intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 57 insertions, 0 deletions

diff --git a/library/cpp/iterator/functools.h b/library/cpp/iterator/functools.h
new file mode 100644
index 0000000000..57a0d66373
--- /dev/null
+++ b/library/cpp/iterator/functools.h
@@ -0,0 +1,57 @@
+#pragma once
+
+#include "cartesian_product.h"
+#include "concatenate.h"
+#include "enumerate.h"
+#include "filtering.h"
+#include "mapped.h"
+#include "zip.h"
+
+#include <util/generic/adaptor.h>
+#include <util/generic/xrange.h>
+
+#include <tuple>
+#include <algorithm>
+
+
+namespace NFuncTools {
+    using ::Enumerate;
+    using ::Reversed;
+    using ::Zip;
+    using ::Concatenate;
+    using ::CartesianProduct;
+
+    template <typename TValue>
+    auto Range(TValue from, TValue to, TValue step) {
+        return xrange(from, to, step);
+    }
+
+    template <typename TValue>
+    auto Range(TValue from, TValue to) {
+        return xrange(from, to);
+    }
+
+    template <typename TValue>
+    auto Range(TValue to) {
+        return xrange(to);
+    }
+
+    //! Usage: for (i32 x : Map([](i32 x) { return x * x; }, a)) {...}
+    template <typename TMapper, typename TContainerOrRef>
+    auto Map(TMapper&& mapper, TContainerOrRef&& container) {
+        return ::MakeMappedRange(std::forward<TContainerOrRef>(container), std::forward<TMapper>(mapper));
+    }
+
+    //! Usage: for (auto i : Map<int>(floats)) {...}
+    template <typename TMapResult, typename TContainerOrRef>
+    auto Map(TContainerOrRef&& container) {
+        return Map([](const auto& x) { return TMapResult(x); }, std::forward<TContainerOrRef>(container));
+    }
+
+    //! Usage: for (i32 x : Filter(predicate, container)) {...}
+    template <typename TPredicate, typename TContainerOrRef>
+    auto Filter(TPredicate&& predicate, TContainerOrRef&& container) {
+        return ::MakeFilteringRange(std::forward<TContainerOrRef>(container), std::forward<TPredicate>(predicate));
+    }
+
+}