Fix flow scalar trailing whitespace folding, close #307

Author: puzrin

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - Fix parsing of properties on the first implicit block mapping key, #62.
+- Fix trailing whitespace handling when folding flow scalar lines, #307.
 - Reject top-level block scalars without content indentation, #280.
 - Ensure numbers survive round-trip, #737.
 - Fix test coverage for issue #221.

lib/loader.js

@@ -680,7 +680,9 @@ function readSingleQuotedScalar (state, nodeIndent) {
       throwError(state, 'unexpected end of the document within a single quoted scalar')
     } else {
       state.position++
-      captureEnd = state.position
+      if (!isWhiteSpace(ch)) {
+        captureEnd = state.position
+      }
     }
   }
 
@@ -749,7 +751,9 @@ function readDoubleQuotedScalar (state, nodeIndent) {
       throwError(state, 'unexpected end of the document within a double quoted scalar')
     } else {
       state.position++
-      captureEnd = state.position
+      if (!isWhiteSpace(ch)) {
+        captureEnd = state.position
+      }
     }
   }
 

test/core/issues/0307.js

@@ -0,0 +1,25 @@
+'use strict'
+
+const { it } = require('node:test')
+
+const assert = require('assert')
+const yaml = require('js-yaml')
+
+it('Trims trailing whitespace when folding flow scalar lines', function () {
+  // https://github.com/nodeca/js-yaml/issues/307
+  // https://yaml.org/spec/1.2.0/#id2787745
+  assert.strictEqual(
+    yaml.load('"folded \nto a space,\t\n \nto a line feed, or \t\\\n \\ \tnon-content"'),
+    'folded to a space,\nto a line feed, or \t \tnon-content'
+  )
+
+  assert.strictEqual(
+    yaml.load("'folded \nto a space,\t\n \nto a line feed'"),
+    'folded to a space,\nto a line feed'
+  )
+})
+
+it('Preserves trailing whitespace in the final line of quoted scalars', function () {
+  assert.strictEqual(yaml.load('"line \t"'), 'line \t')
+  assert.strictEqual(yaml.load("'line \t'"), 'line \t')
+})