Closes #271: 2nd try, remove unescaping of backquote replacements

* Fixes previous fix (big blunder, expansion unusable)
* Added more tests
* Fixed previously broken tests.

yasnippet-tests.el

@@ -153,7 +153,7 @@
       (yas-expand-snippet "Look ma! `(yas/selected-text)`")
       (should (string= (yas--buffer-contents) "Look ma! He\"\)\\o world!")))
     (yas-exit-all-snippets)
-    (erase-buffer))))
+    (erase-buffer)))
 
 (ert-deftest be-careful-when-escaping-in-yas-selected-text-2 ()
   (with-temp-buffer
@@ -176,15 +176,33 @@
 (ert-deftest primary-field-transformation ()
   (with-temp-buffer
     (yas-minor-mode 1)
-    ;; The rules here is: to output a literal `"' you need to escape
-    ;; it with one backslash. You don't need to escape them in
-    ;; embedded elisp.
     (let ((snippet "${1:$$(upcase yas/text)}${1:$(concat \"bar\" yas/text)}"))
       (yas-expand-snippet snippet)
       (should (string= (yas--buffer-contents) "bar"))
       (ert-simulate-command `(yas-mock-insert "foo"))
       (should (string= (yas--buffer-contents) "FOObarFOO")))))
 
+(ert-deftest example-for-issue-271 ()
+  (with-temp-buffer
+    (yas-minor-mode 1)
+    (let ((yas-selected-text "aaa")
+          (snippet "if ${1:condition}\n`yas/selected-text`\nelse\n$3\nend"))
+      (yas-expand-snippet snippet)
+      (yas-next-field)
+      (ert-simulate-command `(yas-mock-insert "bbb"))
+      (should (string= (yas--buffer-contents) "if condition\naaa\nelse\nbbb\nend")))))
+
+(ert-deftest another-example-for-issue-271 ()
+  (with-temp-buffer
+    (yas-minor-mode 1)
+    (let ((snippet "\\${${1:1}:`yas/selected-text`}"))
+      (insert "aaabbbccc")
+      (set-mark 4)
+      (goto-char 7)
+      (yas-expand-snippet snippet)
+      (ert-simulate-command `(yas-mock-insert "bbb"))
+      (should (string= (yas--buffer-contents) "if condition\naaa\nelse\nbbb\nend")))))
+
 
 ;;; Misc tests
 ;;;

yasnippet.el

@@ -3451,22 +3451,22 @@ considered when expanding the snippet."
   (run-hooks 'yas-before-expand-snippet-hook)
 
   ;;
-  (let ((yas-selected-text (or yas-selected-text
-                               (and (region-active-p)
-                                    (buffer-substring-no-properties (region-beginning)
-                                                                    (region-end)))))
-        (to-delete (and start
-                        end
-                        (buffer-substring-no-properties start end)))
-        (start (or start
-                   (and (region-active-p)
-                        (region-beginning))
-                   (point)))
-        (end (or end
-                 (and (region-active-p)
-                      (region-end))
-                 (point)))
-        snippet)
+  (let* ((yas-selected-text (or yas-selected-text
+                                (and (region-active-p)
+                                     (buffer-substring-no-properties (region-beginning)
+                                                                     (region-end)))))
+         (start (or start
+                    (and (region-active-p)
+                         (region-beginning))
+                    (point)))
+         (end (or end
+                  (and (region-active-p)
+                       (region-end))
+                  (point)))
+         (to-delete (and start
+                         end
+                         (buffer-substring-no-properties start end)))
+         snippet)
     (goto-char start)
     (setq yas--indent-original-column (current-column))
     ;; Delete the region to delete, this *does* get undo-recorded.
@@ -3762,9 +3762,9 @@ Meant to be called in a narrowed buffer, does various passes"
     ;; Reset the yas--dollar-regions
     ;;
     (setq yas--dollar-regions nil)
-    ;; protect escaped quote, backquotes and backslashes
+    ;; protect escaped characters
     ;;
-    (yas--protect-escapes nil `(?\\ ?` ?'))
+    (yas--protect-escapes)
     ;; replace all backquoted expressions
     ;;
     (goto-char parse-start)
@@ -3927,7 +3927,7 @@ with their evaluated value into `yas--backquote-markers-and-strings'"
   (while (re-search-forward yas--backquote-lisp-expression-regexp nil t)
     (let ((current-string (match-string 1)) transformed)
       (delete-region (match-beginning 0) (match-end 0))
-      (setq transformed (yas--eval-lisp (yas--read-lisp (yas--restore-escapes current-string))))
+      (setq transformed (yas--eval-lisp (yas--read-lisp current-string)))
       (goto-char (match-beginning 0))
       (when transformed
         (let ((marker (make-marker)))