readline: properly handle 0-width characters

TimothyGu · jasnell · commit 01aeb388000b · 2017-06-28T21:50:49.000-07:00
PR-URL: #13918 Reviewed-By: James M Snell <jasnell@gmail.com>
diff --git a/lib/readline.js b/lib/readline.js
@@ -682,13 +682,14 @@ Interface.prototype._getDisplayPos = function(str) {
       row += 1;
       continue;
     }
-    if (isFullWidthCodePoint(code)) {
+    const width = getStringWidth(code);
+    if (width === 0 || width === 1) {
+      offset += width;
+    } else { // width === 2
       if ((offset + 1) % col === 0) {
         offset++;
       }
       offset += 2;
-    } else {
-      offset++;
     }
   }
   var cols = offset % col;
diff --git a/test/parallel/test-readline-position.js b/test/parallel/test-readline-position.js
@@ -0,0 +1,31 @@
+'use strict';
+require('../common');
+const { PassThrough } = require('stream');
+const readline = require('readline');
+const assert = require('assert');
+
+const ctrlU = { ctrl: true, name: 'u' };
+
+{
+  const input = new PassThrough();
+  const rl = readline.createInterface({
+    terminal: true,
+    input: input,
+    prompt: ''
+  });
+
+  for (const [cursor, string] of [
+    [1, 'a'],
+    [2, 'ab'],
+    [2, '丁'],
+    [0, '\u0301'],   // COMBINING ACUTE ACCENT
+    [1, 'a\u0301'],  // á
+    [0, '\u20DD'],   // COMBINING ENCLOSING CIRCLE
+    [2, 'a\u20DDb'], // a⃝b
+    [0, '\u200E']    // LEFT-TO-RIGHT MARK
+  ]) {
+    rl.write(string);
+    assert.strictEqual(rl._getCursorPos().cols, cursor);
+    rl.write(null, ctrlU);
+  }
+}

Original file line number	Diff line number	Diff line change
`@@ -682,13 +682,14 @@ Interface.prototype._getDisplayPos = function(str) {`
`682`	`682`	`row += 1;`
`683`	`683`	`continue;`
`684`	`684`	`}`
`685`		`- if (isFullWidthCodePoint(code)) {`
	`685`	`+ const width = getStringWidth(code);`
	`686`	`+ if (width === 0 \|\| width === 1) {`
	`687`	`+ offset += width;`
	`688`	`+ } else { // width === 2`
`686`	`689`	`if ((offset + 1) % col === 0) {`
`687`	`690`	`offset++;`
`688`	`691`	`}`
`689`	`692`	`offset += 2;`
`690`		`- } else {`
`691`		`- offset++;`
`692`	`693`	`}`
`693`	`694`	`}`
`694`	`695`	`var cols = offset % col;`