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app_vue/node_modules/eslint-plugin-vue/lib/rules/no-unused-refs.js

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+/**
+ * @fileoverview Disallow unused refs.
+ * @author Yosuke Ota
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const utils = require('../utils')
+
+// ------------------------------------------------------------------------------
+// Helpers
+// ------------------------------------------------------------------------------
+
+/**
+ * Extract names from references objects.
+ * @param {VReference[]} references
+ */
+function getReferences(references) {
+  return references.filter((ref) => ref.variable == null).map((ref) => ref.id)
+}
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'disallow unused refs',
+      categories: undefined,
+      url: 'https://eslint.vuejs.org/rules/no-unused-refs.html'
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      unused: "'{{name}}' is defined as ref, but never used."
+    }
+  },
+  /** @param {RuleContext} context */
+  create(context) {
+    /** @type {Set<string>} */
+    const usedRefs = new Set()
+
+    /** @type {VLiteral[]} */
+    const defineRefs = []
+    let hasUnknown = false
+
+    /**
+     * Report all unused refs.
+     */
+    function reportUnusedRefs() {
+      for (const defineRef of defineRefs) {
+        if (usedRefs.has(defineRef.value)) {
+          continue
+        }
+
+        context.report({
+          node: defineRef,
+          messageId: 'unused',
+          data: {
+            name: defineRef.value
+          }
+        })
+      }
+    }
+
+    /**
+     * Extract the use ref names for ObjectPattern.
+     * @param {ObjectPattern} node
+     * @returns {void}
+     */
+    function extractUsedForObjectPattern(node) {
+      for (const prop of node.properties) {
+        if (prop.type === 'Property') {
+          const name = utils.getStaticPropertyName(prop)
+          if (name) {
+            usedRefs.add(name)
+          } else {
+            hasUnknown = true
+            return
+          }
+        } else {
+          hasUnknown = true
+          return
+        }
+      }
+    }
+    /**
+     * Extract the use ref names.
+     * @param {Identifier | MemberExpression} refsNode
+     * @returns {void}
+     */
+    function extractUsedForPattern(refsNode) {
+      /** @type {Identifier | MemberExpression | ChainExpression} */
+      let node = refsNode
+      while (node.parent.type === 'ChainExpression') {
+        node = node.parent
+      }
+      const parent = node.parent
+      if (parent.type === 'AssignmentExpression') {
+        if (parent.right === node) {
+          if (parent.left.type === 'ObjectPattern') {
+            // `({foo} = $refs)`
+            extractUsedForObjectPattern(parent.left)
+          } else if (parent.left.type === 'Identifier') {
+            // `foo = $refs`
+            hasUnknown = true
+          }
+        }
+      } else if (parent.type === 'VariableDeclarator') {
+        if (parent.init === node) {
+          if (parent.id.type === 'ObjectPattern') {
+            // `const {foo} = $refs`
+            extractUsedForObjectPattern(parent.id)
+          } else if (parent.id.type === 'Identifier') {
+            // `const foo = $refs`
+            hasUnknown = true
+          }
+        }
+      } else if (parent.type === 'MemberExpression') {
+        if (parent.object === node) {
+          // `$refs.foo`
+          const name = utils.getStaticPropertyName(parent)
+          if (name) {
+            usedRefs.add(name)
+          } else {
+            hasUnknown = true
+          }
+        }
+      } else if (parent.type === 'CallExpression') {
+        const argIndex = parent.arguments.indexOf(node)
+        if (argIndex > -1) {
+          // `foo($refs)`
+          hasUnknown = true
+        }
+      } else if (
+        parent.type === 'ForInStatement' ||
+        parent.type === 'ReturnStatement'
+      ) {
+        hasUnknown = true
+      }
+    }
+
+    return utils.defineTemplateBodyVisitor(
+      context,
+      {
+        /**
+         * @param {VExpressionContainer} node
+         */
+        VExpressionContainer(node) {
+          if (hasUnknown) {
+            return
+          }
+          for (const id of getReferences(node.references)) {
+            if (id.name !== '$refs') {
+              continue
+            }
+            extractUsedForPattern(id)
+          }
+        },
+        /**
+         * @param {VAttribute} node
+         */
+        'VAttribute[directive=false]'(node) {
+          if (hasUnknown) {
+            return
+          }
+          if (node.key.name === 'ref' && node.value != null) {
+            defineRefs.push(node.value)
+          }
+        },
+        "VElement[parent.type!='VElement']:exit"() {
+          if (hasUnknown) {
+            return
+          }
+          reportUnusedRefs()
+        }
+      },
+      utils.compositingVisitors(
+        utils.isScriptSetup(context)
+          ? {
+              Program() {
+                const globalScope =
+                  context.getSourceCode().scopeManager.globalScope
+                if (!globalScope) {
+                  return
+                }
+                for (const variable of globalScope.variables) {
+                  if (variable.defs.length > 0) {
+                    usedRefs.add(variable.name)
+                  }
+                }
+                const moduleScope = globalScope.childScopes.find(
+                  (scope) => scope.type === 'module'
+                )
+                if (!moduleScope) {
+                  return
+                }
+                for (const variable of moduleScope.variables) {
+                  if (variable.defs.length > 0) {
+                    usedRefs.add(variable.name)
+                  }
+                }
+              }
+            }
+          : {},
+        utils.defineVueVisitor(context, {
+          onVueObjectEnter(node) {
+            for (const prop of utils.iterateProperties(
+              node,
+              new Set(['setup'])
+            )) {
+              usedRefs.add(prop.name)
+            }
+          }
+        }),
+        {
+          Identifier(id) {
+            if (hasUnknown) {
+              return
+            }
+            if (id.name !== '$refs') {
+              return
+            }
+            /** @type {Identifier | MemberExpression} */
+            let refsNode = id
+            if (id.parent.type === 'MemberExpression') {
+              if (id.parent.property === id) {
+                // `this.$refs.foo`
+                refsNode = id.parent
+              }
+            }
+            extractUsedForPattern(refsNode)
+          }
+        }
+      )
+    )
+  }
+}