wasSharp – Rev 55
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///////////////////////////////////////////////////////////////////////////
// Copyright (C) Wizardry and Steamworks 2013 - License: GNU GPLv3 //
// Please see: http://www.gnu.org/licenses/gpl.html for legal details, //
// rights of fair usage, the disclaimer and warranty conditions. //
///////////////////////////////////////////////////////////////////////////
using System;
using System.Collections.Generic;
using System.Linq;
namespace wasSharp.Lambda
{
public static class Extensions
{
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// A functional implementation of a switch clause.
/// </summary>
/// <typeparam name="T">the type of items in the query</typeparam>
/// <param name="query">the selector query</param>
/// <param name="default">the function to execute when no case matches</param>
/// <param name="case">a list of predicates representing the switch cases,
/// where each predicate has to return True or False indicating whether
/// fallthrough should occur.
/// </param>
/// <remarks>when used, the default action must be explicitly specified
/// due to language restrictions
/// </remarks>
public static void Switch<T>(this IEnumerable<T> query,
// default
Action<T> @default,
// case
// case
// ...
params Predicate<T>[] @case)
{
if (@case.Length % 2 != 0)
throw new ArgumentException("Pairs of predicates expected.");
var enumerable = query as IList<T> ?? query.ToList();
using (var iter = enumerable.GetEnumerator())
{
while (iter.MoveNext())
{
var match = false;
for (var i = 0; i < @case.Length; i += 2)
{
if (!@case[i].Invoke(iter.Current))
continue;
if (@case[i + 1].Invoke(iter.Current))
return;
match = true;
}
if (!match)
@default.Invoke(iter.Current);
}
}
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// A functional implementation of a switch clause.
/// </summary>
/// <typeparam name="T">the type of the item to query</typeparam>
/// <param name="query">the selector query</param>
/// <param name="default">the function to execute when no case matches</param>
/// <param name="case">a list of predicates representing the switch cases,
/// where each predicate has to return True or False indicating whether
/// fallthrough should occur.
/// </param>
/// <remarks>when used, the default action must be explicitly specified
/// due to language restrictions
/// </remarks>
public static void Switch<T>(this T query,
// default
Action<T> @default,
// case
// case
// ...
params Predicate<T>[] @case)
{
if (@case.Length % 2 != 0)
throw new ArgumentException("Pairs of predicates expected.");
var match = false;
for (var i = 0; i < @case.Length; i += 2)
{
if (!@case[i].Invoke(query))
continue;
if (@case[i + 1].Invoke(query))
return;
match = true;
}
if (!match)
@default.Invoke(query);
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pf in case the predicate p resolves or qf in case the predicate q resolves, or ef otherwise.
/// </summary>
/// <typeparam name="T">the type of items in the query</typeparam>
/// <param name="query">the selector query</param>
/// <param name="p">the condition for invoking pf</param>
/// <param name="pf">the action to invoke in case p resolves</param>
/// <param name="q">the condition for invoking qf</param>
/// <param name="qf">the action to invoke in case q resolves</param>
/// <param name="ef">the action to invoke otherwise</param>
public static void ForAll<T>(this ParallelQuery<T> query, Predicate<T> p, Action<T> pf, Predicate<T> q, Action<T> qf, Action<T> ef)
{
query.ForAll(o =>
{
if (p.Invoke(o))
{
pf.Invoke(o);
}
else if (q.Invoke(o))
{
qf.Invoke(o);
}
else
{
ef.Invoke(o);
}
});
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pf in case the predicate p resolves or qf in case the predicate q resolves.
/// </summary>
/// <typeparam name="T">the type of items in the query</typeparam>
/// <param name="query">the selector query</param>
/// <param name="p">the condition for invoking pf</param>
/// <param name="pf">the action to invoke in case p resolves</param>
/// <param name="q">the condition for invoking qf</param>
/// <param name="qf">the action to invoke in case q resolves</param>
public static void ForAll<T>(this ParallelQuery<T> query, Predicate<T> p, Action<T> pf, Predicate<T> q, Action<T> qf)
{
query.ForAll(o =>
{
if (p.Invoke(o))
{
pf.Invoke(o);
return;
}
if (q.Invoke(o))
{
qf.Invoke(o);
return;
}
});
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pass if and only if predicate resovles or fail otherwise.
/// </summary>
/// <typeparam name="T">the type of items in the query</typeparam>
/// <param name="query">the selector query</param>
/// <param name="condition">the condition for invoking pf</param>
/// <param name="pass">the function to invoke in case the predicate resolves</param>
/// <param name="fail">the function to invoke otherwise</param>
public static void ForAll<T>(this ParallelQuery<T> query, Predicate<T> condition, Action<T> pass, Action<T> fail)
{
query.ForAll(o =>
{
switch (condition.Invoke(o))
{
case true:
pass.Invoke(o);
return;
default:
fail.Invoke(o);
return;
}
});
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pass if and only if condition holds or fail otherwise.
/// </summary>
/// <typeparam name="T">the return type of the pass and fail functions</typeparam>
/// <param name="condition">the branch condition</param>
/// <param name="pass">function with no parameters and return type T in case condition passes</param>
/// <param name="fail">function with no parameters and return type T in case condition fails</param>
/// <returns>the result of pass in case condition holds or the result of fail otherwise</returns>
public static V IfElse<T, V>(this T arg, Func<T, bool> condition, Func<T, V> pass, Func<T, V> fail)
{
return condition.Invoke(arg) ? pass.Invoke(arg) : fail.Invoke(arg);
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pass if and only if condition holds or fail otherwise.
/// </summary>
/// <typeparam name="T">the return type of the pass and fail functions</typeparam>
/// <param name="condition">the branch condition</param>
/// <param name="pass">function with no parameters and return type T in case condition passes</param>
/// <param name="fail">function with no parameters and return type T in case condition fails</param>
/// <returns>the result of pass in case condition holds or the result of fail otherwise</returns>
public static T IfElse<T>(this bool condition, Func<T> pass, Func<T> fail)
{
return condition ? pass.Invoke() : fail.Invoke();
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pass if and only if condition holds or fail otherwise.
/// </summary>
/// <typeparam name="U">the type of the argument to pass and fail</typeparam>
/// <typeparam name="V">the return type of pass and fail</typeparam>
/// <param name="condition">the branch condition</param>
/// <param name="pass">function that takes argument arg and returns type V in case condition holds</param>
/// <param name="fail">function that takes argument arg and returns type V in case condition fails</param>
/// <param name="arg">the argument passed to pass or fail functions</param>
/// <returns>the result of pass in case condition holds or the result of fail otherwise</returns>
public static V IfElse<U, V>(this bool condition, Func<U, V> pass, Func<U, V> fail, U arg = default(U))
{
return condition ? pass.Invoke(arg) : fail.Invoke(arg);
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pass if and only if condition holds or fail otherwise.
/// </summary>
/// <typeparam name="T">the type of the argument to pass and fail</typeparam>
/// <param name="condition">the branch condition</param>
/// <param name="pass">function that takes argument arg and returns nothing in case condition holds</param>
/// <param name="fail">function that takes argument arg and returns nothing in case condition fails</param>
/// <param name="arg">the optional argument passed to pass or fail functions</param>
public static void IfElse<T>(this bool condition, Action<T> pass, Action<T> fail, T arg = default(T))
{
switch (condition)
{
case true:
pass.Invoke(arg);
return;
default:
fail.Invoke(arg);
return;
}
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2017 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Invokes pass if and only if condition holds or fail otherwise.
/// </summary>
/// <typeparam name="U">the type of the first argument to the pass or fail functions</typeparam>
/// <typeparam name="V">the type of the second argument to the pass or fail functions</typeparam>
/// <param name="condition">the branch condition</param>
/// <param name="pass">function that takes argument arg and returns nothing in case condition holds</param>
/// <param name="fail">function that takes argument arg and returns nothing in case condition fails</param>
/// <param name="arga">first optional argument passed to pass or fail functions</param>
/// <param name="argb">second optional argument passed to pass or fail functions</param>
public static void IfElse<U, V>(this bool condition, Action<U, V> pass, Action<U, V> fail, U arga = default(U), V argb = default(V))
{
switch (condition)
{
case true:
pass.Invoke(arga, argb);
return;
default:
fail.Invoke(arga, argb);
return;
}
}
///////////////////////////////////////////////////////////////////////////
// Copyright (C) 2016 Wizardry and Steamworks - License: GNU GPLv3 //
///////////////////////////////////////////////////////////////////////////
/// <summary>
/// Returns true of an enumerable contains more than one element.
/// </summary>
/// <typeparam name="T">the type of the enumeration</typeparam>
/// <param name="e">the enumeration</param>
/// <returns>true if enumeration contains more than one element</returns>
/// <remarks>O(2) worst case</remarks>
public static bool Some<T>(this IEnumerable<T> e)
{
var i = 0;
using (var iter = e.GetEnumerator())
{
while (iter.MoveNext())
{
if (++i > 1)
return true;
}
return false;
}
}
}
}