Implemented host_keymaps

host_keymaps enable defining keymaps in a natural fashion.
Instead of using Key constants like Key_A or LSHIFT(Key_A) it allows to
conveniently write "a" or "A".

The mappings between ascii and unicode characters to USB-HID keys
works by reverse engineering the host keymaps of a linux system.
The information of the provided keymap files allows for precisely
figuring out the Kaleidoscope-Key that is needed to generate a
specific utf8 character in a given keymap. For non-unicode
keycodes, the linux XKB-keysym name is mapped to a Kaleidoscope-Key.

The newly introduced host_keymap system is easily extensible and allows
users to define their own non-english keymaps, if necessary
by extending an existing keymap.

Signed-off-by: Florian Fleissner <florian.fleissner@inpartik.de>

examples/Keystrokes/HostKeymap/HostKeymap.ino

@@ -0,0 +1,56 @@
+/* -*- mode: c++ -*-
+ * Kaleidoscope-Unicode -- Unicode input helpers
+ * Copyright (C) 2016, 2017, 2018  Keyboard.io, Inc
+ *
+ * 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, version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <Kaleidoscope.h>
+
+#include "kaleidoscope/host_keymap/linux/us/standard/keymap.h"
+
+USE_HOST_KEYMAP(linux, us, standard)
+
+// *INDENT-OFF*
+
+KEYMAPS(
+  [0] = KEYMAP_STACKED
+  (
+      XXX,   "1",   "2",   "3",   "4",   "5",   XXX,
+      "`",   "q",   "w",   "e",   "r",   "t",   "\t",
+     L"⇞",   "a",   "s",   "d",   "f",   "g",
+     L"⇟",   "z",   "x",   "c",   "v",   "b",   L"⎋",
+
+     L"⌃", L"⌫", L"⌘", L"⇧",
+      XXX,
+
+      XXX,   "6",   "7",   "8",   "9",   "0",   XXX,
+     L"⎆",   "y",   "u",   "i",   "o",   "p",   "=",
+             "h",   "j",   "k",   "l",   ";",  "\"",
+      XXX,   "n",   "m",   ",",   ".",   "/",   "-",
+
+    L"r⇧", L"r⌥",  L"␣", L"r⌃",
+      XXX
+  )
+)
+// *INDENT-ON*
+
+//KALEIDOSCOPE_INIT_PLUGINS();
+
+void setup() {
+  Kaleidoscope.setup();
+}
+
+void loop() {
+  Kaleidoscope.loop();
+}

src/kaleidoscope/host_keymap/README

@@ -0,0 +1 @@
+The linux keymaps were generated on an Ubuntu 19.04 system based on XKeyboardConfig 2.23.

src/kaleidoscope/host_keymap/ascii.h

@@ -0,0 +1,96 @@
+/* Kaleidoscope - Firmware for computer input devices
+ * Copyright (C) 2013-2018  Keyboard.io, Inc.
+ *
+ * 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, version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "kaleidoscope/host_keymap/host_keymap.h"
+
+namespace kaleidoscope {
+namespace host_keymap {
+namespace ascii {
+
+struct CharProcessor {
+  static constexpr bool isEscapeChar(char c) {
+    return c == '#';
+  }
+
+  static constexpr bool isSeparator(char c) {
+    return (c == ' ')
+           || (c == '\t')
+           || (c == '+');
+  }
+
+  static constexpr bool isMirrorChar(char c) {
+    return c == 'r';
+  }
+};
+
+#define _HOST_KEYMAP_CAST_ON_MODIFIERS_ASCII(OP)                               \
+   OP('s', LSHIFT(k))                                                          \
+   OP('S', LSHIFT(k))                                                          \
+   OP('c', LCTRL(k))                                                           \
+   OP('C', LCTRL(k))                                                           \
+   OP('a', LALT(k))                                                            \
+   OP('A', RALT(k))                                                            \
+   OP('m', LGUI(k))                                                            \
+   OP('M', LGUI(k))                                                            \
+   OP('g', LGUI(k))                                                            \
+   OP('G', LGUI(k))
+
+// Define a AsciiConverterBase template base class that any ascii keymap converters
+// are derived from by means of invoking the HOST_KEYMAP_ASCII_LANGUAGE_CONVERTER
+// function macro.
+//
+_HOST_KEYMAP_DEFINE_CHAR_CONVERTER(
+  ConverterBase, char, _HOST_KEYMAP_CAST_ON_MODIFIERS_ASCII)
+
+#undef _HOST_KEYMAP_CAST_ON_MODIFIERS_ASCII
+
+typedef _CharParsingStandardFallback<char> CharParsingStandardFallback;
+
+} // namespace ascii
+} // namespace host_keymap
+} // namespace kaleidoscope
+
+#define HOST_KEYMAP_ASCII_CONVERTER(LANGUAGE_KEYMAP, CHAR_PARSING_FALLBACK)    \
+   struct AsciiConverter                                                       \
+      : public ascii::ConverterBase<AsciiConverter, ascii::CharProcessor>      \
+   {                                                                           \
+      typedef ascii::ConverterBase<AsciiConverter, ascii::CharProcessor> Parent; \
+                                                                               \
+      using typename Parent::StringMemberType;                                 \
+      using typename Parent::CharType;                                         \
+                                                                               \
+      static constexpr bool isKeyChar(char c) {                                \
+         return LANGUAGE_KEYMAP(_HOST_KEYMAP_IS_KEY_CHAR)                      \
+               CHAR_PARSING_FALLBACK::isKeyChar(c);                            \
+      }                                                                        \
+                                                                               \
+      static constexpr Key charToKey(char c) {                                 \
+         return LANGUAGE_KEYMAP(                                               \
+                  _HOST_KEYMAP_MAP_KEY_CHAR_TO_KALEIDOSCOPE_KEY                \
+               )                                                               \
+               CHAR_PARSING_FALLBACK::charToKey(c);                            \
+      }                                                                        \
+   };                                                                          \
+                                                                               \
+   constexpr Key convertToKey(char c) {                                        \
+      return AsciiConverter::convertToKey(c);                                  \
+   }                                                                           \
+   template<int _Size>                                                         \
+   constexpr Key convertToKey(char const(&string) [_Size]) {                   \
+      return AsciiConverter::convertToKey(string);                             \
+   }

src/kaleidoscope/host_keymap/common.h

@@ -0,0 +1,21 @@
+/* Kaleidoscope - Firmware for computer input devices
+ * Copyright (C) 2013-2018  Keyboard.io, Inc.
+ *
+ * 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, version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "kaleidoscope/host_keymap/ascii.h"
+#include "kaleidoscope/host_keymap/unicode.h"
+#include "kaleidoscope/host_keymap/non_printable.h"