prop-types.js

/**
 * @fileoverview Prevent missing props validation in a React component definition
 * @author Yannick Croissant
 */
'use strict';

// As for exceptions for props.children or props.className (and alike) look at
// https://github.com/yannickcr/eslint-plugin-react/issues/7

var has = require('has');
var Components = require('../util/Components');
var variable = require('../util/variable');
var annotations = require('../util/annotations');

// ------------------------------------------------------------------------------
// Constants
// ------------------------------------------------------------------------------

var PROPS_REGEX = /^(props|nextProps)$/;
var DIRECT_PROPS_REGEX = /^(props|nextProps)\s*(\.|\[)/;

// ------------------------------------------------------------------------------
// Rule Definition
// ------------------------------------------------------------------------------

module.exports = {
  meta: {
    docs: {
      description: 'Prevent missing props validation in a React component definition',
      category: 'Best Practices',
      recommended: true
    },

    schema: [{
      type: 'object',
      properties: {
        ignore: {
          type: 'array',
          items: {
            type: 'string'
          }
        },
        customValidators: {
          type: 'array',
          items: {
            type: 'string'
          }
        },
        skipUndeclared: {
          type: 'boolean'
        }
      },
      additionalProperties: false
    }]
  },

  create: Components.detect(function(context, components, utils) {

    var sourceCode = context.getSourceCode();
    var configuration = context.options[0] || {};
    var ignored = configuration.ignore || [];
    var customValidators = configuration.customValidators || [];
    var skipUndeclared = configuration.skipUndeclared || false;
    // Used to track the type annotations in scope.
    // Necessary because babel's scopes do not track type annotations.
    var stack = null;

    var MISSING_MESSAGE = '\'{{name}}\' is missing in props validation';

    /**
     * Helper for accessing the current scope in the stack.
     * @param {string} key The name of the identifier to access. If omitted, returns the full scope.
     * @param {ASTNode} value If provided sets the new value for the identifier.
     * @returns {Object|ASTNode} Either the whole scope or the ASTNode associated with the given identifier.
     */
    function typeScope(key, value) {
      if (arguments.length === 0) {
        return stack[stack.length - 1];
      } else if (arguments.length === 1) {
        return stack[stack.length - 1][key];
      }
      stack[stack.length - 1][key] = value;
      return value;
    }

    /**
     * Check if we are in a class constructor
     * @return {boolean} true if we are in a class constructor, false if not
     */
    function inConstructor() {
      var scope = context.getScope();
      while (scope) {
        if (scope.block && scope.block.parent && scope.block.parent.kind === 'constructor') {
          return true;
        }
        scope = scope.upper;
      }
      return false;
    }

    /**
     * Check if we are in a class constructor
     * @return {boolean} true if we are in a class constructor, false if not
     */
    function inComponentWillReceiveProps() {
      var scope = context.getScope();
      while (scope) {
        if (
          scope.block && scope.block.parent &&
          scope.block.parent.key && scope.block.parent.key.name === 'componentWillReceiveProps'
        ) {
          return true;
        }
        scope = scope.upper;
      }
      return false;
    }

    /**
     * Checks if we are using a prop
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if we are using a prop, false if not.
     */
    function isPropTypesUsage(node) {
      var isClassUsage = (
        (utils.getParentES6Component() || utils.getParentES5Component()) &&
        node.object.type === 'ThisExpression' && node.property.name === 'props'
      );
      var isStatelessFunctionUsage = node.object.name === 'props';
      var isNextPropsUsage = node.object.name === 'nextProps' && inComponentWillReceiveProps();
      return isClassUsage || isStatelessFunctionUsage || isNextPropsUsage;
    }

    /**
     * Checks whether the given identifier or member expression points to
     * `Component`, `React.Component` or `React.PureComponent`.
     * Doesn't support aliasing react to anything other than `React`.
     * @param {ASTNode} node The AST node being checke.d
     * @returns {Boolean} True if the node points to react, otherwise false.
     */
    function isReactComponentClass(node) {
      if (!node) {
        return false;
      }
      if (node.type === 'Identifier' && node.name === 'Component') {
        return true;
      } else if (node.type === 'MemberExpression' && node.object.type === 'Identifier') {
        return (
          node.object.name === 'React' &&
          node.property.type === 'Identifier' &&
          (node.property.name === 'Component' || node.property.name === 'PureComponent')
        );
      }
      return false;
    }

    /**
     * Checks if we are declaring a class which extends `React.Component`
     * with `superTypeParameters`, e.g:
     *   `class Foo extends React.Component<null, Object, null> {}`.
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if the node is a type annotated props declaration, false if not.
     */
    function isAnnotatedClass(node) {
      if (node && (node.type === 'ClassExpression' || node.type === 'ClassDeclaration')) {
        if (isReactComponentClass(node.superClass) && node.superTypeParameters) {
          return true;
        }
      }
      return false;
    }

    /**
     * Checks if we are declaring a `props` class property with a flow type annotation.
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if the node is a type annotated props declaration, false if not.
     */
    function isAnnotatedClassPropsDeclaration(node) {
      if (node && node.type === 'ClassProperty') {
        var tokens = context.getFirstTokens(node, 2);
        if (
          node.typeAnnotation && (
            tokens[0].value === 'props' ||
            (tokens[1] && tokens[1].value === 'props')
          )
        ) {
          return true;
        }
      }
      return false;
    }

    /**
     * Checks if we are declaring a prop
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if we are declaring a prop, false if not.
     */
    function isPropTypesDeclaration(node) {
      // Special case for class properties
      // (babel-eslint does not expose property name so we have to rely on tokens)
      if (node && node.type === 'ClassProperty') {
        var tokens = context.getFirstTokens(node, 2);
        if (
          tokens[0].value === 'propTypes' ||
          (tokens[1] && tokens[1].value === 'propTypes')
        ) {
          return true;
        }
        return false;
      }

      return Boolean(
        node &&
        node.name === 'propTypes'
      );

    }

    /**
     * Checks if the prop is ignored
     * @param {String} name Name of the prop to check.
     * @returns {Boolean} True if the prop is ignored, false if not.
     */
    function isIgnored(name) {
      return ignored.indexOf(name) !== -1;
    }

    /**
     * Checks if prop should be validated by plugin-react-proptypes
     * @param {String} validator Name of validator to check.
     * @returns {Boolean} True if validator should be checked by custom validator.
     */
    function hasCustomValidator(validator) {
      return customValidators.indexOf(validator) !== -1;
    }

    /**
     * Checks if the component must be validated
     * @param {Object} component The component to process
     * @returns {Boolean} True if the component must be validated, false if not.
     */
    function mustBeValidated(component) {
      var isSkippedByConfig = skipUndeclared && typeof component.declaredPropTypes === 'undefined';
      return Boolean(
        component &&
        component.usedPropTypes &&
        !component.ignorePropsValidation &&
        !isSkippedByConfig
      );
    }

    /**
     * Internal: Checks if the prop is declared
     * @param {Object} declaredPropTypes Description of propTypes declared in the current component
     * @param {String[]} keyList Dot separated name of the prop to check.
     * @returns {Boolean} True if the prop is declared, false if not.
     */
    function _isDeclaredInComponent(declaredPropTypes, keyList) {
      for (var i = 0, j = keyList.length; i < j; i++) {
        var key = keyList[i];
        var propType = (
          declaredPropTypes && (
            // Check if this key is declared
            (declaredPropTypes[key] || // If not, check if this type accepts any key
            declaredPropTypes.__ANY_KEY__)
          )
        );

        if (!propType) {
          // If it's a computed property, we can't make any further analysis, but is valid
          return key === '__COMPUTED_PROP__';
        }
        if (propType === true) {
          return true;
        }
        // Consider every children as declared
        if (propType.children === true) {
          return true;
        }
        if (propType.acceptedProperties) {
          return key in propType.acceptedProperties;
        }
        if (propType.type === 'union') {
          // If we fall in this case, we know there is at least one complex type in the union
          if (i + 1 >= j) {
            // this is the last key, accept everything
            return true;
          }
          // non trivial, check all of them
          var unionTypes = propType.children;
          var unionPropType = {};
          for (var k = 0, z = unionTypes.length; k < z; k++) {
            unionPropType[key] = unionTypes[k];
            var isValid = _isDeclaredInComponent(
              unionPropType,
              keyList.slice(i)
            );
            if (isValid) {
              return true;
            }
          }

          // every possible union were invalid
          return false;
        }
        declaredPropTypes = propType.children;
      }
      return true;
    }

    /**
     * Checks if the prop is declared
     * @param {ASTNode} node The AST node being checked.
     * @param {String[]} names List of names of the prop to check.
     * @returns {Boolean} True if the prop is declared, false if not.
     */
    function isDeclaredInComponent(node, names) {
      while (node) {
        var component = components.get(node);
        var isDeclared =
          component && component.confidence === 2 &&
          _isDeclaredInComponent(component.declaredPropTypes || {}, names)
        ;
        if (isDeclared) {
          return true;
        }
        node = node.parent;
      }
      return false;
    }

    /**
     * Checks if the prop has spread operator.
     * @param {ASTNode} node The AST node being marked.
     * @returns {Boolean} True if the prop has spread operator, false if not.
     */
    function hasSpreadOperator(node) {
      var tokens = sourceCode.getTokens(node);
      return tokens.length && tokens[0].value === '...';
    }

    /**
     * Retrieve the name of a key node
     * @param {ASTNode} node The AST node with the key.
     * @return {string} the name of the key
     */
    function getKeyValue(node) {
      if (node.type === 'ObjectTypeProperty') {
        var tokens = context.getFirstTokens(node, 2);
        return (tokens[0].value === '+' || tokens[0].value === '-'
          ? tokens[1].value
          : tokens[0].value
        );
      }
      var key = node.key || node.argument;
      return key.type === 'Identifier' ? key.name : key.value;
    }

    /**
     * Iterates through a properties node, like a customized forEach.
     * @param {Object[]} properties Array of properties to iterate.
     * @param {Function} fn Function to call on each property, receives property key
        and property value. (key, value) => void
     */
    function iterateProperties(properties, fn) {
      if (properties.length && typeof fn === 'function') {
        for (var i = 0, j = properties.length; i < j; i++) {
          var node = properties[i];
          var key = getKeyValue(node);

          var value = node.value;
          fn(key, value);
        }
      }
    }

    /**
     * Creates the representation of the React propTypes for the component.
     * The representation is used to verify nested used properties.
     * @param {ASTNode} value Node of the React.PropTypes for the desired property
     * @return {Object|Boolean} The representation of the declaration, true means
     *    the property is declared without the need for further analysis.
     */
    function buildReactDeclarationTypes(value) {
      if (
        value &&
        value.callee &&
        value.callee.object &&
        hasCustomValidator(value.callee.object.name)
      ) {
        return true;
      }

      if (
        value &&
        value.type === 'MemberExpression' &&
        value.property &&
        value.property.name &&
        value.property.name === 'isRequired'
      ) {
        value = value.object;
      }

      // Verify React.PropTypes that are functions
      if (
        value &&
        value.type === 'CallExpression' &&
        value.callee &&
        value.callee.property &&
        value.callee.property.name &&
        value.arguments &&
        value.arguments.length > 0
      ) {
        var callName = value.callee.property.name;
        var argument = value.arguments[0];
        switch (callName) {
          case 'shape':
            if (argument.type !== 'ObjectExpression') {
              // Invalid proptype or cannot analyse statically
              return true;
            }
            var shapeTypeDefinition = {
              type: 'shape',
              children: {}
            };
            iterateProperties(argument.properties, function(childKey, childValue) {
              shapeTypeDefinition.children[childKey] = buildReactDeclarationTypes(childValue);
            });
            return shapeTypeDefinition;
          case 'arrayOf':
          case 'objectOf':
            return {
              type: 'object',
              children: {
                __ANY_KEY__: buildReactDeclarationTypes(argument)
              }
            };
          case 'oneOfType':
            if (
              !argument.elements ||
              !argument.elements.length
            ) {
              // Invalid proptype or cannot analyse statically
              return true;
            }
            var unionTypeDefinition = {
              type: 'union',
              children: []
            };
            for (var i = 0, j = argument.elements.length; i < j; i++) {
              var type = buildReactDeclarationTypes(argument.elements[i]);
              // keep only complex type
              if (type !== true) {
                if (type.children === true) {
                  // every child is accepted for one type, abort type analysis
                  unionTypeDefinition.children = true;
                  return unionTypeDefinition;
                }
              }

              unionTypeDefinition.children.push(type);
            }
            if (unionTypeDefinition.length === 0) {
              // no complex type found, simply accept everything
              return true;
            }
            return unionTypeDefinition;
          case 'instanceOf':
            return {
              type: 'instance',
              // Accept all children because we can't know what type they are
              children: true
            };
          case 'oneOf':
          default:
            return true;
        }
      }
      // Unknown property or accepts everything (any, object, ...)
      return true;
    }

    /**
     * Creates the representation of the React props type annotation for the component.
     * The representation is used to verify nested used properties.
     * @param {ASTNode} annotation Type annotation for the props class property.
     * @param {Set<ASTNode>} seen Keeps track of annotations we've already seen.
     * @return {Object|Boolean} The representation of the declaration, true means
     *    the property is declared without the need for further analysis.
     */
    function buildTypeAnnotationDeclarationTypes(annotation, seen) {
      if (seen === void 0) {
        // Keeps track of annotations we've already seen to
        // prevent problems with cyclic types.
        seen = new Set();
      }
      if (seen.has(annotation)) {
        // this must be a recursive type annotation, just accept anything.
        return true;
      }
      seen.add(annotation);
      switch (annotation.type) {
        case 'GenericTypeAnnotation':
          if (typeScope(annotation.id.name)) {
            return buildTypeAnnotationDeclarationTypes(typeScope(annotation.id.name), seen);
          }
          return true;
        case 'ObjectTypeAnnotation':
          var shapeTypeDefinition = {
            type: 'shape',
            children: {}
          };
          iterateProperties(annotation.properties, function(childKey, childValue) {
            shapeTypeDefinition.children[childKey] = buildTypeAnnotationDeclarationTypes(childValue, seen);
          });
          return shapeTypeDefinition;
        case 'UnionTypeAnnotation':
          var unionTypeDefinition = {
            type: 'union',
            children: []
          };
          for (var i = 0, j = annotation.types.length; i < j; i++) {
            var type = buildTypeAnnotationDeclarationTypes(annotation.types[i], seen);
            // keep only complex type
            if (type !== true) {
              if (type.children === true) {
                // every child is accepted for one type, abort type analysis
                unionTypeDefinition.children = true;
                return unionTypeDefinition;
              }
            }

            unionTypeDefinition.children.push(type);
          }
          if (unionTypeDefinition.children.length === 0) {
            // no complex type found, simply accept everything
            return true;
          }
          return unionTypeDefinition;
        case 'ArrayTypeAnnotation':
          return {
            type: 'object',
            children: {
              __ANY_KEY__: buildTypeAnnotationDeclarationTypes(annotation.elementType, seen)
            }
          };
        default:
          // Unknown or accepts everything.
          return true;
      }
    }

    /**
     * Retrieve the name of a property node
     * @param {ASTNode} node The AST node with the property.
     * @return {string} the name of the property or undefined if not found
     */
    function getPropertyName(node) {
      var isDirectProp = DIRECT_PROPS_REGEX.test(sourceCode.getText(node));
      var isInClassComponent = utils.getParentES6Component() || utils.getParentES5Component();
      var isNotInConstructor = !inConstructor();
      var isNotInComponentWillReceiveProps = !inComponentWillReceiveProps();
      if (isDirectProp && isInClassComponent && isNotInConstructor && isNotInComponentWillReceiveProps) {
        return void 0;
      }
      if (!isDirectProp) {
        node = node.parent;
      }
      var property = node.property;
      if (property) {
        switch (property.type) {
          case 'Identifier':
            if (node.computed) {
              return '__COMPUTED_PROP__';
            }
            return property.name;
          case 'MemberExpression':
            return void 0;
          case 'Literal':
            // Accept computed properties that are literal strings
            if (typeof property.value === 'string') {
              return property.value;
            }
            // falls through
          default:
            if (node.computed) {
              return '__COMPUTED_PROP__';
            }
            break;
        }
      }
      return void 0;
    }

    /**
     * Mark a prop type as used
     * @param {ASTNode} node The AST node being marked.
     */
    function markPropTypesAsUsed(node, parentNames) {
      parentNames = parentNames || [];
      var type;
      var name;
      var allNames;
      var properties;
      switch (node.type) {
        case 'MemberExpression':
          name = getPropertyName(node);
          if (name) {
            allNames = parentNames.concat(name);
            if (node.parent.type === 'MemberExpression') {
              markPropTypesAsUsed(node.parent, allNames);
            }
            // Do not mark computed props as used.
            type = name !== '__COMPUTED_PROP__' ? 'direct' : null;
          } else if (
            node.parent.id &&
            node.parent.id.properties &&
            node.parent.id.properties.length &&
            getKeyValue(node.parent.id.properties[0])
          ) {
            type = 'destructuring';
            properties = node.parent.id.properties;
          }
          break;
        case 'ArrowFunctionExpression':
        case 'FunctionDeclaration':
        case 'FunctionExpression':
          type = 'destructuring';
          properties = node.params[0].properties;
          break;
        case 'VariableDeclarator':
          for (var i = 0, j = node.id.properties.length; i < j; i++) {
            // let {props: {firstname}} = this
            var thisDestructuring = (
              !hasSpreadOperator(node.id.properties[i]) &&
              (PROPS_REGEX.test(node.id.properties[i].key.name) || PROPS_REGEX.test(node.id.properties[i].key.value)) &&
              node.id.properties[i].value.type === 'ObjectPattern'
            );
            // let {firstname} = props
            var directDestructuring =
              PROPS_REGEX.test(node.init.name) &&
              (utils.getParentStatelessComponent() || inConstructor() || inComponentWillReceiveProps())
            ;

            if (thisDestructuring) {
              properties = node.id.properties[i].value.properties;
            } else if (directDestructuring) {
              properties = node.id.properties;
            } else {
              continue;
            }
            type = 'destructuring';
            break;
          }
          break;
        default:
          throw new Error(node.type + ' ASTNodes are not handled by markPropTypesAsUsed');
      }

      var component = components.get(utils.getParentComponent());
      var usedPropTypes = (component && component.usedPropTypes || []).slice();

      switch (type) {
        case 'direct':
          // Ignore Object methods
          if (Object.prototype[name]) {
            break;
          }

          var isDirectProp = DIRECT_PROPS_REGEX.test(sourceCode.getText(node));

          usedPropTypes.push({
            name: name,
            allNames: allNames,
            node: (
              !isDirectProp && !inConstructor() && !inComponentWillReceiveProps() ? node.parent.property :
              node.property
            )
          });
          break;
        case 'destructuring':
          for (var k = 0, l = properties.length; k < l; k++) {
            if (hasSpreadOperator(properties[k]) || properties[k].computed) {
              continue;
            }
            var propName = getKeyValue(properties[k]);

            var currentNode = node;
            allNames = [];
            while (currentNode.property && !PROPS_REGEX.test(currentNode.property.name)) {
              allNames.unshift(currentNode.property.name);
              currentNode = currentNode.object;
            }
            allNames.push(propName);

            if (propName) {
              usedPropTypes.push({
                name: propName,
                allNames: allNames,
                node: properties[k]
              });
            }
          }
          break;
        default:
          break;
      }

      components.set(node, {
        usedPropTypes: usedPropTypes
      });
    }

    /**
     * Mark a prop type as declared
     * @param {ASTNode} node The AST node being checked.
     * @param {propTypes} node The AST node containing the proptypes
     */
    function markPropTypesAsDeclared(node, propTypes) {
      var componentNode = node;
      while (componentNode && !components.get(componentNode)) {
        componentNode = componentNode.parent;
      }
      var component = components.get(componentNode);
      var declaredPropTypes = component && component.declaredPropTypes || {};
      var ignorePropsValidation = false;

      switch (propTypes && propTypes.type) {
        case 'ObjectTypeAnnotation':
          iterateProperties(propTypes.properties, function(key, value) {
            declaredPropTypes[key] = buildTypeAnnotationDeclarationTypes(value);
          });
          break;
        case 'ObjectExpression':
          iterateProperties(propTypes.properties, function(key, value) {
            if (!value) {
              ignorePropsValidation = true;
              return;
            }
            declaredPropTypes[key] = buildReactDeclarationTypes(value);
          });
          break;
        case 'MemberExpression':
          var curDeclaredPropTypes = declaredPropTypes;
          // Walk the list of properties, until we reach the assignment
          // ie: ClassX.propTypes.a.b.c = ...
          while (
            propTypes &&
            propTypes.parent &&
            propTypes.parent.type !== 'AssignmentExpression' &&
            propTypes.property &&
            curDeclaredPropTypes
          ) {
            var propName = propTypes.property.name;
            if (propName in curDeclaredPropTypes) {
              curDeclaredPropTypes = curDeclaredPropTypes[propName].children;
              propTypes = propTypes.parent;
            } else {
              // This will crash at runtime because we haven't seen this key before
              // stop this and do not declare it
              propTypes = null;
            }
          }
          if (propTypes && propTypes.parent && propTypes.property) {
            curDeclaredPropTypes[propTypes.property.name] =
              buildReactDeclarationTypes(propTypes.parent.right);
          } else {
            ignorePropsValidation = true;
          }
          break;
        case 'Identifier':
          var variablesInScope = variable.variablesInScope(context);
          for (var i = 0, j = variablesInScope.length; i < j; i++) {
            if (variablesInScope[i].name !== propTypes.name) {
              continue;
            }
            var defInScope = variablesInScope[i].defs[variablesInScope[i].defs.length - 1];
            markPropTypesAsDeclared(node, defInScope.node && defInScope.node.init);
            return;
          }
          ignorePropsValidation = true;
          break;
        case null:
          break;
        default:
          ignorePropsValidation = true;
          break;
      }

      components.set(node, {
        declaredPropTypes: declaredPropTypes,
        ignorePropsValidation: ignorePropsValidation
      });
    }

    /**
     * Reports undeclared proptypes for a given component
     * @param {Object} component The component to process
     */
    function reportUndeclaredPropTypes(component) {
      var allNames;
      for (var i = 0, j = component.usedPropTypes.length; i < j; i++) {
        allNames = component.usedPropTypes[i].allNames;
        if (
          isIgnored(allNames[0]) ||
          isDeclaredInComponent(component.node, allNames)
        ) {
          continue;
        }
        context.report(
          component.usedPropTypes[i].node,
          MISSING_MESSAGE, {
            name: allNames.join('.').replace(/\.__COMPUTED_PROP__/g, '[]')
          }
        );
      }
    }

    /**
     * Resolve the type annotation for a given node.
     * Flow annotations are sometimes wrapped in outer `TypeAnnotation`
     * and `NullableTypeAnnotation` nodes which obscure the annotation we're
     * interested in.
     * This method also resolves type aliases where possible.
     *
     * @param {ASTNode} node The annotation or a node containing the type annotation.
     * @returns {ASTNode} The resolved type annotation for the node.
     */
    function resolveTypeAnnotation(node) {
      var annotation = node.typeAnnotation || node;
      while (annotation && (annotation.type === 'TypeAnnotation' || annotation.type === 'NullableTypeAnnotation')) {
        annotation = annotation.typeAnnotation;
      }
      if (annotation.type === 'GenericTypeAnnotation' && typeScope(annotation.id.name)) {
        return typeScope(annotation.id.name);
      }
      return annotation;
    }

    /**
     * @param {ASTNode} node We expect either an ArrowFunctionExpression,
     *   FunctionDeclaration, or FunctionExpression
     */
    function markDestructuredFunctionArgumentsAsUsed(node) {
      var destructuring = node.params && node.params[0] && node.params[0].type === 'ObjectPattern';
      if (destructuring && components.get(node)) {
        markPropTypesAsUsed(node);
      }
    }

    /**
     * @param {ASTNode} node We expect either an ArrowFunctionExpression,
     *   FunctionDeclaration, or FunctionExpression
     */
    function markAnnotatedFunctionArgumentsAsDeclared(node) {
      if (!node.params || !node.params.length || !annotations.isAnnotatedFunctionPropsDeclaration(node, context)) {
        return;
      }
      markPropTypesAsDeclared(node, resolveTypeAnnotation(node.params[0]));
    }

    /**
     * @param {ASTNode} node We expect either an ArrowFunctionExpression,
     *   FunctionDeclaration, or FunctionExpression
     */
    function handleStatelessComponent(node) {
      markDestructuredFunctionArgumentsAsUsed(node);
      markAnnotatedFunctionArgumentsAsDeclared(node);
    }

    /**
     * Handles classes possibly annotated with Flow.
     * @param {ASTNode} node We expect either a ClassDeclaration or ClassExpression.
     */
    function handleClass(node) {
      if (isAnnotatedClass(node)) {
        var typeParameters = node.superTypeParameters.params;
        if (typeParameters.length > 1) {
          markPropTypesAsDeclared(node, resolveTypeAnnotation(typeParameters[1]));
        }
      }
    }

    // --------------------------------------------------------------------------
    // Public
    // --------------------------------------------------------------------------

    return {
      ClassDeclaration: handleClass,

      ClassExpression: handleClass,

      ClassProperty: function(node) {
        if (isAnnotatedClassPropsDeclaration(node)) {
          markPropTypesAsDeclared(node, resolveTypeAnnotation(node));
        } else if (isPropTypesDeclaration(node)) {
          markPropTypesAsDeclared(node, node.value);
        }
      },

      VariableDeclarator: function(node) {
        var destructuring = node.init && node.id && node.id.type === 'ObjectPattern';
        // let {props: {firstname}} = this
        var thisDestructuring = destructuring && node.init.type === 'ThisExpression';
        // let {firstname} = props
        var directDestructuring =
          destructuring &&
          PROPS_REGEX.test(node.init.name) &&
          (utils.getParentStatelessComponent() || inConstructor() || inComponentWillReceiveProps())
        ;

        if (!thisDestructuring && !directDestructuring) {
          return;
        }
        markPropTypesAsUsed(node);
      },

      FunctionDeclaration: handleStatelessComponent,

      ArrowFunctionExpression: handleStatelessComponent,

      FunctionExpression: handleStatelessComponent,

      MemberExpression: function(node) {
        var type;
        if (isPropTypesUsage(node)) {
          type = 'usage';
        } else if (isPropTypesDeclaration(node.property)) {
          type = 'declaration';
        }

        switch (type) {
          case 'usage':
            markPropTypesAsUsed(node);
            break;
          case 'declaration':
            var component = utils.getRelatedComponent(node);
            if (!component) {
              return;
            }
            markPropTypesAsDeclared(component.node, node.parent.right || node.parent);
            break;
          default:
            break;
        }
      },

      MethodDefinition: function(node) {
        if (!isPropTypesDeclaration(node.key)) {
          return;
        }

        var i = node.value.body.body.length - 1;
        for (; i >= 0; i--) {
          if (node.value.body.body[i].type === 'ReturnStatement') {
            break;
          }
        }

        if (i >= 0) {
          markPropTypesAsDeclared(node, node.value.body.body[i].argument);
        }
      },

      ObjectExpression: function(node) {
        // Search for the proptypes declaration
        node.properties.forEach(function(property) {
          if (!isPropTypesDeclaration(property.key)) {
            return;
          }
          markPropTypesAsDeclared(node, property.value);
        });
      },

      TypeAlias: function(node) {
        typeScope(node.id.name, node.right);
      },

      Program: function() {
        stack = [{}];
      },

      BlockStatement: function () {
        stack.push(Object.create(typeScope()));
      },

      'BlockStatement:exit': function () {
        stack.pop();
      },

      'Program:exit': function() {
        stack = null;
        var list = components.list();
        // Report undeclared proptypes for all classes
        for (var component in list) {
          if (!has(list, component) || !mustBeValidated(list[component])) {
            continue;
          }
          reportUndeclaredPropTypes(list[component]);
        }
      }
    };

  })
};