Improve trusted-replace-argument scriptlet

As discussed with filter list maintainers, added ability to
partially replace an argument using the `repl:` prefix. Updated
documentation:

---

@Scriptlet trusted-replace-argument.js

@description
Replace an argument passed to a method. Requires a trusted source.

@param propChain
The property chain to the function which argument must be replaced when
called.

@param argposRaw
The zero-based position of the argument in the argument list. Use a negative
number for a position relative to the last argument.

@param argraw
The replacement value, validated using the same heuristic as with the
`set-constant.js` scriptlet.
If the replacement value matches `json:...`, the value will be the
json-parsed string after `json:`.
If the replacement value matches `repl:/.../.../`, the target argument will
be replaced according the regex-replacement directive following `repl:`

@param [, condition, pattern]
Optional. The replacement will occur only when pattern matches the target
argument.

---

Aditionally, more scriptlets moved into their own files.

assets/resources/attribute.js

@@ -18,8 +18,6 @@
 
     Home: https://github.com/gorhill/uBlock
 
-    The scriptlets below are meant to be injected only into a
-    web page context.
 */
 
 import { registerScriptlet } from './base.js';

assets/resources/base.js

@@ -18,8 +18,6 @@
 
     Home: https://github.com/gorhill/uBlock
 
-    The scriptlets below are meant to be injected only into a
-    web page context.
 */
 
 export const registeredScriptlets = [];

assets/resources/cookie.js

@@ -18,8 +18,6 @@
 
     Home: https://github.com/gorhill/uBlock
 
-    The scriptlets below are meant to be injected only into a
-    web page context.
 */
 
 import { registerScriptlet } from './base.js';

assets/resources/localstorage.js

@@ -18,8 +18,6 @@
 
     Home: https://github.com/gorhill/uBlock
 
-    The scriptlets below are meant to be injected only into a
-    web page context.
 */
 
 import { getSafeCookieValuesFn } from './cookie.js';

assets/resources/parse-replace.js

@@ -0,0 +1,54 @@
+/*******************************************************************************
+
+    uBlock Origin - a comprehensive, efficient content blocker
+    Copyright (C) 2019-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
+
+*/
+
+import { createArglistParser } from './shared.js';
+import { registerScriptlet } from './base.js';
+
+/******************************************************************************/
+
+export function parseReplaceFn(s) {
+    if ( s.charCodeAt(0) !== 0x2F /* / */ ) { return; }
+    const parser = createArglistParser('/');
+    parser.nextArg(s, 1);
+    let pattern = s.slice(parser.argBeg, parser.argEnd);
+    if ( parser.transform ) {
+        pattern = parser.normalizeArg(pattern);
+    }
+    if ( pattern === '' ) { return; }
+    parser.nextArg(s, parser.separatorEnd);
+    let replacement = s.slice(parser.argBeg, parser.argEnd);
+    if ( parser.separatorEnd === parser.separatorBeg ) { return; }
+    if ( parser.transform ) {
+        replacement = parser.normalizeArg(replacement);
+    }
+    const flags = s.slice(parser.separatorEnd);
+    try {
+        return { re: new RegExp(pattern, flags), replacement };
+    } catch(_) {
+    }
+}
+registerScriptlet(parseReplaceFn, {
+    name: 'parse-replace.fn',
+    dependencies: [
+        createArglistParser,
+    ],
+});

assets/resources/proxy-apply.js

@@ -0,0 +1,109 @@
+/*******************************************************************************
+
+    uBlock Origin - a comprehensive, efficient content blocker
+    Copyright (C) 2019-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
+
+*/
+
+import { registerScriptlet } from './base.js';
+
+/******************************************************************************/
+
+export function proxyApplyFn(
+    target = '',
+    handler = ''
+) {
+    let context = globalThis;
+    let prop = target;
+    for (;;) {
+        const pos = prop.indexOf('.');
+        if ( pos === -1 ) { break; }
+        context = context[prop.slice(0, pos)];
+        if ( context instanceof Object === false ) { return; }
+        prop = prop.slice(pos+1);
+    }
+    const fn = context[prop];
+    if ( typeof fn !== 'function' ) { return; }
+    if ( proxyApplyFn.CtorContext === undefined ) {
+        proxyApplyFn.ctorContexts = [];
+        proxyApplyFn.CtorContext = class {
+            constructor(...args) {
+                this.init(...args);
+            }
+            init(callFn, callArgs) {
+                this.callFn = callFn;
+                this.callArgs = callArgs;
+                return this;
+            }
+            reflect() {
+                const r = Reflect.construct(this.callFn, this.callArgs);
+                this.callFn = this.callArgs = undefined;
+                proxyApplyFn.ctorContexts.push(this);
+                return r;
+            }
+            static factory(...args) {
+                return proxyApplyFn.ctorContexts.length !== 0
+                    ? proxyApplyFn.ctorContexts.pop().init(...args)
+                    : new proxyApplyFn.CtorContext(...args);
+            }
+        };
+        proxyApplyFn.applyContexts = [];
+        proxyApplyFn.ApplyContext = class {
+            constructor(...args) {
+                this.init(...args);
+            }
+            init(callFn, thisArg, callArgs) {
+                this.callFn = callFn;
+                this.thisArg = thisArg;
+                this.callArgs = callArgs;
+                return this;
+            }
+            reflect() {
+                const r = Reflect.apply(this.callFn, this.thisArg, this.callArgs);
+                this.callFn = this.thisArg = this.callArgs = undefined;
+                proxyApplyFn.applyContexts.push(this);
+                return r;
+            }
+            static factory(...args) {
+                return proxyApplyFn.applyContexts.length !== 0
+                    ? proxyApplyFn.applyContexts.pop().init(...args)
+                    : new proxyApplyFn.ApplyContext(...args);
+            }
+        };
+    }
+    const fnStr = fn.toString();
+    const toString = (function toString() { return fnStr; }).bind(null);
+    const proxyDetails = {
+        apply(target, thisArg, args) {
+            return handler(proxyApplyFn.ApplyContext.factory(target, thisArg, args));
+        },
+        get(target, prop) {
+            if ( prop === 'toString' ) { return toString; }
+            return Reflect.get(target, prop);
+        },
+    };
+    if ( fn.prototype?.constructor === fn ) {
+        proxyDetails.construct = function(target, args) {
+            return handler(proxyApplyFn.CtorContext.factory(target, args));
+        };
+    }
+    context[prop] = new Proxy(fn, proxyDetails);
+}
+registerScriptlet(proxyApplyFn, {
+    name: 'proxy-apply.fn',
+});

assets/resources/replace-argument.js

@@ -0,0 +1,105 @@
+/*******************************************************************************
+
+    uBlock Origin - a comprehensive, efficient content blocker
+    Copyright (C) 2019-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
+
+*/
+
+import { parseReplaceFn } from './parse-replace.js';
+import { proxyApplyFn } from './proxy-apply.js';
+import { registerScriptlet } from './base.js';
+import { safeSelf } from './safe-self.js';
+import { validateConstantFn } from './set-constant.js';
+
+/**
+ * @scriptlet trusted-replace-argument.js
+ * 
+ * @description
+ * Replace an argument passed to a method. Requires a trusted source.
+ * 
+ * @param propChain
+ * The property chain to the function which argument must be replaced when
+ * called.
+ * 
+ * @param argposRaw
+ * The zero-based position of the argument in the argument list. Use a negative
+ * number for a position relative to the last argument.
+ * 
+ * @param argraw
+ * The replacement value, validated using the same heuristic as with the
+ * `set-constant.js` scriptlet.
+ * If the replacement value matches `json:...`, the value will be the
+ * json-parsed string after `json:`.
+ * If the replacement value matches `repl:/.../.../`, the target argument will
+ * be replaced according the regex-replacement directive following `repl:`
+ * 
+ * @param [, condition, pattern]
+ * Optional. The replacement will occur only when pattern matches the target
+ * argument.
+ * 
+ * */
+
+export function trustedReplaceArgument(
+    propChain = '',
+    argposRaw = '',
+    argraw = ''
+) {
+    if ( propChain === '' ) { return; }
+    const safe = safeSelf();
+    const logPrefix = safe.makeLogPrefix('trusted-replace-argument', propChain, argposRaw, argraw);
+    const argoffset = parseInt(argposRaw, 10) || 0;
+    const extraArgs = safe.getExtraArgs(Array.from(arguments), 3);
+    const replacer = argraw.startsWith('repl:/') &&
+        parseReplaceFn(argraw.slice(5)) || undefined;
+    const value = replacer === undefined &&
+        validateConstantFn(true, argraw, extraArgs) || undefined;
+    const reCondition = extraArgs.condition
+        ? safe.patternToRegex(extraArgs.condition)
+        : /^/;
+    proxyApplyFn(propChain, function(context) {
+        const { callArgs } = context;
+        if ( argposRaw === '' ) {
+            safe.uboLog(logPrefix, `Arguments:\n${callArgs.join('\n')}`);
+            return context.reflect();
+        }
+        const argpos = argoffset >= 0 ? argoffset : callArgs.length - argoffset;
+        if ( argpos < 0 || argpos >= callArgs.length ) {
+            return context.reflect();
+        }
+        const argBefore = callArgs[argpos];
+        if ( safe.RegExp_test.call(reCondition, argBefore) === false ) {
+            return context.reflect();
+        }
+        const argAfter = replacer && typeof argBefore === 'string'
+            ? argBefore.replace(replacer.re, replacer.replacement)
+            : value;
+        callArgs[argpos] = argAfter;
+        safe.uboLog(logPrefix, `Replaced argument:\nBefore: ${JSON.stringify(argBefore)}\nAfter: ${argAfter}`);
+        return context.reflect();
+    });
+}
+registerScriptlet(trustedReplaceArgument, {
+    name: 'trusted-replace-argument.js',
+    requiresTrust: true,
+    dependencies: [
+        parseReplaceFn,
+        proxyApplyFn,
+        safeSelf,
+        validateConstantFn,
+    ],
+});

assets/resources/run-at.js

@@ -18,8 +18,6 @@
 
     Home: https://github.com/gorhill/uBlock
 
-    The scriptlets below are meant to be injected only into a
-    web page context.
 */
 
 import { registerScriptlet } from './base.js';

assets/resources/safe-self.js

@@ -18,8 +18,6 @@
 
     Home: https://github.com/gorhill/uBlock
 
-    The scriptlets below are meant to be injected only into a
-    web page context.
 */
 
 import { registerScriptlet } from './base.js';