'libxml-parse(html|xml)-region': new optional param 'discard-comments'.

* doc/lispref/text.texi (Parsing HTML/XML): Document new optional parameter
'discard-comments' of 'libxml-parse(html|xml)-region'.

* src/xml.c (parse_region): Take care of new optional parameter
'discard-comments' of 'libxml-parse(html|xml)-region'.
(Flibxml_parse_html_region, Flibxml_parse_xml_region): New
optional parameter 'discard-comments'.

* test/automated/libxml-tests.el
(libxml-tests--data-comments-preserved): Renamed from
'libxml-tests--data'.
(libxml-tests--data-comments-discarded): New.
(libxml-tests): Check whether 'libxml-parse-xml-region' is
discarding comments correctly.

6 files changed, 74 insertions, 27 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 6706f936c5e..0c8792af81f 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2014-11-21  Ulf Jasper  <ulf.jasper@web.de>
+
+        * text.texi (Parsing HTML/XML): Document new optional parameter
+        'discard-comments' of 'libxml-parse(html|xml)-region'.
+
 2014-11-18  Leo Liu  <sdl.web@gmail.com>
 
         * functions.texi (Advising Named Functions): Document
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index d1a1e6fa6b9..7c88a5b25d1 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -4324,7 +4324,7 @@ coding instead.
 When Emacs is compiled with libxml2 support, the following functions
 are available to parse HTML or XML text into Lisp object trees.
 
-@defun libxml-parse-html-region start end &optional base-url
+@defun libxml-parse-html-region start end &optional base-url discard-comments
 This function parses the text between @var{start} and @var{end} as
 HTML, and returns a list representing the HTML @dfn{parse tree}.  It
 attempts to handle ``real world'' HTML by robustly coping with syntax
@@ -4333,6 +4333,9 @@ mistakes.
 The optional argument @var{base-url}, if non-@code{nil}, should be a
 string specifying the base URL for relative URLs occurring in links.
 
+If the optional argument @var{discard-comments} is non-@code{nil},
+then the parse tree is created without any comments.
+
 In the parse tree, each HTML node is represented by a list in which
 the first element is a symbol representing the node name, the second
 element is an alist of node attributes, and the remaining elements are
@@ -4368,7 +4371,7 @@ buffer.  The argument @var{dom} should be a list as generated by
 @end defun
 
 @cindex parsing xml
-@defun libxml-parse-xml-region start end &optional base-url
+@defun libxml-parse-xml-region start end &optional base-url discard-comments
 This function is the same as @code{libxml-parse-html-region}, except
 that it parses the text as XML rather than HTML (so it is stricter
 about syntax).
diff --git a/src/ChangeLog b/src/ChangeLog
index b169479a274..f8c9c5afd69 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2014-11-21  Ulf Jasper  <ulf.jasper@web.de>
+
+        * xml.c (parse_region): Take care of new optional parameter
+        'discard-comments' of 'libxml-parse(html|xml)-region'.
+        (Flibxml_parse_html_region, Flibxml_parse_xml_region): New
+        optional parameter 'discard-comments'.
+
 2014-11-17  Paul Eggert  <eggert@cs.ucla.edu>
 
         Improve time stamp handling, and be more consistent about it.
diff --git a/src/xml.c b/src/xml.c
index 7e99beb1d05..d418202182b 100644
--- a/src/xml.c
+++ b/src/xml.c
@@ -175,7 +175,7 @@ make_dom (xmlNode *node)
 }
 
 static Lisp_Object
-parse_region (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, int htmlp)
+parse_region (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, Lisp_Object discard_comments, int htmlp)
 {
   xmlDoc *doc;
   Lisp_Object result = Qnil;
@@ -214,21 +214,24 @@ parse_region (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, int html
 
   if (doc != NULL)
     {
-      /* If the document is just comments, then this should get us the
-         nodes anyway. */
-      xmlNode *n = doc->children;
       Lisp_Object r = Qnil;
-
-      while (n) {
-        if (!NILP (r))
-          result = Fcons (r, result);
-        r = make_dom (n);
-        n = n->next;
-      }
+      if (NILP(discard_comments))
+        {
+          /* If the document has toplevel comments, then this should
+             get us the nodes and the comments. */
+          xmlNode *n = doc->children;
+
+          while (n) {
+            if (!NILP (r))
+              result = Fcons (r, result);
+            r = make_dom (n);
+            n = n->next;
+          }
+        }
 
       if (NILP (result)) {
-        /* The document isn't just comments, so get the tree the
-           proper way. */
+        /* The document doesn't have toplevel comments or we discarded
+           them.  Get the tree the proper way. */
         xmlNode *node = fn_xmlDocGetRootElement (doc);
         if (node != NULL)
           result = make_dom (node);
@@ -251,25 +254,27 @@ xml_cleanup_parser (void)
 
 DEFUN ("libxml-parse-html-region", Flibxml_parse_html_region,
        Slibxml_parse_html_region,
-       2, 3, 0,
+       2, 4, 0,
        doc: /* Parse the region as an HTML document and return the parse tree.
-If BASE-URL is non-nil, it is used to expand relative URLs.  */)
-  (Lisp_Object start, Lisp_Object end, Lisp_Object base_url)
+If BASE-URL is non-nil, it is used to expand relative URLs.
+If DISCARD-COMMENTS is non-nil, all HTML comments are discarded. */)
+  (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, Lisp_Object discard_comments)
 {
   if (init_libxml2_functions ())
-    return parse_region (start, end, base_url, 1);
+    return parse_region (start, end, base_url, discard_comments, 1);
   return Qnil;
 }
 
 DEFUN ("libxml-parse-xml-region", Flibxml_parse_xml_region,
        Slibxml_parse_xml_region,
-       2, 3, 0,
+       2, 4, 0,
        doc: /* Parse the region as an XML document and return the parse tree.
-If BASE-URL is non-nil, it is used to expand relative URLs.  */)
-  (Lisp_Object start, Lisp_Object end, Lisp_Object base_url)
+If BASE-URL is non-nil, it is used to expand relative URLs.
+If DISCARD-COMMENTS is non-nil, all HTML comments are discarded. */)
+  (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, Lisp_Object discard_comments)
 {
   if (init_libxml2_functions ())
-    return parse_region (start, end, base_url, 0);
+    return parse_region (start, end, base_url, discard_comments, 0);
   return Qnil;
 }
 
diff --git a/test/ChangeLog b/test/ChangeLog
index 475b6a3f473..d0988e42076 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,3 +1,12 @@
+2014-11-21  Ulf Jasper  <ulf.jasper@web.de>
+
+        * automated/libxml-tests.el
+        (libxml-tests--data-comments-preserved): Renamed from
+        'libxml-tests--data'.
+        (libxml-tests--data-comments-discarded): New.
+        (libxml-tests): Check whether 'libxml-parse-xml-region' is
+        discarding comments correctly.
+
 2014-11-17  Michal Nazarewicz  <mina86@mina86.com>
 
         * automated/tildify-tests.el (tildify-test-html, tildify-test-xml):
diff --git a/test/automated/libxml-tests.el b/test/automated/libxml-tests.el
index ced0df7b3c4..6b6d0170562 100644
--- a/test/automated/libxml-tests.el
+++ b/test/automated/libxml-tests.el
@@ -27,7 +27,7 @@
 
 (require 'ert)
 
-(defvar libxml-tests--data
+(defvar libxml-tests--data-comments-preserved
   `(;; simple case
     ("<?xml version=\"1.0\"?><foo baz=\"true\">bar</foo>"
      . (foo ((baz . "true")) "bar"))
@@ -40,17 +40,35 @@
               "<bar>blub</bar></foo><!--comment-b--><!--comment-c-->")
      . (top nil (comment nil "comment-a") (foo ((a . "b")) (bar nil "blub"))
             (comment nil "comment-b") (comment nil "comment-c"))))
-  "Alist of XML strings and their expected parse trees.")
+  "Alist of XML strings and their expected parse trees for preserved comments.")
+
+(defvar libxml-tests--data-comments-discarded
+  `(;; simple case
+    ("<?xml version=\"1.0\"?><foo baz=\"true\">bar</foo>"
+     . (foo ((baz . "true")) "bar"))
+    ;; toplevel comments -- first document child must not get lost
+    (,(concat "<?xml version=\"1.0\"?><foo>bar</foo><!--comment-1-->"
+              "<!--comment-2-->")
+     . (foo nil "bar"))
+    (,(concat "<?xml version=\"1.0\"?><!--comment-a--><foo a=\"b\">"
+              "<bar>blub</bar></foo><!--comment-b--><!--comment-c-->")
+     . (foo ((a . "b")) (bar nil "blub"))))
+  "Alist of XML strings and their expected parse trees for discarded comments.")
 
 
 (ert-deftest libxml-tests ()
   "Test libxml."
   (when (fboundp 'libxml-parse-xml-region)
     (with-temp-buffer
-      (dolist (test libxml-tests--data)
+      (dolist (test libxml-tests--data-comments-preserved)
+        (erase-buffer)
+        (insert (car test))
+        (should (equal (cdr test)
+                       (libxml-parse-xml-region (point-min) (point-max)))))
+      (dolist (test libxml-tests--data-comments-discarded)
         (erase-buffer)
         (insert (car test))
         (should (equal (cdr test)
-                       (libxml-parse-xml-region (point-min) (point-max))))))))
+                       (libxml-parse-xml-region (point-min) (point-max) nil t)))))))
 
 ;;; libxml-tests.el ends here