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

diff --git a/src/svgtiny_css.c b/src/svgtiny_css.c
index 3b03d9148273bac2a5bbe97597b514fb60f30a65..95d37726c8f9c17e2b519d04741958e44cf6bf20 100644 (file)
--- a/src/svgtiny_css.c
+++ b/src/svgtiny_css.c
@@ -33,6 +33,9 @@ static css_error node_has_attribute_dashmatch(void *pw, void *node,
 static css_error node_has_attribute_includes(void *pw, void *node,
                const css_qname *qname, lwc_string *word,
                bool *match);
+static css_error node_has_attribute_prefix(void *pw, void *node,
+               const css_qname *qname, lwc_string *prefix,
+               bool *match);
 
 
 /**
@@ -911,3 +914,88 @@ css_error node_has_attribute_includes(void *pw, void *node,
 
        return CSS_OK;
 }
+
+
+/**
+ * Test the given node for an attribute whose value begins with the
+ * given prefix
+ *
+ * This will return true (via the "match" pointer) if the libdom node
+ * has an attribute with the given name and whose value begins with
+ * the given prefix string. The comparison is case-sensitive. This
+ * corresponds to [attr^=value] in CSS.
+ *
+ * \param pw       Pointer to the current SVG parser state
+ * \param node     Libdom SVG node to test
+ * \param qname    Attribute name to check for
+ * \param prefix   Value prefix to check for
+ * \param match    Pointer to the test result
+ *
+ * \return Returns CSS_OK if successful and CSS_NOMEM if we cannot
+ *         intern the attribute name (which usually indicates memory
+ *         exhaustion)
+ */
+css_error node_has_attribute_prefix(void *pw, void *node,
+               const css_qname *qname, lwc_string *prefix,
+               bool *match)
+{
+       UNUSED(pw);
+       dom_string *name;
+       dom_string *attr_val;
+       dom_exception err;
+       const char *avdata; /* attribute value data */
+       size_t avdata_len; /* length of that attribute value data */
+       size_t prefixlen; /* length of "prefix" */
+
+       prefixlen = lwc_string_length(prefix);
+       if (prefixlen == 0) {
+               /* In this case, the spec says that "if 'val' is the
+                * empty string, it will never represent anything." */
+               return CSS_OK;
+       }
+
+       /* Intern the attribute name as a dom_string so we can
+        * use dom_element_get_attribute() */
+       err = dom_string_create_interned(
+               (const uint8_t *) lwc_string_data(qname->name),
+               lwc_string_length(qname->name),
+               &name);
+       if (err != DOM_NO_ERR) {
+               return CSS_NOMEM;
+       }
+
+       err = dom_element_get_attribute((dom_node *)node, name, &attr_val);
+       if ((err != DOM_NO_ERR) || (attr_val == NULL)) {
+               /* There was an error getting the attribute's value or
+                * the attribute doesn't exist. So, no match? */
+               dom_string_unref(name);
+               *match = false;
+               return CSS_OK;
+       }
+
+       /* Otherwise, we have the attribute value from the given node,
+        * and the first thing we want to do is check to see if the
+        * whole thing matches the prefix. */
+       dom_string_unref(name);
+       *match = dom_string_lwc_isequal(attr_val, prefix);
+
+       /* If not, check to see if an, uh, prefix matches the
+        * prefix */
+       if (*match == false) {
+               avdata = dom_string_data(attr_val);
+               avdata_len = dom_string_byte_length(attr_val);
+               if ((avdata_len >= prefixlen) &&
+                               (strncasecmp(avdata,
+                                       lwc_string_data(prefix),
+                                       prefixlen) == 0)) {
+                       /* Use strncasecmp to compare only the first
+                        * "n" characters, where "n" is the length of
+                        * the prefix. */
+                       *match = true;
+               }
+       }
+
+       dom_string_unref(attr_val);
+
+       return CSS_OK;
+}