::IfElse::cast(node).unwrap(); + self.compile_if_else(node) + } + kind => { println!("visiting unsupported node: {:?}", kind); Ok(()) @@ -143,12 +148,16 @@ impl Compiler { BinOpKind::MoreOrEq => self.chunk.add_op(OpCode::OpMoreOrEq), BinOpKind::Concat => self.chunk.add_op(OpCode::OpConcat), + BinOpKind::And => todo!(), + BinOpKind::Or => todo!(), + BinOpKind::Implication => todo!(), + BinOpKind::NotEqual => { self.chunk.add_op(OpCode::OpEqual); self.chunk.add_op(OpCode::OpInvert) } - _ => todo!(), + BinOpKind::IsSet => todo!("? operator"), }; Ok(()) @@ -269,6 +278,51 @@ impl Compiler { self.chunk.add_op(OpCode::OpList(count)); Ok(()) } + + // Compile conditional expressions using jumping instructions in the VM. + // + // ┌────────────────────┐ + // │ 0 [ conditional ] │ + // │ 1 JUMP_IF_FALSE →┼─┐ + // │ 2 [ main body ] │ │ Jump to else body if + // ┌┼─3─← JUMP │ │ condition is false. + // Jump over else body ││ 4 [ else body ]←┼─┘ + // if condition is true.└┼─5─→ ... │ + // └────────────────────┘ + fn compile_if_else(&mut self, node: rnix::types::IfElse) -> EvalResult<()> { + self.compile(node.condition().unwrap())?; + + let then_idx = self.chunk.add_op(OpCode::OpJumpIfFalse(0)); + + self.chunk.add_op(OpCode::OpPop); // discard condition value + self.compile(node.body().unwrap())?; + + let else_idx = self.chunk.add_op(OpCode::OpJump(0)); + + self.patch_jump(then_idx); // patch jump *to* else_body + self.chunk.add_op(OpCode::OpPop); // discard condition value + self.compile(node.else_body().unwrap())?; + + self.patch_jump(else_idx); // patch jump *over* else body + + Ok(()) + } + + fn patch_jump(&mut self, idx: CodeIdx) { + let offset = self.chunk.code.len() - 1 - idx.0; + + match &mut self.chunk.code[idx.0] { + OpCode::OpJump(n) => { + *n = offset; + } + + OpCode::OpJumpIfFalse(n) => { + *n = offset; + } + + op => panic!("attempted to patch unsupported op: {:?}", op), + } + } } pub fn compile(ast: rnix::AST) -> EvalResult<Chunk> { diff --git a/tvix/eval/src/opcode.rs b/tvix/eval/src/opcode.rs index b1e6d3259363..8bb8fe9a1f31 100644 --- a/tvix/eval/src/opcode.rs +++ b/tvix/eval/src/opcode.rs @@ -12,6 +12,9 @@ pub enum OpCode { // Push a constant onto the stack. OpConstant(ConstantIdx), + // Discard a value from the stack. + OpPop, + // Push a literal value. OpNull, OpTrue, @@ -27,13 +30,17 @@ pub enum OpCode { OpMul, OpDiv, - // Logical binary operators + // Comparison operators OpEqual, OpLess, OpLessOrEq, OpMore, OpMoreOrEq, + // Logical operators & generic jumps + OpJump(usize), + OpJumpIfFalse(usize), + // Attribute sets OpAttrs(usize), OpAttrPath(usize), diff --git a/tvix/eval/src/value/mod.rs b/tvix/eval/src/value/mod.rs index 0c9042dbfe25..4a343797480e 100644 --- a/tvix/eval/src/value/mod.rs +++ b/tvix/eval/src/value/mod.rs @@ -52,9 +52,9 @@ impl Value { } } - pub fn as_bool(self) -> EvalResult<bool> { + pub fn as_bool(&self) -> EvalResult<bool> { match self { - Value::Bool(b) => Ok(b), + Value::Bool(b) => Ok(*b), other => Err(Error::TypeError { expected: "bool", actual: other.type_of(), diff --git a/tvix/eval/src/vm.rs b/tvix/eval/src/vm.rs index a64e0b337aea..4ea1b3b65cf5 100644 --- a/tvix/eval/src/vm.rs +++ b/tvix/eval/src/vm.rs @@ -83,6 +83,10 @@ impl VM { self.stack.push(value) } + fn peek(&self, offset: usize) -> &Value { + &self.stack[self.stack.len() - 1 - offset] + } + fn run(&mut self) -> EvalResult<Value> { loop { match self.inc_ip() { @@ -91,6 +95,10 @@ impl VM { self.push(c); } + OpCode::OpPop => { + self.pop(); + } + OpCode::OpAdd => { let b = self.pop(); let a = self.pop(); @@ -163,6 +171,16 @@ impl VM { } OpCode::OpInterpolate(count) => self.run_interpolate(count)?, + + OpCode::OpJump(offset) => { + self.ip += offset; + } + + OpCode::OpJumpIfFalse(offset) => { + if !self.peek(0).as_bool()? { + self.ip += offset; + } + } } if self.ip == self.chunk.code.len() { |