[vim mode] #5753 Feature request: Support &/$0 in vim substitute replacements

Author: ilyakharlamov

keymap/vim.js

@@ -4073,7 +4073,7 @@
     }
 
     // Unescape \ and / in the replace part, for PCRE mode.
-    var unescapes = {'\\/': '/', '\\\\': '\\', '\\n': '\n', '\\r': '\r', '\\t': '\t'};
+    var unescapes = {'\\/': '/', '\\\\': '\\', '\\n': '\n', '\\r': '\r', '\\t': '\t', '\\&':'&'};
     function unescapeRegexReplace(str) {
       var stream = new CodeMirror.StringStream(str);
       var output = [];
@@ -4871,7 +4871,7 @@
           }
           if (replacePart !== undefined) {
             if (getOption('pcre')) {
-              replacePart = unescapeRegexReplace(replacePart);
+              replacePart = unescapeRegexReplace(replacePart.replace(/([^\\])&/g,"$1$$&"));
             } else {
               replacePart = translateRegexReplace(replacePart);
             }

test/vim_test.js

@@ -3939,6 +3939,24 @@ testSubstitute('ex_substitute_forward_slash_regex', {
   expectedValue: 'forward slash  was here',
   expr: '%s#\\/##g',
   noPcreExpr: '%s#/##g'});
+testVim("ex_substitute_ampersand_pcre", function(cm, vim, helpers) {
+    cm.setCursor(0, 0);
+    CodeMirror.Vim.setOption('pcre', true);
+    helpers.doEx('%s/foo/namespace.&/');
+    eq("namespace.foo", cm.getValue());
+  }, { value: 'foo' });
+testVim("ex_substitute_ampersand_multiple_pcre", function(cm, vim, helpers) {
+    cm.setCursor(0, 0);
+    CodeMirror.Vim.setOption('pcre', true);
+    helpers.doEx('%s/f.o/namespace.&/');
+    eq("namespace.foo\nnamespace.fzo", cm.getValue());
+  }, { value: 'foo\nfzo' });
+testVim("ex_escaped_ampersand_should_not_substitute_pcre", function(cm, vim, helpers) {
+    cm.setCursor(0, 0);
+    CodeMirror.Vim.setOption('pcre', true);
+    helpers.doEx('%s/foo/namespace.\\&/');
+    eq("namespace.&", cm.getValue());
+  }, { value: 'foo' });
 testSubstitute('ex_substitute_backslashslash_regex', {
   value: 'one\\two \n three\\four',
   expectedValue: 'one,two \n three,four',