add processor option

README.md

@@ -157,12 +157,12 @@ setPropertyFromFile({}, 'index.js', {ext: true}, function(err, res) {
 });
 ```
 
-##### options.encoding
+##### options.processor
 
-Type: `String` or `Function`  
+Type: `Function`  
 Default: `undefined`
 
-If you set this option to a function, it will be used to process file contents before setting the property.
+Specify a function to process file contents before setting the properties.
 
 ```javascript
 // foo.txt (abcde)

index.js

@@ -10,7 +10,6 @@ var fs = require('graceful-fs');
 var isRelativePath = require('is-relative');
 var objectPath = require('object-path');
 var stripBom = require('strip-bom');
-var xtend = require('xtend');
 
 module.exports = function setPropertyFromFile(target, filePath, options, cb) {
   if (!target || typeof target !== 'object') {
@@ -34,11 +33,11 @@ module.exports = function setPropertyFromFile(target, filePath, options, cb) {
     throw new Error('Second argument must be a relative path.');
   }
 
-  var encoder;
-
-  if (typeof options.encoding === 'function') {
-    encoder = options.encoding;
-    options = xtend(options, {encoding: null});
+  if (options.processor && typeof options.processor !== 'function') {
+    throw new TypeError(
+      options.processor +
+      ' is not a function. processor option must be a function.'
+    );
   }
 
   if (typeof cb !== 'function') {
@@ -69,8 +68,8 @@ module.exports = function setPropertyFromFile(target, filePath, options, cb) {
 
     result = stripBom(result);
 
-    if (encoder) {
-      result = encoder(result);
+    if (options.processor) {
+      result = options.processor(result);
     }
 
     objectPath.set(target, props, result);

package.json

@@ -41,8 +41,7 @@
     "graceful-fs": "^3.0.5",
     "is-relative": "^0.1.3",
     "object-path": "^0.8.1",
-    "strip-bom": "^1.0.0",
-    "xtend": "^4.0.0"
+    "strip-bom": "^1.0.0"
   },
   "devDependencies": {
     "eslint": "^0.10.1",

test/test.js

@@ -5,7 +5,7 @@ var setPropertyFromFile = require('../');
 var test = require('tape');
 
 test('setPropertyFromFile()', function(t) {
-  t.plan(15);
+  t.plan(16);
 
   var obj = {};
   setPropertyFromFile(obj, '.gitattributes', 'utf8', function(err, res) {
@@ -73,15 +73,15 @@ test('setPropertyFromFile()', function(t) {
     );
   });
 
-  var option = {encoding: Boolean};
+  var option = {processor: Boolean};
 
   setPropertyFromFile({}, 'index.js', option, function(err, res) {
     t.deepEqual(
       [err, res],
       [null, {index: true}],
-      'should process file content with a function using `encoding` option.'
+      'should process file content with a function using `processor` option.'
     );
-    t.deepEqual(option, {encoding: Boolean}, 'should not modify option object.');
+    t.deepEqual(option, {processor: Boolean}, 'should not modify option object.');
   });
 
   setPropertyFromFile({}, 'test/fixtures/a.txt', {ext: true}, function(err, res) {
@@ -92,7 +92,7 @@ test('setPropertyFromFile()', function(t) {
     );
   });
 
-  setPropertyFromFile({}, 'node_modules', function(err) {
+  setPropertyFromFile({}, 'node_modules', {processor: null}, function(err) {
     t.equal(
       err.code,
       'EISDIR',
@@ -113,7 +113,13 @@ test('setPropertyFromFile()', function(t) {
   );
 
   t.throws(
-    setPropertyFromFile.bind(null, {}, '.gitattributes', {}),
+    setPropertyFromFile.bind(null, {}, '.gitattributes', {processor: true}, noop),
+    /TypeError.*must be a function/,
+    'should throw a type error when the `processor` option is not a function.'
+  );
+
+  t.throws(
+    setPropertyFromFile.bind(null, {}, '.gitattributes', {}, [noop]),
     /TypeError.*must be a function/,
     'should throw a type error when the last argument is not a function.'
   );