Expressions reboot

- Created A3.{h,cpp} which will be a simpler, lightweight version of
  Arguments.{h,cpp} that does less, but does it better.
- Created E9.{h,cpp} which will be a better implementation of
  Expression.{h,cpp} that does less, but does it better.
- Integrated A3 into Context::initialize, and Arguments and A3 will
  coexist until A3 surpasses Arguments.

src/A3.h

@@ -0,0 +1,140 @@
+////////////////////////////////////////////////////////////////////////////////
+// taskwarrior - a command line task list manager.
+//
+// Copyright 2006 - 2011, Paul Beckingham, Federico Hernandez.
+// All rights reserved.
+//
+// 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 2 of the License, or (at your option) any later
+// version.
+//
+// This program 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 General Public License for more
+// details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program; if not, write to the
+//
+//     Free Software Foundation, Inc.,
+//     51 Franklin Street, Fifth Floor,
+//     Boston, MA
+//     02110-1301
+//     USA
+//
+////////////////////////////////////////////////////////////////////////////////
+#ifndef INCLUDED_A3
+#define INCLUDED_A3
+#define L10N                                           // Localization complete.
+
+#include <vector>
+#include <string>
+#include <File.h>
+
+#define ARGUMENTS_SEQUENCE_MAX_RANGE 1000
+
+class Arg
+{
+public:
+  Arg (
+    const std::string& raw,
+    const std::string& category)
+  : _raw (raw)
+  , _category (category)
+  {
+  }
+
+  Arg (const Arg& other)
+  {
+    _raw      = other._raw;
+    _category = other._category;
+  }
+
+  Arg& operator= (const Arg& other)
+  {
+    if (this != &other)
+    {
+      _raw      = other._raw;
+      _category = other._category;
+    }
+
+    return *this;
+  }
+
+  bool operator== (const Arg& other) const
+  {
+    return _raw      == other._raw  &&
+           _category == other._category;
+  }
+
+public:
+  std::string _raw;      // Raw input token, never modified
+  std::string _category; // Categorized argument
+};
+
+class A3 : public std::vector <Arg>
+{
+public:
+  A3 ();
+  ~A3 ();
+
+  void capture (int, const char**);
+  void capture (const std::string&);
+  void capture_first (const std::string&);
+
+  void categorize ();
+
+  static bool is_command (const std::vector <std::string>&, std::string&);
+
+/*
+  void append_stdin ();
+  void rc_override (std::string&, File&);
+  void get_data_location (std::string&);
+  void apply_overrides ();
+  void resolve_aliases ();
+  void inject_defaults ();
+
+  std::vector <std::string> list ();
+  static std::vector <std::string> operator_list ();
+  std::string combine ();
+
+  bool find_command (std::string&);
+  std::string find_limit ();
+
+  static bool is_multipart (const std::string&, std::vector <std::string>&);
+  static bool is_attr (const std::string&);
+  static bool is_attmod (const std::string&);
+  static bool is_subst (const std::string&);
+  static bool is_pattern (const std::string&);
+  static bool is_id (const std::string&);
+  static bool is_uuid (const std::string&);
+  static bool is_tag (const std::string&);
+  static bool is_operator (const std::string&);
+  static bool is_operator (const std::string&, char&, int&, char&);
+  static bool is_symbol_operator (const std::string&);
+  static bool is_attribute (const std::string&, std::string&);
+  static bool is_modifier (const std::string&);
+  static bool is_expression (const std::string&);
+
+  static bool extract_attr (const std::string&, std::string&, std::string&);
+  static bool extract_attmod (const std::string&, std::string&, std::string&, std::string&, std::string&);
+  static bool extract_subst (const std::string&, std::string&, std::string&, bool&);
+  static bool extract_pattern (const std::string&, std::string&);
+  static bool extract_id (const std::string&, std::vector <int>&);
+  static bool extract_uuid (const std::string&, std::vector <std::string>&);
+  static bool extract_tag (const std::string&, char&, std::string&);
+  static bool extract_operator (const std::string&, std::string&);
+
+  A3 extract_read_only_filter ();
+  A3 extract_write_filter ();
+  A3 extract_modifications (bool include_seq = false);
+  A3 extract_simple_words ();
+
+  static bool valid_modifier (const std::string&);
+*/
+  void dump (const std::string&);
+};
+
+#endif
+////////////////////////////////////////////////////////////////////////////////