analyze-scope.ts

import {
  TSESTree,
  TSESLintScope,
  AST_NODE_TYPES,
} from '@typescript-eslint/experimental-utils';
import { getKeys as fallback } from 'eslint-visitor-keys';

import { ParserOptions } from './parser-options';
import { ScopeManager } from './scope/scope-manager';
import { visitorKeys as childVisitorKeys } from '@typescript-eslint/typescript-estree';

/**
 * Define the override function of `Scope#__define` for global augmentation.
 * @param {Function} define The original Scope#__define method.
 * @returns {Function} The override function.
 */
function overrideDefine(
  define: (node: TSESTree.Node, def: TSESLintScope.Definition) => void,
) {
  return function (
    this: TSESLintScope.Scope,
    node: TSESTree.Node,
    definition: TSESLintScope.Definition,
  ): void {
    define.call(this, node, definition);

    // Set `variable.eslintUsed` to tell ESLint that the variable is exported.
    const variable =
      'name' in node &&
      typeof node.name === 'string' &&
      this.set.get(node.name);
    if (variable) {
      variable.eslintUsed = true;
    }
  };
}

class PatternVisitor extends TSESLintScope.PatternVisitor {
  constructor(
    options: TSESLintScope.PatternVisitorOptions,
    rootPattern: TSESTree.BaseNode,
    callback: TSESLintScope.PatternVisitorCallback,
  ) {
    super(options, rootPattern, callback);
  }

  Identifier(node: TSESTree.Identifier): void {
    super.Identifier(node);
    if (node.decorators) {
      this.rightHandNodes.push(...node.decorators);
    }
    if (node.typeAnnotation) {
      this.rightHandNodes.push(node.typeAnnotation);
    }
  }

  ArrayPattern(node: TSESTree.ArrayPattern): void {
    node.elements.forEach(this.visit, this);
    if (node.decorators) {
      this.rightHandNodes.push(...node.decorators);
    }
    if (node.typeAnnotation) {
      this.rightHandNodes.push(node.typeAnnotation);
    }
  }

  ObjectPattern(node: TSESTree.ObjectPattern): void {
    node.properties.forEach(this.visit, this);
    if (node.decorators) {
      this.rightHandNodes.push(...node.decorators);
    }
    if (node.typeAnnotation) {
      this.rightHandNodes.push(node.typeAnnotation);
    }
  }

  RestElement(node: TSESTree.RestElement): void {
    super.RestElement(node);
    if (node.decorators) {
      this.rightHandNodes.push(...node.decorators);
    }
    if (node.typeAnnotation) {
      this.rightHandNodes.push(node.typeAnnotation);
    }
  }

  TSParameterProperty(node: TSESTree.TSParameterProperty): void {
    this.visit(node.parameter);
    if (node.decorators) {
      this.rightHandNodes.push(...node.decorators);
    }
  }
}

class Referencer extends TSESLintScope.Referencer<ScopeManager> {
  protected typeMode: boolean;

  constructor(
    options: TSESLintScope.ScopeManagerOptions,
    scopeManager: ScopeManager,
  ) {
    super(options, scopeManager);
    this.typeMode = false;
  }

  /**
   * Override to use PatternVisitor we overrode.
   * @param node The Identifier node to visit.
   * @param [options] The flag to visit right-hand side nodes.
   * @param callback The callback function for left-hand side nodes.
   */
  visitPattern<T extends TSESTree.BaseNode>(
    node: T,
    options: TSESLintScope.PatternVisitorOptions,
    callback: TSESLintScope.PatternVisitorCallback,
  ): void {
    if (!node) {
      return;
    }

    if (typeof options === 'function') {
      callback = options;
      options = { processRightHandNodes: false };
    }

    const visitor = new PatternVisitor(this.options, node, callback);
    visitor.visit(node);

    if (options.processRightHandNodes) {
      visitor.rightHandNodes.forEach(this.visit, this);
    }
  }

  /**
   * Override.
   * Visit `node.typeParameters` and `node.returnType` additionally to find `typeof` expressions.
   * @param node The function node to visit.
   */
  visitFunction(
    node:
      | TSESTree.FunctionDeclaration
      | TSESTree.FunctionExpression
      | TSESTree.ArrowFunctionExpression,
  ): void {
    const { type, id, typeParameters, params, returnType, body } = node;
    const scopeManager = this.scopeManager;
    const upperScope = this.currentScope();

    // Process the name.
    if (type === AST_NODE_TYPES.FunctionDeclaration && id) {
      upperScope.__define(
        id,
        new TSESLintScope.Definition(
          'FunctionName',
          id,
          node,
          null,
          null,
          null,
        ),
      );

      // Remove overload definition to avoid confusion of no-redeclare rule.
      const { defs, identifiers } = upperScope.set.get(id.name)!;
      for (let i = 0; i < defs.length; ++i) {
        const def = defs[i];
        if (
          def.type === 'FunctionName' &&
          def.node.type === AST_NODE_TYPES.TSDeclareFunction
        ) {
          defs.splice(i, 1);
          identifiers.splice(i, 1);
          break;
        }
      }
    } else if (type === AST_NODE_TYPES.FunctionExpression && id) {
      scopeManager.__nestFunctionExpressionNameScope(node);
    }

    // Open the function scope.
    scopeManager.__nestFunctionScope(node, this.isInnerMethodDefinition);
    const innerScope = this.currentScope();

    // Process the type parameters
    this.visit(typeParameters);

    // Process parameter declarations.
    for (let i = 0; i < params.length; ++i) {
      this.visitPattern(
        params[i],
        { processRightHandNodes: true },
        (pattern, info) => {
          if (
            pattern.type !== AST_NODE_TYPES.Identifier ||
            pattern.name !== 'this'
          ) {
            innerScope.__define(
              pattern,
              new TSESLintScope.ParameterDefinition(
                pattern,
                node,
                i,
                info.rest,
              ),
            );
            this.referencingDefaultValue(pattern, info.assignments, null, true);
          }
        },
      );
    }

    // Process the return type.
    this.visit(returnType);

    // Process the body.
    if (body && body.type === AST_NODE_TYPES.BlockStatement) {
      this.visitChildren(body);
    } else {
      this.visit(body);
    }

    // Close the function scope.
    this.close(node);
  }

  /**
   * Override.
   * Visit decorators.
   * @param node The class node to visit.
   */
  visitClass(node: TSESTree.ClassDeclaration | TSESTree.ClassExpression): void {
    this.visitDecorators(node.decorators);

    const upperTypeMode = this.typeMode;
    this.typeMode = true;
    if (node.superTypeParameters) {
      this.visit(node.superTypeParameters);
    }
    if (node.implements) {
      node.implements.forEach(this.visit, this);
    }
    this.typeMode = upperTypeMode;

    super.visitClass(node);
  }

  /**
   * Visit typeParameters.
   * @param node The node to visit.
   */
  visitTypeParameters(node: {
    typeParameters?:
      | TSESTree.TSTypeParameterDeclaration
      | TSESTree.TSTypeParameterInstantiation;
  }): void {
    if (node.typeParameters) {
      const upperTypeMode = this.typeMode;
      this.typeMode = true;
      this.visit(node.typeParameters);
      this.typeMode = upperTypeMode;
    }
  }

  /**
   * Override.
   */
  JSXOpeningElement(node: TSESTree.JSXOpeningElement): void {
    this.visit(node.name);
    this.visitTypeParameters(node);
    node.attributes.forEach(this.visit, this);
  }

  /**
   * Override.
   * Don't create the reference object in the type mode.
   * @param node The Identifier node to visit.
   */
  Identifier(node: TSESTree.Identifier): void {
    this.visitDecorators(node.decorators);

    if (!this.typeMode) {
      super.Identifier(node);
    }

    this.visit(node.typeAnnotation);
  }

  /**
   * Override.
   * Visit decorators.
   * @param node The MethodDefinition node to visit.
   */
  MethodDefinition(
    node: TSESTree.MethodDefinition | TSESTree.TSAbstractMethodDefinition,
  ): void {
    this.visitDecorators(node.decorators);
    super.MethodDefinition(node);
  }

  /**
   * Don't create the reference object for the key if not computed.
   * @param node The ClassProperty node to visit.
   */
  ClassProperty(
    node: TSESTree.ClassProperty | TSESTree.TSAbstractClassProperty,
  ): void {
    const upperTypeMode = this.typeMode;
    const { computed, decorators, key, typeAnnotation, value } = node;

    this.typeMode = false;
    this.visitDecorators(decorators);
    if (computed) {
      this.visit(key);
    }
    this.typeMode = true;
    this.visit(typeAnnotation);
    this.typeMode = false;
    this.visit(value);

    this.typeMode = upperTypeMode;
  }

  /**
   * Visit new expression.
   * @param node The NewExpression node to visit.
   */
  NewExpression(node: TSESTree.NewExpression): void {
    this.visitTypeParameters(node);
    this.visit(node.callee);

    node.arguments.forEach(this.visit, this);
  }

  /**
   * Override.
   * Visit call expression.
   * @param node The CallExpression node to visit.
   */
  CallExpression(node: TSESTree.CallExpression): void {
    this.visitTypeParameters(node);

    this.visit(node.callee);

    node.arguments.forEach(this.visit, this);
  }

  /**
   * Visit optional member expression.
   * @param node The OptionalMemberExpression node to visit.
   */
  OptionalMemberExpression(node: TSESTree.OptionalMemberExpression): void {
    this.visit(node.object);
    if (node.computed) {
      this.visit(node.property);
    }
  }

  /**
   * Visit optional call expression.
   * @param node The OptionalMemberExpression node to visit.
   */
  OptionalCallExpression(node: TSESTree.OptionalCallExpression): void {
    this.visitTypeParameters(node);

    this.visit(node.callee);

    node.arguments.forEach(this.visit, this);
  }

  /**
   * Define the variable of this function declaration only once.
   * Because to avoid confusion of `no-redeclare` rule by overloading.
   * @param node The TSDeclareFunction node to visit.
   */
  TSDeclareFunction(node: TSESTree.TSDeclareFunction): void {
    const scopeManager = this.scopeManager;
    const upperScope = this.currentScope();
    const { id, typeParameters, params, returnType } = node;

    // Ignore this if other overload have already existed.
    if (id) {
      const variable = upperScope.set.get(id.name);
      const defs = variable?.defs;
      const existed = defs?.some((d): boolean => d.type === 'FunctionName');
      if (!existed) {
        upperScope.__define(
          id,
          new TSESLintScope.Definition(
            'FunctionName',
            id,
            node,
            null,
            null,
            null,
          ),
        );
      }
    }

    // Open the function scope.
    scopeManager.__nestEmptyFunctionScope(node);
    const innerScope = this.currentScope();

    // Process the type parameters
    this.visit(typeParameters);

    // Process parameter declarations.
    for (let i = 0; i < params.length; ++i) {
      this.visitPattern(
        params[i],
        { processRightHandNodes: true },
        (pattern, info) => {
          innerScope.__define(
            pattern,
            new TSESLintScope.ParameterDefinition(pattern, node, i, info.rest),
          );

          // Set `variable.eslintUsed` to tell ESLint that the variable is used.
          const variable = innerScope.set.get(pattern.name);
          if (variable) {
            variable.eslintUsed = true;
          }
          this.referencingDefaultValue(pattern, info.assignments, null, true);
        },
      );
    }

    // Process the return type.
    this.visit(returnType);

    // Close the function scope.
    this.close(node);
  }

  /**
   * Create reference objects for the references in parameters and return type.
   * @param node The TSEmptyBodyFunctionExpression node to visit.
   */
  TSEmptyBodyFunctionExpression(
    node: TSESTree.TSEmptyBodyFunctionExpression,
  ): void {
    const upperTypeMode = this.typeMode;
    const { typeParameters, params, returnType } = node;

    this.typeMode = true;
    this.visit(typeParameters);
    params.forEach(this.visit, this);
    this.visit(returnType);
    this.typeMode = upperTypeMode;
  }

  /**
   * Don't make variable because it declares only types.
   * Switch to the type mode and visit child nodes to find `typeof x` expression in type declarations.
   * @param node The TSInterfaceDeclaration node to visit.
   */
  TSInterfaceDeclaration(node: TSESTree.TSInterfaceDeclaration): void {
    this.visitTypeNodes(node);
  }

  /**
   * Don't make variable because it declares only types.
   * Switch to the type mode and visit child nodes to find `typeof x` expression in type declarations.
   * @param node The TSClassImplements node to visit.
   */
  TSClassImplements(node: TSESTree.TSClassImplements): void {
    this.visitTypeNodes(node);
  }

  /**
   * Don't make variable because it declares only types.
   * Switch to the type mode and visit child nodes to find `typeof x` expression in type declarations.
   * @param node The TSIndexSignature node to visit.
   */
  TSIndexSignature(node: TSESTree.TSIndexSignature): void {
    this.visitTypeNodes(node);
  }

  /**
   * Visit type assertion.
   * @param node The TSTypeAssertion node to visit.
   */
  TSTypeAssertion(node: TSESTree.TSTypeAssertion): void {
    if (this.typeMode) {
      this.visit(node.typeAnnotation);
    } else {
      this.typeMode = true;
      this.visit(node.typeAnnotation);
      this.typeMode = false;
    }

    this.visit(node.expression);
  }

  /**
   * Visit as expression.
   * @param node The TSAsExpression node to visit.
   */
  TSAsExpression(node: TSESTree.TSAsExpression): void {
    this.visit(node.expression);

    if (this.typeMode) {
      this.visit(node.typeAnnotation);
    } else {
      this.typeMode = true;
      this.visit(node.typeAnnotation);
      this.typeMode = false;
    }
  }

  /**
   * Switch to the type mode and visit child nodes to find `typeof x` expression in type declarations.
   * @param node The TSTypeAnnotation node to visit.
   */
  TSTypeAnnotation(node: TSESTree.TSTypeAnnotation): void {
    this.visitTypeNodes(node);
  }

  /**
   * Switch to the type mode and visit child nodes to find `typeof x` expression in type declarations.
   * @param node The TSTypeParameterDeclaration node to visit.
   */
  TSTypeParameterDeclaration(node: TSESTree.TSTypeParameterDeclaration): void {
    this.visitTypeNodes(node);
  }

  /**
   * Create reference objects for the references in `typeof` expression.
   * @param node The TSTypeQuery node to visit.
   */
  TSTypeQuery(node: TSESTree.TSTypeQuery): void {
    if (this.typeMode) {
      this.typeMode = false;
      this.visitChildren(node);
      this.typeMode = true;
    } else {
      this.visitChildren(node);
    }
  }

  /**
   * @param node The TSTypeParameter node to visit.
   */
  TSTypeParameter(node: TSESTree.TSTypeParameter): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSInferType node to visit.
   */
  TSInferType(node: TSESTree.TSInferType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSTypeReference node to visit.
   */
  TSTypeReference(node: TSESTree.TSTypeReference): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSTypeLiteral node to visit.
   */
  TSTypeLiteral(node: TSESTree.TSTypeLiteral): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSLiteralType node to visit.
   */
  TSLiteralType(node: TSESTree.TSLiteralType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSIntersectionType node to visit.
   */
  TSIntersectionType(node: TSESTree.TSIntersectionType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSConditionalType node to visit.
   */
  TSConditionalType(node: TSESTree.TSConditionalType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSIndexedAccessType node to visit.
   */
  TSIndexedAccessType(node: TSESTree.TSIndexedAccessType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSMappedType node to visit.
   */
  TSMappedType(node: TSESTree.TSMappedType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSOptionalType node to visit.
   */
  TSOptionalType(node: TSESTree.TSOptionalType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSParenthesizedType node to visit.
   */
  TSParenthesizedType(node: TSESTree.TSParenthesizedType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSRestType node to visit.
   */
  TSRestType(node: TSESTree.TSRestType): void {
    this.visitTypeNodes(node);
  }

  /**
   * @param node The TSTupleType node to visit.
   */
  TSTupleType(node: TSESTree.TSTupleType): void {
    this.visitTypeNodes(node);
  }

  /**
   * Create reference objects for the object part. (This is `obj.prop`)
   * @param node The TSQualifiedName node to visit.
   */
  TSQualifiedName(node: TSESTree.TSQualifiedName): void {
    this.visit(node.left);
  }

  /**
   * Create reference objects for the references in computed keys.
   * @param node The TSPropertySignature node to visit.
   */
  TSPropertySignature(node: TSESTree.TSPropertySignature): void {
    const upperTypeMode = this.typeMode;
    const { computed, key, typeAnnotation, initializer } = node;

    if (computed) {
      this.typeMode = false;
      this.visit(key);
      this.typeMode = true;
    } else {
      this.typeMode = true;
      this.visit(key);
    }
    this.visit(typeAnnotation);
    this.visit(initializer);

    this.typeMode = upperTypeMode;
  }

  /**
   * Create reference objects for the references in computed keys.
   * @param node The TSMethodSignature node to visit.
   */
  TSMethodSignature(node: TSESTree.TSMethodSignature): void {
    const upperTypeMode = this.typeMode;
    const { computed, key, typeParameters, params, returnType } = node;

    if (computed) {
      this.typeMode = false;
      this.visit(key);
      this.typeMode = true;
    } else {
      this.typeMode = true;
      this.visit(key);
    }
    this.visit(typeParameters);
    params.forEach(this.visit, this);
    this.visit(returnType);

    this.typeMode = upperTypeMode;
  }

  /**
   * Create variable object for the enum.
   * The enum declaration creates a scope for the enum members.
   *
   * enum E {
   *   A,
   *   B,
   *   C = A + B // A and B are references to the enum member.
   * }
   *
   * const a = 0
   * enum E {
   *   A = a // a is above constant.
   * }
   *
   * @param node The TSEnumDeclaration node to visit.
   */
  TSEnumDeclaration(node: TSESTree.TSEnumDeclaration): void {
    const { id, members } = node;
    const scopeManager = this.scopeManager;
    const scope = this.currentScope();

    if (id) {
      scope.__define(id, new TSESLintScope.Definition('EnumName', id, node));
    }

    scopeManager.__nestEnumScope(node);
    for (const member of members) {
      this.visit(member);
    }
    this.close(node);
  }

  /**
   * Create variable object for the enum member and create reference object for the initializer.
   * And visit the initializer.
   *
   * @param node The TSEnumMember node to visit.
   */
  TSEnumMember(node: TSESTree.TSEnumMember): void {
    const { id, initializer } = node;
    const scope = this.currentScope();

    scope.__define(
      id,
      new TSESLintScope.Definition('EnumMemberName', id, node),
    );
    if (initializer) {
      scope.__referencing(
        id,
        TSESLintScope.Reference.WRITE,
        initializer,
        null,
        false,
        true,
      );
      this.visit(initializer);
    }
  }

  /**
   * Create the variable object for the module name, and visit children.
   * @param node The TSModuleDeclaration node to visit.
   */
  TSModuleDeclaration(node: TSESTree.TSModuleDeclaration): void {
    const scope = this.currentScope();
    const { id, body } = node;

    if (node.global) {
      this.visitGlobalAugmentation(node);
      return;
    }

    if (id && id.type === AST_NODE_TYPES.Identifier) {
      scope.__define(
        id,
        new TSESLintScope.Definition(
          'NamespaceName',
          id,
          node,
          null,
          null,
          null,
        ),
      );
    }
    this.visit(body);
  }

  TSTypeAliasDeclaration(node: TSESTree.TSTypeAliasDeclaration): void {
    this.typeMode = true;
    this.visitChildren(node);
    this.typeMode = false;
  }

  /**
   * Process the module block.
   * @param node The TSModuleBlock node to visit.
   */
  TSModuleBlock(node: TSESTree.TSModuleBlock): void {
    this.scopeManager.__nestBlockScope(node);
    this.visitChildren(node);
    this.close(node);
  }

  TSAbstractClassProperty(node: TSESTree.TSAbstractClassProperty): void {
    this.ClassProperty(node);
  }
  TSAbstractMethodDefinition(node: TSESTree.TSAbstractMethodDefinition): void {
    this.MethodDefinition(node);
  }

  /**
   * Process import equal declaration
   * @param node The TSImportEqualsDeclaration node to visit.
   */
  TSImportEqualsDeclaration(node: TSESTree.TSImportEqualsDeclaration): void {
    const { id, moduleReference } = node;
    if (id && id.type === AST_NODE_TYPES.Identifier) {
      this.currentScope().__define(
        id,
        new TSESLintScope.Definition(
          'ImportBinding',
          id,
          node,
          null,
          null,
          null,
        ),
      );
    }
    this.visit(moduleReference);
  }

  /**
   * Process the global augmentation.
   * 1. Set the global scope as the current scope.
   * 2. Configure the global scope to set `variable.eslintUsed = true` for all defined variables. This means `no-unused-vars` doesn't warn those.
   * @param node The TSModuleDeclaration node to visit.
   */
  visitGlobalAugmentation(node: TSESTree.TSModuleDeclaration): void {
    const scopeManager = this.scopeManager;
    const currentScope = this.currentScope();
    const globalScope = scopeManager.globalScope;
    const originalDefine = globalScope.__define;

    globalScope.__define = overrideDefine(originalDefine);
    scopeManager.__currentScope = globalScope;

    // Skip TSModuleBlock to avoid to create that block scope.
    if (node.body && node.body.type === AST_NODE_TYPES.TSModuleBlock) {
      node.body.body.forEach(this.visit, this);
    }

    scopeManager.__currentScope = currentScope;
    globalScope.__define = originalDefine;
  }

  /**
   * Process decorators.
   * @param decorators The decorator nodes to visit.
   */
  visitDecorators(decorators?: TSESTree.Decorator[]): void {
    if (decorators) {
      decorators.forEach(this.visit, this);
    }
  }

  /**
   * Process all child of type nodes
   * @param node node to be processed
   */
  visitTypeNodes(node: TSESTree.Node): void {
    if (this.typeMode) {
      this.visitChildren(node);
    } else {
      this.typeMode = true;
      this.visitChildren(node);
      this.typeMode = false;
    }
  }
}

export function analyzeScope(
  ast: TSESTree.Program,
  parserOptions: ParserOptions,
): ScopeManager {
  const options = {
    ignoreEval: true,
    optimistic: false,
    directive: false,
    nodejsScope:
      parserOptions.sourceType === 'script' &&
      parserOptions.ecmaFeatures?.globalReturn === true,
    impliedStrict: false,
    sourceType: parserOptions.sourceType,
    ecmaVersion: parserOptions.ecmaVersion ?? 2018,
    childVisitorKeys,
    fallback,
  };

  const scopeManager = new ScopeManager(options);
  const referencer = new Referencer(options, scopeManager);

  referencer.visit(ast);

  return scopeManager;
}