|
public static Catch ( System.Linq.Expressions.ParameterExpression variable, |
||
| variable | System.Linq.Expressions.ParameterExpression | A |
| body | The body of the catch statement. | |
| return | ||
public EvaluationCallback Create(Node node)
{
var compilerstate = new CompilerState
{
FunctionState = Exp.Parameter(typeof(Character), "state"),
ErrorVariable = Exp.Parameter(typeof(bool), "error")
};
var result = Make(compilerstate, node);
if (result.Type == typeof(bool))
{
result = ToInteger(result);
}
if (result.Type == typeof(int) || result.Type == typeof(float))
{
// int or float convert to number
var constructor = typeof(Number).GetConstructor(new[] { result.Type });
result = Exp.New(constructor, new[] { result });
// wrap the evaluation in a try..catch
var exceptionParameter = Exp.Parameter(typeof(Exception), "e");
var writeLineMethod = typeof(Console).GetMethod(nameof(Console.WriteLine), new Type[] { typeof(string) });
var toStringMethod = typeof(Exception).GetMethod(nameof(Exception.ToString));
var catchBody = Exp.Block(
Exp.Call(null, writeLineMethod, Exp.Call(exceptionParameter, toStringMethod)),
Exp.Constant(new Number(0)));
result = Exp.TryCatch(result, Exp.Catch(exceptionParameter, catchBody));
// create lambda
var func = Exp.Lambda <Func <Character, bool, Number> >(result, compilerstate.FunctionState, compilerstate.ErrorVariable).Compile();
return(new EvaluationCallback(o => func(o, false)));
}
throw new Exception();
}
public void TryCatchTypeBody()
{
var expected = LinqExpression.TryCatch(
LinqExpression.Constant(0L),
LinqExpression.Catch(
typeof(Exception),
LinqExpression.Constant(0L)));
using var g = new GraphEngine.Graph();
g.LoadFromString(@"
@prefix : <http://example.com/> .
:s
:tryBody _:zero ;
:tryHandlers (
[
:catchType [
:typeName ""System.Exception"" ;
] ;
:catchBody _:zero ;
]
) ;
.
_:zero
:constantValue 0 ;
.
");
var s = g.GetUriNode(":s");
var actual = Expression.Parse(s).LinqExpression;
Console.WriteLine(actual.GetDebugView());
actual.Should().Be(expected);
}
public LambdaExpression CreateLambda(Type from, Type to)
{
var input = Ex.Parameter(from, "input");
var convert = ConvertMethod(from, to);
var exception = Ex.Parameter(typeof(Exception), "exception");
var block = Ex.TryCatch(
Result(to, Ex.Call(convert, convert.GetParameters().Select(pi => getParameter(pi, input)))),
Ex.Catch(exception, NoResult(to)));
var lambda = Ex.Lambda(block, input);
return(lambda);
}
public void TryCatchVariableBodyFilter()
{
var expected = LinqExpression.TryCatch(
LinqExpression.Constant(0L),
LinqExpression.Catch(
LinqExpression.Parameter(
typeof(Exception)),
LinqExpression.Constant(0L),
LinqExpression.Equal(
LinqExpression.Constant(0L),
LinqExpression.Constant(0L))));
using var g = new GraphEngine.Graph();
g.LoadFromString(@"
@prefix : <http://example.com/> .
@prefix xt: <http://example.com/ExpressionTypes/> .
:s
:tryBody _:zero ;
:tryHandlers (
[
:catchVariable [
:parameterType [
:typeName ""System.Exception"" ;
] ;
] ;
:catchBody _:zero ;
:catchFilter [
:binaryExpressionType xt:Equal ;
:binaryLeft _:zero ;
:binaryRight _:zero ;
] ;
]
) ;
.
_:zero
:constantValue 0 ;
.
");
var s = g.GetUriNode(":s");
var actual = Expression.Parse(s).LinqExpression;
Console.WriteLine(actual.GetDebugView());
actual.Should().Be(expected);
}
public static Expression <Func <string[], int> > WrapMain(Expression program)
{
LabelTarget label = Expression.Label(typeof(int));
BlockExpression programReturningNoErrorCode = Expression.Block(program, Expression.Constant(0));
Expression <Action <Exception> > writeLine = s => Console.Error.WriteLine(s);
ParameterExpression exitException = Expression.Variable(typeof(ExitException));
ParameterExpression exception = Expression.Variable(typeof(Exception));
TryExpression programCatchingExceptions = Expression.TryCatch(programReturningNoErrorCode,
Expression.Catch(exitException, Expression.Property(exitException, "Code")),
Expression.Catch(exception, Expression.Block(writeLine.eInvoke(exception), Expression.Constant(1))));
LabelExpression returnLabel = Expression.Label(label, programCatchingExceptions);
ParameterExpression parameter = Expression.Parameter(typeof(string[]), "args");
Expression <Func <string[], int> > lambda = Expression.Lambda <Func <string[], int> >(returnLabel, parameter);
return(lambda);
}
static void Main()
{
var asm = AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName("bar"), AssemblyBuilderAccess.Save);
var mod = asm.DefineDynamicModule("bar.dll");
var typ = mod.DefineType("Foo");
var lblRet = Expression.Label(typeof(int));
var lbl1 = Expression.Label(typeof(int));
var ex = Expression.Parameter(typeof(Exception));
var expressions = new Expression[]
{
Expression.TryFault(
Expression.Constant(1),
Expression.Constant(2)
),
Expression.Block(
Expression.TryFault(
Expression.Goto(lblRet, Expression.Constant(1)),
Expression.Constant(2)
),
Expression.Label(lblRet, Expression.Constant(0))
),
Expression.Block(
Expression.TryFault(
Expression.Block(
Expression.Goto(lblRet, Expression.Constant(1)),
Expression.Constant(2)
),
Expression.Constant(3)
),
Expression.Label(lblRet, Expression.Constant(0))
),
Expression.Block(
Expression.TryFault(
Expression.Block(
Expression.Goto(lbl1, Expression.Constant(1)),
Expression.Goto(lblRet, Expression.Constant(2))
),
Expression.Constant(3)
),
Expression.Label(lbl1, Expression.Constant(-1)),
Expression.Label(lblRet, Expression.Constant(0))
),
Expression.TryCatch(
Expression.Constant(1),
Expression.Catch(ex, Expression.Constant(2), Expression.Constant(true))
),
};
var i = 0;
foreach (var expression in expressions)
{
var mtd = typ.DefineMethod("M" + i, MethodAttributes.Public | MethodAttributes.Static, typeof(int), new Type[0]);
Expression.Lambda <Func <int> >(expression).CompileToMethod(mtd);
var cw = Expression.Lambda <Func <int> >(expression).CompileWithExceptionHandling();
cw();
i++;
}
}
public void MiscellaneousExpression_Try()
{
var tryCatch = Expr.TryCatch(Expr.Constant(false), Expr.Catch(typeof(Exception), Expr.Constant(false)));
UnsupportedExpr(Property.Id, id => tryCatch, ExpressionType.Try);
}
static LambdaExpression ApplyMethodHandler(string functionName, LambdaExpression functionLambda, IFunctionExecutionHandler handler)
{
// public static int MyMethod(object arg0, int arg1) { ... }
// becomes:
// (the 'handler' object is captured and called mh)
// public static int MyMethodWrapped(object arg0, int arg1)
// {
// var fhArgs = new FunctionExecutionArgs("MyMethod", new object[] { arg0, arg1});
// int result = default(int);
// try
// {
// fh.OnEntry(fhArgs);
// if (fhArgs.FlowBehavior == FlowBehavior.Return)
// {
// result = (int)fhArgs.ReturnValue;
// }
// else
// {
// // Inner call
// result = MyMethod(arg0, arg1);
// fhArgs.ReturnValue = result;
// fh.OnSuccess(fhArgs);
// result = (int)fhArgs.ReturnValue;
// }
// }
// catch ( Exception ex )
// {
// fhArgs.Exception = ex;
// fh.OnException(fhArgs);
// // Makes no sense to me yet - I've removed this FlowBehavior enum value.
// // if (fhArgs.FlowBehavior == FlowBehavior.Continue)
// // {
// // // Finally will run, but can't change return value
// // // Should we assign result...?
// // // So Default value will be returned....?????
// // fhArgs.Exception = null;
// // }
// // else
// if (fhArgs.FlowBehavior == FlowBehavior.Return)
// {
// // Clear the Exception and return the ReturnValue instead
// // Finally will run, but can't further change return value
// fhArgs.Exception = null;
// result = (int)fhArgs.ReturnValue;
// }
// else if (fhArgs.FlowBehavior == FlowBehavior.ThrowException)
// {
// throw fhArgs.Exception;
// }
// else // if (fhArgs.FlowBehavior == FlowBehavior.Default || fhArgs.FlowBehavior == FlowBehavior.RethrowException)
// {
// throw;
// }
// }
// finally
// {
// fh.OnExit(fhArgs);
// // NOTE: fhArgs.ReturnValue is not used again here...!
// }
//
// return result;
// }
// }
// CONSIDER: There are some helpers in .NET to capture the exception context, which would allow us to preserve the stack trace in a fresh throw.
// Ensure the handler object is captured.
var mh = Expression.Constant(handler);
var funcName = Expression.Constant(functionName);
// Prepare the functionHandlerArgs that will be threaded through the handler,
// and a bunch of expressions that access various properties on it.
var fhArgs = Expr.Variable(typeof(FunctionExecutionArgs), "fhArgs");
var fhArgsReturnValue = SymbolExtensions.GetProperty(fhArgs, (FunctionExecutionArgs mea) => mea.ReturnValue);
var fhArgsException = SymbolExtensions.GetProperty(fhArgs, (FunctionExecutionArgs mea) => mea.Exception);
var fhArgsFlowBehaviour = SymbolExtensions.GetProperty(fhArgs, (FunctionExecutionArgs mea) => mea.FlowBehavior);
// Set up expressions to call the various handler methods.
// TODO: Later we can determine which of these are actually implemented, and only write out the code needed in the particular case.
var onEntry = Expr.Call(mh, SymbolExtensions.GetMethodInfo <IFunctionExecutionHandler>(meh => meh.OnEntry(null)), fhArgs);
var onSuccess = Expr.Call(mh, SymbolExtensions.GetMethodInfo <IFunctionExecutionHandler>(meh => meh.OnSuccess(null)), fhArgs);
var onException = Expr.Call(mh, SymbolExtensions.GetMethodInfo <IFunctionExecutionHandler>(meh => meh.OnException(null)), fhArgs);
var onExit = Expr.Call(mh, SymbolExtensions.GetMethodInfo <IFunctionExecutionHandler>(meh => meh.OnExit(null)), fhArgs);
// Create the new parameters for the wrapper
var outerParams = functionLambda.Parameters.Select(p => Expr.Parameter(p.Type, p.Name)).ToArray();
// Create the array of parameter values that will be put into the method handler args.
var paramsArray = Expr.NewArrayInit(typeof(object), outerParams.Select(p => Expr.Convert(p, typeof(object))));
// Prepare the result and ex(ception) local variables
var result = Expr.Variable(functionLambda.ReturnType, "result");
var ex = Expression.Parameter(typeof(Exception), "ex");
// A bunch of helper expressions:
// : new FunctionExecutionArgs(new object[] { arg0, arg1 })
var fhArgsConstr = typeof(FunctionExecutionArgs).GetConstructor(new[] { typeof(string), typeof(object[]) });
var newfhArgs = Expr.New(fhArgsConstr, funcName, paramsArray);
// : result = (int)fhArgs.ReturnValue
var resultFromReturnValue = Expr.Assign(result, Expr.Convert(fhArgsReturnValue, functionLambda.ReturnType));
// : fhArgs.ReturnValue = (object)result
var returnValueFromResult = Expr.Assign(fhArgsReturnValue, Expr.Convert(result, typeof(object)));
// : result = function(arg0, arg1)
var resultFromInnerCall = Expr.Assign(result, Expr.Invoke(functionLambda, outerParams));
// Build the Lambda wrapper, with the original parameters
var lambda = Expr.Lambda(
Expr.Block(new[] { fhArgs, result },
Expr.Assign(fhArgs, newfhArgs),
Expr.Assign(result, Expr.Default(result.Type)),
Expr.TryCatchFinally(
Expr.Block(
onEntry,
Expr.IfThenElse(
Expr.Equal(fhArgsFlowBehaviour, Expr.Constant(FlowBehavior.Return)),
resultFromReturnValue,
Expr.Block(
resultFromInnerCall,
returnValueFromResult,
onSuccess,
resultFromReturnValue))),
onExit, // finally
Expr.Catch(ex,
Expr.Block(
Expr.Assign(fhArgsException, ex),
onException,
Expr.IfThenElse(
Expr.Equal(fhArgsFlowBehaviour, Expr.Constant(FlowBehavior.Return)),
Expr.Block(
Expr.Assign(fhArgsException, Expr.Constant(null, typeof(Exception))),
resultFromReturnValue),
Expr.IfThenElse(
Expr.Equal(fhArgsFlowBehaviour, Expr.Constant(FlowBehavior.ThrowException)),
Expr.Throw(fhArgsException),
Expr.Rethrow()))))
),
result),
functionName,
outerParams);
return(lambda);
}
internal System.Linq.Expressions.CatchBlock ToCatchBlock() => SysExpr.Catch(Variable.ToParameterExpression(), Body.ToExpression());
public static Expression TryNoCatch(this Expression expression) => Expression.TryCatch(expression, Expression.Catch(typeof(Exception).ToParameter(), Expression.Empty()));