Add ZipMap

MoreLinq.Test/ZipMapTest.cs

@@ -0,0 +1,55 @@
+#region License and Terms
+// MoreLINQ - Extensions to LINQ to Objects
+// Copyright (c) 2008 Jonathan Skeet. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#endregion
+
+namespace MoreLinq.Test
+{
+    using System.Text.RegularExpressions;
+    using NUnit.Framework;
+
+    [TestFixture]
+    public class ZipMapTest
+    {
+        [Test]
+        public void ZipMapIsLazy()
+        {
+            new BreakingSequence<object>().ZipMap(o => o);
+        }
+
+        [Test]
+        public void ZipMapEmptySequence()
+        {
+            object[] objects = {};
+            var result = objects.ZipMap(o => o);
+            result.AssertSequenceEqual();
+        }
+
+        [Test]
+        public void ZipMapStrings()
+        {
+            string[] strings = { "foo", "bar", "baz" };
+            var result = strings.ZipMap(s => Regex.IsMatch(s, @"^b"));
+            result.AssertSequenceEqual(("foo", false), ("bar", true), ("baz", true));
+        }
+
+        [Test]
+        public void ZipMapFromSequence()
+        {
+            var result = MoreEnumerable.Sequence(5, 8).ZipMap(i => i % 2 == 0);
+            result.AssertSequenceEqual((5, false), (6, true), (7, false), (8, true));
+        }
+    }
+}

MoreLinq/Extensions.g.cs

@@ -6844,6 +6844,41 @@ public static IEnumerable<TResult> ZipLongest<T1, T2, T3, T4, TResult>(
 
     }
 
+    /// <summary><c>ZipMap</c> extension.</summary>
+
+    [GeneratedCode("MoreLinq.ExtensionsGenerator", "1.0.0.0")]
+    public static partial class ZipMapExtension
+    {
+        /// <summary>
+        /// Applies a function on each element and returns a sequence of
+        /// tuples with the source element and the result from the function.
+        /// </summary>
+        /// <typeparam name="TSource">The type of the elements of <paramref name="source"/>.</typeparam>
+        /// <typeparam name="TResult">The type of the elements returned by <paramref name="func"/>.</typeparam>
+        /// <param name="source">The sequence to iterate over.</param>
+        /// <param name="func">The function to apply on each element.</param>
+        /// <returns>
+        /// Returns a sequence of tuples with the source element and the
+        /// result from <paramref name="func"/> parameter.
+        /// </returns>
+        /// <remarks>
+        /// This operator uses deferred execution and streams its results.
+        /// </remarks>
+        /// <example>
+        /// <code><![CDATA[
+        /// string[] strings = { "foo", "bar", "baz" };
+        /// var result = strings.ZipMap(s => Regex.IsMatch(s, @"^b"));
+        /// ]]></code>
+        /// The <c>result</c> variable, when iterated over, will yield
+        /// ("foo", false"), ("bar", true) and ("baz", true), in turn.
+        /// </example>
+
+        public static IEnumerable<(TSource Item, TResult Result)> ZipMap<TSource, TResult>(
+            this IEnumerable<TSource> source, Func<TSource, TResult> func)
+            => MoreEnumerable.ZipMap(source, func);
+
+    }
+
     /// <summary><c>ZipShortest</c> extension.</summary>
 
     [GeneratedCode("MoreLinq.ExtensionsGenerator", "1.0.0.0")]

MoreLinq/MoreLinq.csproj

@@ -111,6 +111,7 @@
         - WindowLeft
         - WindowRight
         - ZipLongest
+        - ZipMap
         - ZipShortest
     </Description>
     <Description>$([System.Text.RegularExpressions.Regex]::Replace($(Description), `\s+`, ` `).Trim().Replace(` - `, `, `).Replace(`:,`, `:`))</Description>

MoreLinq/ZipMap.cs

@@ -0,0 +1,61 @@
+#region License and Terms
+// MoreLINQ - Extensions to LINQ to Objects
+// Copyright (c) 2008 Jonathan Skeet. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#endregion
+
+namespace MoreLinq
+{
+    using System;
+    using System.Collections.Generic;
+
+    static partial class MoreEnumerable
+    {
+        /// <summary>
+        /// Applies a function on each element and returns a sequence of
+        /// tuples with the source element and the result from the function.
+        /// </summary>
+        /// <typeparam name="TSource">The type of the elements of <paramref name="source"/>.</typeparam>
+        /// <typeparam name="TResult">The type of the elements returned by <paramref name="func"/>.</typeparam>
+        /// <param name="source">The sequence to iterate over.</param>
+        /// <param name="func">The function to apply on each element.</param>
+        /// <returns>
+        /// Returns a sequence of tuples with the source element and the
+        /// result from <paramref name="func"/> parameter.
+        /// </returns>
+        /// <remarks>
+        /// This operator uses deferred execution and streams its results.
+        /// </remarks>
+        /// <example>
+        /// <code><![CDATA[
+        /// string[] strings = { "foo", "bar", "baz" };
+        /// var result = strings.ZipMap(s => Regex.IsMatch(s, @"^b"));
+        /// ]]></code>
+        /// The <c>result</c> variable, when iterated over, will yield
+        /// ("foo", false"), ("bar", true) and ("baz", true), in turn.
+        /// </example>
+
+        public static IEnumerable<(TSource Item, TResult Result)> ZipMap<TSource, TResult>(
+            this IEnumerable<TSource> source, Func<TSource, TResult> func)
+        {
+            if (source == null) throw new ArgumentNullException(nameof(source));
+            if (func == null) throw new ArgumentNullException(nameof(func));
+
+            foreach (var item in source)
+            {
+                yield return (item, func(item));
+            }
+        }
+    }
+}

README.md

@@ -717,6 +717,11 @@ for padding.
 
 This method has 3 overloads.
 
+### ZipMap
+
+Returns a sequence of tuples containing the source elements and the result of
+a function applied on each element.
+
 ### ZipShortest
 
 Returns a projection of tuples, where each tuple contains the N-th