AK: Add generic SimpleIterator class to replace VectorIterator.

Author: https://github.com/asynts
Commit: https://github.com/SerenityOS/serenity/commit/1b3ecb01a5c
Pull-request: https://github.com/SerenityOS/serenity/pull/3426

AK/FixedArray.h

@@ -26,8 +26,9 @@
 
 #pragma once
 
+#include <AK/Iterator.h>
 #include <AK/Span.h>
-#include <AK/Vector.h>
+#include <AK/kmalloc.h>
 
 namespace AK {
 
@@ -142,13 +143,14 @@ public:
         ::swap(m_size, other.m_size);
     }
 
-    using Iterator = VectorIterator<FixedArray, T>;
-    Iterator begin() { return Iterator(*this, 0); }
-    Iterator end() { return Iterator(*this, size()); }
+    using ConstIterator = SimpleIterator<const FixedArray, const T>;
+    using Iterator = SimpleIterator<FixedArray, T>;
 
-    using ConstIterator = VectorIterator<const FixedArray, const T>;
-    ConstIterator begin() const { return ConstIterator(*this, 0); }
-    ConstIterator end() const { return ConstIterator(*this, size()); }
+    ConstIterator begin() const { return ConstIterator::begin(*this); }
+    Iterator begin() { return Iterator::begin(*this); }
+
+    ConstIterator end() const { return ConstIterator::end(*this); }
+    Iterator end() { return Iterator::end(*this); }
 
     operator Bytes() { return bytes(); }
     operator ReadonlyBytes() const { return bytes(); }

AK/Forward.h

@@ -61,6 +61,12 @@ class CircularDuplexStream;
 template<typename T>
 class Span;
 
+template<typename T>
+class Array;
+
+template<typename Container, typename ValueType>
+class SimpleIterator;
+
 using ReadonlyBytes = Span<const u8>;
 using Bytes = Span<u8>;
 
@@ -123,6 +129,7 @@ class Vector;
 
 }
 
+using AK::Array;
 using AK::Atomic;
 using AK::Badge;
 using AK::Bitmap;

AK/Iterator.h

@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Forward.h>
+
+namespace AK {
+
+template<typename Container, typename ValueType>
+class SimpleIterator {
+public:
+    friend Container;
+
+    constexpr bool is_end() const { return m_index == SimpleIterator::end(m_container).m_index; }
+    constexpr size_t index() const { return m_index; }
+
+    constexpr bool operator==(SimpleIterator other) const { return m_index == other.m_index; }
+    constexpr bool operator!=(SimpleIterator other) const { return m_index != other.m_index; }
+    constexpr bool operator<(SimpleIterator other) const { return m_index < other.m_index; }
+    constexpr bool operator>(SimpleIterator other) const { return m_index > other.m_index; }
+    constexpr bool operator<=(SimpleIterator other) const { return m_index <= other.m_index; }
+    constexpr bool operator>=(SimpleIterator other) const { return m_index >= other.m_index; }
+
+    constexpr SimpleIterator operator+(ptrdiff_t delta) const { return SimpleIterator { m_container, m_index + delta }; }
+    constexpr SimpleIterator operator-(ptrdiff_t delta) const { return SimpleIterator { m_container, m_index - delta }; }
+
+    constexpr ptrdiff_t operator-(SimpleIterator other) const { return static_cast<ptrdiff_t>(m_index) - other.m_index; }
+
+    constexpr SimpleIterator operator++()
+    {
+        ++m_index;
+        return *this;
+    }
+    constexpr SimpleIterator operator++(int)
+    {
+        ++m_index;
+        return SimpleIterator { m_container, m_index - 1 };
+    }
+
+    constexpr SimpleIterator operator--()
+    {
+        --m_index;
+        return *this;
+    }
+    constexpr SimpleIterator operator--(int)
+    {
+        --m_index;
+        return SimpleIterator { m_container, m_index + 1 };
+    }
+
+    constexpr const ValueType& operator*() const { return m_container[m_index]; }
+    constexpr ValueType& operator*() { return m_container[m_index]; }
+
+    constexpr const ValueType* operator->() const { return &m_container[m_index]; }
+    constexpr ValueType* operator->() { return &m_container[m_index]; }
+
+private:
+    static constexpr SimpleIterator begin(Container& container) { return { container, 0 }; }
+    static constexpr SimpleIterator end(Container& container)
+    {
+        using RawContainerType = typename RemoveCV<Container>::Type;
+
+        if constexpr (IsSame<StringView, RawContainerType>::value || IsSame<String, RawContainerType>::value)
+            return { container, container.length() };
+        else
+            return { container, container.size() };
+    }
+
+    constexpr SimpleIterator(Container& container, size_t index)
+        : m_container(container)
+        , m_index(index)
+    {
+    }
+
+    Container& m_container;
+    size_t m_index;
+};
+
+}

AK/NonnullPtrVector.h

@@ -51,13 +51,14 @@ public:
 
     using Base::size;
 
-    using Iterator = VectorIterator<NonnullPtrVector, T>;
-    Iterator begin() { return Iterator(*this, 0); }
-    Iterator end() { return Iterator(*this, size()); }
+    using ConstIterator = SimpleIterator<const NonnullPtrVector, const T>;
+    using Iterator = SimpleIterator<NonnullPtrVector, T>;
 
-    using ConstIterator = VectorIterator<const NonnullPtrVector, const T>;
-    ConstIterator begin() const { return ConstIterator(*this, 0); }
-    ConstIterator end() const { return ConstIterator(*this, size()); }
+    constexpr ConstIterator begin() const { return ConstIterator::begin(*this); }
+    constexpr Iterator begin() { return Iterator::begin(*this); }
+
+    constexpr ConstIterator end() const { return ConstIterator::end(*this); }
+    constexpr Iterator end() { return Iterator::end(*this); }
 
     PtrType& ptr_at(int index) { return Base::at(index); }
     const PtrType& ptr_at(int index) const { return Base::at(index); }

AK/Span.h

@@ -28,6 +28,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/Checked.h>
+#include <AK/Iterator.h>
 #include <AK/Types.h>
 
 namespace AK {
@@ -102,9 +103,6 @@ protected:
 template<typename T>
 class Span : public Detail::Span<T> {
 public:
-    using Iterator = T*;
-    using ConstIterator = const T*;
-
     using Detail::Span<T>::Span;
 
     ALWAYS_INLINE Span(std::nullptr_t)
@@ -120,23 +118,14 @@ public:
     ALWAYS_INLINE const T* data() const { return this->m_values; }
     ALWAYS_INLINE T* data() { return this->m_values; }
 
-    ALWAYS_INLINE ConstIterator begin() const
-    {
-        return this->m_values;
-    }
-    ALWAYS_INLINE ConstIterator end() const
-    {
-        return begin() + size();
-    }
+    using ConstIterator = SimpleIterator<const Span, const T>;
+    using Iterator = SimpleIterator<Span, T>;
 
-    ALWAYS_INLINE Iterator begin()
-    {
-        return this->m_values;
-    }
-    ALWAYS_INLINE Iterator end()
-    {
-        return begin() + size();
-    }
+    constexpr ConstIterator begin() const { return ConstIterator::begin(*this); }
+    constexpr Iterator begin() { return Iterator::begin(*this); }
+
+    constexpr ConstIterator end() const { return ConstIterator::end(*this); }
+    constexpr Iterator end() { return Iterator::end(*this); }
 
     ALWAYS_INLINE size_t size() const { return this->m_size; }
 
@@ -220,6 +209,7 @@ public:
 
 using ReadonlyBytes = Span<const u8>;
 using Bytes = Span<u8>;
+
 }
 
 using AK::Bytes;

AK/String.h

@@ -58,8 +58,6 @@ namespace AK {
 
 class String {
 public:
-    using ConstIterator = const char*;
-
     ~String() { }
 
     String() { }
@@ -155,8 +153,10 @@ public:
         return (*m_impl)[i];
     }
 
-    ConstIterator begin() const { return characters(); }
-    ConstIterator end() const { return begin() + length(); }
+    using ConstIterator = SimpleIterator<const String, const char>;
+
+    constexpr ConstIterator begin() const { return ConstIterator::begin(*this); }
+    constexpr ConstIterator end() const { return ConstIterator::end(*this); }
 
     bool starts_with(const StringView&, CaseSensitivity = CaseSensitivity::CaseSensitive) const;
     bool ends_with(const StringView&, CaseSensitivity = CaseSensitivity::CaseSensitive) const;

AK/StringView.h

@@ -37,8 +37,6 @@ namespace AK {
 
 class StringView {
 public:
-    using ConstIterator = const char*;
-
     ALWAYS_INLINE constexpr StringView() { }
     ALWAYS_INLINE constexpr StringView(const char* characters, size_t length)
         : m_characters(characters)
@@ -77,8 +75,10 @@ public:
 
     const char& operator[](size_t index) const { return m_characters[index]; }
 
-    ConstIterator begin() const { return characters_without_null_termination(); }
-    ConstIterator end() const { return begin() + length(); }
+    using ConstIterator = SimpleIterator<const StringView, const char>;
+
+    constexpr ConstIterator begin() const { return ConstIterator::begin(*this); }
+    constexpr ConstIterator end() const { return ConstIterator::end(*this); }
 
     unsigned hash() const;
 

AK/Vector.h

@@ -28,6 +28,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/Forward.h>
+#include <AK/Iterator.h>
 #include <AK/Optional.h>
 #include <AK/Span.h>
 #include <AK/StdLibExtras.h>
@@ -47,49 +48,6 @@
 
 namespace AK {
 
-template<typename VectorType, typename ElementType>
-class VectorIterator {
-public:
-    bool operator!=(const VectorIterator& other) const { return m_index != other.m_index; }
-    bool operator==(const VectorIterator& other) const { return m_index == other.m_index; }
-    bool operator<(const VectorIterator& other) const { return m_index < other.m_index; }
-    bool operator>(const VectorIterator& other) const { return m_index > other.m_index; }
-    bool operator>=(const VectorIterator& other) const { return m_index >= other.m_index; }
-    ALWAYS_INLINE VectorIterator& operator++()
-    {
-        ++m_index;
-        return *this;
-    }
-    VectorIterator& operator--()
-    {
-        --m_index;
-        return *this;
-    }
-    VectorIterator operator-(size_t value) { return { m_vector, m_index - value }; }
-    VectorIterator operator+(size_t value) { return { m_vector, m_index + value }; }
-    VectorIterator& operator=(const VectorIterator& other)
-    {
-        m_index = other.m_index;
-        return *this;
-    }
-    ALWAYS_INLINE ElementType& operator*() { return m_vector[m_index]; }
-    ALWAYS_INLINE ElementType* operator->() { return &m_vector[m_index]; }
-    size_t operator-(const VectorIterator& other) { return m_index - other.m_index; }
-
-    bool is_end() const { return m_index == m_vector.size(); }
-    size_t index() const { return m_index; }
-
-private:
-    friend VectorType;
-    VectorIterator(VectorType& vector, size_t index)
-        : m_vector(vector)
-        , m_index(index)
-    {
-    }
-    VectorType& m_vector;
-    size_t m_index { 0 };
-};
-
 template<typename T>
 class TypedTransfer {
 public:
@@ -582,13 +540,14 @@ public:
         return resize(new_size, true);
     }
 
-    using Iterator = VectorIterator<Vector, T>;
-    Iterator begin() { return Iterator(*this, 0); }
-    Iterator end() { return Iterator(*this, size()); }
+    using ConstIterator = SimpleIterator<const Vector, const T>;
+    using Iterator = SimpleIterator<Vector, T>;
 
-    using ConstIterator = VectorIterator<const Vector, const T>;
-    ConstIterator begin() const { return ConstIterator(*this, 0); }
-    ConstIterator end() const { return ConstIterator(*this, size()); }
+    ConstIterator begin() const { return ConstIterator::begin(*this); }
+    Iterator begin() { return Iterator::begin(*this); }
+
+    ConstIterator end() const { return ConstIterator::end(*this); }
+    Iterator end() { return Iterator::end(*this); }
 
     template<typename Finder>
     ConstIterator find(Finder finder) const
@@ -605,7 +564,7 @@ public:
     {
         for (size_t i = 0; i < m_size; ++i) {
             if (finder(at(i)))
-                return Iterator(*this, i);
+                return Iterator { *this, i };
         }
         return end();
     }