203 lines
8.8 KiB
Rust
203 lines
8.8 KiB
Rust
//! 构造共享 VM 调用序列与同帧循环驱动的字节码。
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//! 用托管函数串联步骤，避免为每个布局节点反复创建独立解释器调用；重复驱动会保留同一个执行帧和预算域。
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//!
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//! Validated call sequences share the current VM budget and explicit frames.
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use endor_core::{
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CodeLayout, EndorCode, EndorCodeObject, Instruction, NativeContext, ObjectRef, Opcode, Value,
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VmError,
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};
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/// 将零参数调用列表编成一个托管驱动，按输入顺序执行，返回最后一次调用的值。
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/// 空列表返回 Nil。所有调用都在调用者的 VM 预算内运行，避免宿主逐个调用时重置预算。
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/// name 用于诊断位置；desktop 用来给生成函数挂接桌面 Function 类型。
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pub fn build(
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cx: &mut NativeContext<'_>,
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calls: Vec<ObjectRef>,
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name: &'static str,
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desktop: ObjectRef,
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) -> Result<ObjectRef, VmError> {
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// 每个函数放入常量池。LoadConst/PushNull/Call 组成零参数调用，
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// 中间结果由 PopTop 丢弃；最后结果留在栈顶交给 ReturnValue。
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let mut instructions = Vec::with_capacity(calls.len() * 4 + 2);
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let mut constants: Vec<Value> = calls.into_iter().map(Value::Object).collect();
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for index in 0..constants.len() {
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instructions.push(Instruction::new(Opcode::LoadConst, index as u32));
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instructions.push(Instruction::simple(Opcode::PushNull));
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instructions.push(Instruction::new(Opcode::Call, 0));
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if index + 1 != constants.len() {
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instructions.push(Instruction::simple(Opcode::PopTop));
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}
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}
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// 没有调用时也必须给 ReturnValue 提供合法栈顶，不能返回一个空栈。
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if constants.is_empty() {
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constants.push(Value::Nil);
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instructions.push(Instruction::new(Opcode::LoadConst, 0));
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}
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instructions.push(Instruction::simple(Opcode::ReturnValue));
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let code = EndorCode::from_instructions(&instructions, constants, CodeLayout::default())?
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.with_location(name, "<tessera>", 1);
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let code = cx.allocate(EndorCodeObject::new(code))?;
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let globals = cx.new_dict()?;
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let driver = cx.new_function(name, code, globals)?;
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crate::ui_bridge::attach_desktop_type(cx, driver, "Function", desktop)?;
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Ok(driver)
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}
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/// A fixed-size driver. Each callback returns whether another occurrence is
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/// needed; delegated source calls and all iterations share this VM budget.
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/// 构造重复调用同一托管函数的驱动，保持共享参数与引用生命周期。
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pub fn repeat_call(
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cx: &mut NativeContext<'_>,
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callback: ObjectRef,
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name: &'static str,
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desktop: ObjectRef,
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) -> Result<ObjectRef, VmError> {
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// 回调返回 Bool；repeat_while 消费这个条件并决定是否跳回本帧开头。
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// 退出后显式返回 Nil，回调的继续条件不会泄露为驱动返回值。
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let mut instructions = vec![
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Instruction::new(Opcode::LoadConst, 0),
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Instruction::simple(Opcode::PushNull),
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Instruction::new(Opcode::Call, 0),
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];
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repeat_while(&mut instructions)?;
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instructions.extend([
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Instruction::new(Opcode::LoadConst, 1),
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Instruction::simple(Opcode::ReturnValue),
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]);
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driver(
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cx,
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instructions,
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vec![Value::Object(callback), Value::Nil],
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name,
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desktop,
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)
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}
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/// Prepare only the current occurrence, collect its result, then continue the
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/// outer driver. The helper frame and its managed captures die before the next.
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/// 将一步调用结果收集到驱动状态，再安排下一步调用。
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pub fn collect_and_continue(
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cx: &mut NativeContext<'_>,
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collector: ObjectRef,
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function: ObjectRef,
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arguments: Vec<Value>,
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name: &'static str,
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desktop: ObjectRef,
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) -> Result<ObjectRef, VmError> {
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// 常量布局固定为 collector、function、各实参、true。
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// 先把 collector 的调用前缀压栈，再执行 function，使其返回值直接成为 collector 的唯一实参。
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let count = arguments.len();
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let mut constants = vec![Value::Object(collector), Value::Object(function)];
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constants.extend(arguments);
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constants.push(Value::Bool(true));
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let mut instructions = vec![
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Instruction::new(Opcode::LoadConst, 0),
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Instruction::simple(Opcode::PushNull),
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Instruction::new(Opcode::LoadConst, 1),
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Instruction::simple(Opcode::PushNull),
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];
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for index in 0..count {
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instructions.push(Instruction::new(Opcode::LoadConst, index as u32 + 2));
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}
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// 收集器返回值不参与外层调度；丢弃后返回 true，通知重复驱动继续取下一项。
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instructions.extend([
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Instruction::new(Opcode::Call, count as u32),
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Instruction::new(Opcode::Call, 1),
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Instruction::simple(Opcode::PopTop),
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Instruction::new(Opcode::LoadConst, count as u32 + 2),
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Instruction::simple(Opcode::ReturnValue),
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]);
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driver(cx, instructions, constants, name, desktop)
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}
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/// 建立承载整个步骤序列的托管函数，使续体可以在同一个 VM 帧中恢复。
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fn driver(
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cx: &mut NativeContext<'_>,
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instructions: Vec<Instruction>,
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constants: Vec<Value>,
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name: &'static str,
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desktop: ObjectRef,
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) -> Result<ObjectRef, VmError> {
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let code = EndorCode::from_instructions(&instructions, constants, CodeLayout::default())?
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.with_location(name, "<tessera>", 1);
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let code = cx.allocate(EndorCodeObject::new(code))?;
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let globals = cx.new_dict()?;
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let function = cx.new_function(name, code, globals)?;
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crate::ui_bridge::attach_desktop_type(cx, function, "Function", desktop)?;
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Ok(function)
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}
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/// Consume the condition on the stack: true repeats this same frame from zero,
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/// false falls through. Operand widths include EXTENDED_ARG code units.
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/// 构造由继续条件决定是否再执行一轮的同帧循环。
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pub fn repeat_while(instructions: &mut Vec<Instruction>) -> Result<(), VmError> {
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// 跳转单位是编码后的双字节 code unit，不是 Instruction 数量。
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// 大操作数会生成 EXTENDED_ARG，因此必须编码后计算实际长度。
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let body = Instruction::encode_all(instructions)?.len() / 2;
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let mut back = Instruction::new(Opcode::JumpBackward, 0);
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// 回跳距离包含自身宽度；而距离变大又可能扩大自身编码宽度。
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// 迭代到宽度/距离一致后，false 跳过回跳指令，true 回到整个驱动的起点。
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loop {
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let units = Instruction::encode_all(&[back])?.len() / 2;
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let distance = u32::try_from(body + 1 + units)
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.map_err(|_| VmError::ExecutionLimit("layout bytecode"))?;
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if back.argument == distance {
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instructions.push(Instruction::new(Opcode::PopJumpIfFalse, units as u32));
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instructions.push(back);
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return Ok(());
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}
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back.argument = distance;
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use endor_core::{ExecutionLimits, Vm};
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#[test]
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/// 生成超过单字节跳距的循环，false 条件正常返回，true 条件只耗尽指令预算而非一帧预算；释放后对象数归零。
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fn repeated_bytecode_handles_extended_operands_and_keeps_one_frame() {
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// 300 个 Nop 强制跨越单字节跳转距离：false 应正常退出；true 应耗尽指令预算，
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// 而非耗尽帧预算，从而验证循环确实复用同一个执行帧。
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for condition in [false, true] {
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let mut instructions = vec![Instruction::simple(Opcode::Nop); 300];
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instructions.push(Instruction::new(Opcode::LoadConst, 0));
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repeat_while(&mut instructions).unwrap();
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instructions.extend([
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Instruction::new(Opcode::LoadConst, 1),
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Instruction::simple(Opcode::ReturnValue),
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]);
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let code = EndorCode::from_instructions(
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&instructions,
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vec![Value::Bool(condition), Value::Nil],
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CodeLayout::default(),
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)
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.unwrap();
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let mut vm = Vm::new().unwrap();
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let code = vm.new_code(code).unwrap();
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let globals = vm.new_dict().unwrap();
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let result = vm.execute_with_limits(
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code,
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globals,
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ExecutionLimits {
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max_frames: 1,
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max_instructions: 1000,
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},
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);
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if condition {
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assert!(matches!(
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result,
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Err(VmError::ExecutionLimit("instructions"))
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));
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} else {
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assert_eq!(result.unwrap(), Value::Nil);
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}
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vm.release(code).unwrap();
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vm.release(globals).unwrap();
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// 释放代码与全局字典后执行循环回收，确认生成的常量/函数没有遗留托管对象。
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vm.collect_cycles();
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assert_eq!(vm.object_count(), 0);
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}
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}
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}
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