Don't quote literals with : except when necessary

fix #470

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Reduced nesting of `/lib` folder.
 - Parse numbers according to YAML 1.2 instead of YAML 1.1 (`01234` is now decimal,
   `0o1234` is octal, `1:23` is parsed as string instead of base60).
+- `dump()` no longer quotes `:` except when necessary, #470.
 
 ### Added
 - Added `.mjs` (es modules) support.

lib/dumper.js

@@ -57,6 +57,8 @@ var DEPRECATED_BOOLEANS_SYNTAX = [
   'n', 'N', 'no', 'No', 'NO', 'off', 'Off', 'OFF'
 ];
 
+var DEPRECATED_BASE60_SYNTAX = /^[-+]?[0-9_]+(?::[0-9_]+)+(?:\.[0-9_]*)?$/;
+
 function compileStyleMap(schema, map) {
   var result, keys, index, length, tag, style, type;
 
@@ -221,10 +223,13 @@ function isPlainSafe(c, prev) {
     && c !== CHAR_RIGHT_SQUARE_BRACKET
     && c !== CHAR_LEFT_CURLY_BRACKET
     && c !== CHAR_RIGHT_CURLY_BRACKET
-    // - ":" - "#"
+    // - "#"
     // /* An ns-char preceding */ "#"
-    && c !== CHAR_COLON
-    && ((c !== CHAR_SHARP) || (prev && isNsChar(prev)));
+    && ((c !== CHAR_SHARP) || (prev && isNsChar(prev)))
+    // - ":"
+    && ((c !== CHAR_COLON) || (prev && isNsChar(prev)))
+    // - but ": " isn't plain-safe
+    && !(prev && prev === CHAR_COLON && !isNsChar(c));
 }
 
 // Simplified test for values allowed as the first character in plain style.
@@ -259,6 +264,12 @@ function isPlainSafeFirst(c) {
     && c !== CHAR_GRAVE_ACCENT;
 }
 
+// Simplified test for values allowed as the last character in plain style.
+function isPlainSafeLast(c) {
+  // just not whitespace or colon, it will be checked to be plain character later
+  return !isWhitespace(c) && c !== CHAR_COLON;
+}
+
 // Same as 'string'.codePointAt(pos), but works in older browsers.
 function codePointAt(string, pos) {
   var first = string.charCodeAt(pos), second;
@@ -302,7 +313,7 @@ function chooseScalarStyle(string, singleLineOnly, indentPerLevel, lineWidth,
   var shouldTrackWidth = lineWidth !== -1;
   var previousLineBreak = -1; // count the first line correctly
   var plain = isPlainSafeFirst(codePointAt(string, 0))
-          && !isWhitespace(codePointAt(string, string.length - 1));
+          && isPlainSafeLast(codePointAt(string, string.length - 1));
 
   if (singleLineOnly || forceQuotes) {
     // Case: no block styles.
@@ -375,7 +386,8 @@ function writeScalar(state, string, level, iskey) {
       return state.quotingType === QUOTING_TYPE_DOUBLE ? '""' : "''";
     }
     if (!state.noCompatMode &&
-        DEPRECATED_BOOLEANS_SYNTAX.indexOf(string) !== -1) {
+        DEPRECATED_BOOLEANS_SYNTAX.indexOf(string) !== -1 ||
+        DEPRECATED_BASE60_SYNTAX.test(string)) {
       return state.quotingType === QUOTING_TYPE_DOUBLE ? ('"' + string + '"') : ("'" + string + "'");
     }
 

test/issues/0470.js

@@ -0,0 +1,25 @@
+'use strict';
+
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+it('Don\'t quote strings with : without need', function () {
+  var data = {
+    // no quotes needed
+    'http://example.com': 'http://example.com',
+    // quotes required
+    'foo: bar': 'foo: bar',
+    'foo:': 'foo:'
+  };
+
+  var expected = `
+http://example.com: http://example.com
+'foo: bar': 'foo: bar'
+'foo:': 'foo:'
+`.replace(/^\n/, '');
+
+  assert.strictEqual(yaml.dump(data), expected);
+  assert.deepStrictEqual(yaml.load(expected), data);
+});