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node_modules/eslint-plugin-react/lib/rules/no-redundant-should-component-update.js

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+/**
+ * @fileoverview Flag shouldComponentUpdate when extending PureComponent
+ */
+
+'use strict';
+
+const astUtil = require('../util/ast');
+const componentUtil = require('../util/componentUtil');
+const docsUrl = require('../util/docsUrl');
+const report = require('../util/report');
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+const messages = {
+  noShouldCompUpdate: '{{component}} does not need shouldComponentUpdate when extending React.PureComponent.',
+};
+
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    docs: {
+      description: 'Disallow usage of shouldComponentUpdate when extending React.PureComponent',
+      category: 'Possible Errors',
+      recommended: false,
+      url: docsUrl('no-redundant-should-component-update'),
+    },
+
+    messages,
+
+    schema: [],
+  },
+
+  create(context) {
+    /**
+     * Checks for shouldComponentUpdate property
+     * @param {ASTNode} node The AST node being checked.
+     * @returns {boolean} Whether or not the property exists.
+     */
+    function hasShouldComponentUpdate(node) {
+      const properties = astUtil.getComponentProperties(node);
+      return properties.some((property) => {
+        const name = astUtil.getPropertyName(property);
+        return name === 'shouldComponentUpdate';
+      });
+    }
+
+    /**
+     * Get name of node if available
+     * @param {ASTNode} node The AST node being checked.
+     * @return {string} The name of the node
+     */
+    function getNodeName(node) {
+      if (node.id) {
+        return node.id.name;
+      }
+      if (node.parent && node.parent.id) {
+        return node.parent.id.name;
+      }
+      return '';
+    }
+
+    /**
+     * Checks for violation of rule
+     * @param {ASTNode} node The AST node being checked.
+     */
+    function checkForViolation(node) {
+      if (componentUtil.isPureComponent(node, context)) {
+        const hasScu = hasShouldComponentUpdate(node);
+        if (hasScu) {
+          const className = getNodeName(node);
+          report(context, messages.noShouldCompUpdate, 'noShouldCompUpdate', {
+            node,
+            data: {
+              component: className,
+            },
+          });
+        }
+      }
+    }
+
+    return {
+      ClassDeclaration: checkForViolation,
+      ClassExpression: checkForViolation,
+    };
+  },
+};