Add getters to path object (#13448)

Co-authored-by: fisker Cheung <lionkay@gmail.com>

src/common/ast-path.js

@@ -1,35 +1,73 @@
 import getLast from "../utils/get-last.js";
-
-function getNodeHelper(path, count) {
-  const stackIndex = getNodeStackIndexHelper(path.stack, count);
-  return stackIndex === -1 ? null : path.stack[stackIndex];
-}
-
-function getNodeStackIndexHelper(stack, count) {
-  for (let i = stack.length - 1; i >= 0; i -= 2) {
-    const value = stack[i];
-    if (value && !Array.isArray(value) && --count < 0) {
-      return i;
-    }
-  }
-  return -1;
-}
+import { getPenultimate } from "./util.js";
 
 class AstPath {
   constructor(value) {
     this.stack = [value];
   }
 
+  get key() {
+    const { stack, siblings } = this;
+    return stack[stack.length - (siblings === null ? 4 : 2)] ?? null;
+  }
+
+  get index() {
+    return this.siblings === null ? null : getPenultimate(this.stack);
+  }
+
+  get node() {
+    return getLast(this.stack);
+  }
+
+  get parent() {
+    return this.getNode(1);
+  }
+
+  get grandparent() {
+    return this.getNode(2);
+  }
+
+  get isInArray() {
+    return this.siblings !== null;
+  }
+
+  get siblings() {
+    const { stack } = this;
+    const maybeArray = stack[stack.length - 3];
+    return Array.isArray(maybeArray) ? maybeArray : null;
+  }
+
+  get next() {
+    return this.siblings[this.index + 1];
+  }
+
+  get previous() {
+    return this.siblings[this.index - 1];
+  }
+
+  get isFirst() {
+    return this.index === 0;
+  }
+
+  get isLast() {
+    const { siblings, index } = this;
+    return siblings !== null && index === siblings.length - 1;
+  }
+
+  get isRoot() {
+    return this.stack.length === 1;
+  }
+
   // The name of the current property is always the penultimate element of
-  // this.stack, and always a String.
+  // this.stack, and always a string/number/symbol.
   getName() {
     const { stack } = this;
     const { length } = stack;
     if (length > 1) {
       return stack[length - 2];
     }
-    // Since the name is always a string, null is a safe sentinel value to
-    // return if we do not know the name of the (root) value.
+    // Since the name is a string/number/symbol, null is a safe sentinel value
+    // to return if we do not know the name of the (root) value.
     /* istanbul ignore next */
     return null;
   }
@@ -41,11 +79,22 @@ class AstPath {
   }
 
   getNode(count = 0) {
-    return getNodeHelper(this, count);
+    const stackIndex = this.#getNodeStackIndex(count);
+    return stackIndex === -1 ? null : this.stack[stackIndex];
   }
 
   getParentNode(count = 0) {
-    return getNodeHelper(this, count + 1);
+    return this.getNode(count + 1);
+  }
+
+  #getNodeStackIndex(count) {
+    const { stack } = this;
+    for (let i = stack.length - 1; i >= 0; i -= 2) {
+      if (!Array.isArray(stack[i]) && --count < 0) {
+        return i;
+      }
+    }
+    return -1;
   }
 
   // Temporarily push properties named by string arguments given after the
@@ -70,7 +119,7 @@ class AstPath {
   }
 
   callParent(callback, count = 0) {
-    const stackIndex = getNodeStackIndexHelper(this.stack, count + 1);
+    const stackIndex = this.#getNodeStackIndex(count + 1);
     const parentValues = this.stack.splice(stackIndex + 1);
     try {
       return callback(this);

src/language-markdown/printer-markdown.js

@@ -55,7 +55,7 @@ const SIBLING_NODE_TYPES = new Set([
 ]);
 
 function genericPrint(path, options, print) {
-  const node = path.getValue();
+  const { node } = path;
 
   if (shouldRemainTheSameContent(path)) {
     return splitText(
@@ -137,13 +137,11 @@ function genericPrint(path, options, print) {
       return escapedValue;
     }
     case "whitespace": {
-      const parentNode = path.getParentNode();
-      const index = parentNode.children.indexOf(node);
-      const nextNode = parentNode.children[index + 1];
+      const { next } = path;
 
       const proseWrap =
         // leading char that may cause different syntax
-        nextNode && /^>|^(?:[*+-]|#{1,6}|\d+[).])$/.test(nextNode.value)
+        next && /^>|^(?:[*+-]|#{1,6}|\d+[).])$/.test(next.value)
           ? "never"
           : options.proseWrap;
 
@@ -154,21 +152,14 @@ function genericPrint(path, options, print) {
       if (isAutolink(node.children[0])) {
         style = options.originalText[node.position.start.offset];
       } else {
-        const parentNode = path.getParentNode();
-        const index = parentNode.children.indexOf(node);
-        const prevNode = parentNode.children[index - 1];
-        const nextNode = parentNode.children[index + 1];
+        const { previous, next } = path;
         const hasPrevOrNextWord = // `1*2*3` is considered emphasis but `1_2_3` is not
-          (prevNode &&
-            prevNode.type === "sentence" &&
-            prevNode.children.length > 0 &&
-            getLast(prevNode.children).type === "word" &&
-            !getLast(prevNode.children).hasTrailingPunctuation) ||
-          (nextNode &&
-            nextNode.type === "sentence" &&
-            nextNode.children.length > 0 &&
-            nextNode.children[0].type === "word" &&
-            !nextNode.children[0].hasLeadingPunctuation);
+          (previous?.type === "sentence" &&
+            getLast(previous.children)?.type === "word" &&
+            !getLast(previous.children).hasTrailingPunctuation) ||
+          (next?.type === "sentence" &&
+            next.children[0]?.type === "word" &&
+            !next.children[0].hasLeadingPunctuation);
         style =
           hasPrevOrNextWord || getAncestorNode(path, "emphasis") ? "*" : "_";
       }
@@ -269,9 +260,9 @@ function genericPrint(path, options, print) {
       ];
     }
     case "html": {
-      const parentNode = path.getParentNode();
+      const { parent } = path;
       const value =
-        parentNode.type === "root" && getLast(parentNode.children) === node
+        parent.type === "root" && getLast(parent.children) === node
           ? node.value.trimEnd()
           : node.value;
       const isHtmlComment = /^<!--.*-->$/s.test(value);
@@ -283,10 +274,7 @@ function genericPrint(path, options, print) {
       );
     }
     case "list": {
-      const nthSiblingIndex = getNthListSiblingIndex(
-        node,
-        path.getParentNode()
-      );
+      const nthSiblingIndex = getNthListSiblingIndex(node, path.parent);
 
       const isGitDiffFriendlyOrderedList = hasGitDiffFriendlyOrderedList(
         node,
@@ -296,7 +284,7 @@ function genericPrint(path, options, print) {
       return printChildren(path, options, print, {
         processor: (childPath, index) => {
           const prefix = getPrefix();
-          const childNode = childPath.getValue();
+          const childNode = childPath.node;
 
           if (
             childNode.children.length === 2 &&
@@ -392,7 +380,6 @@ function genericPrint(path, options, print) {
     case "footnoteReference":
       return ["[^", node.identifier, "]"];
     case "footnoteDefinition": {
-      const nextNode = path.getParentNode().children[path.getName() + 1];
       const shouldInlineFootnote =
         node.children.length === 1 &&
         node.children[0].type === "paragraph" &&
@@ -414,9 +401,7 @@ function genericPrint(path, options, print) {
                     index === 0 ? group([softline, print()]) : print(),
                 })
               ),
-              nextNode && nextNode.type === "footnoteDefinition"
-                ? softline
-                : "",
+              path.next?.type === "footnoteDefinition" ? softline : "",
             ]),
       ];
     }
@@ -464,13 +449,13 @@ function genericPrint(path, options, print) {
 }
 
 function printListItem(path, options, print, listPrefix) {
-  const node = path.getValue();
+  const { node } = path;
   const prefix = node.checked === null ? "" : node.checked ? "[x] " : "[ ] ";
   return [
     prefix,
     printChildren(path, options, print, {
       processor: (childPath, index) => {
-        if (index === 0 && childPath.getValue().type !== "list") {
+        if (index === 0 && childPath.node.type !== "list") {
           return align(" ".repeat(prefix.length), print());
         }
 
@@ -560,7 +545,7 @@ function printLine(path, value, options) {
 }
 
 function printTable(path, options, print) {
-  const node = path.getValue();
+  const { node } = path;
 
   const columnMaxWidths = [];
   // { [rowIndex: number]: { [columnIndex: number]: {text: string, width: number} } }
@@ -644,7 +629,7 @@ function printRoot(path, options, print) {
   /** @type {IgnorePosition | null} */
   let ignoreStart = null;
 
-  const { children } = path.getValue();
+  const { children } = path.node;
   for (const [index, childNode] of children.entries()) {
     switch (isPrettierIgnore(childNode)) {
       case "start":
@@ -702,13 +687,13 @@ function printChildren(path, options, print, events = {}) {
   const { postprocessor } = events;
   const processor = events.processor || (() => print());
 
-  const node = path.getValue();
+  const { node } = path;
   const parts = [];
 
   let lastChildNode;
 
   path.each((childPath, index) => {
-    const childNode = childPath.getValue();
+    const childNode = childPath.node;
 
     const result = processor(childPath, index);
     if (result !== false) {
@@ -833,7 +818,7 @@ function shouldPrePrintDoubleHardline(node, data) {
 }
 
 function shouldPrePrintTripleHardline(node, data) {
-  const isPrevNodeList = data.prevNode && data.prevNode.type === "list";
+  const isPrevNodeList = data.prevNode?.type === "list";
   const isIndentedCode = node.type === "code" && node.isIndented;
 
   return isPrevNodeList && isIndentedCode;
@@ -904,14 +889,7 @@ function clamp(value, min, max) {
 }
 
 function hasPrettierIgnore(path) {
-  const index = Number(path.getName());
-
-  if (index === 0) {
-    return false;
-  }
-
-  const prevNode = path.getParentNode().children[index - 1];
-  return isPrettierIgnore(prevNode) === "next";
+  return path.index > 0 && isPrettierIgnore(path.previous) === "next";
 }
 
 const printer = {