add expression evaluator for spinbox input boxes. also knows a little about units.

needs more work to fully integrate it in all of inkscape spinboxes
also needs documentation rework

(bzr r10162)

1 files changed, 80 insertions, 0 deletions

diff --git a/src/util/expression-evaluator.h b/src/util/expression-evaluator.h
new file mode 100644
index 000000000..90789a25f
--- /dev/null
+++ b/src/util/expression-evaluator.h
@@ -0,0 +1,80 @@
+/* LIBGIMP - The GIMP Library
+ * Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
+ *
+ * Original file from libgimpwidgets: gimpeevl.h
+ * Copyright (C) 2008-2009 Fredrik Alstromer <roe@excu.se>
+ * Copyright (C) 2008-2009 Martin Nordholts <martinn@svn.gnome.org>
+ * Modified for Inkscape by Johan Engelen
+ * Copyright (C) 2011 Johan Engelen
+ *
+ * This library is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_EEVL_H__
+#define __GIMP_EEVL_H__
+
+#include "util/units.h"
+
+#include <exception>
+#include <sstream>
+#include <string>
+
+namespace Inkscape {
+namespace Util {
+
+class Unit;
+
+/**
+* GimpEevlQuantity:
+* @value: In reference units.
+* @dimension: in has a dimension of 1, in^2 has a dimension of 2 etc
+*/
+typedef struct
+{
+    double value;
+    gint dimension;
+} GimpEevlQuantity;
+
+typedef bool (* GimpEevlUnitResolverProc) (const gchar      *identifier,
+                                               GimpEevlQuantity *result,
+                                               Unit* unit);
+
+GimpEevlQuantity gimp_eevl_evaluate (const gchar* string, Unit* unit = NULL);
+
+/**
+ * Special exception class for the expression evaluator.
+ */
+class EvaluatorException : public std::exception {
+public:
+    EvaluatorException(const char * message, const char *at_position) {
+        std::ostringstream os;
+        const char* token = at_position ? at_position : "<End of input>";
+        os << "Expression evaluator error: " << message << " at '" << token << "'";
+        msgstr = os.str();
+    }
+
+    virtual ~EvaluatorException() throw() {} // necessary to destroy the string object!!!
+
+    virtual const char* what() const throw () {
+        return msgstr.c_str();
+    }
+protected:
+    std::string msgstr;
+};
+
+}
+}
+
+#endif /* __GIMP_EEVL_H__ */