src/svgtiny_css.c: implement node_is_link() select handler

diff --git a/src/svgtiny_css.c b/src/svgtiny_css.c
index ebf432d3fa6bbfeb5e0ec5aa3b67f56ab3f5dccf..fec0ed4a4596006148585662913b64bbf7a0a965 100644 (file)
--- a/src/svgtiny_css.c
+++ b/src/svgtiny_css.c
@@ -46,6 +46,7 @@ static css_error node_is_root(void *pw, void *node, bool *match);
 static css_error node_count_siblings(void *pw, void *node,
                bool same_name, bool after, int32_t *count);
 static css_error node_is_empty(void *pw, void *node, bool *is_empty);
+static css_error node_is_link(void *pw, void *node, bool *is_link);
 
 
 /**
@@ -1426,3 +1427,58 @@ css_error node_is_empty(void *pw, void *node, bool *is_empty)
 
        return CSS_OK;
 }
+
+
+/**
+ * Determine whether or not the given node is a link
+ *
+ * A node is a link if it is an element node whose name is "a" and if
+ * it has an "href" attribute (case-sensitive). This selector
+ * corresponds to node:link pseudo-class in CSS.
+ *
+ * This pseudo-class is a bit awkward because the two standards (HTML5
+ * and CSS) disagree on what it means, and because libsvgtiny does not
+ * have enough information to determine if a link has been "visited"
+ * yet -- that's a UI property. CSS says that :link is for unvisited
+ * links, which we can't determine. HTML5 says that each link must
+ * be either a :link or :visited. Since we can't decide either way,
+ * It seems less wrong to declare that all links are unvisited; i.e.
+ * that they match :link.
+ *
+ * \param pw          Pointer to the current SVG parser state
+ * \param node        Libdom SVG node to check
+ * \param is_link     Pointer to the boolean return value
+ *
+ * \return CSS_OK on success, or CSS_NOMEM if anything goes wrong
+ */
+css_error node_is_link(void *pw, void *node, bool *is_link)
+{
+       dom_exception exc;
+       dom_node *dnode; /* node, but with the right type */
+       dom_string *dnode_name;
+       bool has_href;
+       struct svgtiny_parse_state* state;
+
+       dnode = (dom_node *)node;
+       dnode_name = NULL;
+       has_href = false; /* assume no href attribute */
+       *is_link = false; /* assume that it's not a link */
+
+       exc = dom_node_get_node_name(dnode, &dnode_name);
+       if ((exc != DOM_NO_ERR) || (dnode_name == NULL)) {
+               return CSS_NOMEM;
+       }
+
+       state = (struct svgtiny_parse_state *)pw;
+       if (dom_string_isequal(dnode_name, state->interned_a)) {
+               exc = dom_element_has_attribute(node,
+                                       state->interned_href,
+                                       &has_href);
+               if (exc == DOM_NO_ERR && has_href) {
+                       *is_link = true;
+               }
+       }
+
+       dom_string_unref(dnode_name);
+       return CSS_OK;
+}