[gnome-calculator/60-split-out-a-backend-library] gcalc: added MathVariables classes

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 1f57a09c3cfaac97c25e156ccd9cc2b4597985dd
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Dec 5 18:30:46 2018 -0600

    gcalc: added MathVariables classes

 gcalc/gcalc-math-variables.vala | 168 ++++++++++++++++++++++++++++++++++++++++
 gcalc/meson.build               |   1 +
 2 files changed, 169 insertions(+)
---
diff --git a/gcalc/gcalc-math-variables.vala b/gcalc/gcalc-math-variables.vala
new file mode 100644
index 00000000..49f36978
--- /dev/null
+++ b/gcalc/gcalc-math-variables.vala
@@ -0,0 +1,168 @@
+/*
+ * Copyright (C) 2008-2012 Robert Ancell
+ * Copyright (C) 2018 Daniel Espinosa <esodan gmail com>
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later
+ * version. See http://www.gnu.org/copyleft/gpl.html the full text of the
+ * license.
+ */
+
+namespace GCalc {
+  public class MathVariables : Object
+  {
+      private string file_name;
+      private HashTable<string, Number?> registers;
+      private Serializer serializer;
+
+      public signal void variable_added (string name, Number value);
+      public signal void variable_edited (string name, Number new_value);
+      public signal void variable_deleted (string name);
+
+      public MathVariables ()
+      {
+          registers = new HashTable <string, Number?> (str_hash, str_equal);
+          file_name = Path.build_filename (Environment.get_user_data_dir (), "gnome-calculator", 
"registers");
+          serializer = new Serializer (DisplayFormat.SCIENTIFIC, 10, 50);
+          serializer.set_radix ('.');
+          registers_load ();
+      }
+
+      private void registers_load ()
+      {
+          string data;
+          try
+          {
+              FileUtils.get_contents (file_name, out data);
+          }
+          catch (FileError e)
+          {
+              return;
+          }
+
+          registers.remove_all ();
+
+          var lines = data.split ("\n");
+          foreach (var line in lines)
+          {
+              var i = line.index_of_char ('=');
+              if (i < 0)
+                  continue;
+
+              var name = line.substring (0, i).strip ();
+              var value = line.substring (i+1).strip ();
+
+              var t = mp_set_from_string (value);
+              if (t != null)
+                  registers.insert (name, t);
+          }
+      }
+
+      private void save ()
+      {
+          var data = "";
+          var iter = HashTableIter<string, Number?> (registers);
+          string name;
+          Number? value;
+          while (iter.next (out name, out value))
+          {
+              var number = serializer.to_string (value);
+              data += "%s=%s\n".printf (name, number);
+          }
+
+          var dir = Path.get_dirname (file_name);
+          DirUtils.create_with_parents (dir, 0700);
+          try
+          {
+              FileUtils.set_contents (file_name, data);
+          }
+          catch (FileError e)
+          {
+          }
+      }
+
+      private string[] array_sort_string (string[] array)
+      {
+          bool swapped = true;
+          int j = (array[array.length - 1] == null ? 1 : 0);
+          string tmp;
+
+          while (swapped)
+          {
+              swapped = false;
+              j++;
+              for (int i = 0; i < array.length - j; i++)
+              {
+                  if (array[i] < array[i + 1])
+                  {
+                      tmp = array[i];
+                      array[i] = array[i + 1];
+                      array[i + 1] = tmp;
+                      swapped = true;
+                  }
+              }
+          }
+          return array;
+      }
+
+      public string[] get_names ()
+      {
+          var names = new string[registers.size () + 1];
+
+          var iter = HashTableIter<string, Number?> (registers);
+          var i = 0;
+          string name;
+          Number? value;
+          while (iter.next (out name, out value))
+          {
+              names[i] = name;
+              i++;
+          }
+          names[i] = null;
+
+          return array_sort_string (names);
+      }
+
+      public string[] variables_eligible_for_autocompletion (string text)
+      {
+          string[] eligible_variables = {};
+          if (text.length <=1)
+              return eligible_variables;
+
+          string[] variables = get_names ();
+          foreach (var variable in variables)
+          {
+              if (variable == null)
+                  break;
+              if (variable.has_prefix (text))
+                  eligible_variables += variable;
+          }
+
+          return eligible_variables;
+      }
+
+      public new void set (string name, Number value)
+      {
+          bool editing = registers.contains (name);
+          registers[name] = value;
+          save ();
+          if (editing)
+              variable_edited (name, value);
+          else
+              variable_added (name, value);
+      }
+
+      public new Number? get (string name)
+      {
+          return registers[name];
+      }
+
+      public void delete (string name)
+      {
+          registers.remove (name);
+          save ();
+          variable_deleted (name);
+      }
+  }
+}
diff --git a/gcalc/meson.build b/gcalc/meson.build
index 36d53f18..8b97ff01 100644
--- a/gcalc/meson.build
+++ b/gcalc/meson.build
@@ -47,6 +47,7 @@ sources = files([
        'gcalc-equation-lexer.vala',
        'gcalc-function-manager.vala',
        'gcalc-math-function.vala',
+       'gcalc-math-variables.vala',
        'gcalc-number.vala',
        'gcalc-serializer.vala',
        'gcalc-unit-manager.vala'