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using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Web.Mvc.ExpressionUtil;
using System.Web.Mvc.Properties;
namespace System.Web.Mvc
{
public static class ExpressionHelper
{
public static string GetExpressionText(string expression)
{
return
String.Equals(expression, "model", StringComparison.OrdinalIgnoreCase)
? String.Empty // If it's exactly "model", then give them an empty string, to replicate the lambda behavior
: expression;
}
public static string GetExpressionText(LambdaExpression expression)
{
// Split apart the expression string for property/field accessors to create its name
Stack<string> nameParts = new Stack<string>();
Expression part = expression.Body;
while (part != null)
{
if (part.NodeType == ExpressionType.Call)
{
MethodCallExpression methodExpression = (MethodCallExpression)part;
if (!IsSingleArgumentIndexer(methodExpression))
{
break;
}
nameParts.Push(
GetIndexerInvocation(
methodExpression.Arguments.Single(),
expression.Parameters.ToArray()));
part = methodExpression.Object;
}
else if (part.NodeType == ExpressionType.ArrayIndex)
{
BinaryExpression binaryExpression = (BinaryExpression)part;
nameParts.Push(
GetIndexerInvocation(
binaryExpression.Right,
expression.Parameters.ToArray()));
part = binaryExpression.Left;
}
else if (part.NodeType == ExpressionType.MemberAccess)
{
MemberExpression memberExpressionPart = (MemberExpression)part;
nameParts.Push("." + memberExpressionPart.Member.Name);
part = memberExpressionPart.Expression;
}
else if (part.NodeType == ExpressionType.Parameter)
{
// Dev10 Bug #907611
// When the expression is parameter based (m => m.Something...), we'll push an empty
// string onto the stack and stop evaluating. The extra empty string makes sure that
// we don't accidentally cut off too much of m => m.Model.
nameParts.Push(String.Empty);
part = null;
}
else
{
break;
}
}
// If it starts with "model", then strip that away
if (nameParts.Count > 0 && String.Equals(nameParts.Peek(), ".model", StringComparison.OrdinalIgnoreCase))
{
nameParts.Pop();
}
if (nameParts.Count > 0)
{
return nameParts.Aggregate((left, right) => left + right).TrimStart('.');
}
return String.Empty;
}
private static string GetIndexerInvocation(Expression expression, ParameterExpression[] parameters)
{
Expression converted = Expression.Convert(expression, typeof(object));
ParameterExpression fakeParameter = Expression.Parameter(typeof(object), null);
Expression<Func<object, object>> lambda = Expression.Lambda<Func<object, object>>(converted, fakeParameter);
Func<object, object> func;
try
{
func = CachedExpressionCompiler.Process(lambda);
}
catch (InvalidOperationException ex)
{
throw new InvalidOperationException(
String.Format(
CultureInfo.CurrentCulture,
MvcResources.ExpressionHelper_InvalidIndexerExpression,
expression,
parameters[0].Name),
ex);
}
return "[" + Convert.ToString(func(null), CultureInfo.InvariantCulture) + "]";
}
internal static bool IsSingleArgumentIndexer(Expression expression)
{
MethodCallExpression methodExpression = expression as MethodCallExpression;
if (methodExpression == null || methodExpression.Arguments.Count != 1)
{
return false;
}
return methodExpression.Method
.DeclaringType
.GetDefaultMembers()
.OfType<PropertyInfo>()
.Any(p => p.GetGetMethod() == methodExpression.Method);
}
}
}
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