[general] moving ios and android project under ./platform folder

include/mbgl/util/char_array_buffer.hpp

@@ -0,0 +1,55 @@
+#pragma once
+
+#include <streambuf>
+
+namespace mbgl {
+namespace util {
+
+// ref https://artofcode.wordpress.com/2010/12/12/deriving-from-stdstreambuf/
+
+class CharArrayBuffer : public std::streambuf
+{
+public:
+    CharArrayBuffer(char const* data, std::size_t size)
+        : begin_(data), end_(data + size), current_(data) {}
+
+private:
+    int_type underflow() final {
+        if (current_ == end_) {
+            return traits_type::eof();
+        }
+        return traits_type::to_int_type(*current_);
+    }
+
+    int_type uflow() final {
+        if (current_ == end_) {
+            return traits_type::eof();
+        }
+        return traits_type::to_int_type(*current_++);
+    }
+
+    int_type pbackfail(int_type ch) final {
+        if (current_ == begin_ || (ch != traits_type::eof() && ch != current_[-1])) {
+            return traits_type::eof();
+        }
+        return traits_type::to_int_type(*--current_);
+    }
+
+    std::streamsize showmanyc() final {
+        return end_ - current_;
+    }
+
+    pos_type seekoff(off_type off, std::ios_base::seekdir dir, std::ios_base::openmode) final {
+        if (dir == std::ios_base::beg) current_ = std::min(begin_ + off, end_);
+        else if (dir == std::ios_base::cur) current_ = std::min(current_ + off, end_);
+        else current_ = std::max(end_ - off, begin_); // dir == std::ios_base::end
+        return {off_type(current_ - begin_)};
+    }
+
+    char const * const begin_;
+    char const * const end_;
+    char const * current_;
+};
+
+} // namespace util
+} // namespace mbgl