readline: use named constant for surrogate checks

This commit defines a named constant instead of using a mix of 2 ** 16 and 0X10000 throughout the code.
nodejs · Jul 10, 2019 · 9ff7ccb · 9ff7ccb
1 parent f763ff0
commit 9ff7ccb
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Showing 2 changed files with 7 additions and 4 deletions.
diff --git a/lib/internal/readline/interface.js b/lib/internal/readline/interface.js
@@ -9,6 +9,7 @@ const {
   getStringWidth,
   isFullWidthCodePoint,
   kEscapeCodeTimeout,
+  kUTF16SurrogateThreshold,
   moveCursor,
   stripVTControlCharacters
 } = require('internal/readline/utils');
@@ -1051,8 +1052,8 @@ function charLengthLeft(str, i) {
   if (i <= 0)
     return 0;
 
-  if (i > 1 && str.codePointAt(i - 2) >= 2 ** 16 ||
-      str.codePointAt(i - 1) >= 2 ** 16) {
+  if (i > 1 && str.codePointAt(i - 2) >= kUTF16SurrogateThreshold ||
+      str.codePointAt(i - 1) >= kUTF16SurrogateThreshold) {
     return 2;
   }
 
@@ -1063,7 +1064,7 @@ function charLengthLeft(str, i) {
 function charLengthAt(str, i) {
   if (str.length <= i)
     return 0;
-  return str.codePointAt(i) >= 2 ** 16 ? 2 : 1;
+  return str.codePointAt(i) >= kUTF16SurrogateThreshold ? 2 : 1;
 }
 
 

diff --git a/lib/internal/readline/utils.js b/lib/internal/readline/utils.js
@@ -17,6 +17,7 @@ const kEscapeCodeTimeout = 500;
 
 const kKeypressDecoder = Symbol('keypress-decoder');
 const kEscapeDecoder = Symbol('escape-decoder');
+const kUTF16SurrogateThreshold = 0x10000; // 2 ** 16
 const kEscape = '\x1b';
 
 let StringDecoder;  // Lazy loaded.
@@ -72,7 +73,7 @@ if (internalBinding('config').hasIntl) {
     for (var i = 0; i < str.length; i++) {
       const code = str.codePointAt(i);
 
-      if (code >= 0x10000) { // surrogates
+      if (code >= kUTF16SurrogateThreshold) { // Surrogates.
         i++;
       }
 
@@ -580,6 +581,7 @@ module.exports = {
   getStringWidth,
   isFullWidthCodePoint,
   kEscapeCodeTimeout,
+  kUTF16SurrogateThreshold,
   moveCursor,
   stripVTControlCharacters,
   CSI // CSI is only exported for testing purposes.