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public abstract BeginCatchBlock ( |
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| exceptionType | The type of exception to handle. | |
| return | void | |
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals() { NonDefaultSourceSpanBehavior = true };
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// Unlike in .NET, in javascript there are no restrictions on what can appear inside
// try, catch and finally blocks. The one restriction which causes problems is the
// inability to jump out of .NET finally blocks. This is required when break, continue
// or return statements appear inside of a finally block. To work around this, when
// inside a finally block these instructions throw an exception instead.
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
optimizationInfo.InsideTryCatchOrFinally = true;
// Finally requires two exception nested blocks.
if (this.FinallyBlock != null)
generator.BeginExceptionBlock();
// Begin the exception block.
generator.BeginExceptionBlock();
// Generate code for the try block.
this.TryBlock.GenerateCode(generator, optimizationInfo);
// Generate code for the catch block.
ILLocalVariable skipFinallyBlock = null;
// Begin a catch block. The exception is on the top of the stack.
generator.BeginCatchBlock(typeof(Exception));
// Check the exception is catchable by calling CanCatchException(ex).
// We need to handle the case where JS code calls into .NET code which then throws
// a JavaScriptException from a different ScriptEngine.
// If CatchBlock is null, we need to rethrow the exception in every case.
var endOfIfLabel = generator.CreateLabel();
generator.Duplicate(); // ex
var exceptionTemporary = generator.CreateTemporaryVariable(typeof(Exception));
generator.StoreVariable(exceptionTemporary);
EmitHelpers.LoadScriptEngine(generator);
generator.LoadVariable(exceptionTemporary);
generator.ReleaseTemporaryVariable(exceptionTemporary);
generator.Call(ReflectionHelpers.ScriptEngine_CanCatchException);
generator.BranchIfTrue(endOfIfLabel);
if (this.FinallyBlock != null)
{
generator.LoadBoolean(true);
skipFinallyBlock = generator.DeclareVariable(typeof(bool), "skipFinallyBlock");
generator.StoreVariable(skipFinallyBlock);
}
if (this.CatchBlock == null)
generator.DefineLabelPosition(endOfIfLabel);
generator.Rethrow();
if (this.CatchBlock != null)
generator.DefineLabelPosition(endOfIfLabel);
if (this.CatchBlock != null) {
// Create a new DeclarativeScope.
this.CatchScope.GenerateScopeCreation(generator, optimizationInfo);
// Store the error object in the variable provided.
generator.Call(ReflectionHelpers.JavaScriptException_ErrorObject);
var catchVariable = new NameExpression(this.CatchScope, this.CatchVariableName);
catchVariable.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
// Make sure the scope is reverted even if an exception is thrown.
generator.BeginExceptionBlock();
// Emit code for the statements within the catch block.
this.CatchBlock.GenerateCode(generator, optimizationInfo);
// Revert the scope.
generator.BeginFinallyBlock();
this.CatchScope.GenerateScopeDestruction(generator, optimizationInfo);
generator.EndExceptionBlock();
}
// Generate code for the finally block.
if (this.FinallyBlock != null)
{
generator.BeginFinallyBlock();
// If an exception was thrown that wasn't handled by the catch block, then don't
// run the finally block either. This prevents user code from being run when a
// ThreadAbortException is thrown.
var endOfFinallyBlock = generator.CreateLabel();
generator.LoadVariable(skipFinallyBlock);
generator.BranchIfTrue(endOfFinallyBlock);
var branches = new List<ILLabel>();
var previousStackSize = optimizationInfo.LongJumpStackSizeThreshold;
optimizationInfo.LongJumpStackSizeThreshold = optimizationInfo.BreakOrContinueStackSize;
var previousCallback = optimizationInfo.LongJumpCallback;
optimizationInfo.LongJumpCallback = (generator2, label) =>
{
// It is not possible to branch out of a finally block - therefore instead of
// generating LEAVE instructions we throw an exception then catch it to transfer
// control out of the finally block.
generator2.LoadInt32(branches.Count);
generator2.NewObject(ReflectionHelpers.LongJumpException_Constructor);
generator2.Throw();
// Record any branches that are made within the finally code.
branches.Add(label);
};
// Emit code for the finally block.
this.FinallyBlock.GenerateCode(generator, optimizationInfo);
// Define the position at the end of the finally block.
generator.DefineLabelPosition(endOfFinallyBlock);
// End the main exception block.
generator.EndExceptionBlock();
// Begin a catch block to catch any LongJumpExceptions. The exception object is on
// the top of the stack.
generator.BeginCatchBlock(typeof(LongJumpException));
if (branches.Count > 0)
{
// switch (exception.RouteID)
// {
// case 0: goto label1;
// case 1: goto label2;
// }
ILLabel[] switchLabels = new ILLabel[branches.Count];
for (int i = 0; i < branches.Count; i++)
switchLabels[i] = generator.CreateLabel();
generator.Call(ReflectionHelpers.LongJumpException_RouteID);
generator.Switch(switchLabels);
for (int i = 0; i < branches.Count; i++)
{
generator.DefineLabelPosition(switchLabels[i]);
generator.Leave(branches[i]);
}
}
// Reset the state we clobbered.
optimizationInfo.LongJumpStackSizeThreshold = previousStackSize;
optimizationInfo.LongJumpCallback = previousCallback;
}
// End the exception block.
generator.EndExceptionBlock();
// Reset the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals() { NonDefaultSourceSpanBehavior = true };
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// Unlike in .NET, in javascript there are no restrictions on what can appear inside
// try, catch and finally blocks. The one restriction which causes problems is the
// inability to jump out of .NET finally blocks. This is required when break, continue
// or return statements appear inside of a finally block. To work around this, when
// inside a finally block these instructions throw an exception instead.
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
optimizationInfo.InsideTryCatchOrFinally = true;
// Finally requires two exception nested blocks.
if (this.FinallyBlock != null)
generator.BeginExceptionBlock();
// Begin the exception block.
generator.BeginExceptionBlock();
// Generate code for the try block.
this.TryBlock.GenerateCode(generator, optimizationInfo);
// Generate code for the catch block.
if (this.CatchBlock != null)
{
// Begin a catch block. The exception is on the top of the stack.
generator.BeginCatchBlock(typeof(JavaScriptException));
// Create a new DeclarativeScope.
this.CatchScope.GenerateScopeCreation(generator, optimizationInfo);
// Store the error object in the variable provided.
generator.Call(ReflectionHelpers.JavaScriptException_ErrorObject);
var catchVariable = new NameExpression(this.CatchScope, this.CatchVariableName);
catchVariable.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
// Make sure the scope is reverted even if an exception is thrown.
generator.BeginExceptionBlock();
// Emit code for the statements within the catch block.
this.CatchBlock.GenerateCode(generator, optimizationInfo);
// Revert the scope.
generator.BeginFinallyBlock();
this.CatchScope.GenerateScopeDestruction(generator, optimizationInfo);
generator.EndExceptionBlock();
}
// Generate code for the finally block.
if (this.FinallyBlock != null)
{
generator.BeginFinallyBlock();
var branches = new List<ILLabel>();
var previousStackSize = optimizationInfo.LongJumpStackSizeThreshold;
optimizationInfo.LongJumpStackSizeThreshold = optimizationInfo.BreakOrContinueStackSize;
var previousCallback = optimizationInfo.LongJumpCallback;
optimizationInfo.LongJumpCallback = (generator2, label) =>
{
// It is not possible to branch out of a finally block - therefore instead of
// generating LEAVE instructions we throw an exception then catch it to transfer
// control out of the finally block.
generator2.LoadInt32(branches.Count);
generator2.NewObject(ReflectionHelpers.LongJumpException_Constructor);
generator2.Throw();
// Record any branches that are made within the finally code.
branches.Add(label);
};
// Emit code for the finally block.
this.FinallyBlock.GenerateCode(generator, optimizationInfo);
// End the main exception block.
generator.EndExceptionBlock();
// Begin a catch block to catch any LongJumpExceptions. The exception object is on
// the top of the stack.
generator.BeginCatchBlock(typeof(LongJumpException));
if (branches.Count > 0)
{
// switch (exception.RouteID)
// {
// case 0: goto label1;
// case 1: goto label2;
// }
ILLabel[] switchLabels = new ILLabel[branches.Count];
for (int i = 0; i < branches.Count; i++)
switchLabels[i] = generator.CreateLabel();
generator.Call(ReflectionHelpers.LongJumpException_RouteID);
generator.Switch(switchLabels);
for (int i = 0; i < branches.Count; i++)
{
generator.DefineLabelPosition(switchLabels[i]);
generator.Leave(branches[i]);
}
}
// Reset the state we clobbered.
optimizationInfo.LongJumpStackSizeThreshold = previousStackSize;
optimizationInfo.LongJumpCallback = previousCallback;
}
// End the exception block.
generator.EndExceptionBlock();
// Reset the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals();
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// Unlike in .NET, in javascript there are no restrictions on what can appear inside
// try, catch and finally blocks. The one restriction which causes problems is the
// inability to jump out of .NET finally blocks. This is required when break, continue
// or return statements appear inside of a finally block. To work around this, when
// inside a finally block these instructions throw an exception instead.
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
optimizationInfo.InsideTryCatchOrFinally = true;
// Finally requires two exception nested blocks.
if (this.FinallyBlock != null)
{
generator.BeginExceptionBlock();
}
// Begin the exception block.
generator.BeginExceptionBlock();
// Generate code for the try block.
this.TryBlock.GenerateCode(generator, optimizationInfo);
// Generate code for the catch block.
if (this.CatchBlock != null)
{
// Begin a catch block. The exception is on the top of the stack.
generator.BeginCatchBlock(typeof(JavaScriptException));
// Create a new DeclarativeScope.
this.CatchScope.GenerateScopeCreation(generator, optimizationInfo);
// Store the error object in the variable provided.
generator.Call(ReflectionHelpers.JavaScriptException_ErrorObject);
var catchVariable = new NameExpression(this.CatchScope, this.CatchVariableName);
catchVariable.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
// Make sure the scope is reverted even if an exception is thrown.
generator.BeginExceptionBlock();
// Emit code for the statements within the catch block.
this.CatchBlock.GenerateCode(generator, optimizationInfo);
// Revert the scope.
generator.BeginFinallyBlock();
this.CatchScope.GenerateScopeDestruction(generator, optimizationInfo);
generator.EndExceptionBlock();
}
// Generate code for the finally block.
if (this.FinallyBlock != null)
{
generator.BeginFinallyBlock();
var branches = new List <ILLabel>();
var previousStackSize = optimizationInfo.LongJumpStackSizeThreshold;
optimizationInfo.LongJumpStackSizeThreshold = optimizationInfo.BreakOrContinueStackSize;
var previousCallback = optimizationInfo.LongJumpCallback;
optimizationInfo.LongJumpCallback = (generator2, label) =>
{
// It is not possible to branch out of a finally block - therefore instead of
// generating LEAVE instructions we throw an exception then catch it to transfer
// control out of the finally block.
generator2.LoadInt32(branches.Count);
generator2.NewObject(ReflectionHelpers.LongJumpException_Constructor);
generator2.Throw();
// Record any branches that are made within the finally code.
branches.Add(label);
};
// Emit code for the finally block.
this.FinallyBlock.GenerateCode(generator, optimizationInfo);
// End the main exception block.
generator.EndExceptionBlock();
// Begin a catch block to catch any LongJumpExceptions. The exception object is on
// the top of the stack.
generator.BeginCatchBlock(typeof(LongJumpException));
if (branches.Count > 0)
{
// switch (exception.RouteID)
// {
// case 0: goto label1;
// case 1: goto label2;
// }
ILLabel[] switchLabels = new ILLabel[branches.Count];
for (int i = 0; i < branches.Count; i++)
{
switchLabels[i] = generator.CreateLabel();
}
generator.Call(ReflectionHelpers.LongJumpException_RouteID);
generator.Switch(switchLabels);
for (int i = 0; i < branches.Count; i++)
{
generator.DefineLabelPosition(switchLabels[i]);
generator.Leave(branches[i]);
}
}
// Reset the state we clobbered.
optimizationInfo.LongJumpStackSizeThreshold = previousStackSize;
optimizationInfo.LongJumpCallback = previousCallback;
}
// End the exception block.
generator.EndExceptionBlock();
// Reset the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}