Add append and prepend methods

README.md

@@ -89,6 +89,7 @@ int DenisUniqueContactCount =
 - `skip(count)`, `skipWhile(predicate)`, `skipWhile_i(predicate)`
 - `orderBy()`, `orderBy(transform)`
 - `distinct()`, `distinct(transform)`
+- `append(items)`, `prepend(items)`
 - `concat(linq)`
 - `reverse()`
 - `cast<T>()`

include/boolinq/boolinq.h

@@ -152,6 +152,51 @@ namespace boolinq {
             return skipWhile_i([predicate](T value, int /*i*/) { return predicate(value); });
         }
 
+        template<typename SS, typename TT>
+        struct LinqValueIndex {
+            Linq<SS, TT> linq;
+            std::vector<TT> values;
+            int index;
+        };
+
+        template<typename ... Types>
+        Linq<LinqValueIndex<S, T>, T> append(Types ... newValues) const
+        {
+            return Linq<LinqValueIndex<S, T>, T>(
+                {*this, { newValues... }, -1},
+                [](LinqValueIndex<S, T> &tuple) {
+                    if (tuple.index == -1) {
+                        try {
+                            return tuple.linq.next();
+                        }
+                        catch (LinqEndException &) {
+                            tuple.index = 0;
+                        }
+                    }
+
+                    if (tuple.index < tuple.values.size()) {
+                        return tuple.values[tuple.index++];
+                    }
+
+                    throw LinqEndException();
+                }
+            );
+        }
+
+        template<typename ... Types>
+        Linq<LinqValueIndex<S, T>, T> prepend(Types ... newValues) const
+        {
+            return Linq<LinqValueIndex<S, T>, T>(
+                {*this, { newValues... }, 0},
+                [](LinqValueIndex<S, T> &tuple) {
+                    if (tuple.index < tuple.values.size()) {
+                        return tuple.values[tuple.index++];
+                    }
+                    return tuple.linq.next();
+                }
+            );
+        }
+
         template<typename F, typename _TRet = typename std::result_of<F(T, int)>::type>
         Linq<LinqIndex<S, T>, _TRet> select_i(F apply) const
         {

test/AppendTest.cpp

+#include <vector>
+#include <string>
+
+#include <gtest/gtest.h>
+#include "CommonTests.h"
+
+#include "boolinq.h"
+
+using namespace boolinq;
+
+TEST(Append, ThreePlusOne)
+{
+    std::vector<int> src = {1,2,3};
+
+    auto rng = from(src).append(4);
+    int ans[] = {1,2,3,4};
+
+    CheckRangeEqArray(rng, ans);
+}
+
+TEST(Append, ThreePlusTwo)
+{
+    std::vector<int> src = {1,2,3};
+
+    auto rng = from(src).append(4, 5);
+    int ans[] = {1,2,3,4,5};
+
+    CheckRangeEqArray(rng, ans);
+}
+
+TEST(Append, ZeroPlusTwo)
+{
+    std::vector<int> src;
+
+    auto rng = from(src).append(7,8);
+    int ans[] = {7,8};
+
+    CheckRangeEqArray(rng, ans);
+}
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test/CMakeLists.txt

@@ -23,6 +23,7 @@ SET (
     ${PROJECT_SOURCE_DIR}/test/AllTest.cpp
     ${PROJECT_SOURCE_DIR}/test/AnyTest.cpp
     ${PROJECT_SOURCE_DIR}/test/AvgTest.cpp
+    ${PROJECT_SOURCE_DIR}/test/AppendTest.cpp
     ${PROJECT_SOURCE_DIR}/test/BitsTest.cpp
     ${PROJECT_SOURCE_DIR}/test/BytesTest.cpp
     ${PROJECT_SOURCE_DIR}/test/ConcatTest.cpp
@@ -38,6 +39,7 @@ SET (
     ${PROJECT_SOURCE_DIR}/test/MaxTest.cpp
     ${PROJECT_SOURCE_DIR}/test/MinTest.cpp
     ${PROJECT_SOURCE_DIR}/test/OrderByTest.cpp
+    ${PROJECT_SOURCE_DIR}/test/PrependTest.cpp
     ${PROJECT_SOURCE_DIR}/test/ReverseTest.cpp
     ${PROJECT_SOURCE_DIR}/test/SelectTest.cpp
     ${PROJECT_SOURCE_DIR}/test/SkipTest.cpp

test/PrependTest.cpp

+#include <vector>
+#include <string>
+
+#include <gtest/gtest.h>
+#include "CommonTests.h"
+
+#include "boolinq.h"
+
+using namespace boolinq;
+
+TEST(Prepend, ThreePlusOne)
+{
+    std::vector<int> src = {1,2,3};
+
+    auto rng = from(src).prepend(4);
+    int ans[] = {4,1,2,3};
+
+    CheckRangeEqArray(rng, ans);
+}
+
+TEST(Prepend, ThreePlusTwo)
+{
+    std::vector<int> src = {1,2,3};
+
+    auto rng = from(src).prepend(4, 5);
+    int ans[] = {4,5,1,2,3};
+
+    CheckRangeEqArray(rng, ans);
+}
+
+TEST(Prepend, ZeroPlusTwo)
+{
+    std::vector<int> src;
+
+    auto rng = from(src).prepend(7,8);
+    int ans[] = {7,8};
+
+    CheckRangeEqArray(rng, ans);
+}
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