Support parsing and compiling previous translations in obsolete entries

lib/pocompiler.js

@@ -70,9 +70,10 @@ function Compiler (table = {}, options = {}) {
  * in the form of {translator:'', reference: '', extracted: '', flag: '', previous:''}
  *
  * @param {Object} comments A comments object
+ * @param {boolean} [obsolete] This comments object is for an obsolete block
  * @return {String} A comment string for the PO file
  */
-Compiler.prototype._drawComments = function (comments) {
+Compiler.prototype._drawComments = function (comments, obsolete = false) {
   const lines = [];
   const types = [{
     key: 'translator',
@@ -88,7 +89,7 @@ Compiler.prototype._drawComments = function (comments) {
     prefix: '#, '
   }, {
     key: 'previous',
-    prefix: '#| '
+    prefix: obsolete ? '#~| ' : '#| '
   }];
 
   types.forEach(type => {
@@ -121,7 +122,7 @@ Compiler.prototype._drawBlock = function (block, override = {}, obsolete = false
   let comments = override.comments || block.comments;
 
   // add comments
-  if (comments && (comments = this._drawComments(comments))) {
+  if (comments && (comments = this._drawComments(comments, obsolete))) {
     response.push(comments);
   }
 

lib/poparser.js

@@ -161,6 +161,13 @@ Parser.prototype._lexer = function (chunk) {
           };
           this._lex.push(this._node);
           this._state = this.states.comments;
+        } else if (chr === '|') {
+          this._node = {
+            type: this.types.comments,
+            value: chr
+          };
+          this._lex.push(this._node);
+          this._state = this.states.comments;
         } else if (!chr.match(this.symbols.whitespace)) {
           this._node = {
             type: this.types.key,

test/fixtures/obsolete.json

@@ -38,6 +38,17 @@
                     "One",
                     "Two"
                 ]
+            },
+            "Obsolete message with previous translation": {
+                "msgid": "Obsolete message with previous translation",
+                "comments": {
+                    "flag": "fuzzy",
+                    "previous": "msgid \"Obsolete message with previous tr\"",
+                    "translator": "Obsolete message with previous"
+                },
+                "msgstr": [
+                    "Translation"
+                ]
             }
         },
         "Obsolete context": {

test/fixtures/obsolete.po

@@ -16,6 +16,12 @@ msgstr "Test msgstr"
 #~ msgstr[0] "One"
 #~ msgstr[1] "Two"
 
+# Obsolete message with previous
+#, fuzzy
+#~| msgid "Obsolete message with previous tr"
+#~ msgid "Obsolete message with previous translation"
+#~ msgstr "Translation"
+
 # Obsolete message with context
 #, fuzzy
 #~ msgctxt "Obsolete context"