From d89d98c07001fc6fc54b1bd9be7eaa3ca64b6294 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Fri, 13 Oct 2023 20:42:35 -0400
Subject: [PATCH] src/svgtiny_css.c: implement node_is_root() select handler

---
 src/svgtiny_css.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/src/svgtiny_css.c b/src/svgtiny_css.c
index a1f9565..80d4de1 100644
--- a/src/svgtiny_css.c
+++ b/src/svgtiny_css.c
@@ -42,6 +42,7 @@ static css_error node_has_attribute_suffix(void *pw, void *node,
 static css_error node_has_attribute_substring(void *pw, void *node,
 		const css_qname *qname, lwc_string *substring,
 		bool *match);
+static css_error node_is_root(void *pw, void *node, bool *match);
 
 
 /**
@@ -1189,3 +1190,45 @@ css_error node_has_attribute_substring(void *pw, void *node,
 
 	return CSS_OK;
 }
+
+
+/**
+ * Test whether or not the given node is the document's root element
+ * This corresponds to the CSS :root pseudo-selector.
+ *
+ * \param pw          Pointer to the current SVG parser state
+ * \param node        Libdom SVG node to test
+ * \param match       Pointer to the test result
+ *
+ * \return CSS_OK on success, or CSS_NOMEM if anything goes wrong
+ */
+css_error node_is_root(void *pw, void *node, bool *match)
+{
+	UNUSED(pw);
+	dom_node *parent;
+	dom_node_type type;
+	dom_exception err;
+
+	err = dom_node_get_parent_node((dom_node *)node, &parent);
+	if (err != DOM_NO_ERR) {
+		return CSS_NOMEM;
+	}
+
+	/* It's the root element if it doesn't have a parent element */
+	if (parent != NULL) {
+		err = dom_node_get_node_type(parent, &type);
+		dom_node_unref(parent);
+		if (err != DOM_NO_ERR) {
+			return CSS_NOMEM;
+		}
+		if (type != DOM_DOCUMENT_NODE) {
+			/* DOM_DOCUMENT_NODE is the only allowable
+			 * type of parent node for the root element */
+			*match = false;
+			return CSS_OK;
+		}
+	}
+
+	*match = true;
+	return CSS_OK;
+}
-- 
2.44.2