/// <summary>
/// Emit code to dynamically check for errors. If an error would occur clear out the stack and jump away to the given label
/// </summary>
/// <typeparam name="TEmit"></typeparam>
/// <param name="emitter"></param>
/// <param name="errorLabel"></param>
/// <param name="parameters"></param>
public void EmitDynamicWillThrow <TEmit>(OptimisingEmitter <TEmit> emitter, Compiler.Emitter.Instructions.ExceptionBlock errorLabel, IReadOnlyList <Local> parameters)
{
// Load parameters back onto stack
for (var i = parameters.Count - 1; i >= 0; i--)
{
emitter.LoadLocal(parameters[i]);
}
// Invoke the `will throw` method to discover if this invocation would trigger a runtime error
emitter.Call(WillThrow);
// Create a label to jump past the error handling for the normal case
var noThrowLabel = emitter.DefineLabel();
// Jump past error handling if this is ok
emitter.BranchIfFalse(noThrowLabel);
// If execution reaches here it means an error would occur in this operation
emitter.Leave(errorLabel);
emitter.MarkLabel(noThrowLabel);
}
/// <summary>
/// Compile a line of Yolol into the given IL emitter
/// </summary>
/// <param name="line"></param>
/// <param name="emit"></param>
/// <param name="lineNumber"></param>
/// <param name="maxLines"></param>
/// <param name="maxStringLength"></param>
/// <param name="internalVariableMap"></param>
/// <param name="externalVariableMap"></param>
/// <param name="staticTypes"></param>
/// <param name="changeDetection"></param>
public static void Compile(
this Line line,
Emit <Func <ArraySegment <Value>, ArraySegment <Value>, LineResult> > emit,
int lineNumber,
int maxLines,
int maxStringLength,
IReadonlyInternalsMap internalVariableMap,
IReadonlyExternalsMap externalVariableMap,
IReadOnlyDictionary <VariableName, Type>?staticTypes = null,
bool changeDetection = false
)
{
using (var emitter = new OptimisingEmitter <Func <ArraySegment <Value>, ArraySegment <Value>, LineResult> >(emit))
{
void EmitFallthroughCalc()
{
if (lineNumber == maxLines)
{
emitter.LoadConstant(1);
}
else
{
emitter.LoadConstant(lineNumber + 1);
}
}
// Special case for totally empty lines
if (line.Statements.Statements.Count == 0)
{
EmitFallthroughCalc();
emitter.LoadConstant(0ul);
emitter.NewObject <ChangeSet, ulong>();
emitter.NewObject(typeof(LineResult).GetConstructor(new[] { typeof(int), typeof(ChangeSet) }) !);
emitter.Return();
return;
}
// Begin an exception block to catch Yolol runtime errors
var exBlock = emitter.BeginExceptionBlock();
// Create a local to store the return address from inside the try/catch block
var retAddr = emitter.DeclareLocal <int>("ret_addr", initializeReused: false);
// Create a local for the change bit set
var changeSet = changeDetection ? emitter.DeclareLocal <ulong>("change_set") : null;
// Store the default return address to go to
EmitFallthroughCalc();
emitter.StoreLocal(retAddr);
// Create a label which any `goto` statements can use. They drop their destination PC on the stack and then jump to this label
var gotoLabel = emitter.DefineLabel2("encountered_goto");
var types = new StaticTypeTracker(staticTypes);
// Create a memory accessor which manages reading and writing the memory arrays
using (var accessor = new ArraySegmentMemoryAccessor <Func <ArraySegment <Value>, ArraySegment <Value>, LineResult> >(
emitter,
1,
0,
internalVariableMap,
externalVariableMap,
types,
changeSet
))
{
accessor.EmitLoad(line);
// Convert the entire line into IL
var converter = new ConvertLineVisitor <Func <ArraySegment <Value>, ArraySegment <Value>, LineResult> >(emitter, maxLines, accessor, exBlock, gotoLabel, types, maxStringLength);
converter.Visit(line);
// When a line finishes (with no gotos in the line) call flow eventually reaches here. Go to the next line.
emitter.Leave(exBlock);
// Create a block to handle gotos. The destination will already be on the stack, so just return
if (gotoLabel.IsUsed)
{
emitter.MarkLabel(gotoLabel);
emitter.StoreLocal(retAddr);
emitter.Leave(exBlock);
}
// Catch all execution exceptions and return the appropriate next line number to fall through to
var catchBlock = emitter.BeginCatchBlock <ExecutionException>(exBlock);
#if DEBUG
using (var ex = emitter.DeclareLocal(typeof(ExecutionException), initializeReused: false))
{
emitter.StoreLocal(ex);
emitter.WriteLine("execution exception: {0}", ex);
}
#else
emitter.Pop();
#endif
// Close the exception block which was wrapping the entire method
emitter.EndCatchBlock(catchBlock);
emitter.EndExceptionBlock(exBlock);
}
// Load the return address from inside the catch block
emitter.LoadLocal(retAddr);
// Create the change set, either from the computer value or the default value (which indicates that everything has changed)
if (changeSet != null)
{
emitter.LoadLocal(changeSet);
}
else
{
emitter.LoadConstant(ulong.MaxValue);
}
emitter.NewObject <ChangeSet, ulong>();
emitter.NewObject(typeof(LineResult).GetConstructor(new[] { typeof(int), typeof(ChangeSet) }) !);
emitter.Return();
emitter.Optimise();
#if DEBUG
Console.WriteLine($"// {line}");
Console.WriteLine(emitter.ToString());
Console.WriteLine($"------------------------------");
#endif
}
}