From c79e5757f99958ad9ccb5cea7897608a82b6c0b3 Mon Sep 17 00:00:00 2001
From: q66 <daniel@octaforge.org>
Date: Thu, 16 Apr 2015 00:18:00 +0100
Subject: [PATCH] initial proof-of-concept implementation of ranges and range
 iterator

---
 octa/range.h  | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++
 octa/vector.h | 65 ++++++++++++++++++++++++++++++++++
 2 files changed, 161 insertions(+)
 create mode 100644 octa/range.h

diff --git a/octa/range.h b/octa/range.h
new file mode 100644
index 0000000..dc62dc9
--- /dev/null
+++ b/octa/range.h
@@ -0,0 +1,96 @@
+/* Ranges for OctaSTD.
+ *
+ * This file is part of OctaSTD. See COPYING.md for futher information.
+ */
+
+#ifndef OCTA_RANGE_H
+#define OCTA_RANGE_H
+
+#include <stddef.h>
+
+#include "octa/types.h"
+
+namespace octa {
+    template<typename T>
+    struct RangeTraits {
+        typedef typename T::type::difference difference;
+        typedef typename T::type::value      value;
+        typedef typename T::type::pointer    pointer;
+        typedef typename T::type::reference  reference;
+    };
+
+    template<typename T>
+    struct RangeTraits<T *> {
+        typedef ptrdiff_t  difference;
+        typedef T          value;
+        typedef T         *pointer;
+        typedef T         &reference;
+    };
+
+    template<typename T>
+    struct RangeTraits<const T *> {
+        typedef ptrdiff_t  difference;
+        typedef T          value;
+        typedef const T   *pointer;
+        typedef const T   &reference;
+    };
+
+    template<>
+    struct RangeTraits<void *> {
+        typedef ptrdiff_t  difference;
+        typedef uchar      value;
+        typedef void      *pointer;
+        typedef uchar     &reference;
+    };
+
+    template<>
+    struct RangeTraits<const void *> {
+        typedef ptrdiff_t    difference;
+        typedef uchar        value;
+        typedef const void  *pointer;
+        typedef const uchar &reference;
+    };
+
+    template<typename T>
+    class RangeIterator {
+        T p_range;
+
+    public:
+        struct type {
+            typedef typename RangeTraits<T>::difference difference;
+            typedef typename RangeTraits<T>::value      value;
+            typedef typename RangeTraits<T>::pointer    pointer;
+            typedef typename RangeTraits<T>::reference  reference;
+        };
+
+        RangeIterator(): p_range() {}
+        RangeIterator(const T &range): p_range(range) {}
+
+        template<typename U>
+        RangeIterator(const RangeIterator<U> &it): p_range(it.range()) {}
+
+        T range() const { return p_range; }
+
+        RangeIterator &operator++() {
+            p_range.pop_first();
+            return *this;
+        }
+
+        typename type::reference operator*() {
+            return p_range.first();
+        }
+
+        template<typename U>
+        friend bool operator!=(const RangeIterator &a, const RangeIterator<U> &b) {
+            return a.range() != b.range();
+        }
+    };
+
+    template<typename T>
+    struct Range {
+        RangeIterator<T> begin() { return RangeIterator<T>((const T &)*this); }
+        RangeIterator<T> end() { return RangeIterator<T>(); }
+    };
+}
+
+#endif
\ No newline at end of file
diff --git a/octa/vector.h b/octa/vector.h
index 05d61fe..cd2f7f4 100644
--- a/octa/vector.h
+++ b/octa/vector.h
@@ -12,8 +12,69 @@
 #include "octa/new.h"
 #include "octa/traits.h"
 #include "octa/utility.h"
+#include "octa/range.h"
 
 namespace octa {
+    template<typename T>
+    class VectorRange: public Range<VectorRange<T> > {
+        T *p_beg, *p_end;
+
+    public:
+        struct type {
+            typedef ptrdiff_t  difference;
+            typedef T          value;
+            typedef T         *pointer;
+            typedef T         &reference;
+        };
+
+        VectorRange(): p_beg(nullptr), p_end(nullptr) {}
+        VectorRange(const VectorRange &v): p_beg(v.p_beg), p_end(v.p_end) {}
+        VectorRange(T *beg, T *end): p_beg(beg), p_end(end) {}
+
+        /* satisfy InputRange */
+
+        bool empty() const { return p_beg == nullptr; }
+
+        T &first() { return *p_beg; }
+        const T &first() const { return *p_beg; }
+
+        void pop_first() {
+            if (p_beg == nullptr) return;
+            if (++p_beg == p_end) p_beg = p_end = nullptr;
+        }
+
+        template<typename U>
+        friend bool operator==(const VectorRange &a, const VectorRange<U> &b) {
+            return a.p_beg == b.p_beg && a.p_end == b.p_end;
+        }
+
+        template<typename U>
+        friend bool operator!=(const VectorRange &a, const VectorRange<U> &b) {
+            return a.p_beg != b.p_beg || a.p_end != b.p_end;
+        }
+
+        /* satisfy ForwardRange */
+
+        VectorRange save() { return *this; }
+
+        /* satisfy BidirectionalRange */
+
+        T &last() { return *(p_end - 1); }
+        const T &last() const { return *(p_end - 1); }
+
+        void pop_last() {
+            if (p_end-- == p_beg) { p_end = nullptr; return; }
+            if (p_end   == p_beg) p_beg = p_end = nullptr;
+        }
+
+        /* satisfy RandomAccessRange */
+
+        T &operator[](size_t i) { return p_beg[i]; }
+        const T &operator[](size_t i) const { return p_beg[i]; }
+
+        size_t length() const { return p_end - p_beg; }
+    };
+
     template<typename T>
     class Vector {
         T *p_buf;
@@ -221,6 +282,10 @@ namespace octa {
             for (size_t i = 0; i < n; ++i) p_buf[idx + i] = v[i];
             return &p_buf[idx];
         }
+
+        VectorRange<T> each() {
+            return VectorRange<T>(p_buf, p_buf + p_len);
+        }
     };
 }