Re-implement :has(> by marking first selector isRoot

esquery.js

@@ -75,7 +75,7 @@ function inPath(node, ancestor, path, fromPathIndex) {
  * @param {?SelectorAST} selector
  * @param {external:AST[]} [ancestry=[]]
  * @param {ESQueryOptions} [options]
- * @returns {void}
+ * @returns {boolean}
 */
 
 /**
@@ -91,7 +91,7 @@ const MATCHER_CACHE = typeof WeakMap === 'function' ? new WeakMap : null;
  * @param {?SelectorAST} selector
  * @returns {SelectorMatcher}
  */
-function getMatcher(selector) {
+function getMatcherOrig(selector) {
     if (selector == null) {
         return () => true;
     }
@@ -108,6 +108,18 @@ function getMatcher(selector) {
 
     return generateMatcher(selector);
 }
+/**
+ * @param {?SelectorAST} selector
+ * @returns {SelectorMatcher}
+ */
+function getMatcher(selector) {
+    const matcher = getMatcherOrig(selector);
+    return (node, ancestry, options) => {
+        // `has` traversal pushes its parent node into ancestry; so expect 1 ancestor even at the root
+        const satisfiesIsRoot = selector && selector.isRoot ? ancestry.length < 2 : true;
+        return matcher(node, ancestry, options) && satisfiesIsRoot;
+    };
+}
 
 /**
  * Create a matcher function for `selector`,
@@ -127,11 +139,6 @@ function generateMatcher(selector) {
             };
         }
 
-        case 'exactNode':
-            return (node, ancestry) => {
-                return ancestry.length === 0;
-            };
-
         case 'field': {
             const path = selector.name.split('.');
             return (node, ancestry) => {
@@ -553,7 +560,7 @@ function subjects(selector, ancestor) {
  * @param {?SelectorAST} selector
  * @param {TraverseVisitor} visitor
  * @param {ESQueryOptions} [options]
- * @returns {external:AST[]}
+ * @returns {void}
  */
 function traverse(ast, selector, visitor, options) {
     if (!selector) { return; }

grammar.pegjs

@@ -30,21 +30,10 @@ binaryOp
   / _ "+" _ { return 'adjacent'; }
   / " " _ { return 'descendant'; }
 
-hasSelectors = s:hasSelector ss:(_ "," _ hasSelector)* {
-  return [s].concat(ss.map(function (s) { return s[3]; }));
-}
-
 selectors = s:selector ss:(_ "," _ selector)* {
   return [s].concat(ss.map(function (s) { return s[3]; }));
 }
 
-
-hasSelector
-  = op:binaryOp? s:selector {
-    if (!op) return s;
-    return { type: op, left: { type: 'exactNode' }, right: s };
-  }
-
 selector
   = a:sequence ops:(binaryOp sequence)* {
     return ops.reduce(function (memo, rhs) {
@@ -53,9 +42,10 @@ selector
   }
 
 sequence
-  = subject:"!"? as:atom+ {
+  = subject:"!"? isRoot:(_">"_)? as:atom+ {
     const b = as.length === 1 ? as[0] : { type: 'compound', selectors: as };
     if(subject) b.subject = true;
+    if(isRoot) as[0].isRoot = true;
     return b;
   }
 
@@ -107,7 +97,7 @@ field = "." i:identifierName is:("." identifierName)* {
 
 negation = ":not(" _ ss:selectors _ ")" { return { type: 'not', selectors: ss }; }
 matches = ":matches(" _ ss:selectors _ ")" { return { type: 'matches', selectors: ss }; }
-has = ":has(" _ ss:hasSelectors _ ")" { return { type: 'has', selectors: ss }; }
+has = ":has(" _ ss:selectors _ ")" { return { type: 'has', selectors: ss }; }
 
 firstChild = ":first-child" { return nth(1); }
 lastChild = ":last-child" { return nthLast(1); }