1 files changed, 112 insertions, 0 deletions
diff --git a/src/util/share.h b/src/util/share.h
new file mode 100644
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+++ b/src/util/share.h
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Inkscape::Util::ptr_shared<T> - like T const *, but stronger.
+ * Used to hold c-style strings for objects that are managed by the gc.
+ *
+ * Authors:
+ *   MenTaLguY <mental@rydia.net>
+ *
+ * Copyright (C) 2006 MenTaLguY
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef SEEN_INKSCAPE_UTIL_SHARE_H
+#define SEEN_INKSCAPE_UTIL_SHARE_H
+
+#include "inkgc/gc-core.h"
+#include <cstring>
+#include <cstddef>
+
+namespace Inkscape {
+namespace Util {
+
+class ptr_shared {
+public:
+
+    ptr_shared() : _string(nullptr) {}
+        ptr_shared(ptr_shared const &other) = default;
+
+    operator char const *() const { return _string; }
+    operator bool() const { return _string; }
+
+    char const *pointer() const { return _string; }
+    char const &operator[](int i) const { return _string[i]; }
+
+    ptr_shared operator+(int i) const {
+        return share_unsafe(_string+i);
+    }
+    ptr_shared operator-(int i) const {
+        return share_unsafe(_string-i);
+    }
+    //WARNING: No bounds checking in += and -= functions. Moving the pointer
+    //past the end of the string and then back could probably cause the garbage
+    //collector to deallocate the string inbetween, as there's temporary no
+    //valid reference pointing into the allocated space.
+    ptr_shared &operator+=(int i) {
+        _string += i;
+        return *this;
+    }
+    ptr_shared &operator-=(int i) {
+        _string -= i;
+        return *this;
+    }
+    std::ptrdiff_t operator-(ptr_shared const &other) {
+        return _string - other._string;
+    }
+
+    ptr_shared &operator=(ptr_shared const &other) = default;
+
+    bool operator==(ptr_shared const &other) const {
+        return _string == other._string;
+    }
+    bool operator!=(ptr_shared const &other) const {
+        return _string != other._string;
+    }
+    bool operator>(ptr_shared const &other) const {
+        return _string > other._string;
+    }
+    bool operator<(ptr_shared const &other) const {
+        return _string < other._string;
+    }
+
+    friend ptr_shared share_unsafe(char const *string); 
+
+private:
+    ptr_shared(char const *string) : _string(string) {}
+    static ptr_shared share_unsafe(char const *string) {
+        return ptr_shared(string);
+    }
+
+    //This class (and code using it) assumes that it never has to free this
+    //pointer, and that the memory it points to will not be freed as long as a
+    //ptr_shared pointing to it exists.
+    char const *_string;
+};
+
+ptr_shared share_string(char const *string);
+ptr_shared share_string(char const *string, std::size_t length);
+
+inline ptr_shared share_unsafe(char const *string) {
+    return ptr_shared::share_unsafe(string);
+}
+
+//TODO: Do we need this function?
+inline ptr_shared share_static_string(char const *string) {
+    return share_unsafe(string);
+}
+
+}
+}
+
+#endif
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :