lib: extract validation functions

PR-URL: #18421
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

Author: timotew

lib/internal/encoding.js

@@ -32,6 +32,21 @@ function lazyBuffer() {
   return Buffer;
 }
 
+function validateEncoder(obj) {
+  if (obj == null || obj[kEncoder] !== true)
+    throw new errors.TypeError('ERR_INVALID_THIS', 'TextEncoder');
+}
+
+function validateDecoder(obj) {
+  if (obj == null || obj[kDecoder] !== true)
+    throw new errors.TypeError('ERR_INVALID_THIS', 'TextDecoder');
+}
+
+function validateArgument(prop, expected, propName, expectedName) {
+  if (typeof prop !== expected)
+    throw new errors.Error('ERR_INVALID_ARG_TYPE', propName, expectedName);
+}
+
 const CONVERTER_FLAGS_FLUSH = 0x1;
 const CONVERTER_FLAGS_FATAL = 0x2;
 const CONVERTER_FLAGS_IGNORE_BOM = 0x4;
@@ -288,20 +303,17 @@ class TextEncoder {
   }
 
   get encoding() {
-    if (this == null || this[kEncoder] !== true)
-      throw new errors.TypeError('ERR_INVALID_THIS', 'TextEncoder');
+    validateEncoder(this);
     return 'utf-8';
   }
 
   encode(input = '') {
-    if (this == null || this[kEncoder] !== true)
-      throw new errors.TypeError('ERR_INVALID_THIS', 'TextEncoder');
+    validateEncoder(this);
     return encodeUtf8String(`${input}`);
   }
 
   [inspect](depth, opts) {
-    if (this == null || this[kEncoder] !== true)
-      throw new errors.TypeError('ERR_INVALID_THIS', 'TextEncoder');
+    validateEncoder(this);
     if (typeof depth === 'number' && depth < 0)
       return opts.stylize('[Object]', 'special');
     var ctor = getConstructorOf(this);
@@ -329,8 +341,7 @@ const { hasConverter, TextDecoder } =
     makeTextDecoderJS();
 
 function hasTextDecoder(encoding = 'utf-8') {
-  if (typeof encoding !== 'string')
-    throw new errors.Error('ERR_INVALID_ARG_TYPE', 'encoding', 'string');
+  validateArgument(encoding, 'string', 'encoding', 'string');
   return hasConverter(getEncodingFromLabel(encoding));
 }
 
@@ -344,8 +355,7 @@ function makeTextDecoderICU() {
   class TextDecoder {
     constructor(encoding = 'utf-8', options = {}) {
       encoding = `${encoding}`;
-      if (typeof options !== 'object')
-        throw new errors.Error('ERR_INVALID_ARG_TYPE', 'options', 'Object');
+      validateArgument(options, 'object', 'options', 'Object');
 
       const enc = getEncodingFromLabel(encoding);
       if (enc === undefined)
@@ -369,17 +379,14 @@ function makeTextDecoderICU() {
 
 
     decode(input = empty, options = {}) {
-      if (this == null || this[kDecoder] !== true)
-        throw new errors.TypeError('ERR_INVALID_THIS', 'TextDecoder');
+      validateDecoder(this);
       if (isArrayBuffer(input)) {
         input = lazyBuffer().from(input);
       } else if (!isArrayBufferView(input)) {
         throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'input',
                                    ['ArrayBuffer', 'ArrayBufferView']);
       }
-      if (typeof options !== 'object') {
-        throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'options', 'Object');
-      }
+      validateArgument(options, 'object', 'options', 'Object');
 
       var flags = 0;
       if (options !== null)
@@ -416,8 +423,7 @@ function makeTextDecoderJS() {
   class TextDecoder {
     constructor(encoding = 'utf-8', options = {}) {
       encoding = `${encoding}`;
-      if (typeof options !== 'object')
-        throw new errors.Error('ERR_INVALID_ARG_TYPE', 'options', 'Object');
+      validateArgument(options, 'object', 'options', 'Object');
 
       const enc = getEncodingFromLabel(encoding);
       if (enc === undefined || !hasConverter(enc))
@@ -440,8 +446,7 @@ function makeTextDecoderJS() {
     }
 
     decode(input = empty, options = {}) {
-      if (this == null || this[kDecoder] !== true)
-        throw new errors.TypeError('ERR_INVALID_THIS', 'TextDecoder');
+      validateDecoder(this);
       if (isArrayBuffer(input)) {
         input = lazyBuffer().from(input);
       } else if (isArrayBufferView(input)) {
@@ -451,9 +456,7 @@ function makeTextDecoderJS() {
         throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'input',
                                    ['ArrayBuffer', 'ArrayBufferView']);
       }
-      if (typeof options !== 'object') {
-        throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'options', 'Object');
-      }
+      validateArgument(options, 'object', 'options', 'Object');
 
       if (this[kFlags] & CONVERTER_FLAGS_FLUSH) {
         this[kBOMSeen] = false;
@@ -496,27 +499,23 @@ function makeTextDecoderJS() {
     TextDecoder.prototype,
     Object.getOwnPropertyDescriptors({
       get encoding() {
-        if (this == null || this[kDecoder] !== true)
-          throw new errors.TypeError('ERR_INVALID_THIS', 'TextDecoder');
+        validateDecoder(this);
         return this[kEncoding];
       },
 
       get fatal() {
-        if (this == null || this[kDecoder] !== true)
-          throw new errors.TypeError('ERR_INVALID_THIS', 'TextDecoder');
+        validateDecoder(this);
         return (this[kFlags] & CONVERTER_FLAGS_FATAL) === CONVERTER_FLAGS_FATAL;
       },
 
       get ignoreBOM() {
-        if (this == null || this[kDecoder] !== true)
-          throw new errors.TypeError('ERR_INVALID_THIS', 'TextDecoder');
+        validateDecoder(this);
         return (this[kFlags] & CONVERTER_FLAGS_IGNORE_BOM) ===
                CONVERTER_FLAGS_IGNORE_BOM;
       },
 
       [inspect](depth, opts) {
-        if (this == null || this[kDecoder] !== true)
-          throw new errors.TypeError('ERR_INVALID_THIS', 'TextDecoder');
+        validateDecoder(this);
         if (typeof depth === 'number' && depth < 0)
           return opts.stylize('[Object]', 'special');
         var ctor = getConstructorOf(this);