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

diff --git a/src/svgtiny_css.c b/src/svgtiny_css.c
index 0267325df7a7a7b202a36ffd1434e233a644469e..6e808475baa220cdf1d5a7f3a17200d3fe918972 100644 (file)
--- a/src/svgtiny_css.c
+++ b/src/svgtiny_css.c
@@ -23,6 +23,9 @@ static css_error node_has_id(void *pw, void *node,
                lwc_string *name, bool *match);
 static css_error node_has_attribute(void *pw, void *node,
                const css_qname *qname, bool *match);
+static css_error node_has_attribute_equal(void *pw, void *node,
+               const css_qname *qname, lwc_string *value,
+               bool *match);
 
 
 /**
@@ -665,3 +668,62 @@ css_error node_has_attribute(void *pw, void *node,
        dom_string_unref(name);
        return CSS_OK;
 }
+
+
+/**
+ * Test the given node for an attribute with a specific value
+ *
+ * This will return true (via the "match" pointer) if the libdom node
+ * has an attribute with the given name and value. The comparison is
+ * case-sensitive. It corresponds to node[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 value    Attribute value 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_equal(void *pw, void *node,
+               const css_qname *qname, lwc_string *value,
+               bool *match)
+{
+       /* Implementation note: NetSurf always returns "no match" when
+        * the value is empty (length zero). We allow it, because why
+        * not? */
+
+       UNUSED(pw);
+       dom_string *name;
+       dom_string *attr_val;
+       dom_exception err;
+
+       /* 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 all we need to do is compare. */
+       dom_string_unref(name);
+       *match = dom_string_lwc_isequal(attr_val, value);
+       dom_string_unref(attr_val);
+
+       return CSS_OK;
+}