/// <summary>
/// Translates a given predicate for a given subtype.
/// </summary>
/// <typeparam name="TTranslatedSource">The type of the translated predicate's parameter.</typeparam>
/// <returns>A translated predicate expression.</returns>
public Expression <Func <TTranslatedSource, bool> > To <TTranslatedSource>()
where TTranslatedSource : TSource
{
var s = predicate.Parameters[0];
var t = Expression.Parameter(typeof(TTranslatedSource), s.Name);
var binder = new ParameterBinder(s, t);
return(Expression.Lambda <Func <TTranslatedSource, bool> >(
binder.Visit(predicate.Body), t));
}
/// <summary>
/// Translates a given selector for a given subtype using it's source parameter.
/// </summary>
/// <typeparam name="V">The type of the translated selector's source parameter.</typeparam>
/// <returns>A translated selector expression.</returns>
public Expression <Func <V, U> > Source <V>()
where V : T
{
var t = selector.Parameters[0];
var v = Expression.Parameter(typeof(V), t.Name);
var binder = new ParameterBinder(t, v);
return(Expression.Lambda <Func <V, U> >(
binder.Visit(selector.Body), v));
}
/// <summary>
/// Translates a given selector for a given subtype using it's source parameter.
/// </summary>
/// <typeparam name="TTranslatedSource">The type of the translated selector's source parameter.</typeparam>
/// <returns>A translated selector expression.</returns>
public Expression <Func <TTranslatedSource, TResult> > Source <TTranslatedSource>()
where TTranslatedSource : TSource
{
var s = selector.Parameters[0];
var t = Expression.Parameter(typeof(TTranslatedSource), s.Name);
var binder = new ParameterBinder(s, t);
return(Expression.Lambda <Func <TTranslatedSource, TResult> >(
binder.Visit(selector.Body), t));
}
/// <summary>
/// Translates a given predicate for a given subtype.
/// </summary>
/// <typeparam name="U">The type of the translated predicate's parameter.</typeparam>
/// <returns>A translated predicate expression.</returns>
public Expression <Func <U, bool> > To <U>()
where U : T
{
var t = predicate.Parameters[0];
var u = Expression.Parameter(typeof(U), t.Name);
var binder = new ParameterBinder(t, u);
return(Expression.Lambda <Func <U, bool> >(
binder.Visit(predicate.Body), u));
}
/// <summary>
/// Translates a given predicate for a given related type.
/// </summary>
/// <typeparam name="TTranslatedSource">The type of the translated predicate's parameter.</typeparam>
/// <param name="translation">The translation from the desired type to the given type,
/// using the initially given predicate to be injected into a new predicate.</param>
/// <returns>A translated predicate expression.</returns>
public Expression <Func <TTranslatedSource, bool> > To <TTranslatedSource>(Expression <Func <TTranslatedSource, Func <TSource, bool>, bool> > translation)
{
if (translation == null)
{
throw new ArgumentNullException(nameof(translation));
}
var t = translation.Parameters[0];
var s = translation.Parameters[1];
var binder = new ParameterBinder(s, predicate);
return(Expression.Lambda <Func <TTranslatedSource, bool> >(
binder.Visit(translation.Body), t));
}
/// <summary>
/// Translates a given selector for a given related type using it's source parameter.
/// </summary>
/// <typeparam name="V">The type of the translated selector's source parameter.</typeparam>
/// <param name="translation">The translation from the desired type to the given type,
/// using the initially given selector to be injected into a new selector.</param>
/// <returns>A translated selector expression.</returns>
public Expression <Func <V, U> > Source <V>(Expression <Func <V, Func <T, U>, U> > translation)
{
if (translation == null)
{
throw new ArgumentNullException(nameof(translation));
}
var v = translation.Parameters[0];
var s = translation.Parameters[1];
var binder = new ParameterBinder(s, selector);
return(Expression.Lambda <Func <V, U> >(
binder.Visit(translation.Body), v));
}
/// <summary>
/// Translates a given selector for a given related type using it's source parameter.
/// </summary>
/// <typeparam name="V">The type of the translated selector's source parameter.</typeparam>
/// <param name="path">The path from the desired type to the given type.</param>
/// <returns>A translated selector expression.</returns>
public Expression <Func <V, U> > Source <V>(Expression <Func <V, T> > path)
{
if (path == null)
{
throw new ArgumentNullException(nameof(path));
}
var t = selector.Parameters[0];
var v = path.Parameters[0];
var binder = new ParameterBinder(t, path.Body);
return(Expression.Lambda <Func <V, U> >(
binder.Visit(selector.Body), v));
}
/// <summary>
/// Translates a given predicate for a given related type.
/// </summary>
/// <typeparam name="U">The type of the translated predicate's parameter.</typeparam>
/// <param name="path">The path from the desired type to the given type.</param>
/// <returns>A translated predicate expression.</returns>
public Expression <Func <U, bool> > To <U>(Expression <Func <U, T> > path)
{
if (path == null)
{
throw new ArgumentNullException(nameof(path));
}
var t = predicate.Parameters[0];
var u = path.Parameters[0];
var binder = new ParameterBinder(t, path.Body);
return(Expression.Lambda <Func <U, bool> >(
binder.Visit(predicate.Body), u));
}
/// <summary>
/// Translates a given selector for a given related type using it's source parameter.
/// </summary>
/// <typeparam name="TTranslatedSource">The type of the translated selector's source parameter.</typeparam>
/// <param name="translation">The translation from the desired type to the given type,
/// using the initially given selector to be injected into a new selector.</param>
/// <returns>A translated selector expression.</returns>
public Expression <Func <TTranslatedSource, IEnumerable <TResult> > > Source <TTranslatedSource>(Expression <Func <TTranslatedSource, Func <TSource, TResult>, IEnumerable <TResult> > > translation)
{
if (translation == null)
{
throw new ArgumentNullException(nameof(translation));
}
var t = translation.Parameters[0];
var s = translation.Parameters[1];
var binder = new ParameterBinder(s, selector);
return(Expression.Lambda <Func <TTranslatedSource, IEnumerable <TResult> > >(
binder.Visit(translation.Body), t));
}
/// <summary>
/// Translates a given selector for a given related type using it's source parameter.
/// </summary>
/// <typeparam name="TTranslatedSource">The type of the translated selector's source parameter.</typeparam>
/// <param name="path">The path from the desired type to the given type.</param>
/// <returns>A translated selector expression.</returns>
public Expression <Func <TTranslatedSource, TResult> > Source <TTranslatedSource>(Expression <Func <TTranslatedSource, TSource> > path)
{
if (path == null)
{
throw new ArgumentNullException(nameof(path));
}
var s = selector.Parameters[0];
var t = path.Parameters[0];
var binder = new ParameterBinder(s, path.Body);
return(Expression.Lambda <Func <TTranslatedSource, TResult> >(
binder.Visit(selector.Body), t));
}
/// <summary>
/// Translates a given selector for a given related type using it's result parameter.
/// </summary>
/// <typeparam name="TTranslatedResult">The type of the translated selector's result parameter.</typeparam>
/// <param name="translation">The translation from the desired type to the given type,
/// using the initially given selector to be injected into a new selector.</param>
/// <returns>A translated selector expression.</returns>
public Expression <Func <TSource, TTranslatedResult> > Result <TTranslatedResult>(Expression <Func <TSource, Func <TSource, TResult>, TTranslatedResult> > translation)
{
if (translation is null)
{
throw new ArgumentNullException(nameof(translation));
}
var s = translation.Parameters[0];
var t = translation.Parameters[1];
var binder = new ParameterBinder(t, selector);
return(Expression.Lambda <Func <TSource, TTranslatedResult> >(
binder.Visit(translation.Body), s));
}
/// <summary>
/// Translates a given predicate for a given related type.
/// </summary>
/// <typeparam name="U">The type of the translated predicate's parameter.</typeparam>
/// <param name="translation">The translation from the desired type to the given type,
/// using the initially given predicate to be injected into a new predicate.</param>
/// <returns>A translated predicate expression.</returns>
public Expression <Func <U, bool> > To <U>(Expression <Func <U, Func <T, bool>, bool> > translation)
{
if (translation == null)
{
throw new ArgumentNullException(nameof(translation));
}
var u = translation.Parameters[0];
var p = translation.Parameters[1];
var binder = new ParameterBinder(p, predicate);
return(Expression.Lambda <Func <U, bool> >(
binder.Visit(translation.Body), u));
}
/// <summary>
/// Translates a given predicate for a given related type.
/// </summary>
/// <typeparam name="TTranslatedSource">The type of the translated predicate's parameter.</typeparam>
/// <param name="path">The path from the desired type to the given type.</param>
/// <returns>A translated predicate expression.</returns>
public Expression <Func <TTranslatedSource, bool> > To <TTranslatedSource>(Expression <Func <TTranslatedSource, TSource> > path)
{
if (path == null)
{
throw new ArgumentNullException(nameof(path));
}
var s = predicate.Parameters[0];
var t = path.Parameters[0];
var binder = new ParameterBinder(s, path.Body);
return(Expression.Lambda <Func <TTranslatedSource, bool> >(
binder.Visit(predicate.Body), t));
}
/// <summary>
/// Translates a given selector for a given related type using it's source and result parameter
/// and combines it with another given selector by merging their member bindings.
/// </summary>
/// <typeparam name="TTranslatedSource">The type of the translated selector's source parameter.</typeparam>
/// <typeparam name="TTranslatedResult">The type of the translated selector's result parameter.</typeparam>
/// <param name="translation">The translation from the desired type to the given type,
/// using the initially given selector to be injected into a new selector.</param>
/// <param name="value">The additional selector expression to combine.</param>
/// <returns>A single translated and combined selector expression.</returns>
public Expression <Func <TTranslatedSource, TTranslatedResult> > To <TTranslatedSource, TTranslatedResult>(Expression <Func <TTranslatedSource, Func <TSource, TResult>, TTranslatedResult> > translation, Expression <Func <TTranslatedSource, TTranslatedResult> > value = null)
{
if (translation == null)
{
throw new ArgumentNullException(nameof(translation));
}
var s = translation.Parameters[0];
var t = translation.Parameters[1];
var binder = new ParameterBinder(t, selector);
var result = Expression.Lambda <Func <TTranslatedSource, TTranslatedResult> >(
binder.Visit(translation.Body), s);
return(value != null?result.Apply(value) : result);
}
/// <summary>
/// Translates a given selector for a given related type using it's source and result parameter
/// and combines it with another given selector by merging their member bindings.
/// </summary>
/// <typeparam name="V">The type of the translated selector's source parameter.</typeparam>
/// <typeparam name="W">The type of the translated selector's result parameter.</typeparam>
/// <param name="translation">The translation from the desired type to the given type,
/// using the initially given selector to be injected into a new selector.</param>
/// <param name="value">The additional selector expression to combine.</param>
/// <returns>A single translated and combined selector expression.</returns>
public Expression <Func <V, W> > To <V, W>(Expression <Func <V, Func <T, U>, W> > translation, Expression <Func <V, W> > value = null)
{
if (translation == null)
{
throw new ArgumentNullException(nameof(translation));
}
var v = translation.Parameters[0];
var s = translation.Parameters[1];
var binder = new ParameterBinder(s, selector);
var result = Expression.Lambda <Func <V, W> >(
binder.Visit(translation.Body), v);
return(value != null?result.Apply(value) : result);
}
/// <summary>
/// Combines two given predicates using a conditional OR operation.
/// </summary>
/// <typeparam name="TSource">The type of the predicate's parameter.</typeparam>
/// <param name="left">The first predicate expression to combine.</param>
/// <param name="right">The second predicate expression to combine.</param>
/// <returns>A single combined predicate expression.</returns>
public static Expression <Func <TSource, bool> > Or <TSource>(this Expression <Func <TSource, bool> > left, Expression <Func <TSource, bool> > right)
{
if (left == null)
{
throw new ArgumentNullException(nameof(left));
}
if (right == null)
{
throw new ArgumentNullException(nameof(right));
}
var l = left.Parameters[0];
var r = right.Parameters[0];
var binder = new ParameterBinder(l, r);
return(Expression.Lambda <Func <TSource, bool> >(
Expression.OrElse(binder.Visit(left.Body), right.Body), r));
}
/// <summary>
/// Combines two given selectors by merging their member bindings.
/// </summary>
/// <typeparam name="TSource">The type of the selector's source parameter.</typeparam>
/// <typeparam name="TResult">The type of the selector's result parameter.</typeparam>
/// <param name="left">The first selector expression to combine.</param>
/// <param name="right">The second selector expression to combine.</param>
/// <returns>A single combined selector expression.</returns>
public static Expression <Func <TSource, TResult> > Apply <TSource, TResult>(this Expression <Func <TSource, TResult> > left, Expression <Func <TSource, TResult> > right)
{
if (left == null)
{
throw new ArgumentNullException(nameof(left));
}
if (right == null)
{
throw new ArgumentNullException(nameof(right));
}
var leftInit = left.Body as MemberInitExpression;
var rightInit = right.Body as MemberInitExpression;
var leftNew = left.Body as NewExpression ?? leftInit?.NewExpression;
var rightNew = right.Body as NewExpression ?? rightInit?.NewExpression;
if (leftNew == null || rightNew == null)
{
throw new NotSupportedException("Only member init expressions and new expressions are supported yet.");
}
if (leftNew.Arguments.Any() || rightNew.Arguments.Any())
{
throw new NotSupportedException("Only parameterless constructors are supported yet.");
}
var leftBindings = leftInit?.Bindings ?? Enumerable.Empty <MemberBinding>();
var rightBindings = rightInit?.Bindings ?? Enumerable.Empty <MemberBinding>();
var l = left.Parameters[0];
var r = right.Parameters[0];
var binder = new ParameterBinder(l, r);
return(Expression.Lambda <Func <TSource, TResult> >(
binder.Visit(Expression.MemberInit(Expression.New(typeof(TResult)), leftBindings.Concat(rightBindings))), r));
}
