implement simple string_view

c_os/user/lib/StringView.h

@@ -0,0 +1,61 @@
+#ifndef C_OS_STRINGVIEW_H
+#define C_OS_STRINGVIEW_H
+
+#include "user/lib/String.h"
+#include "user/lib/Iterator.h"
+#include <utility>
+
+namespace bse {
+
+    class string_view {
+    private:
+        std::size_t len = 0;
+        char* buf = nullptr;
+
+    public:
+        using iterator = ContinuousIterator<char>;
+
+        string_view() = default;
+
+        string_view(char* str) : len(strlen(str)), buf(str) {}
+
+        string_view(const string& str) : len(str.size()), buf(static_cast<char*>(str)) {}
+
+        iterator begin() { return iterator(buf); }
+        iterator begin() const { return iterator(buf); }
+        iterator end() { return iterator(&buf[len]); }
+        iterator end() const { return iterator(&buf[len]); }
+
+        explicit operator char*() { return buf; }
+        explicit operator char*() const { return buf; }
+
+        char operator[](std::size_t pos) { return buf[pos]; }
+        char operator[](std::size_t pos) const { return buf[pos]; }
+
+        bool operator==(const string_view& other) const {
+            return buf == other.buf;
+        }
+
+        bool operator!=(const string_view& other) const {
+            return buf != other.buf;
+        }
+
+        string_view substring(std::size_t first, std::size_t last) const {
+            if (first < 0 || first > len || last <= first || last > len) {
+                return nullptr;
+            }
+
+            string_view new_view;
+            new_view.len = last - first;
+            new_view.buf = &buf[first];
+            return new_view;
+        }
+
+        std::size_t size() const {
+            return len;
+        }
+    };
+
+}  // namespace bse
+
+#endif  //C_OS_STRINGVIEW_H