/// <summary>
/// Creates a <see cref="JavaScriptValue"/> representing the host delegate.
/// </summary>
/// <remarks>This call requires an active context.</remarks>
public JavaScriptValue ToJsFunction(object obj, Type type)
{
var invokeInfo = type.GetMethod("Invoke");
if (null == invokeInfo)
{
throw new Exception($"Cannot convert delegate of type: {type} to JavaScript function.");
}
JavaScriptNativeFunction func = (v, s, args, argLength, data) =>
{
var parameters = invokeInfo.GetParameters();
var realParams = new object[parameters.Length];
var argIndex = 1;
for (int j = 0; j < parameters.Length; ++j)
{
var arg = args[argIndex++];
var param = parameters[j];
realParams[j] = ToHostObject(arg, param.ParameterType);
}
var result = invokeInfo.Invoke(obj, realParams);
var resultType = invokeInfo.ReturnType;
if (resultType == typeof(void))
{
return(JavaScriptValue.Invalid);
}
return(ToJsObject(result, JsConversions.TypeFor(result, resultType)));
};
return(_binder.BindFunction(func));
}
/// <summary>
/// Binds all the fields for the instance.
/// </summary>
private void BindFields(JsBinding binding, IHostType hostType, object instance)
{
// TODO: Seems like we can hoist this into JsInterop, which would allow us refactor
// TODO: out the builder class completely.
var fields = hostType.FieldNames;
for (int i = 0; i < fields.Count; ++i)
{
var fieldName = fields[i];
binding.AddProperty(
fieldName,
(v, s, args, argLength, data) =>
{
var fieldInfo = hostType.FieldFor(fieldName).Field;
var result = fieldInfo.GetValue(instance);
var returnType = JsConversions.TypeFor(result, fieldInfo.FieldType);
return(_interop.ToJsObject(result, returnType));
},
(v, s, args, argLength, data) =>
{
var fieldInfo = hostType.FieldFor(fieldName).Field;
var fieldType = fieldInfo.FieldType;
var value = _interop.ToHostObject(args[1], fieldType);
fieldInfo.SetValue(instance, value);
return(JavaScriptValue.Invalid);
});
}
}
/// <summary>
/// Binds all public properties for the instance.
/// </summary>
private void BindProperties(JsBinding binding, IHostType hostType, object instance)
{
// TODO: Seems like we can hoist this into JsInterop, which would allow us refactor
// TODO: out the builder class completely.
var properties = hostType.PropertyNames;
for (int i = 0; i < properties.Count; ++i)
{
var propertyName = properties[i];
binding.AddProperty(
propertyName,
(v, s, args, argLength, data) =>
{
var get = hostType.PropertyFor(propertyName).Getter;
var result = get.Invoke(instance, EmptyParameters);
var returnType = JsConversions.TypeFor(result, get.ReturnType);
return(_interop.ToJsObject(result, returnType));
},
(v, s, args, argLength, data) =>
{
var hostProperty = hostType.PropertyFor(propertyName);
var propType = hostProperty.PropertyType;
var set = hostProperty.Setter;
var value = _interop.ToHostObject(args[1], propType);
set.Invoke(instance, new[] { value });
return(JavaScriptValue.Invalid);
});
}
}
/// <summary>
/// Converts a host object to a javascript value.
/// </summary>
public JavaScriptValue ToJsObject(object obj, Type type)
{
if (null == obj)
{
return(JavaScriptValue.Null);
}
if (JsConversions.IsVoidType(type))
{
return(ToJsVoid(obj, type));
}
if (JsConversions.IsNumberType(type))
{
return(ToJsNumber(obj, type));
}
if (JsConversions.IsStringType(type))
{
return(ToJsString(obj, type));
}
if (JsConversions.IsBoolType(type))
{
return(ToJsBoolean(obj, type));
}
if (JsConversions.IsFunctionType(type))
{
return(ToJsFunction(obj, type));
}
if (type.IsArray)
{
var underlyingType = type.GetElementType();
var hostArray = (Array)obj;
var newArr = JavaScriptValue.CreateArray((uint)hostArray.Length);
for (int i = 0; i < hostArray.Length; ++i)
{
var jsValue = ToJsObject(hostArray.GetValue(i), underlyingType);
newArr.SetIndexedProperty(JavaScriptValue.FromInt32(i), jsValue);
}
return(newArr);
}
// Attempt to bind the object and return it
return(ToBoundJsObject(obj, type));
}
/// <summary>
/// This method type checks each parameter passed by javascript to determine if the method is a suitable
/// match for execution. At this point, we can assume that the provided arguments qualify for the method
/// signature in terms of number of parameters, accounting for optional parameters and var args.
/// </summary>
private bool IsCompatibleMethod(HostMethod method, JavaScriptValue[] args, ushort argLength)
{
var parameters = method.Parameters;
var isVarArg = method.IsVarArgs;
// Parameter Index Pointers - JS parameters include the callee at the first index, so we start after that
var argIndex = 1;
var pIndex = 0;
// The maximum number of iterations we'll have to run to complete type checking each parameter
// This is typically parameters.Length unless there are optional parameters or var args
var iterations = Math.Max(parameters.Length, argLength - 1);
// Loop Max Argument Count
while (iterations-- > 0)
{
// Case 1. We've Type Checked All JS Parameters Against C# Parameters
if (argIndex >= argLength)
{
// For a Var Arg C# Parameter Method, ensure we've indexed into the var arg index
if (isVarArg)
{
// If we haven't, then we ensure that we have an optional parameter. Otherwise,
// we're short JS parameters, so we can't call this method.
if (pIndex != method.VarArgIndex)
{
return(parameters[pIndex].IsOptional);
}
return(true);
}
// For methods without var args, we simply ensure we've typed checked against all required
// parameters.
if (pIndex < parameters.Length)
{
return(parameters[pIndex].IsOptional);
}
return(true);
}
// Case 2. We reach the end of C# Method Parameters, but still have JS Parameters left to check
if (pIndex >= parameters.Length)
{
// This case is only possible with var args (since the params []) counts as a single index
if (!method.IsVarArgs)
{
return(false);
}
// Ensure that pIndex stays at the var arg index for type checking the element type
pIndex = method.VarArgIndex;
}
// Case 3. TypeCheck JS Argument Against C# Parameter
var arg = args[argIndex];
var parameter = parameters[pIndex];
// For Var Args, we need to ensure that we use the var arg type to check against the JS arg.
var paramType = (isVarArg && pIndex >= method.VarArgIndex)
? method.VarArgType
: parameter.ParameterType;
// Increment index pointers
argIndex++;
pIndex++;
// Run type conversion checking, early return on failure
if (!JsConversions.IsAssignable(arg, _binder, paramType))
{
return(false);
}
}
return(true);
}
/// <summary>
/// Adds function bindings for all methods in the <see cref="IHostType"/>.
/// </summary>
private void BindMethods(JsBinding binding, IHostType hostType, object instance)
{
// TODO: Seems like we can hoist this into JsInterop, which would allow us refactor
// TODO: out the builder class completely.
var methods = hostType.MethodNames;
for (int i = 0; i < methods.Count; ++i)
{
var methodName = methods[i];
binding.AddFunction(
methodName,
(v, s, args, argLength, data) =>
{
var totalParameters = argLength - 1;
var hostMethods = hostType.MethodsFor(methodName, totalParameters);
if (hostMethods.Count == 0)
{
var message = $"Calling host function that does not exist: [Method: {methodName}, Instance: {instance}]";
JsErrorHelper.SetJsException(message);
return(JavaScriptValue.Invalid);
}
HostMethod hostMethodInfo;
// Only a single method returned. Call this optimistically
if (hostMethods.Count == 1)
{
hostMethodInfo = hostMethods[0];
}
else
{
// Get the Parameter Key, and look up cached invocation
var invokeKey = JsConversions.ToInvokeKey(methodName, args, argLength);
if (!hostType.TryGetInvocation(invokeKey, out hostMethodInfo))
{
// Otherwise, locate best method for these argument, and cache
hostMethodInfo = FindBestMethod(hostMethods, args, argLength);
hostType.CacheInvocation(invokeKey, hostMethodInfo);
}
}
if (null == hostMethodInfo)
{
LogMethodSelectionFailure(hostMethods, args, argLength);
JsErrorHelper.SetJsException(
$"Calling host function that does not exist: [Method: {methodName}, Instance: {instance}]");
return(JavaScriptValue.Invalid);
}
try
{
var realParams = ToParameters(hostMethodInfo, args, argLength);
var result = hostMethodInfo.Method.Invoke(instance, realParams);
var resultType = hostMethodInfo.ReturnType;
if (resultType == typeof(void))
{
return(JavaScriptValue.Invalid);
}
resultType = JsConversions.TypeFor(result, resultType);
return(_interop.ToJsObject(result, resultType));
}
catch (Exception e)
{
LogMethodInvocationInfo(hostMethodInfo, instance);
throw;
}
});
}
}
