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Fix: Self is not passed to __call metamethod #99

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Merged
merged 4 commits into from
Apr 16, 2025
Merged

Fix: Self is not passed to __call metamethod #99

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6bcfa1b
Fix: Self is not passed to `__call` metamethod
Akeit0 Feb 10, 2025
6b5aef7
Refactor: remove debug codes
Akeit0 Feb 10, 2025
4a99a0b
Fix: metamethod call for TForCall
Akeit0 Apr 16, 2025
c36fcde
Merge branch 'main' into fix-metamethod-__call
Akeit0 Apr 16, 2025
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118 changes: 82 additions & 36 deletions src/Lua/Runtime/LuaVirtualMachine.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -96,15 +96,15 @@ public bool PopFromBuffer(Span<LuaValue> result)
switch (opCode)
{
case OpCode.Call:
{
var c = callInstruction.C;
if (c != 0)
{
var c = callInstruction.C;
if (c != 0)
{
targetCount = c - 1;
}

break;
targetCount = c - 1;
}

break;
}
case OpCode.TForCall:
target += 3;
targetCount = callInstruction.C;
Expand Down Expand Up @@ -1034,11 +1034,15 @@ static bool Call(ref VirtualMachineExecutionContext context, out bool doRestart)
var instruction = context.Instruction;
var RA = instruction.A + context.FrameBase;
var va = context.Stack.Get(RA);
var newBase = RA + 1;
bool isMetamethod = false;
if (!va.TryReadFunction(out var func))
{
if (va.TryGetMetamethod(context.State, Metamethods.Call, out var metamethod) &&
metamethod.TryReadFunction(out func))
{
newBase -= 1;
isMetamethod = true;
}
else
{
Expand All @@ -1047,8 +1051,8 @@ static bool Call(ref VirtualMachineExecutionContext context, out bool doRestart)
}

var thread = context.Thread;
var (newBase, argumentCount, variableArgumentCount) = PrepareForFunctionCall(thread, func, instruction, RA);

var (argumentCount, variableArgumentCount) = PrepareForFunctionCall(thread, func, instruction, newBase, isMetamethod);
newBase += variableArgumentCount;
var newFrame = func.CreateNewFrame(ref context, newBase, variableArgumentCount);

thread.PushCallStackFrame(newFrame);
Expand Down Expand Up @@ -1160,6 +1164,8 @@ static bool TailCall(ref VirtualMachineExecutionContext context, out bool doRest
var instruction = context.Instruction;
var stack = context.Stack;
var RA = instruction.A + context.FrameBase;
var newBase = RA + 1;
bool isMetamethod = false;
var state = context.State;
var thread = context.Thread;

Expand All @@ -1168,19 +1174,23 @@ static bool TailCall(ref VirtualMachineExecutionContext context, out bool doRest
var va = stack.Get(RA);
if (!va.TryReadFunction(out var func))
{
if (!va.TryGetMetamethod(state, Metamethods.Call, out var metamethod) &&
!metamethod.TryReadFunction(out func))
if (va.TryGetMetamethod(state, Metamethods.Call, out var metamethod) &&
metamethod.TryReadFunction(out func))
{
isMetamethod = true;
newBase -= 1;
}
else
{
LuaRuntimeException.AttemptInvalidOperation(GetTracebacks(ref context), "call", metamethod);
}
}

var (newBase, argumentCount, variableArgumentCount) = PrepareForFunctionTailCall(thread, func, instruction, RA);

var (argumentCount, variableArgumentCount) = PrepareForFunctionTailCall(thread, func, instruction, newBase, isMetamethod);
newBase = context.FrameBase + variableArgumentCount;

var lastPc = thread.CallStack.AsSpan()[^1].CallerInstructionIndex;
context.Thread.PopCallStackFrameUnsafe();

var newFrame = func.CreateNewFrame(ref context, newBase, variableArgumentCount);

newFrame.Flags |= CallStackFrameFlags.TailCall;
Expand Down Expand Up @@ -1233,18 +1243,46 @@ static bool TForCall(ref VirtualMachineExecutionContext context, out bool doRest
var instruction = context.Instruction;
var stack = context.Stack;
var RA = instruction.A + context.FrameBase;

bool isMetamethod = false;
var iteratorRaw = stack.Get(RA);
if (!iteratorRaw.TryReadFunction(out var iterator))
{
LuaRuntimeException.AttemptInvalidOperation(GetTracebacks(ref context), "call", iteratorRaw);
if (iteratorRaw.TryGetMetamethod(context.State, Metamethods.Call, out var metamethod) &&
metamethod.TryReadFunction(out iterator))
{
isMetamethod = true;
}
else
{
LuaRuntimeException.AttemptInvalidOperation(GetTracebacks(ref context), "call", metamethod);
}
}

var newBase = RA + 3 + instruction.C;
stack.Get(newBase) = stack.Get(RA + 1);
stack.Get(newBase + 1) = stack.Get(RA + 2);
stack.NotifyTop(newBase + 2);
var newFrame = iterator.CreateNewFrame(ref context, newBase);

if (isMetamethod)
{
stack.Get(newBase) = iteratorRaw;
stack.Get(newBase + 1) = stack.Get(RA + 1);
stack.Get(newBase + 2) = stack.Get(RA + 2);
stack.NotifyTop(newBase + 3);
}
else
{
stack.Get(newBase) = stack.Get(RA + 1);
stack.Get(newBase + 1) = stack.Get(RA + 2);
stack.NotifyTop(newBase + 2);
}

var argumentCount = isMetamethod ? 3 : 2;
var variableArgumentCount = iterator.GetVariableArgumentCount(argumentCount);
if (variableArgumentCount != 0)
{
PrepareVariableArgument(stack, newBase, argumentCount, variableArgumentCount);
newBase += variableArgumentCount;
}

var newFrame = iterator.CreateNewFrame(ref context, newBase, variableArgumentCount);
context.Thread.PushCallStackFrame(newFrame);
if (iterator is LuaClosure)
{
Expand Down Expand Up @@ -1370,7 +1408,7 @@ static bool GetTableValueSlowPath(LuaValue table, LuaValue key, ref VirtualMachi
}

table = metatableValue;
Function:
Function:
if (table.TryReadFunction(out var function))
{
return CallGetTableFunc(targetTable, function, key, ref context, out value, out doRestart);
Expand Down Expand Up @@ -1468,7 +1506,7 @@ static bool SetTableValueSlowPath(LuaValue table, LuaValue key, LuaValue value,

table = metatableValue;

Function:
Function:
if (table.TryReadFunction(out var function))
{
context.PostOperation = PostOperationType.Nop;
Expand Down Expand Up @@ -1732,7 +1770,7 @@ static bool ExecuteCompareOperationMetaMethod(LuaValue vb, LuaValue vc,
// If there are variable arguments, the base of the stack is moved by that number and the values of the variable arguments are placed in front of it.
// see: https://wubingzheng.github.io/build-lua-in-rust/en/ch08-02.arguments.html
[MethodImpl(MethodImplOptions.NoInlining)]
static (int FrameBase, int ArgumentCount, int VariableArgumentCount) PrepareVariableArgument(LuaStack stack, int newBase, int argumentCount,
static ( int ArgumentCount, int VariableArgumentCount) PrepareVariableArgument(LuaStack stack, int newBase, int argumentCount,
int variableArgumentCount)
{
var temp = newBase;
Expand All @@ -1744,51 +1782,59 @@ static bool ExecuteCompareOperationMetaMethod(LuaValue vb, LuaValue vc,
var stackBuffer = stack.GetBuffer()[temp..];
stackBuffer[..argumentCount].CopyTo(stackBuffer[variableArgumentCount..]);
stackBuffer.Slice(argumentCount, variableArgumentCount).CopyTo(stackBuffer);
return (newBase, argumentCount, variableArgumentCount);
return (argumentCount, variableArgumentCount);
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
static (int FrameBase, int ArgumentCount, int VariableArgumentCount) PrepareForFunctionCall(LuaThread thread, LuaFunction function,
Instruction instruction, int RA)
static (int ArgumentCount, int VariableArgumentCount) PrepareForFunctionCall(LuaThread thread, LuaFunction function,
Instruction instruction, int newBase, bool isMetaMethod)
{
var argumentCount = instruction.B - 1;
if (argumentCount == -1)
{
argumentCount = (ushort)(thread.Stack.Count - (RA + 1));
argumentCount = (ushort)(thread.Stack.Count - newBase);
}
else
{
thread.Stack.NotifyTop(RA + 1 + argumentCount);
if (isMetaMethod)
{
argumentCount += 1;
}

thread.Stack.NotifyTop(newBase + argumentCount);
}

var newBase = RA + 1;
var variableArgumentCount = function.GetVariableArgumentCount(argumentCount);

if (variableArgumentCount <= 0)
{
return (newBase, argumentCount, 0);
return (argumentCount, 0);
}

return PrepareVariableArgument(thread.Stack, newBase, argumentCount, variableArgumentCount);
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
static (int FrameBase, int ArgumentCount, int VariableArgumentCount) PrepareForFunctionTailCall(LuaThread thread, LuaFunction function,
Instruction instruction, int RA)
static (int ArgumentCount, int VariableArgumentCount) PrepareForFunctionTailCall(LuaThread thread, LuaFunction function,
Instruction instruction, int newBase, bool isMetaMethod)
{
var stack = thread.Stack;

var argumentCount = instruction.B - 1;
if (instruction.B == 0)
{
argumentCount = (ushort)(stack.Count - (RA + 1));
argumentCount = (ushort)(stack.Count - newBase);
}
else
{
thread.Stack.NotifyTop(RA + 1 + argumentCount);
if (isMetaMethod)
{
argumentCount += 1;
}

thread.Stack.NotifyTop(newBase + argumentCount);
}

var newBase = RA + 1;

// In the case of tailcall, the local variables of the caller are immediately discarded, so there is no need to retain them.
// Therefore, a call can be made without allocating new registers.
Expand All @@ -1804,7 +1850,7 @@ static bool ExecuteCompareOperationMetaMethod(LuaValue vb, LuaValue vc,

if (variableArgumentCount <= 0)
{
return (newBase, argumentCount, 0);
return (argumentCount, 0);
}

return PrepareVariableArgument(thread.Stack, newBase, argumentCount, variableArgumentCount);
Expand Down
25 changes: 25 additions & 0 deletions tests/Lua.Tests/LuaObjectTests.cs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
using Lua.Standard;

namespace Lua.Tests;

[LuaObject]
Expand Down Expand Up @@ -32,6 +34,12 @@ public double InstanceMethodWithReturnValue()
{
return Property;
}

[LuaMetamethod(LuaObjectMetamethod.Call)]
public string Call()
{
return "Called!";
}
}

public class LuaObjectTests
Expand Down Expand Up @@ -120,4 +128,21 @@ public async Task Test_InstanceMethodWithReturnValue()
Assert.That(results, Has.Length.EqualTo(1));
Assert.That(results[0], Is.EqualTo(new LuaValue(1)));
}

[Test]
public async Task Test_CallMetamethod()
{
var userData = new TestUserData();

var state = LuaState.Create();
state.OpenBasicLibrary();
state.Environment["test"] = userData;
var results = await state.DoStringAsync("""
assert(test() == 'Called!')
return test()
""");

Assert.That(results, Has.Length.EqualTo(1));
Assert.That(results[0], Is.EqualTo(new LuaValue("Called!")));
}
}
50 changes: 50 additions & 0 deletions tests/Lua.Tests/MetatableTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,56 @@ public async Task Test_Metamethod_NewIndex()
await state.DoStringAsync(source);
}

[Test]
public async Task Test_Metamethod_Call()
{
var source = @"
metatable = {
__call = function(a, b)
return a.x + b
end
}

local a = {}
a.x = 1
setmetatable(a, metatable)
assert(a(2) == 3)
function tail(a, b)
return a(b)
end
tail(a, 3)
assert(tail(a, 3) == 4)
";
await state.DoStringAsync(source);
}

[Test]
public async Task Test_Metamethod_TForCall()
{
var source = @"
local i =3
function a(...)
local v ={...}
assert(v[1] ==t)
assert(v[2] == nil)
if i ==3 then
assert(v[3] == nil)
else
assert(v[3] == i)
end

i =i -1
if i ==0 then return nil end
return i
end

t =setmetatable({},{__call = a})

for i in t do
end
";
await state.DoStringAsync(source);
}
[Test]
public async Task Test_Hook_Metamethods()
{
Expand Down