Remove direct dependency on lodash

package.json

@@ -34,7 +34,6 @@
     "colors": "^1.1.2",
     "flow-parser": "^0.*",
     "graceful-fs": "^4.1.11",
-    "lodash": "^4.13.1",
     "micromatch": "^2.3.7",
     "neo-async": "^2.5.0",
     "node-dir": "^0.1.17",

src/Collection.js

@@ -11,8 +11,9 @@
 'use strict';
 
 const assert = require('assert');
+const intersection = require('./utils/intersection');
 const recast = require('recast');
-const _ = require('lodash');
+const union = require('./utils/union');
 
 const astTypes = recast.types;
 var types = astTypes.namedTypes;
@@ -260,8 +261,7 @@ function _inferTypes(paths) {
       );
     } else {
       // try to find a common type
-      _types = _.intersection.apply(
-        null,
+      _types = intersection(
         paths.map(path => astTypes.getSupertypeNames(path.node.type))
       );
     }
@@ -274,10 +274,9 @@ function _toTypeArray(value) {
   value = !Array.isArray(value) ? [value] : value;
   value = value.map(v => v.toString());
   if (value.length > 1) {
-    return _.union(value, _.intersection.apply(
-      null,
-      value.map(_getSupertypeNames)
-    ));
+    return union(
+      [value].concat(intersection(value.map(_getSupertypeNames)))
+    );
   } else {
     return value.concat(_getSupertypeNames(value[0]));
   }

src/collections/JSXElement.js

@@ -10,11 +10,11 @@
 
 'use strict';
 
-const _ = require('lodash');
 const Collection = require('../Collection');
 const NodeCollection = require('./Node');
 
 const assert = require('assert');
+const once = require('../utils/once');
 const recast = require('recast');
 const requiresModule = require('./VariableDeclarator').filters.requiresModule;
 
@@ -199,6 +199,6 @@ function register() {
   Collection.registerMethods(traversalMethods, JSXElement);
 }
 
-exports.register = _.once(register);
+exports.register = once(register);
 exports.filters = filterMethods;
 exports.mappings = mappingMethods;

src/collections/Node.js

@@ -10,10 +10,10 @@
 
 'use strict';
 
-const _ = require('lodash');
 const Collection = require('../Collection');
 
 const matchNode = require('../matchNode');
+const once = require('../utils/once');
 const recast = require('recast');
 
 const Node = recast.types.namedTypes.Node;
@@ -186,4 +186,4 @@ function register() {
   Collection.setDefaultCollectionType(Node);
 }
 
-exports.register = _.once(register);
+exports.register = once(register);

src/collections/VariableDeclarator.js

@@ -10,9 +10,9 @@
 
 'use strict';
 
-const _ = require('lodash');
 const Collection = require('../Collection');
 const NodeCollection = require('./Node');
+const once = require('../utils/once');
 const recast = require('recast');
 
 const astNodesAreEquivalent = recast.types.astNodesAreEquivalent;
@@ -134,8 +134,8 @@ const transformMethods = {
             scope = scope.parent;
           }
           if (scope) { // identifier must refer to declared variable
-            
-            // It may look like we filtered out properties, 
+
+            // It may look like we filtered out properties,
             // but the filter only ignored property "keys", not "value"s
             // In shorthand properties, "key" and "value" both have an
             // Identifier with the same structure.
@@ -163,5 +163,5 @@ function register() {
   Collection.registerMethods(transformMethods, VariableDeclarator);
 }
 
-exports.register = _.once(register);
+exports.register = once(register);
 exports.filters = filterMethods;

src/utils/__tests__/intersection-test.js

@@ -0,0 +1,35 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+const intersection = require('../intersection');
+
+function test(testCases) {
+  for (const testName in testCases) {
+    const testCase = testCases[testName];
+    it(testName, function() {
+      expect(intersection(testCase.input)).toEqual(testCase.output);
+    });
+  }
+}
+
+describe('intersection', function() {
+  test({
+    'intersects string values': {
+      input: [['foo', 'bar', 'baz'], ['foo', 'bar'], ['bar', 'baz']],
+      output: ['bar'],
+    },
+
+    'returns empty list if no intersection': {
+      input: [['foo', 'bar', 'baz'], ['foo'], ['bar']],
+      output: [],
+    },
+  });
+});
+

src/utils/__tests__/once-test.js

@@ -0,0 +1,25 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+const once = require('../once');
+
+describe('once', function() {
+  it('executes the function only once', function() {
+    const mock = jest.fn().mockImplementation(foo => foo);
+    const wrapped = once(mock);
+
+    wrapped('foo');
+    const result = wrapped('bar');
+
+    expect(result).toEqual('foo');
+    expect(mock).toHaveBeenCalledTimes(1);
+  });
+});
+

src/utils/__tests__/union-test.js

@@ -0,0 +1,35 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+const union = require('../union');
+
+function test(testCases) {
+  for (const testName in testCases) {
+    const testCase = testCases[testName];
+    it(testName, function() {
+      expect(union(testCase.input)).toEqual(testCase.output);
+    });
+  }
+}
+
+describe('union', function() {
+  test({
+    'unions string values': {
+      input: [['foo', 'bar', 'baz'], ['foo', 'bar'], ['bar', 'baz']],
+      output: ['foo', 'bar', 'baz'],
+    },
+
+    'understands empty input arrays': {
+      input: [[], ['foo'], ['bar']],
+      output: ['foo', 'bar'],
+    },
+  });
+});
+

src/utils/intersection.js

@@ -0,0 +1,29 @@
+/*
+ *  Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+
+module.exports = function(arrays) {
+  const result = new Set(arrays[0]);
+  let resultSize = result.length;
+
+  let i, value, valuesToCheck;
+  for (i = 1; i < arrays.length; i++) {
+    valuesToCheck = new Set(arrays[i]);
+    for (value of result) {
+      if (!valuesToCheck.has(value)) {
+        result.delete(value);
+        resultSize -= 1;
+      }
+      if (resultSize === 0) {
+        return [];
+      }
+    }
+  }
+
+  return Array.from(result);
+};

src/utils/once.js

@@ -0,0 +1,23 @@
+/*
+ *  Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+
+/**
+ * This replicates lodash's once functionality for our purposes.
+ */
+module.exports = function(func) {
+  let called = false;
+  let result;
+  return function(...args) {
+    if (called) {
+      return result;
+    }
+    called = true;
+    return result = func.apply(this, args);
+  };
+};

src/utils/union.js

@@ -0,0 +1,22 @@
+/*
+ *  Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+
+module.exports = function(arrays) {
+  const result = new Set(arrays[0]);
+
+  let i,j, array;
+  for (i = 1; i < arrays.length; i++) {
+    array = arrays[i];
+    for (j = 0; j < array.length; j++) {
+      result.add(array[j]);
+    }
+  }
+
+  return Array.from(result);
+};

yarn.lock

@@ -2197,7 +2197,7 @@ lodash.pickby@^4.0.0:
   version "4.6.0"
   resolved "https://registry.yarnpkg.com/lodash.pickby/-/lodash.pickby-4.6.0.tgz#7dea21d8c18d7703a27c704c15d3b84a67e33aff"
 
-lodash@^4.0.0, lodash@^4.13.1, lodash@^4.14.0, lodash@^4.2.0, lodash@^4.3.0:
+lodash@^4.0.0, lodash@^4.14.0, lodash@^4.2.0, lodash@^4.3.0:
   version "4.17.4"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.4.tgz#78203a4d1c328ae1d86dca6460e369b57f4055ae"