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app_vue/node_modules/eslint-plugin-vue/lib/rules/valid-v-bind-sync.js

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+/**
+ * @fileoverview enforce valid `.sync` modifier on `v-bind` directives
+ * @author Yosuke Ota
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const utils = require('../utils')
+
+// ------------------------------------------------------------------------------
+// Helpers
+// ------------------------------------------------------------------------------
+
+/**
+ * Check whether the given node is valid or not.
+ * @param {VElement} node The element node to check.
+ * @returns {boolean} `true` if the node is valid.
+ */
+function isValidElement(node) {
+  if (!utils.isCustomComponent(node)) {
+    // non Vue-component
+    return false
+  }
+  return true
+}
+
+/**
+ * Check whether the given node is a MemberExpression containing an optional chaining.
+ * e.g.
+ * - `a?.b`
+ * - `a?.b.c`
+ * @param {ASTNode} node The node to check.
+ * @returns {boolean} `true` if the node is a MemberExpression containing an optional chaining.
+ */
+function isOptionalChainingMemberExpression(node) {
+  return (
+    node.type === 'ChainExpression' &&
+    node.expression.type === 'MemberExpression'
+  )
+}
+
+/**
+ * Check whether the given node can be LHS (left-hand side).
+ * @param {ASTNode} node The node to check.
+ * @returns {boolean} `true` if the node can be LHS.
+ */
+function isLhs(node) {
+  return node.type === 'Identifier' || node.type === 'MemberExpression'
+}
+
+/**
+ * Check whether the given node is a MemberExpression of a possibly null object.
+ * e.g.
+ * - `(a?.b).c`
+ * - `(null).foo`
+ * @param {ASTNode} node The node to check.
+ * @returns {boolean} `true` if the node is a MemberExpression of a possibly null object.
+ */
+function maybeNullObjectMemberExpression(node) {
+  if (node.type !== 'MemberExpression') {
+    return false
+  }
+  const { object } = node
+  if (object.type === 'ChainExpression') {
+    // `(a?.b).c`
+    return true
+  }
+  if (object.type === 'Literal' && object.value === null && !object.bigint) {
+    // `(null).foo`
+    return true
+  }
+  if (object.type === 'MemberExpression') {
+    return maybeNullObjectMemberExpression(object)
+  }
+  return false
+}
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'enforce valid `.sync` modifier on `v-bind` directives',
+      categories: ['essential'],
+      url: 'https://eslint.vuejs.org/rules/valid-v-bind-sync.html'
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      unexpectedInvalidElement:
+        "'.sync' modifiers aren't supported on <{{name}}> non Vue-components.",
+      unexpectedOptionalChaining:
+        "Optional chaining cannot appear in 'v-bind' with '.sync' modifiers.",
+      unexpectedNonLhsExpression:
+        "'.sync' modifiers require the attribute value which is valid as LHS.",
+      unexpectedNullObject:
+        "'.sync' modifier has potential null object property access.",
+      unexpectedUpdateIterationVariable:
+        "'.sync' modifiers cannot update the iteration variable '{{varName}}' itself."
+    }
+  },
+  /** @param {RuleContext} context */
+  create(context) {
+    return utils.defineTemplateBodyVisitor(context, {
+      /** @param {VDirective} node */
+      "VAttribute[directive=true][key.name.name='bind']"(node) {
+        if (!node.key.modifiers.map((mod) => mod.name).includes('sync')) {
+          return
+        }
+        const element = node.parent.parent
+        const name = element.name
+
+        if (!isValidElement(element)) {
+          context.report({
+            node,
+            messageId: 'unexpectedInvalidElement',
+            data: { name }
+          })
+        }
+
+        if (!node.value) {
+          return
+        }
+
+        const expression = node.value.expression
+        if (!expression) {
+          // Parsing error
+          return
+        }
+        if (isOptionalChainingMemberExpression(expression)) {
+          context.report({
+            node: expression,
+            messageId: 'unexpectedOptionalChaining'
+          })
+        } else if (!isLhs(expression)) {
+          context.report({
+            node: expression,
+            messageId: 'unexpectedNonLhsExpression'
+          })
+        } else if (maybeNullObjectMemberExpression(expression)) {
+          context.report({
+            node: expression,
+            messageId: 'unexpectedNullObject'
+          })
+        }
+
+        for (const reference of node.value.references) {
+          const id = reference.id
+          if (id.parent.type !== 'VExpressionContainer') {
+            continue
+          }
+          const variable = reference.variable
+          if (variable) {
+            context.report({
+              node: expression,
+              messageId: 'unexpectedUpdateIterationVariable',
+              data: { varName: id.name }
+            })
+          }
+        }
+      }
+    })
+  }
+}