[x3d-public] Routes with JS Proxy

yottzumm at gmail.com yottzumm at gmail.com
Mon Apr 17 00:12:46 PDT 2017


Here’s a version without a scenegraph which almost does what you want.

1.  It doesn’t have full paths to fields, but that could be added easily I think.  I have similar code to the original code running, by uncommenting some parts dealing with MFStrings.  Note that you don’t send the proxies to the routes in this case, since I don’t think they are deep objects (well, I’m not sure if I checked).  You could send proxies.  I am not sure if putting proxies in the scenegraph works or not yet.
2. It uses proxies in the routes.   I am not sure how pulling values out of proxies works, but I have attempted that.  There may be issues here.
3. The proxy’s values aren’t up to date when they get set (bad, I think).
4. The original nodes are changed, despite not being in the routes.
5. Route chaining is working
6. Normal JavaScript variable setting on the proxy works—setField is not called (but the event is not fired on the node, I don’t think, but I might have seen it once).  setField was used to convert an MFString path into a property (see commented out bit).  Conceivably, if setting the node works, we could hide the proxy stuff efficiently I think—but to my knowledge, it doesn’t.
7. I added get functions to the Proxies.  Not sure if I should have or not.  It doesn’t seem to hurt, but I could be doing it wrong.


https://github.com/coderextreme/X3DJSONLD/blob/master/singleroute.js

Maybe with some work, this version can get whipped into shape.  I think I want to support multiple routes on the same fromField (not supported yet).

Do people think of from fields as paths as a good thing.

Another pair of eyes on this would be good.

John
Sent from Mail for Windows 10

From: yottzumm at gmail.com
Sent: Monday, April 17, 2017 12:41 AM
To: Andreas Plesch
Cc: X3D Graphics public mailing list
Subject: RE: Routes with JS Proxy

Actually, I was thinking if you put the proxy in the scenegraph, it would allow for event chaining.  I will look into it.
I just can’t set the fromField in the event handler.

John

Sent from Mail for Windows 10

From: Andreas Plesch
Sent: Saturday, April 15, 2017 4:13 PM
To: John Carlson
Cc: X3D Graphics public mailing list
Subject: Re: Routes with JS Proxy

Hi John,

thanks, I am trying to follow what this is doing and copied the code here:

https://gist.github.com/andreasplesch/59da818dbb4b7bc55c4c1aed401faa7c

I am imagining that after creating a Route with route(), the proxies would automatically ensure that if a value in the js object derived from the JSON is modified (set) (in any way), the routed to property value is also modified immediately. Is that the idea ?.

But then there are custom, public and private setField, and setInternalField functions ? Would it be possible to avoid those and use direct js object manipulation functionality ? 

Here is the short line on how addRoute is defined in the SAI (as a function of an executioncontext):

http://www.web3d.org/documents/specifications/19777-1/V3.3/Part1/functions.html#t-ExecutionContextFunctions

Do you think it would be possible to do this directly for DOM (or XML encoded) scenes as well ? I think it could be since the json path translates to .querySelector and setField to .setAttribute and .addChild

Generally, I think using Proxy as a mechanism to trap setting values and then forwarding those could be a good idea allowing separation from DOM events.

-Andreas


 
Date: Sat, 15 Apr 2017 11:45:57 -0400
From: <yottzumm at gmail.com>
To: X3D Graphics public mailing list <x3d-public at web3d.org>
Subject: [x3d-public] (no subject)
Message-ID: <58f24034.8f2e6b0a.7ce43.ba74 at mx.google.com>
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Inclosed is my first attempt at a new style of routes and events with JavaScript.  Routes are MFString path
Down the JS object hierarchy.  Once the proxy and routes are set up, you can set values in the proxy, and the scenegraphs will change.  Please see my test cases and add more!  It does not handle script functions yet, but there is a path forward.  Perhaps someone will look at this code and find something of value.

John

/****************************************************************************/
'use strict';
/*
Copyright (c) 2017, John Carlson
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

* Neither the name of content nor the names of its
  contributors may be used to endorse or promote products derived from
  this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
*/


test();

/**
 * Override this to get rid of self-test code
 * proxyAction should be paired with a scenegraph exclusively
 */
function test() {
        let fromScenegraph = [ {d: { f: 7 , e: [1, 2, 3]}}, { c : [4]}]
        let toScenegraph = fromScenegraph;
        info("Scenegraph originally "+stringify(fromScenegraph));
        assert(fromScenegraph, toScenegraph);
        let proxyAction = {};
        let proxy = createProxy(proxyAction, fromScenegraph);

        // Create actionable fields in the fromScenegraph, that set
        // fields in the toScenegraph
        //
        // path are MFStirngs which follw a path down the scenegraph, one
        // element at a time.  The final SFSTring is thei field to modify.
        //
        // This does not handle script nodes yet (both getting and setting
        // values, but could possibly be handled by modifying SetInternalField.
        //
        route(proxyAction,
                fromScenegraph, '"0" "d" "e" "0"',
                toScenegraph, '"1" "c"');
        route(proxyAction,
                fromScenegraph, '"0" "d"',
                toScenegraph, '"1"');
        route(proxyAction,
                fromScenegraph, '"0" "A"',
                toScenegraph, '"0" "B"');
        // no changes to scenegraph yet
        assert(fromScenegraph, [{"d":{"f":7,"e":[1,2,3]}},{"c":[4]}]);

        setField(proxy, '"0" "d" "e" "0"', 5);
        assert(fromScenegraph, [{"d":{"f":7,"e":[5,2,3]}},{"c":5}]);
        setField(proxy, '"0" "d" "e" "1"', 8);
        assert(fromScenegraph, [{"d":{"f":7,"e":[5,8,3]}},{"c":5}]);
        setField(proxy, '"0" "d"', 6);
        assert(fromScenegraph, [{"d":6},6]);
        setField(proxy, '"0" "d"', 9);
        assert(fromScenegraph, [{"d":9},9]);
        // add field'
        setField(proxy, '"0" "A"',  10);
        assert(fromScenegraph, [{"d":9,"B":10,"A":10},9]);
        setField(proxy, '"0" "A"', [ "Test!" ]);
        assert(fromScenegraph, [{"d":9,"B":["Test!"],"A":["Test!"]},9]);
        setField(proxy, '"0" "B"', null);
        assert(fromScenegraph, [{"d":9,"B":null,"A":["Test!"]},9]);
        setField(proxy, '"0" "A" "0" "0"', ["Cr"]);  // set a part of a string
        assert(fromScenegraph, [{"d":9,"B":null,"A":["Crest!"]},9]);
        setField(proxy, '"0" "A"', { "/": "/" }); // now A and B point to same
        assert(fromScenegraph, [{"d":9,"B":{"/":"/"},"A":{"/":"/"}},9]);
        setField(proxy, '"0" "A" "/"', "\\");
        assert(fromScenegraph, [{"d":9,"B":{"/":"\\"},"A":{"/":"\\"}},9]);
        setField(proxy, '"0" "A"', { "\\": "\\" }); // now A and B point to same
        assert(fromScenegraph, [{"d":9,"B":{"\\":"\\"},"A":{"\\":"\\"}},9]);
        setField(proxy, '"0" "A" "\\"', "]");
        assert(fromScenegraph, [{"d":9,"B":{"\\":"]"},"A":{"\\":"]"}},9]);
        setField(proxy, '"0" "A"', { "]" : "]" }); // now A and B point to same
        assert(fromScenegraph, [{"d":9,"B":{"]":"]"},"A":{"]":"]"}},9]);
        setField(proxy, '"0" "A" "]"', "[");
        assert(fromScenegraph, [{"d":9,"B":{"]":"["},"A":{"]":"["}},9]);
        setField(proxy, '"0" "A"', { "[" : "[" }); // now A and B point to same
        assert(fromScenegraph, [{"d":9,"B":{"[":"["},"A":{"[":"["}},9]);
        setField(proxy, '"0" "A" "["', "][");
        assert(fromScenegraph, [{"d":9,"B":{"[":"]["},"A":{"[":"]["}},9]);
        setField(proxy, '"0" "A"', { "][" : "][" }); // now A and B point to same
        assert(fromScenegraph, [{"d":9,"B":{"][":"]["},"A":{"][":"]["}},9]);
        setField(proxy, '"0" "A" "]["', "][][" );
        assert(fromScenegraph, [{"d":9,"B":{"][":"][]["},"A":{"][":"][]["}},9]);
        setField(proxy, '"0" "A"', { "][][" : "][][" }); // now A and B point to same
        assert(fromScenegraph, [{"d":9,"B":{"][][":"][]["},"A":{"][][":"][]["}},9]);
        setField(proxy, '"0" "A" "][]["',   "[][]");
        assert(fromScenegraph, [{"d":9,"B":{"][][":"[][]"},"A":{"][][":"[][]"}},9]);
        setField(proxy, '"0" "A"', { "[][]" : "[][]" }); // now A and B point to same
        assert(fromScenegraph, [{"d":9,"B":{"[][]":"[][]"},"A":{"[][]":"[][]"}},9]);
        setField(proxy, '"0" "A" "[][]"', "C");
        assert(fromScenegraph, [{"d":9,"B":{"[][]":"C"},"A":{"[][]":"C"}},9]);
        assert(fromScenegraph, toScenegraph);
        info("Scenegraph finally "+stringify(fromScenegraph));
}

function setField(proxy, fromPath, value) {
        let selector = MFStringToProperty(fromPath);
        raw("\n");
        info("Storing "+fromPath+" = "+selector+" = "+stringify(value)+" in Proxy");
        proxy[selector] = value;
}

/**
 * Override this if you don't want test warnings about scenegraphs
 */

function assert(modifiedScenegraph, goldenScenegraph) {
        var mod = stringify(modifiedScenegraph);
        var testcase = stringify(goldenScenegraph);
        if (mod !== testcase) {
                fatal("Scenegraph "+mod)
                fatal("        != "+testcase);
        } else {
                debug("Scenegraph "+mod+" == "+testcase);
                info("TEST PASSED");
        }
}

/**
 * Pass in a JSON parseable object be stringified,
 * or a regular JSON object.  Or a string to be parsed.
 * selector returned the is the path into the proxy.
 *
 * This should normalize the string, but there may be issues
 * with ordering objects.
 */
function stringify(selectorPath) {
        if (typeof selectorPath === 'string') {
                debug("selector output "+selectorPath);
                return selectorPath;
        /*
                let indexes = parse(selectorPath);
                let selector = JSON.stringify(indexes);
                debug("selector output "+selector);
                return selector;
        */
        } else {
                let selector = JSON.stringify(selectorPath);
                debug("selector output "+selector);
                return selector;
        }
}

/**
 * breaks up selectorPath into component pieces and returns them
 */
function parse(selectorPath) {
        debug("selector input "+selectorPath);
        if (typeof selectorPath === 'string') {
                let indexes = JSON.parse(selectorPath);
                return indexes;
        } else {
                return selectorPath;
        }
}

function MFStringToProperty(string) {
        debug("MFString input "+string+" "+typeof string);
        string = string.replace(/" "/g, ',');
        string = string.substr(1, string.length-2);
        return string;
}

/*
function JsonToMFString(json) {
        let str = stringify(json).split(/,/).join('" "')
        str = "'"+str.substr(1, str.length-2)+'"';
        return str;
}
*/

function PropertyToJson(string) {
        debug("property input "+string+" "+typeof string);
        return string.split(/,/);
}

/** override this function if you want a feature other than a raw message
 */
function raw(string) {
        console.log(string);
}

/** override this function if you want a feature other than a fatal message
 */
function fatal(string) {
        console.error("FATAL: "+string);
}

/** override this function if you want a feature other than a warning message
 */
function warning(string) {
        console.error("============ WARNING: "+string);
}

/** override this function if you want a feature other than console.log or to
 * disable this function
 */
function debug(string) {
        // raw(string);
}

/** override this function if you want a feature other than console.log or to
 * disable this function
 */
function info(string) {
        raw("****** "+string);
}

/**
 * setInternalField() --  set a field in a scenegraph internally.  Use
 * setField() and set up routes and the proxy object on the scenegraph so
 * events flow.
 * Override this if you want a different selector language.
 * The scenegraph is the javascript object to set the path to value on.
 * selectorPath is a JSON array path of keys and indexes into the scenegraph.
 *      You may use quotes to backslashes to escape things
 * The value is set in the scenegraph at the selectorPath location
 *
 * The client may want the select to impact several objects.  That is up
 * to the implementer of setInternalField().  The selectorPath affects the
 * scenegraph.
 * Right now we just have a simple JavaScript implementation.  Something like
 * JSONPath is realizable in this framework I think.
 *
 * You should not use this method to set values on the proxy.
 *
 * Calls:
 *      stringify: to return a string for viewing.
 *      parse: to return javascript object indexes as a selector.
 */
function setInternalField(scenegraph, selectorPath, value) {
        debug("Scenegraph before "+ stringify(scenegraph));
        let skipDescendants = 0; // number of descendents to skip
        let selectedValue = scenegraph;
        let higherValue = selectedValue;
        var selector  = PropertyToJson(selectorPath);
        let depth = (selector.length - skipDescendants);
        debug("Trying to Set "+stringify(scenegraph)+stringify(selector)+" = "+
                stringify(value));
        for (var index = 0; index < depth - 1; index++) {
                debug("Index "+index+" is "+selector[index]);
                higherValue = selectedValue;
                debug("Previous downselected selectedValue === "+
                        stringify(selectedValue));
                debug("Index "+index+" is "+selector[index]);
                debug("New Selected Value === "+selectedValue[selector[index]]);
                selectedValue = selectedValue[selector[index]];
                debug("Now downselected selectedValue === "+selectedValue);
        }
        if (typeof value === 'string') {
                value = value.replace(/\\\\/g, '\u005c');
        }
        debug("Index "+index+" is "+selector[index]);
        /**
         * This is the code that has to change to call functions in X3D Scripts
         * fields.   For toField, I would check to make sure the LHS is a
         * function, and pass a value to the function (along with a timestamp),
         * for From Field, I would make sure value is a function, and call it
         * with a timestamp.
         */
        if (typeof selectedValue === 'string') {
            var str = selectedValue.split('');
                    info("Setting "+ stringify(higherValue) +
                        "[" + selector[depth-2] + "] = "+
                        stringify(value));
                    str[selector[depth-1]] = value;
                    higherValue[selector[depth-2]] = str.join('');
                    // unless there's more than one
        } else {
                info("Setting "+
                        stringify(selectedValue) +
                        "[" + selector[depth-1] + "] = "+ stringify(value));
                selectedValue[selector[depth-1]] = value;
                // unless there's more than one
        }
        raw("RESULT scenegraph "+stringify(scenegraph));
        return true;
}


/**
 * This proxy works on individual values in a scenegraph, because a shadow
 * scenegraph is keep with fromPaths kept as proxy objects.
 *
 * If a route hasn't been set up yet, then the toScenegraph is not affected,
 * unless it's a part of the fromSceneGraph.
 */

function createProxy(proxyAction, fromScenegraph) {
        var proxy = new Proxy(proxyAction, {
                set : function(target, property, value, receiver) {
                        debug("Value set is "+value);
                        debug("property is "+ property);
                        for (let action in proxyAction) {
                                debug(" "+action+" "+typeof proxyAction[property]);
                        }
                        if (typeof proxyAction[property] === 'function') {
                                // set the toScenegraph, act on the route
                                proxyAction[property](property, value);
                        } else {
                                warning("Failed to set value on toScenegraph (no route)");
                        }
                        return setInternalField(fromScenegraph, property, value);
                }
        });
        return proxy;
}

/**
 * Proxy action, set on route.   This should only be called when a route
 * is in place.  It's private an should not be called by others.
 * Scenegraphs are JavaSCript objects
 * Paths are selectors into scenegraphs.
 * property is the property being set and should be equal to fromPath
 * value is the value being set on the toScenegraph.   To set the
 * fromScenegraph, use setField() on the proxy or setInternalField, if you don'
 * want to affect the toScenegraph.
 */
function proxySetAction(fromScenegraph, fromPath, toScenegraph, toPath, property, value) {
        let fromProperty = MFStringToProperty(fromPath);
        if (fromProperty != property) {
                fatal("from"+fromPath+" out of sync with property "+property+".  Did you forget to set a route?");
        }
        debug("fromPath is "+fromPath);
        debug("toPath is "+toPath);
        debug("property is "+property);
        let toProperty = MFStringToProperty(toPath);
        debug("toProperty is "+toProperty);
        if (toScenegraph == fromScenegraph && fromPath == toPath) {
                warning("We don't need to set the same value twice!");
        } else {
                setInternalField(toScenegraph, toProperty, value);
        }

        return true;
}

/**
 * Activate a proxy route from fromPath to toPath
 * The proxy map is a private object which must be passed around.  I will later
 * make it unaccessible.
 * Paths are selectors which can be used with setInternalField()
 * fromScenegraph and toScenegraph may be separate.  If they are the
 * same, be sure that fromField and toField are distinct, or else the
 * results may be undetermined.
 */
function route(proxyAction, fromScenegraph, fromPath, toScenegraph, toPath) {
        info("<ROUTE fromPath='"+ fromPath+ "' "+ "toPath='"+ toPath+ "'/>"
                );
        if (fromScenegraph === toScenegraph &&
                fromPath.startsWith(toPath) &&
                toPath.startsWith(fromPath) &&
                fromPath !== toPath) {
                warning("possible undetermined behavior, fromPath "+fromPath+" and toPath "+toPath+" overlap and the scenegraphs are the same");
        }
        proxyAction[MFStringToProperty(fromPath)] = function(property, value) {
                return proxySetAction(fromScenegraph, fromPath,
                        toScenegraph, toPath,
                        property, value);
        };
}
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