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bower_components/core-a11y-keys/core-a11y-keys.html

-<!--
-    @license
-    Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
-    This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-    The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-    The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-    Code distributed by Google as part of the polymer project is also
-    subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
--->
-
-<!--
-`core-a11y-keys` provides a normalized interface for processing keyboard commands that pertain to [WAI-ARIA best
-practices](http://www.w3.org/TR/wai-aria-practices/#kbd_general_binding). The element takes care of browser differences
-with respect to Keyboard events and uses an expressive syntax to filter key presses.
-
-Use the `keys` attribute to express what combination of keys will trigger the event to fire.
-
-Use the `target` attribute to set up event handlers on a specific node.
-The `keys-pressed` event will fire when one of the key combinations set with the `keys` attribute is pressed.
-
-Example:
-
-This element will call `arrowHandler` on all arrow keys:
-
-    <core-a11y-keys target="{{}}" keys="up down left right" on-keys-pressed="{{arrowHandler}}"></core-a11y-keys>
-
-Keys Syntax:
-
-The `keys` attribute can accepts a space seprated, `+` concatenated set of modifier keys and some common keyboard keys.
-
-The common keys are `a-z`, `0-9` (top row and number pad), `*` (shift 8 and number pad), `F1-F12`, `Page Up`, `Page
-Down`, `Left Arrow`, `Right Arrow`, `Down Arrow`, `Up Arrow`, `Home`, `End`, `Escape`, `Space`, `Tab`, and `Enter` keys.
-
-The modifier keys are `Shift`, `Control`, and `Alt`.
-
-All keys are expected to be lowercase and shortened:
-`Left Arrow` is `left`, `Page Down` is `pagedown`, `Control` is `ctrl`, `F1` is `f1`, `Escape` is `esc` etc.
-
-Keys Syntax Example:
-
-Given the `keys` attribute value "ctrl+shift+f7 up pagedown esc space alt+m", the `<core-a11y-keys>` element will send
-the `keys-pressed` event if any of the follow key combos are pressed: Control and Shift and F7 keys, Up Arrow key, Page
-Down key, Escape key, Space key, Alt and M key.
-
-Slider Example:
-
-The following is an example of the set of keys that fulfil the WAI-ARIA "slider" role [best
-practices](http://www.w3.org/TR/wai-aria-practices/#slider):
-
-    <core-a11y-keys target="{{}}" keys="left pagedown down" on-keys-pressed="{{decrement}}"></core-a11y-keys>
-    <core-a11y-keys target="{{}}" keys="right pageup up" on-keys-pressed="{{increment}}"></core-a11y-keys>
-    <core-a11y-keys target="{{}}" keys="home" on-keys-pressed="{{setMin}}"></core-a11y-keys>
-    <core-a11y-keys target="{{}}" keys="end" on-keys-pressed="{{setMax}}"></core-a11y-keys>
-
-The `increment` function will move the slider a set amount toward the maximum value.
-The `decrement` function will move the slider a set amount toward the minimum value.
-The `setMin` function will move the slider to the minimum value.
-The `setMax` function will move the slider to the maximum value.
-
-Keys Syntax Grammar:
-
-[EBNF](http://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_Form) Grammar of the `keys` attribute.
-
-    modifier = "shift" | "ctrl" | "alt";
-    ascii = ? /[a-z0-9]/ ? ;
-    fnkey = ? f1 through f12 ? ;
-    arrow = "up" | "down" | "left" | "right" ;
-    key = "tab" | "esc" | "space" | "*" | "pageup" | "pagedown" | "home" | "end" | arrow | ascii | fnkey ;
-    keycombo = { modifier, "+" }, key ;
-    keys = keycombo, { " ", keycombo } ;
-
-@group Core Elements
-@element core-a11y-keys
-@homepage github.io
--->
-
-<link rel="import" href="../polymer/polymer.html">
-
-<style shim-shadowdom>
-  html /deep/ core-a11y-keys {
-    display: none;
-  }
-</style>
-
-<polymer-element name="core-a11y-keys">
-<script>
-  (function() {
-    /*
-     * Chrome uses an older version of DOM Level 3 Keyboard Events
-     *
-     * Most keys are labeled as text, but some are Unicode codepoints.
-     * Values taken from: http://www.w3.org/TR/2007/WD-DOM-Level-3-Events-20071221/keyset.html#KeySet-Set
-     */
-    var KEY_IDENTIFIER = {
-      'U+0009': 'tab',
-      'U+001B': 'esc',
-      'U+0020': 'space',
-      'U+002A': '*',
-      'U+0030': '0',
-      'U+0031': '1',
-      'U+0032': '2',
-      'U+0033': '3',
-      'U+0034': '4',
-      'U+0035': '5',
-      'U+0036': '6',
-      'U+0037': '7',
-      'U+0038': '8',
-      'U+0039': '9',
-      'U+0041': 'a',
-      'U+0042': 'b',
-      'U+0043': 'c',
-      'U+0044': 'd',
-      'U+0045': 'e',
-      'U+0046': 'f',
-      'U+0047': 'g',
-      'U+0048': 'h',
-      'U+0049': 'i',
-      'U+004A': 'j',
-      'U+004B': 'k',
-      'U+004C': 'l',
-      'U+004D': 'm',
-      'U+004E': 'n',
-      'U+004F': 'o',
-      'U+0050': 'p',
-      'U+0051': 'q',
-      'U+0052': 'r',
-      'U+0053': 's',
-      'U+0054': 't',
-      'U+0055': 'u',
-      'U+0056': 'v',
-      'U+0057': 'w',
-      'U+0058': 'x',
-      'U+0059': 'y',
-      'U+005A': 'z',
-      'U+007F': 'del'
-    };
-
-    /*
-     * Special table for KeyboardEvent.keyCode.
-     * KeyboardEvent.keyIdentifier is better, and KeyBoardEvent.key is even better than that
-     *
-     * Values from: https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent.keyCode#Value_of_keyCode
-     */
-    var KEY_CODE = {
-      13: 'enter',
-      27: 'esc',
-      33: 'pageup',
-      34: 'pagedown',
-      35: 'end',
-      36: 'home',
-      32: 'space',
-      37: 'left',
-      38: 'up',
-      39: 'right',
-      40: 'down',
-      46: 'del',
-      106: '*'
-    };
-
-    /*
-     * KeyboardEvent.key is mostly represented by printable character made by the keyboard, with unprintable keys labeled
-     * nicely.
-     *
-     * However, on OS X, Alt+char can make a Unicode character that follows an Apple-specific mapping. In this case, we
-     * fall back to .keyCode.
-     */
-    var KEY_CHAR = /[a-z0-9*]/;
-
-    function transformKey(key) {
-      var validKey = '';
-      if (key) {
-        var lKey = key.toLowerCase();
-        if (lKey.length == 1) {
-          if (KEY_CHAR.test(lKey)) {
-            validKey = lKey;
-          }
-        } else if (lKey == 'multiply') {
-          // numpad '*' can map to Multiply on IE/Windows
-          validKey = '*';
-        } else {
-          validKey = lKey;
-        }
-      }
-      return validKey;
-    }
-
-    var IDENT_CHAR = /U\+/;
-    function transformKeyIdentifier(keyIdent) {
-      var validKey = '';
-      if (keyIdent) {
-        if (IDENT_CHAR.test(keyIdent)) {
-          validKey = KEY_IDENTIFIER[keyIdent];
-        } else {
-          validKey = keyIdent.toLowerCase();
-        }
-      }
-      return validKey;
-    }
-
-    function transformKeyCode(keyCode) {
-      var validKey = '';
-      if (Number(keyCode)) {
-        if (keyCode >= 65 && keyCode <= 90) {
-          // ascii a-z
-          // lowercase is 32 offset from uppercase
-          validKey = String.fromCharCode(32 + keyCode);
-        } else if (keyCode >= 112 && keyCode <= 123) {
-          // function keys f1-f12
-          validKey = 'f' + (keyCode - 112);
-        } else if (keyCode >= 48 && keyCode <= 57) {
-          // top 0-9 keys
-          validKey = String(48 - keyCode);
-        } else if (keyCode >= 96 && keyCode <= 105) {
-          // num pad 0-9
-          validKey = String(96 - keyCode);
-        } else {
-          validKey = KEY_CODE[keyCode];
-        }
-      }
-      return validKey;
-    }
-
-    function keyboardEventToKey(ev) {
-      // fall back from .key, to .keyIdentifier, and then to .keyCode
-      var normalizedKey = transformKey(ev.key) || transformKeyIdentifier(ev.keyIdentifier) || transformKeyCode(ev.keyCode) || '';
-      return {
-        shift: ev.shiftKey,
-        ctrl: ev.ctrlKey,
-        meta: ev.metaKey,
-        alt: ev.altKey,
-        key: normalizedKey
-      };
-    }
-
-    /*
-     * Input: ctrl+shift+f7 => {ctrl: true, shift: true, key: 'f7'}
-     * ctrl/space => {ctrl: true} || {key: space}
-     */
-    function stringToKey(keyCombo) {
-      var keys = keyCombo.split('+');
-      var keyObj = Object.create(null);
-      keys.forEach(function(key) {
-        if (key == 'shift') {
-          keyObj.shift = true;
-        } else if (key == 'ctrl') {
-          keyObj.ctrl = true;
-        } else if (key == 'alt') {
-          keyObj.alt = true;
-        } else {
-          keyObj.key = key;
-        }
-      });
-      return keyObj;
-    }
-
-    function keyMatches(a, b) {
-      return Boolean(a.alt) == Boolean(b.alt) && Boolean(a.ctrl) == Boolean(b.ctrl) && Boolean(a.shift) == Boolean(b.shift) && a.key === b.key;
-    }
-
-    /**
-     * Fired when a keycombo in `keys` is pressed.
-     *
-     * @event keys-pressed
-     */
-    function processKeys(ev) {
-      var current = keyboardEventToKey(ev);
-      for (var i = 0, dk; i < this._desiredKeys.length; i++) {
-        dk = this._desiredKeys[i];
-        if (keyMatches(dk, current)) {
-          ev.preventDefault();
-          ev.stopPropagation();
-          this.fire('keys-pressed', current, this, false);
-          break;
-        }
-      }
-    }
-
-    function listen(node, handler) {
-      if (node && node.addEventListener) {
-        node.addEventListener('keydown', handler);
-      }
-    }
-
-    function unlisten(node, handler) {
-      if (node && node.removeEventListener) {
-        node.removeEventListener('keydown', handler);
-      }
-    }
-
-    Polymer('core-a11y-keys', {
-      created: function() {
-        this._keyHandler = processKeys.bind(this);
-      },
-      attached: function() {
-        listen(this.target, this._keyHandler);
-      },
-      detached: function() {
-        unlisten(this.target, this._keyHandler);
-      },
-      publish: {
-        /**
-         * The set of key combinations to listen for.
-         *
-         * @attribute keys
-         * @type string (keys syntax)
-         * @default ''
-         */
-        keys: '',
-        /**
-         * The node that will fire keyboard events.
-         *
-         * @attribute target
-         * @type Node
-         * @default null
-         */
-        target: null
-      },
-      keysChanged: function() {
-        // * can have multiple mappings: shift+8, * on numpad or Multiply on numpad
-        var normalized = this.keys.replace('*', '* shift+*');
-        this._desiredKeys = normalized.toLowerCase().split(' ').map(stringToKey);
-      },
-      targetChanged: function(oldTarget) {
-        unlisten(oldTarget, this._keyHandler);
-        listen(this.target, this._keyHandler);
-      }
-    });
-  })();
-</script>
-</polymer-element>