uBlock/src/js/contentscript-extra.js

/*******************************************************************************

    uBlock Origin - a browser extension to block requests.
    Copyright (C) 2014-present Raymond Hill

    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, either version 3 of the License, or
    (at your option) any later version.

    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/}.

    Home: https://github.com/gorhill/uBlock
*/

'use strict';

if (
    typeof vAPI === 'object' &&
    typeof vAPI.DOMProceduralFilterer !== 'object'
) {
// >>>>>>>> start of local scope

/******************************************************************************/

// TODO: Experiment/evaluate loading procedural operator code using an
//       on demand approach.

// 'P' stands for 'Procedural'

const PSelectorHasTextTask = class {
    constructor(task) {
        let arg0 = task[1], arg1;
        if ( Array.isArray(task[1]) ) {
            arg1 = arg0[1]; arg0 = arg0[0];
        }
        this.needle = new RegExp(arg0, arg1);
    }
    transpose(node, output) {
        if ( this.needle.test(node.textContent) ) {
            output.push(node);
        }
    }
};

const PSelectorIfTask = class {
    constructor(task) {
        this.pselector = new PSelector(task[1]);
    }
    transpose(node, output) {
        if ( this.pselector.test(node) === this.target ) {
            output.push(node);
        }
    }
};
PSelectorIfTask.prototype.target = true;

const PSelectorIfNotTask = class extends PSelectorIfTask {
};
PSelectorIfNotTask.prototype.target = false;

const PSelectorMatchesCSSTask = class {
    constructor(task) {
        this.name = task[1].name;
        let arg0 = task[1].value, arg1;
        if ( Array.isArray(arg0) ) {
            arg1 = arg0[1]; arg0 = arg0[0];
        }
        this.value = new RegExp(arg0, arg1);
    }
    transpose(node, output) {
        const style = window.getComputedStyle(node, this.pseudo);
        if ( style !== null && this.value.test(style[this.name]) ) {
            output.push(node);
        }
    }
};
PSelectorMatchesCSSTask.prototype.pseudo = null;

const PSelectorMatchesCSSAfterTask = class extends PSelectorMatchesCSSTask {
};
PSelectorMatchesCSSAfterTask.prototype.pseudo = ':after';

const PSelectorMatchesCSSBeforeTask = class extends PSelectorMatchesCSSTask {
};
PSelectorMatchesCSSBeforeTask.prototype.pseudo = ':before';

const PSelectorMinTextLengthTask = class {
    constructor(task) {
        this.min = task[1];
    }
    transpose(node, output) {
        if ( node.textContent.length >= this.min ) {
            output.push(node);
        }
    }
};

const PSelectorSpathTask = class {
    constructor(task) {
        this.spath = task[1];
        this.nth = /^(?:\s*[+~]|:)/.test(this.spath);
        if ( this.nth ) { return; }
        if ( /^\s*>/.test(this.spath) ) {
            this.spath = `:scope ${this.spath.trim()}`;
        }
    }
    qsa(node) {
        if ( this.nth === false ) {
            return node.querySelectorAll(this.spath);
        }
        const parent = node.parentElement;
        if ( parent === null ) { return; }
        let pos = 1;
        for (;;) {
            node = node.previousElementSibling;
            if ( node === null ) { break; }
            pos += 1;
        }
        return parent.querySelectorAll(
            `:scope > :nth-child(${pos})${this.spath}`
        );
    }
    transpose(node, output) {
        const nodes = this.qsa(node);
        if ( nodes === undefined ) { return; }
        for ( const node of nodes ) {
            output.push(node);
        }
    }
};

const PSelectorUpwardTask = class {
    constructor(task) {
        const arg = task[1];
        if ( typeof arg === 'number' ) {
            this.i = arg;
        } else {
            this.s = arg;
        }
    }
    transpose(node, output) {
        if ( this.s !== '' ) {
            const parent = node.parentElement;
            if ( parent === null ) { return; }
            node = parent.closest(this.s);
            if ( node === null ) { return; }
        } else {
            let nth = this.i;
            for (;;) {
                node = node.parentElement;
                if ( node === null ) { return; }
                nth -= 1;
                if ( nth === 0 ) { break; }
            }
        }
        output.push(node);
    }
};
PSelectorUpwardTask.prototype.i = 0;
PSelectorUpwardTask.prototype.s = '';

const PSelectorWatchAttrs = class {
    constructor(task) {
        this.observer = null;
        this.observed = new WeakSet();
        this.observerOptions = {
            attributes: true,
            subtree: true,
        };
        const attrs = task[1];
        if ( Array.isArray(attrs) && attrs.length !== 0 ) {
            this.observerOptions.attributeFilter = task[1];
        }
    }
    // TODO: Is it worth trying to re-apply only the current selector?
    handler() {
        const filterer =
            vAPI.domFilterer && vAPI.domFilterer.proceduralFilterer;
        if ( filterer instanceof Object ) {
            filterer.onDOMChanged([ null ]);
        }
    }
    transpose(node, output) {
        output.push(node);
        if ( this.observed.has(node) ) { return; }
        if ( this.observer === null ) {
            this.observer = new MutationObserver(this.handler);
        }
        this.observer.observe(node, this.observerOptions);
        this.observed.add(node);
    }
};

const PSelectorXpathTask = class {
    constructor(task) {
        this.xpe = document.createExpression(task[1], null);
        this.xpr = null;
    }
    transpose(node, output) {
        this.xpr = this.xpe.evaluate(
            node,
            XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
            this.xpr
        );
        let j = this.xpr.snapshotLength;
        while ( j-- ) {
            const node = this.xpr.snapshotItem(j);
            if ( node.nodeType === 1 ) {
                output.push(node);
            }
        }
    }
};

const PSelector = class {
    constructor(o) {
        if ( PSelector.prototype.operatorToTaskMap === undefined ) {
            PSelector.prototype.operatorToTaskMap = new Map([
                [ ':has', PSelectorIfTask ],
                [ ':has-text', PSelectorHasTextTask ],
                [ ':if', PSelectorIfTask ],
                [ ':if-not', PSelectorIfNotTask ],
                [ ':matches-css', PSelectorMatchesCSSTask ],
                [ ':matches-css-after', PSelectorMatchesCSSAfterTask ],
                [ ':matches-css-before', PSelectorMatchesCSSBeforeTask ],
                [ ':min-text-length', PSelectorMinTextLengthTask ],
                [ ':not', PSelectorIfNotTask ],
                [ ':nth-ancestor', PSelectorUpwardTask ],
                [ ':spath', PSelectorSpathTask ],
                [ ':upward', PSelectorUpwardTask ],
                [ ':watch-attr', PSelectorWatchAttrs ],
                [ ':xpath', PSelectorXpathTask ],
            ]);
        }
        this.raw = o.raw;
        this.selector = o.selector;
        this.tasks = [];
        const tasks = o.tasks;
        if ( Array.isArray(tasks) === false ) { return; }
        for ( const task of tasks ) {
            this.tasks.push(
                new (this.operatorToTaskMap.get(task[0]))(task)
            );
        }
    }
    prime(input) {
        const root = input || document;
        if ( this.selector === '' ) { return [ root ]; }
        return Array.from(root.querySelectorAll(this.selector));
    }
    exec(input) {
        let nodes = this.prime(input);
        for ( const task of this.tasks ) {
            if ( nodes.length === 0 ) { break; }
            const transposed = [];
            for ( const node of nodes ) {
                task.transpose(node, transposed);
            }
            nodes = transposed;
        }
        return nodes;
    }
    test(input) {
        const nodes = this.prime(input);
        for ( const node of nodes ) {
            let output = [ node ];
            for ( const task of this.tasks ) {
                const transposed = [];
                for ( const node of output ) {
                    task.transpose(node, transposed);
                }
                output = transposed;
                if ( output.length === 0 ) { break; }
            }
            if ( output.length !== 0 ) { return true; }
        }
        return false;
    }
};
PSelector.prototype.operatorToTaskMap = undefined;

const PSelectorRoot = class extends PSelector {
    constructor(o, styleToken) {
        super(o);
        this.budget = 200; // I arbitrary picked a 1/5 second
        this.raw = o.raw;
        this.cost = 0;
        this.lastAllowanceTime = 0;
        this.styleToken = styleToken;
    }
};
PSelectorRoot.prototype.hit = false;

const ProceduralFilterer = class {
    constructor(domFilterer) {
        this.domFilterer = domFilterer;
        this.domIsReady = false;
        this.domIsWatched = false;
        this.mustApplySelectors = false;
        this.selectors = new Map();
        this.masterToken = vAPI.randomToken();
        this.styleTokenMap = new Map();
        this.styledNodes = new Set();
        if ( vAPI.domWatcher instanceof Object ) {
            vAPI.domWatcher.addListener(this);
        }
    }

    addProceduralSelectors(selectors) {
        const addedSelectors = [];
        let mustCommit = this.domIsWatched;
        for ( const selector of selectors ) {
            if ( this.selectors.has(selector.raw) ) { continue; }
            let style, styleToken;
            if ( selector.action === undefined ) {
                style = vAPI.hideStyle;
            } else if ( selector.action[0] === ':style' ) {
                style = selector.action[1];
            }
            if ( style !== undefined ) {
                styleToken = this.styleTokenFromStyle(style);
            }
            const pselector = new PSelectorRoot(selector, styleToken);
            this.selectors.set(selector.raw, pselector);
            addedSelectors.push(pselector);
            mustCommit = true;
        }
        if ( mustCommit === false ) { return; }
        this.mustApplySelectors = this.selectors.size !== 0;
        this.domFilterer.commit();
        if ( this.domFilterer.hasListeners() ) {
            this.domFilterer.triggerListeners({
                procedural: addedSelectors
            });
        }
    }

    commitNow() {
        if ( this.selectors.size === 0 || this.domIsReady === false ) {
            return;
        }

        this.mustApplySelectors = false;

        //console.time('procedural selectors/dom layout changed');

        // https://github.com/uBlockOrigin/uBlock-issues/issues/341
        //   Be ready to unhide nodes which no longer matches any of
        //   the procedural selectors.
        const toUnstyle = this.styledNodes;
        this.styledNodes = new Set();

        let t0 = Date.now();

        for ( const pselector of this.selectors.values() ) {
            const allowance = Math.floor((t0 - pselector.lastAllowanceTime) / 2000);
            if ( allowance >= 1 ) {
                pselector.budget += allowance * 50;
                if ( pselector.budget > 200 ) { pselector.budget = 200; }
                pselector.lastAllowanceTime = t0;
            }
            if ( pselector.budget <= 0 ) { continue; }
            const nodes = pselector.exec();
            const t1 = Date.now();
            pselector.budget += t0 - t1;
            if ( pselector.budget < -500 ) {
                console.info('uBO: disabling %s', pselector.raw);
                pselector.budget = -0x7FFFFFFF;
            }
            t0 = t1;
            if ( nodes.length === 0 ) { continue; }
            pselector.hit = true;
            this.styleNodes(nodes, pselector.styleToken);
        }

        this.unstyleNodes(toUnstyle);
        //console.timeEnd('procedural selectors/dom layout changed');
    }

    styleTokenFromStyle(style) {
        if ( style === undefined ) { return; }
        let styleToken = this.styleTokenMap.get(style);
        if ( styleToken !== undefined ) { return styleToken; }
        styleToken = vAPI.randomToken();
        this.styleTokenMap.set(style, styleToken);
        this.domFilterer.addCSS(
            `[${this.masterToken}][${styleToken}]\n{${style}}`,
            { silent: true, mustInject: true }
        );
        return styleToken;
    }

    styleNodes(nodes, styleToken) {
        if ( styleToken === undefined ) {
            for ( const node of nodes ) {
                node.textContent = '';
                node.remove();
            }
            return;
        }
        for ( const node of nodes ) {
            node.setAttribute(this.masterToken, '');
            node.setAttribute(styleToken, '');
            this.styledNodes.add(node);
        }
    }

    // TODO: Current assumption is one style per hit element. Could be an
    //       issue if an element has multiple styling and one styling is
    //       brough back. Possibly too rare to care about this for now.
    unstyleNodes(nodes) {
        for ( const node of nodes ) {
            if ( this.styledNodes.has(node) ) { continue; }
            node.removeAttribute(this.masterToken);
        }
    }

    createProceduralFilter(o) {
        return new PSelectorRoot(o);
    }

    onDOMCreated() {
        this.domIsReady = true;
        this.domFilterer.commit();
    }

    onDOMChanged(addedNodes, removedNodes) {
        if ( this.selectors.size === 0 ) { return; }
        this.mustApplySelectors =
            this.mustApplySelectors ||
            addedNodes.length !== 0 ||
            removedNodes;
        this.domFilterer.commit();
    }
};

vAPI.DOMProceduralFilterer = ProceduralFilterer;

/******************************************************************************/

// >>>>>>>> end of local scope
}








/*******************************************************************************

    DO NOT:
    - Remove the following code
    - Add code beyond the following code
    Reason:
    - https://github.com/gorhill/uBlock/pull/3721
    - uBO never uses the return value from injected content scripts

**/

void 0;