135 lines
4.5 KiB
JavaScript
135 lines
4.5 KiB
JavaScript
/**
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* Default method wrapper functions
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*
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* Copyright (C) 2011, 2012, 2013, 2014 Mike Gerwitz
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*
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* This file is part of GNU ease.js.
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*
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* ease.js is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* Method wrappers for standard (non-fallback)
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* @type {Object}
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*/
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exports.standard = {
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wrapOverride: function( method, super_method, cid, getInst )
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{
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return function()
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{
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var context = getInst( this, cid ) || this,
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retval = undefined
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;
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// the _super property will contain the parent method (store the
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// previous value to ensure that calls to multiple overrides will
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// be supported)
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var psup = context.__super;
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context.__super = super_method;
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retval = method.apply( context, arguments );
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// prevent sneaky bastards from breaking encapsulation by stealing
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// method references and ensure that __super is properly restored
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// for nested/multiple override invocations
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context.__super = psup;
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// if the value returned from the method was the context that we
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// passed in, return the actual instance (to ensure we do not break
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// encapsulation)
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if ( retval === context )
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{
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return this;
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}
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return retval;
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};
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},
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wrapNew: function( method, super_method, cid, getInst )
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{
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return function()
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{
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var context = getInst( this, cid ) || this,
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retval = undefined
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;
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// invoke the method
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retval = method.apply( context, arguments );
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// if the value returned from the method was the context that we
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// passed in, return the actual instance (to ensure we do not break
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// encapsulation)
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if ( retval === context )
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{
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return this;
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}
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return retval;
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};
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},
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wrapProxy: function( proxy_to, _, cid, getInst, name, keywords )
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{
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// it is important that we store only a boolean value as to whether or
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// not this method is static *outside* of the returned closure, so as
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// not to keep an unnecessary reference to the keywords object
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var is_static = keywords && keywords[ 'static' ];
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var ret = function()
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{
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var context = getInst( this, cid ) || this,
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retval = undefined,
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dest = ( ( is_static )
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? context.$( proxy_to )
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: context[ proxy_to ]
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)
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;
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// rather than allowing a cryptic error to be thrown, attempt to
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// detect when the proxy call will fail and provide a useful error
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// message
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if ( !( ( dest !== null ) && ( typeof dest === 'object' )
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&& ( typeof dest[ name ] === 'function' )
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) )
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{
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throw TypeError(
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"Unable to proxy " + name + "() call to '" + proxy_to +
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"'; '" + proxy_to + "' is undefined or '" + name +
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"' is not a function."
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);
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}
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retval = dest[ name ].apply( dest, arguments );
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// if the object we are proxying to returns itself, then instead
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// return a reference to *ourself* (so as not to break encapsulation
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// and to provide a more consistent and sensible API)
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return ( retval === dest )
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? this
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: retval;
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};
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// ensures that proxies can be used to provide concrete
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// implementations of abstract methods with param requirements (we
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// have no idea what we'll be proxying to at runtime, so we need to
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// just power through it; see test case for more info)
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ret.__length = NaN;
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return ret;
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},
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};
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