Add new procedural operator: :min-text-length(x)

Where `x` is the minimal text length of the subject
DOM element. DOM elements whose text length is
greater than or equal to `x` will be selected.

The original rationale for such procedural cosmetic
operator[1] is to be able to remove inline script
elements according to a minimum text length using
HTML filtering.

[1] As a result of internal discussion with filter
    list maintainers @ uAssets.

src/js/contentscript.js

@@ -540,6 +540,21 @@ vAPI.DOMFilterer = (function() {
         }
     };
 
+    const PSelectorMinTextLengthTask = class {
+        constructor(task) {
+            this.min = task[1];
+        }
+        exec(input) {
+            const output = [];
+            for ( const node of input ) {
+                if ( node.textContent.length >= this.min ) {
+                    output.push(node);
+                }
+            }
+            return output;
+        }
+    };
+
     const PSelectorNthAncestorTask = class {
         constructor(task) {
             this.nth = task[1];
@@ -658,6 +673,7 @@ vAPI.DOMFilterer = (function() {
                     [ ':matches-css', PSelectorMatchesCSSTask ],
                     [ ':matches-css-after', PSelectorMatchesCSSAfterTask ],
                     [ ':matches-css-before', PSelectorMatchesCSSBeforeTask ],
+                    [ ':min-text-length', PSelectorMinTextLengthTask ],
                     [ ':not', PSelectorIfNotTask ],
                     [ ':nth-ancestor', PSelectorNthAncestorTask ],
                     [ ':spath', PSelectorSpathTask ],

src/js/html-filtering.js

@@ -82,11 +82,26 @@
 
     const PSelectorIfNotTask = class extends PSelectorIfTask {
         constructor(task) {
-            super.call(task);
+            super(task);
             this.target = false;
         }
     };
 
+    const PSelectorMinTextLengthTask = class {
+        constructor(task) {
+            this.min = task[1];
+        }
+        exec(input) {
+            const output = [];
+            for ( const node of input ) {
+                if ( node.textContent.length >= this.min ) {
+                    output.push(node);
+                }
+            }
+            return output;
+        }
+    };
+
     const PSelectorNthAncestorTask = class {
         constructor(task) {
             this.nth = task[1];
@@ -191,6 +206,7 @@
         [ ':has-text', PSelectorHasTextTask ],
         [ ':if', PSelectorIfTask ],
         [ ':if-not', PSelectorIfNotTask ],
+        [ ':min-text-length', PSelectorMinTextLengthTask ],
         [ ':not', PSelectorIfNotTask ],
         [ ':nth-ancestor', PSelectorNthAncestorTask ],
         [ ':xpath', PSelectorXpathTask ]

src/js/static-ext-filtering.js

@@ -166,6 +166,7 @@
                 'matches-css',
                 'matches-css-after',
                 'matches-css-before',
+                'min-text-length',
                 'not',
                 'nth-ancestor',
                 'watch-attrs',
@@ -231,6 +232,14 @@
             return compile(s);
         };
 
+        const compileInteger = function(s, min = 0, max = 0x7FFFFFFF) {
+            if ( /^\d+$/.test(s) === false ) { return; }
+            const n = parseInt(s, 10);
+            if ( n >= min && n < max ) {
+                return n;
+            }
+        };
+
         const compileNotSelector = function(s) {
             // https://github.com/uBlockOrigin/uBlock-issues/issues/341#issuecomment-447603588
             //   Reject instances of :not() filters for which the argument is
@@ -242,10 +251,7 @@
         };
 
         const compileNthAncestorSelector = function(s) {
-            const n = parseInt(s, 10);
-            if ( isNaN(n) === false && n >= 1 && n < 256 ) {
-                return n;
-            }
+            return compileInteger(s, 1, 256);
         };
 
         const compileSpathExpression = function(s) {
@@ -289,6 +295,7 @@
             [ ':matches-css', compileCSSDeclaration ],
             [ ':matches-css-after', compileCSSDeclaration ],
             [ ':matches-css-before', compileCSSDeclaration ],
+            [ ':min-text-length', compileInteger ],
             [ ':not', compileNotSelector ],
             [ ':nth-ancestor', compileNthAncestorSelector ],
             [ ':spath', compileSpathExpression ],
@@ -344,12 +351,11 @@
                 case ':if-not':
                     raw.push(`:not(${decompile(task[1])})`);
                     break;
-                case ':nth-ancestor':
-                    raw.push(`:nth-ancestor(${task[1]})`);
-                    break;
                 case ':spath':
                     raw.push(task[1]);
                     break;
+                case ':min-text-length':
+                case ':nth-ancestor':
                 case ':watch-attrs':
                 case ':xpath':
                     raw.push(`${task[0]}(${task[1]})`);