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app_vue/node_modules/eslint-plugin-vue/lib/rules/no-computed-properties-in-data.js

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+/**
+ * @author  Yosuke Ota
+ * See LICENSE file in root directory for full license.
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const utils = require('../utils')
+
+/**
+ * @typedef {import('../utils').VueObjectData} VueObjectData
+ */
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow accessing computed properties in `data`.',
+      categories: ['vue3-essential', 'essential'],
+      url: 'https://eslint.vuejs.org/rules/no-computed-properties-in-data.html'
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      cannotBeUsed:
+        'The computed property cannot be used in `data()` because it is before initialization.'
+    }
+  },
+  /** @param {RuleContext} context */
+  create(context) {
+    /** @type {Map<ObjectExpression, {data: FunctionExpression | ArrowFunctionExpression, computedNames:Set<string>}>} */
+    const contextMap = new Map()
+
+    /**
+     * @typedef {object} ScopeStack
+     * @property {ScopeStack | null} upper
+     * @property {FunctionExpression | FunctionDeclaration | ArrowFunctionExpression} node
+     */
+    /** @type {ScopeStack | null} */
+    let scopeStack = null
+
+    return utils.compositingVisitors(
+      {
+        /**
+         * @param {FunctionExpression | FunctionDeclaration | ArrowFunctionExpression} node
+         */
+        ':function'(node) {
+          scopeStack = {
+            upper: scopeStack,
+            node
+          }
+        },
+        ':function:exit'() {
+          scopeStack = scopeStack && scopeStack.upper
+        }
+      },
+      utils.defineVueVisitor(context, {
+        onVueObjectEnter(node) {
+          const dataProperty = utils.findProperty(node, 'data')
+          if (
+            !dataProperty ||
+            (dataProperty.value.type !== 'FunctionExpression' &&
+              dataProperty.value.type !== 'ArrowFunctionExpression')
+          ) {
+            return
+          }
+          const computedNames = new Set()
+          for (const computed of utils.iterateProperties(
+            node,
+            new Set(['computed'])
+          )) {
+            computedNames.add(computed.name)
+          }
+
+          contextMap.set(node, { data: dataProperty.value, computedNames })
+        },
+        /**
+         * @param {MemberExpression} node
+         * @param {VueObjectData} vueData
+         */
+        MemberExpression(node, vueData) {
+          if (!scopeStack || !utils.isThis(node.object, context)) {
+            return
+          }
+          const ctx = contextMap.get(vueData.node)
+          if (!ctx || ctx.data !== scopeStack.node) {
+            return
+          }
+          const name = utils.getStaticPropertyName(node)
+          if (!name || !ctx.computedNames.has(name)) {
+            return
+          }
+          context.report({
+            node,
+            messageId: 'cannotBeUsed'
+          })
+        }
+      })
+    )
+  }
+}