/// <summary>
/// Builds an expression for the specified <see cref="ConstructorBinding" />.
/// Called by <see cref="Build(ConstructorTarget, IExpressionCompileContext, IExpressionCompiler)" />
/// </summary>
/// <param name="binding">The binding.</param>
/// <param name="context">The context.</param>
/// <param name="compiler">The compiler to be used to build the target.</param>
/// <remarks>The returned expression will either be a NewExpression or a MemberInitExpression</remarks>
protected virtual Expression Build(ConstructorBinding binding, IExpressionCompileContext context, IExpressionCompiler compiler)
{
var newExpr = Expression.New(binding.Constructor,
binding.BoundArguments.Select(
a => compiler.Build(a.Target, context.NewContext(a.Parameter.ParameterType))));
if (binding.MemberBindings.Length == 0)
{
return(newExpr);
}
else
{
ParameterExpression localVar = null;
List <MemberAssignment> memberBindings = new List <MemberAssignment>();
List <Expression> adHocBindings = new List <Expression>();
foreach (var mb in binding.MemberBindings)
{
// as soon as we have one list binding (which we can actually implement
// using the list binding expression) we need to capture the locally newed
// object into a local variable and pass it to the function below
if (mb is ListMemberBinding listBinding)
{
if (localVar == null)
{
localVar = Expression.Parameter(newExpr.Type, "toReturn");
}
adHocBindings.Add(GenerateListBindingExpression(localVar, listBinding, context, compiler));
}
else
{
memberBindings.Add(Expression.Bind(mb.Member, compiler.Build(mb.Target, context.NewContext(mb.MemberType))));
}
}
Expression toReturn = newExpr;
if (memberBindings.Count != 0)
{
toReturn = Expression.MemberInit(newExpr, memberBindings);
}
if (adHocBindings.Count != 0)
{
List <Expression> blockCode = new List <Expression>
{
Expression.Assign(localVar, toReturn)
};
blockCode.AddRange(adHocBindings);
blockCode.Add(localVar);
toReturn = Expression.Block(new[] { localVar }, blockCode);
}
return(toReturn);
}
}
/// <summary>
/// Builds an expression for the given <paramref name="target"/>.
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />. Note that unlike on the interface, where this
/// parameter is optional, this will always be provided</param>
/// <exception cref="System.InvalidOperationException"></exception>
protected override Expression Build(ResolvedTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
var staticTarget = target.Bind(context);
Expression staticExpr;
if (staticTarget != null)
{
staticExpr = compiler.Build(staticTarget, context.NewContext(target.DeclaredType));
if (staticExpr == null)
{
throw new InvalidOperationException(string.Format(ExceptionResources.TargetReturnedNullExpressionFormat, staticTarget.GetType(), context.TargetType));
}
if (staticExpr.Type != target.DeclaredType)
{
staticExpr = Expression.Convert(staticExpr, target.DeclaredType);
}
}
else
{
// this should generate a missing dependency exception if executed
// or, might actually yield a result if registrations have been added
// after the expression is compiled.
staticExpr = Methods.CallResolveContext_Resolve_Strong_Method(
context.ResolveContextParameterExpression,
target.DeclaredType);
}
return(staticExpr);
}
/// <summary>
/// Builds an expression which represents an instance of <see cref="IEnumerable{T}"/> whose elements are created by the
/// <see cref="EnumerableTarget.Targets"/> of the passed <paramref name="target"/>.
/// </summary>
/// <param name="target">The target for which an expression is to be built.</param>
/// <param name="context">The current compilation context.</param>
/// <param name="compiler">The compiler to use when building expressions for child targets.</param>
/// <returns>An expression which can be compiled into a delegate that, when executed, will create an instance of the enumerable
/// represented by <paramref name="target"/>
/// </returns>
/// <remarks>
/// The compiler is capable of producing both lazy-loaded and eager-loaded enumerables, which can be controlled via
/// target container options.
///
/// ## Lazy vs Eager loading
///
/// The option <see cref="Options.LazyEnumerables"/> is read from the <paramref name="context"/> for the
/// <see cref="EnumerableTarget.ElementType"/> of the <paramref name="target"/>. If it is equivalent to <c>true</c>
/// (the <see cref="Options.LazyEnumerables.Default"/>), then a lazily-loaded enumerable is constructed which will
/// create new instances of each object in the enumerable each time it is enumerated.
///
/// If the option is instead equivalent to <c>false</c>, then all instances will be created in advance, and an already-materialised
/// enumerable is constructed.</remarks>
protected override Expression Build(EnumerableTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
if (context.GetOption(target.ElementType, Options.LazyEnumerables.Default))
{
var funcs =
target.Targets.Select(t => compiler.BuildResolveLambdaStrong(t, context.NewContext(target.ElementType)).Compile())
.ToArray();
var lazyType = typeof(LazyEnumerable <>).MakeGenericType(target.ElementType);
var ctor = lazyType.GetConstructor(new[] { typeof(Delegate[]) });
var lazy = ctor.Invoke(new object[] { funcs });
return(Expression.Call(
Expression.Constant(lazy),
"GetInstances",
null,
context.ResolveContextParameterExpression));
}
else
{
List <Expression> all = new List <Expression>();
for (var f = 0; f < target.Targets.Length; f++)
{
all.Add(compiler.Build(target.Targets[f], context.NewContext(target.ElementType)));
}
return(Expression.New(
typeof(EagerEnumerable <>).MakeGenericType(target.ElementType).GetConstructors()[0],
Expression.NewArrayInit(target.ElementType, all)));
}
}
/// <summary>
/// Builds the conversion expression represented by the <paramref name="target"/>
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />.</param>
protected override Expression Build(VariantMatchTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
// Here, the target type is *key*, especially for singletons
return(Expression.Convert(compiler.Build(target.Target,
context.NewContext(target.RegisteredType, scopeBehaviourOverride: context.ScopeBehaviourOverride)), target.RequestedType));
}
/// <summary>
/// Builds the conversion expression represented by the <paramref name="target"/>
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />.</param>
protected override Expression Build(ChangeTypeTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
// build the inner target's expression; and wrap it in a conversion expression for the
// target type of the ChangeTypeTarget.
// note that if the compilation context was overriding the scoping behaviour before - then we pass that through,
// because this target defaults to 'None'
return(Expression.Convert(compiler.Build(target.InnerTarget,
context.NewContext(target.InnerTarget.DeclaredType, scopeBehaviourOverride: context.ScopeBehaviourOverride)), target.DeclaredType));
}
/// <summary>
/// Builds an expression from the specified target for the given <see cref="IExpressionCompileContext" />
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />. Note that unlike on the interface, where this
/// parameter is optional, this will always be provided</param>
/// <exception cref="NotImplementedException"></exception>
protected override Expression Build(DelegateTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
var bindings = ParameterBinding.BindWithRezolvedArguments(target.Factory.GetMethodInfo());
return(Expression.Invoke(Expression.Constant(target.Factory),
bindings.Select(b => b.Parameter.ParameterType == typeof(ResolveContext) ?
context.ResolveContextParameterExpression
: compiler.Build(b.Target, context.NewContext(b.Parameter.ParameterType)))));
}
/// <summary>
/// Builds an expression for the given <paramref name="target"/>.
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />. Note that unlike on the interface, where this
/// parameter is optional, this will always be provided</param>
protected override Expression Build(ScopedTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
// all we need to do is force the inner target's scope behaviour to None - and this builder's
// base code will ensure that the whole resulting expression is converted into an explicitly scoped one
// note that this scope deactivation is only in place for this one target - if it has any child targets then
// scoping behaviour for those returns to normal if compiled with a new context (which they always should be)
return(compiler.Build(target.InnerTarget, context.NewContext(scopeBehaviourOverride: ScopeBehaviour.None)));
}
/// <summary>
/// Builds an expression for the passed <paramref name="target"/>
/// </summary>
/// <param name="target"></param>
/// <param name="context"></param>
/// <param name="compiler"></param>
/// <returns></returns>
protected override Expression Build(ProjectionTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
// functionally the same as the DecoratorTargetBuilder
var newContext = context.NewContext(target.ImplementationType);
newContext.Register(target.InputTarget, target.InputType ?? target.InputTarget.DeclaredType);
// projection target acts as an anchor for the target it wraps - this allows a single registered
// target which is either a singleton or scoped to be reused for multiple input targets.
newContext.SetOption(new TargetIdentityOverride(target.Id), target.DeclaredType);
return(compiler.Build(target.OutputTarget, newContext));
}
/// <summary>
/// Similar to <see cref="BuildResolveLambda(IExpressionCompiler, ITarget, IExpressionCompileContext)"/>, except this builds a
/// lambda whose type is a strongly-typed delegate instead of object - i.e. Func{ResolveContext, T}
/// </summary>
/// <param name="compiler"></param>
/// <param name="target"></param>
/// <param name="context"></param>
/// <returns></returns>
public static LambdaExpression BuildResolveLambdaStrong(this IExpressionCompiler compiler, ITarget target, IExpressionCompileContext context)
{
if (compiler == null)
{
throw new ArgumentNullException(nameof(compiler));
}
if (target == null)
{
throw new ArgumentNullException(nameof(target));
}
var expression = compiler.Build(target, context);
return(compiler.BuildStrongFactoryLambda(expression, context));
}
/// <summary>
/// This method is a shortcut for building a lambda expression directly from an <see cref="ITarget" />.
/// It calls <see cref="IExpressionCompiler.Build(ITarget, IExpressionCompileContext)" /> and passes the result to
/// <see cref="IExpressionCompiler.BuildObjectFactoryLambda(Expression, IExpressionCompileContext)" />, which should yield an
/// optimised lambda expression for the expression produced from the target which can then be
/// compiled and used as the factory for that target.
/// </summary>
/// <param name="compiler">The compiler.</param>
/// <param name="target">The target.</param>
/// <param name="context">The current compilation context.</param>
public static Expression <Func <ResolveContext, object> > BuildResolveLambda(this IExpressionCompiler compiler, ITarget target, IExpressionCompileContext context)
{
if (compiler == null)
{
throw new ArgumentNullException(nameof(compiler));
}
if (target == null)
{
throw new ArgumentNullException(nameof(target));
}
var expression = compiler.Build(target, context);
return(compiler.BuildObjectFactoryLambda(expression, context));
}
/// <summary>
/// Creates a new compilation context, registers the target's <see cref="DecoratorTarget.DecoratedTarget"/>
/// into it as the correct target for the <see cref="DecoratorTarget.DecoratedType"/>, and then builds the
/// expression for the <see cref="DecoratorTarget.InnerTarget"/> (which is typically a constructor target).
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />. Note that unlike on the interface, where this
/// parameter is optional, this will always be provided</param>
protected override Expression Build(DecoratorTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
// need a new context for this, into which we can override the registration of the decorated type
// to be the decorated target so that the decorator target will resolve that.
// there's a potential hole here in that if another container resolves this same decorator after it
// has been compiled, it might end up decorating itself - might need a test scenario for that.
var newContext = context.NewContext();
// add the decorated target into the compile context under the type which the enclosing decorator
// was registered against. If the inner target is bound to a type which correctly implements the decorator
// pattern over the common decorated type, then the decorated instance should be resolved when constructor
// arguments are resolved.
newContext.Register(target.DecoratedTarget, target.DecoratedType);
// TODO: Do the same target anchoring that SingletonTargetBuilder is doing.
return(compiler.Build(target.InnerTarget, newContext));
}
/// <summary>
/// Builds an expression which either represents creating an array or a list of objects using an
/// enumerable of targets from the <paramref name="target"/>'s <see cref="ListTarget.Items"/>.
///
/// The target's <see cref="ListTarget.AsArray"/> flag is used to determine which expression to build.
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />. Note that unlike on the interface, where this
/// parameter is optional, this will always be provided</param>
protected override Expression Build(ListTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
var items = new List <Expression>();
foreach (var itemTarget in target.Items)
{
items.Add(compiler.Build(itemTarget, context.NewContext(target.ElementType)));
}
var arrayExpr = Expression.NewArrayInit(target.ElementType, items);
if (target.AsArray)
{
return(arrayExpr);
}
else
{
return(Expression.New(target.ListConstructor, arrayExpr));
}
}
private Expression GenerateListBindingExpression(Expression targetObj, ListMemberBinding listBinding, IExpressionCompileContext context, IExpressionCompiler compiler)
{
var method = AddToCollection_Method.MakeGenericMethod(listBinding.ElementType);
var enumType = typeof(IEnumerable <>).MakeGenericType(listBinding.ElementType);
var enumerable = compiler.Build(listBinding.Target, context.NewContext(enumType));
var enumLocal = Expression.Parameter(enumType, "enumerable");
var enumAssign = Expression.Assign(enumLocal, enumerable);
var addDelegateParam = Expression.Parameter(listBinding.ElementType, "item");
var callAddToCollection = Expression.Call(null,
method,
Expression.Lambda(
Expression.Call(
listBinding.Member is PropertyInfo prop ? Expression.Property(targetObj, prop) : Expression.Field(targetObj, (FieldInfo)listBinding.Member),
listBinding.AddMethod,
addDelegateParam),
addDelegateParam),
enumLocal);
return(Expression.Block(new[] { enumLocal, addDelegateParam },
enumAssign,
callAddToCollection));
}
/// <summary>
/// Obtains the bound target for the <paramref name="target"/> passed (by calling
/// <see cref="GenericConstructorTarget.Bind(ICompileContext)"/>, and passes it to the
/// <paramref name="compiler"/> to have an expression built for it.
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />. Note that unlike on the interface, where this
/// parameter is optional, this will always be provided</param>
protected override Expression Build(GenericConstructorTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
// simply bind the generic target to the context, obtain the target that is produced
// and then build it.
return(compiler.Build(target.Bind(context), context));
}
/// <summary>
/// Builds an expression for the given <paramref name="target"/>.
/// </summary>
/// <param name="target">The target whose expression is to be built.</param>
/// <param name="context">The compilation context.</param>
/// <param name="compiler">The expression compiler to be used to build any other expressions for targets
/// which might be required by the <paramref name="target" />. Note that unlike on the interface, where this
/// parameter is optional, this will always be provided</param>
protected override Expression Build(UnscopedTarget target, IExpressionCompileContext context, IExpressionCompiler compiler)
{
// force scoping off for the inner target
return(compiler.Build(target.Inner, context.NewContext(scopeBehaviourOverride: ScopeBehaviour.None)));
}
