public static bool IsTypeMatcher(this Type type, out Type typeMatcherType)
{
if (type.IsTypeMatcher())
{
var attr = (TypeMatcherAttribute)Attribute.GetCustomAttribute(type, typeof(TypeMatcherAttribute));
typeMatcherType = attr.Type ?? type;
Guard.ImplementsTypeMatcherProtocol(typeMatcherType);
return(true);
}
else
{
typeMatcherType = null;
return(false);
}
}
/// <summary>
/// Splits an expression such as `<c>m => m.A.B(x).C[y] = z</c>` into a chain of parts
/// that can be set up one at a time:
/// <list>
/// <item>`<c>m => m.A</c>`</item>,
/// <item>`<c>... => ....B(x)</c>`</item>,
/// <item>`<c>... => ....C</c>`</item>,
/// <item>`<c>... => ...[y] = z</c>`</item>.
/// </list>
/// <para>
/// The split points are chosen such that each part has exactly one associated
/// <see cref="MethodInfo"/> and optionally some argument expressions.
/// </para>
/// </summary>
/// <exception cref="ArgumentException">
/// It was not possible to completely split up the expression.
/// </exception>
internal static Stack <InvocationShape> Split(this LambdaExpression expression)
{
Debug.Assert(expression != null);
var parts = new Stack <InvocationShape>();
Expression remainder = expression.Body;
while (CanSplit(remainder))
{
Split(remainder, out remainder, out var part);
parts.Push(part);
}
if (parts.Count > 0 && remainder is ParameterExpression)
{
return(parts);
}
else
{
throw new ArgumentException(
string.Format(
CultureInfo.CurrentCulture,
Resources.UnsupportedExpression,
remainder.ToStringFixed()));
}
bool CanSplit(Expression e)
{
switch (e.NodeType)
{
case ExpressionType.Assign:
case ExpressionType.AddAssign:
case ExpressionType.SubtractAssign:
{
var assignmentExpression = (BinaryExpression)e;
return(CanSplit(assignmentExpression.Left));
}
case ExpressionType.Call:
case ExpressionType.Index:
{
return(true);
}
case ExpressionType.Invoke:
{
var invocationExpression = (InvocationExpression)e;
return(typeof(Delegate).IsAssignableFrom(invocationExpression.Expression.Type));
}
case ExpressionType.MemberAccess:
{
var memberAccessExpression = (MemberExpression)e;
return(memberAccessExpression.Member is PropertyInfo);
}
case ExpressionType.Parameter:
default:
{
return(false);
}
}
}
void Split(Expression e, out Expression r /* remainder */, out InvocationShape p /* part */)
{
const string ParameterName = "...";
switch (e.NodeType)
{
case ExpressionType.Assign: // assignment to a property or indexer
case ExpressionType.AddAssign: // subscription of event handler to event
case ExpressionType.SubtractAssign: // unsubscription of event handler from event
{
var assignmentExpression = (BinaryExpression)e;
Split(assignmentExpression.Left, out r, out var lhs);
PropertyInfo property;
if (lhs.Expression.Body is MemberExpression me)
{
Debug.Assert(me.Member is PropertyInfo);
property = (PropertyInfo)me.Member;
}
else
{
Debug.Assert(lhs.Expression.Body is IndexExpression);
property = ((IndexExpression)lhs.Expression.Body).Indexer;
}
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var arguments = new Expression[lhs.Arguments.Count + 1];
for (var ai = 0; ai < arguments.Length - 1; ++ai)
{
arguments[ai] = lhs.Arguments[ai];
}
arguments[arguments.Length - 1] = assignmentExpression.Right;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.MakeBinary(e.NodeType, lhs.Expression.Body, assignmentExpression.Right),
parameter),
method: property.GetSetMethod(true),
arguments);
return;
}
case ExpressionType.Call: // regular method call
{
var methodCallExpression = (MethodCallExpression)e;
if (methodCallExpression.Method.IsGenericMethod)
{
foreach (var typeArgument in methodCallExpression.Method.GetGenericArguments())
{
if (typeArgument.IsTypeMatcher(out var typeMatcherType))
{
Guard.ImplementsTypeMatcherProtocol(typeMatcherType);
}
}
}
if (!methodCallExpression.Method.IsStatic)
{
r = methodCallExpression.Object;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var method = methodCallExpression.Method;
var arguments = methodCallExpression.Arguments;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.Call(parameter, method, arguments),
parameter),
method,
arguments);
}
else
{
Debug.Assert(methodCallExpression.Method.IsExtensionMethod());
Debug.Assert(methodCallExpression.Arguments.Count > 0);
r = methodCallExpression.Arguments[0];
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var method = methodCallExpression.Method;
var arguments = methodCallExpression.Arguments.ToArray();
arguments[0] = parameter;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.Call(method, arguments),
parameter),
method,
arguments);
}
return;
}
case ExpressionType.Index: // indexer query
{
var indexExpression = (IndexExpression)e;
r = indexExpression.Object;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var indexer = indexExpression.Indexer;
var arguments = indexExpression.Arguments;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.MakeIndex(parameter, indexer, arguments),
parameter),
method: indexer.GetGetMethod(true),
arguments);
return;
}
case ExpressionType.Invoke: // delegate invocation
{
var invocationExpression = (InvocationExpression)e;
Debug.Assert(invocationExpression.Expression.Type.IsDelegateType());
r = invocationExpression.Expression;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var arguments = invocationExpression.Arguments;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.Invoke(parameter, arguments),
parameter),
method: r.Type.GetMethod("Invoke", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance),
arguments);
return;
}
case ExpressionType.MemberAccess: // property query
{
var memberAccessExpression = (MemberExpression)e;
Debug.Assert(memberAccessExpression.Member is PropertyInfo);
r = memberAccessExpression.Expression;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var property = memberAccessExpression.GetReboundProperty();
var method = property.CanRead(out var getter) ? getter : property.GetSetMethod(true);
// ^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^
// We're in the switch case block for property read access, therefore we prefer the
// getter. When a read-write property is being assigned to, we end up here, too, and
// select the wrong accessor. However, that doesn't matter because it will be over-
// ridden in the above `Assign` case. Finally, if a write-only property is being
// assigned to, we fall back to the setter here in order to not end up without a
// method at all.
p = new InvocationShape(
expression: Expression.Lambda(
Expression.MakeMemberAccess(parameter, property),
parameter),
method);
return;
}
default:
Debug.Assert(!CanSplit(e));
throw new InvalidOperationException(); // this should be unreachable
}
}
}
/// <summary>
/// Splits an expression such as `<c>m => m.A.B(x).C[y] = z</c>` into a chain of parts
/// that can be set up one at a time:
/// <list>
/// <item>`<c>m => m.A</c>`</item>,
/// <item>`<c>... => ....B(x)</c>`</item>,
/// <item>`<c>... => ....C</c>`</item>,
/// <item>`<c>... => ...[y] = z</c>`</item>.
/// </list>
/// <para>
/// The split points are chosen such that each part has exactly one associated
/// <see cref="MethodInfo"/> and optionally some argument expressions.
/// </para>
/// </summary>
/// <exception cref="ArgumentException">
/// It was not possible to completely split up the expression.
/// </exception>
internal static Stack <InvocationShape> Split(this LambdaExpression expression, bool allowNonOverridableLastProperty = false)
{
Debug.Assert(expression != null);
var parts = new Stack <InvocationShape>();
Expression remainder = expression.Body;
while (CanSplit(remainder))
{
Split(remainder, out remainder, out var part, allowNonOverridableLastProperty: allowNonOverridableLastProperty && parts.Count == 0);
parts.Push(part);
}
if (parts.Count > 0 && remainder is ParameterExpression)
{
return(parts);
}
else
{
throw new ArgumentException(
string.Format(
CultureInfo.CurrentCulture,
Resources.UnsupportedExpression,
remainder.ToStringFixed()));
}
void Split(Expression e, out Expression r /* remainder */, out InvocationShape p /* part */, bool assignment = false, bool allowNonOverridableLastProperty = false)
{
const string ParameterName = "...";
switch (e.NodeType)
{
case ExpressionType.Assign: // assignment to a property or indexer
case ExpressionType.AddAssign: // subscription of event handler to event
case ExpressionType.SubtractAssign: // unsubscription of event handler from event
{
var assignmentExpression = (BinaryExpression)e;
Split(assignmentExpression.Left, out r, out var lhs, assignment: true);
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var arguments = new Expression[lhs.Method.GetParameters().Length];
for (var ai = 0; ai < arguments.Length - 1; ++ai)
{
arguments[ai] = lhs.Arguments[ai];
}
arguments[arguments.Length - 1] = assignmentExpression.Right;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.MakeBinary(e.NodeType, lhs.Expression.Body, assignmentExpression.Right),
parameter),
method: lhs.Method,
arguments);
return;
}
case ExpressionType.Call: // regular method call
{
var methodCallExpression = (MethodCallExpression)e;
if (methodCallExpression.Method.IsGenericMethod)
{
foreach (var typeArgument in methodCallExpression.Method.GetGenericArguments())
{
if (typeArgument.IsTypeMatcher(out var typeMatcherType))
{
Guard.ImplementsTypeMatcherProtocol(typeMatcherType);
}
}
}
if (!methodCallExpression.Method.IsStatic)
{
r = methodCallExpression.Object;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var method = methodCallExpression.Method;
var arguments = methodCallExpression.Arguments;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.Call(parameter, method, arguments),
parameter),
method,
arguments);
}
else
{
Debug.Assert(methodCallExpression.Method.IsExtensionMethod());
Debug.Assert(methodCallExpression.Arguments.Count > 0);
r = methodCallExpression.Arguments[0];
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var method = methodCallExpression.Method;
var arguments = methodCallExpression.Arguments.ToArray();
arguments[0] = parameter;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.Call(method, arguments),
parameter),
method,
arguments);
}
return;
}
case ExpressionType.Index: // indexer query
{
var indexExpression = (IndexExpression)e;
r = indexExpression.Object;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var indexer = indexExpression.Indexer;
var arguments = indexExpression.Arguments;
var method = !assignment && indexer.CanRead(out var getter) ? getter
: indexer.CanWrite(out var setter) ? setter
: null;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.MakeIndex(parameter, indexer, arguments),
parameter),
method,
arguments,
skipMatcherInitialization: assignment,
allowNonOverridable: allowNonOverridableLastProperty);
return;
}
case ExpressionType.Invoke: // delegate invocation
{
var invocationExpression = (InvocationExpression)e;
Debug.Assert(invocationExpression.Expression.Type.IsDelegateType());
r = invocationExpression.Expression;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var arguments = invocationExpression.Arguments;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.Invoke(parameter, arguments),
parameter),
method: r.Type.GetMethod("Invoke", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance),
arguments);
return;
}
case ExpressionType.MemberAccess: // property query
{
var memberAccessExpression = (MemberExpression)e;
Debug.Assert(memberAccessExpression.Member is PropertyInfo);
r = memberAccessExpression.Expression;
var parameter = Expression.Parameter(r.Type, r is ParameterExpression ope ? ope.Name : ParameterName);
var property = memberAccessExpression.GetReboundProperty();
var method = !assignment && property.CanRead(out var getter) ? getter
: property.CanWrite(out var setter) ? setter
: null;
p = new InvocationShape(
expression: Expression.Lambda(
Expression.MakeMemberAccess(parameter, property),
parameter),
method,
skipMatcherInitialization: assignment,
allowNonOverridable: allowNonOverridableLastProperty);
return;
}
default:
Debug.Assert(!CanSplit(e));
throw new InvalidOperationException(); // this should be unreachable
}
}
}
