feat: Implement SourceCode#traverse()

Refs #16999
eslint · Aug 3, 2023 · 2b31aa1 · 2b31aa1
1 parent a1635d6
commit 2b31aa1
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Showing 2 changed files with 37 additions and 17 deletions.
diff --git a/lib/linter/linter.js b/lib/linter/linter.js
@@ -923,22 +923,12 @@ const BASE_TRAVERSAL_CONTEXT = Object.freeze(
  * @param {string | undefined} cwd cwd of the cli
  * @param {string} physicalFilename The full path of the file on disk without any code block information
  * @returns {LintMessage[]} An array of reported problems
+ * @throws {Error} If traversal into a node fails.
  */
 function runRules(sourceCode, configuredRules, ruleMapper, parserName, languageOptions, settings, filename, disableFixes, cwd, physicalFilename) {
     const emitter = createEmitter();
-    const nodeQueue = [];
     let currentNode = sourceCode.ast;
-
-    Traverser.traverse(sourceCode.ast, {
-        enter(node, parent) {
-            node.parent = parent;
-            nodeQueue.push({ isEntering: true, node });
-        },
-        leave(node) {
-            nodeQueue.push({ isEntering: false, node });
-        },
-        visitorKeys: sourceCode.visitorKeys
-    });
+    const nodeQueue = sourceCode.traverse();
 
     /*
      * Create a frozen object with the ruleContext properties and methods that are shared by all rules.
@@ -1073,15 +1063,15 @@ function runRules(sourceCode, configuredRules, ruleMapper, parserName, languageO
     });
 
     // only run code path analyzer if the top level node is "Program", skip otherwise
-    const eventGenerator = nodeQueue[0].node.type === "Program"
+    const eventGenerator = sourceCode.ast.type === "Program"
         ? new CodePathAnalyzer(new NodeEventGenerator(emitter, { visitorKeys: sourceCode.visitorKeys, fallback: Traverser.getKeys }))
         : new NodeEventGenerator(emitter, { visitorKeys: sourceCode.visitorKeys, fallback: Traverser.getKeys });
 
-    nodeQueue.forEach(traversalInfo => {
-        currentNode = traversalInfo.node;
+    for (const { isEntering, target } of nodeQueue) {
+        currentNode = target;
 
         try {
-            if (traversalInfo.isEntering) {
+            if (isEntering) {
                 eventGenerator.enterNode(currentNode);
             } else {
                 eventGenerator.leaveNode(currentNode);
@@ -1090,7 +1080,7 @@ function runRules(sourceCode, configuredRules, ruleMapper, parserName, languageO
             err.currentNode = currentNode;
             throw err;
         }
-    });
+    }
 
     return lintingProblems;
 }

diff --git a/lib/source-code/source-code.js b/lib/source-code/source-code.js
@@ -724,6 +724,36 @@ class SourceCode extends TokenStore {
     }
 
 
+    traverse() {
+
+        const steps = [];
+
+        Traverser.traverse(this.ast, {
+            enter(node, parent) {
+
+                // save the parent node on a property for backwards compatibility
+                node.parent = parent;
+
+                steps.push({
+                    type: "visit",
+                    target: node,
+                    isEntering: true,
+                    args: [node, parent]
+                });
+            },
+            leave(node, parent) {
+                steps.push({
+                    type: "visit",
+                    target: node,
+                    isEntering: false,
+                    args: [node, parent]
+                });
+            },
+            visitorKeys: this.visitorKeys
+        });
+
+        return steps;
+    }
 }
 
 module.exports = SourceCode;