Angularjs理解三-$location

function $LocationProvider() {
var hashPrefix = '',
html5Mode = {
enabled: false,
requireBase: true,
rewriteLinks: true
};

/**
* @ngdoc method
* @name $locationProvider#hashPrefix
* @description
* @param {string=} prefix Prefix for hash part (containing path and search)
* @returns {*} current value if used as getter or itself (chaining) if used as setter
*/
this.hashPrefix = function(prefix) {
if (isDefined(prefix)) {
hashPrefix = prefix;
return this;
} else {
return hashPrefix;
}
};

/**
* @ngdoc method
* @name $locationProvider#html5Mode
* @description
* @param {(boolean|Object)=} mode If boolean, sets `html5Mode.enabled` to value.
*   If object, sets `enabled`, `requireBase` and `rewriteLinks` to respective values. Supported
*   properties:
*   - **enabled** – `{boolean}` – (default: false) If true, will rely on `history.pushState` to
*     change urls where supported. Will fall back to hash-prefixed paths in browsers that do not
*     support `pushState`.
*   - **requireBase** - `{boolean}` - (default: `true`) When html5Mode is enabled, specifies
*     whether or not a <base> tag is required to be present. If `enabled` and `requireBase` are
*     true, and a base tag is not present, an error will be thrown when `$location` is injected.
*     See the {@link guide/$location $location guide for more information}
*   - **rewriteLinks** - `{boolean}` - (default: `true`) When html5Mode is enabled,
*     enables/disables url rewriting for relative links.
*
* @returns {Object} html5Mode object if used as getter or itself (chaining) if used as setter
*/
this.html5Mode = function(mode) {
if (isBoolean(mode)) {
html5Mode.enabled = mode;
return this;
} else if (isObject(mode)) {

if (isBoolean(mode.enabled)) {
html5Mode.enabled = mode.enabled;
}

if (isBoolean(mode.requireBase)) {
html5Mode.requireBase = mode.requireBase;
}

if (isBoolean(mode.rewriteLinks)) {
html5Mode.rewriteLinks = mode.rewriteLinks;
}

return this;
} else {
return html5Mode;
}
};

/**
* @ngdoc event
* @name $location#$locationChangeStart
* @eventType broadcast on root scope
* @description
* Broadcasted before a URL will change.
*
* This change can be prevented by calling
* `preventDefault` method of the event. See {@link ng.$rootScope.Scope#$on} for more
* details about event object. Upon successful change
* {@link ng.$location#$locationChangeSuccess $locationChangeSuccess} is fired.
*
* The `newState` and `oldState` parameters may be defined only in HTML5 mode and when
* the browser supports the HTML5 History API.
*
* @param {Object} angularEvent Synthetic event object.
* @param {string} newUrl New URL
* @param {string=} oldUrl URL that was before it was changed.
* @param {string=} newState New history state object
* @param {string=} oldState History state object that was before it was changed.
*/

/**
* @ngdoc event
* @name $location#$locationChangeSuccess
* @eventType broadcast on root scope
* @description
* Broadcasted after a URL was changed.
*
* The `newState` and `oldState` parameters may be defined only in HTML5 mode and when
* the browser supports the HTML5 History API.
*
* @param {Object} angularEvent Synthetic event object.
* @param {string} newUrl New URL
* @param {string=} oldUrl URL that was before it was changed.
* @param {string=} newState New history state object
* @param {string=} oldState History state object that was before it was changed.
*/

this.$get = ['$rootScope', '$browser', '$sniffer', '$rootElement', '$window',
function($rootScope, $browser, $sniffer, $rootElement, $window) {
var $location,
LocationMode,
baseHref = $browser.baseHref(), // if base[href] is undefined, it defaults to ''
initialUrl = $browser.url(),
appBase;

if (html5Mode.enabled) {
if (!baseHref && html5Mode.requireBase) {
throw $locationMinErr('nobase',
"$location in HTML5 mode requires a <base> tag to be present!");
}
appBase = serverBase(initialUrl) + (baseHref || '/');
LocationMode = $sniffer.history ? LocationHtml5Url : LocationHashbangInHtml5Url;
} else {
appBase = stripHash(initialUrl);
LocationMode = LocationHashbangUrl;
}
$location = new LocationMode(appBase, '#' + hashPrefix);
$location.$$parseLinkUrl(initialUrl, initialUrl);

$location.$$state = $browser.state();

var IGNORE_URI_REGEXP = /^\s*(javascript|mailto):/i;

function setBrowserUrlWithFallback(url, replace, state) {
var oldUrl = $location.url();
var oldState = $location.$$state;
try {
$browser.url(url, replace, state);

// Make sure $location.state() returns referentially identical (not just deeply equal)
// state object; this makes possible quick checking if the state changed in the digest
// loop. Checking deep equality would be too expensive.
$location.$$state = $browser.state();
} catch (e) {
// Restore old values if pushState fails
$location.url(oldUrl);
$location.$$state = oldState;

throw e;
}
}

$rootElement.on('click', function(event) {
// TODO(vojta): rewrite link when opening in new tab/window (in legacy browser)
// currently we open nice url link and redirect then

if (!html5Mode.rewriteLinks || event.ctrlKey || event.metaKey || event.shiftKey || event.which == 2 || event.button == 2) return;

var elm = jqLite(event.target);

// traverse the DOM up to find first A tag
while (nodeName_(elm[0]) !== 'a') {
// ignore rewriting if no A tag (reached root element, or no parent - removed from document)
if (elm[0] === $rootElement[0] || !(elm = elm.parent())[0]) return;
}

var absHref = elm.prop('href');
// get the actual href attribute - see
// http://msdn.microsoft.com/en-us/library/ie/dd347148(v=vs.85).aspx var relHref = elm.attr('href') || elm.attr('xlink:href');

if (isObject(absHref) && absHref.toString() === '[object SVGAnimatedString]') {
// SVGAnimatedString.animVal should be identical to SVGAnimatedString.baseVal, unless during
// an animation.
absHref = urlResolve(absHref.animVal).href;
}

// Ignore when url is started with javascript: or mailto:
if (IGNORE_URI_REGEXP.test(absHref)) return;

if (absHref && !elm.attr('target') && !event.isDefaultPrevented()) {
if ($location.$$parseLinkUrl(absHref, relHref)) {
// We do a preventDefault for all urls that are part of the angular application,
// in html5mode and also without, so that we are able to abort navigation without
// getting double entries in the location history.
event.preventDefault();
// update location manually
if ($location.absUrl() != $browser.url()) {
$rootScope.$apply();
// hack to work around FF6 bug 684208 when scenario runner clicks on links
$window.angular['ff-684208-preventDefault'] = true;
}
}
}
});

// rewrite hashbang url <> html5 url
if (trimEmptyHash($location.absUrl()) != trimEmptyHash(initialUrl)) {
$browser.url($location.absUrl(), true);
}

var initializing = true;

// update $location when $browser url changes
$browser.onUrlChange(function(newUrl, newState) {
$rootScope.$evalAsync(function() {
var oldUrl = $location.absUrl();
var oldState = $location.$$state;
var defaultPrevented;

$location.$$parse(newUrl);
$location.$$state = newState;

defaultPrevented = $rootScope.$broadcast('$locationChangeStart', newUrl, oldUrl,
newState, oldState).defaultPrevented;

// if the location was changed by a `$locationChangeStart` handler then stop
// processing this location change
if ($location.absUrl() !== newUrl) return;

if (defaultPrevented) {
$location.$$parse(oldUrl);
$location.$$state = oldState;
setBrowserUrlWithFallback(oldUrl, false, oldState);
} else {
initializing = false;
afterLocationChange(oldUrl, oldState);
}
});
if (!$rootScope.$$phase) $rootScope.$digest();
});

// update browser
$rootScope.$watch(function $locationWatch() {
var oldUrl = trimEmptyHash($browser.url());
var newUrl = trimEmptyHash($location.absUrl());
var oldState = $browser.state();
var currentReplace = $location.$$replace;
var urlOrStateChanged = oldUrl !== newUrl ||
($location.$$html5 && $sniffer.history && oldState !== $location.$$state);

if (initializing || urlOrStateChanged) {
initializing = false;

$rootScope.$evalAsync(function() {
var newUrl = $location.absUrl();
var defaultPrevented = $rootScope.$broadcast('$locationChangeStart', newUrl, oldUrl,
$location.$$state, oldState).defaultPrevented;

// if the location was changed by a `$locationChangeStart` handler then stop
// processing this location change
if ($location.absUrl() !== newUrl) return;

if (defaultPrevented) {
$location.$$parse(oldUrl);
$location.$$state = oldState;
} else {
if (urlOrStateChanged) {
setBrowserUrlWithFallback(newUrl, currentReplace,
oldState === $location.$$state ? null : $location.$$state);
}
afterLocationChange(oldUrl, oldState);
}
});
}

$location.$$replace = false;

// we don't need to return anything because $evalAsync will make the digest loop dirty when
// there is a change
});

return $location;

function afterLocationChange(oldUrl, oldState) {
$rootScope.$broadcast('$locationChangeSuccess', $location.absUrl(), oldUrl,
$location.$$state, oldState);
}
}];
}