From: Michael Orlitzky <michael@orlitzky.com>
Date: Thu, 12 Oct 2023 18:43:39 +0000 (-0400)
Subject: src/svgtiny_css.c: implement sibling_node() select handler
X-Git-Url: http://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=99489346fc8214d7c9473b89361b0c8d17b985db;p=libsvgtiny.git

src/svgtiny_css.c: implement sibling_node() select handler
---

diff --git a/src/svgtiny_css.c b/src/svgtiny_css.c
index 76ee4cc..c7faffd 100644
--- a/src/svgtiny_css.c
+++ b/src/svgtiny_css.c
@@ -14,6 +14,7 @@ static css_error named_sibling_node(void *pw, void *node,
 static css_error named_generic_sibling_node(void *pw, void *node,
 		const css_qname *qname, void **sibling);
 static css_error parent_node(void *pw, void *node, void **parent);
+static css_error sibling_node(void *pw, void *node, void **sibling);
 
 
 /**
@@ -433,3 +434,73 @@ css_error parent_node(void *pw, void *node, void **parent)
 
 	return CSS_OK;
 }
+
+
+/**
+ * Find the "next-sibling" of the given element
+ *
+ * This search corresponds "+ *" in CSS and will find the first
+ * element node that immediately precedes the given node under the
+ * same parent in the DOM. In CSS the tree is viewed top-down and in
+ * libdom it is viewed from the bottom-up; as a result "next" and
+ * "previous" are sometimes backwards.
+ *
+ * \param pw       Pointer to the current SVG parser state
+ * \param node     Libdom SVG node
+ * \param sibling  Address at which to store the sibling node pointer
+ *
+ * \return Always returns CSS_OK
+ *
+ * \post If a suitable element is found, a pointer to it will be
+ *       stored at the address pointed to by \a sibling; otherwise,
+ *       NULL will be stored at the address pointed to by \a sibling
+ */
+css_error sibling_node(void *pw, void *node, void **sibling)
+{
+	UNUSED(pw);
+	dom_node *n = node; /* the current node */
+	dom_node *prev;     /* the previous node */
+	dom_exception err;
+	dom_node_type type;
+
+	*sibling = NULL; /* default to nothing found */
+
+	/* Begin the search; the first iteration we do outside of the
+	 * loop. Implementation detil: dom_node_get_previous_sibling()
+	 * increments the reference counter on the returned node. A
+	 * comment within named_parent_node() explains why we
+	 * decrement it ASAP. */
+	err = dom_node_get_previous_sibling(n, &n);
+	if (err != DOM_NO_ERR) {
+		return CSS_OK;
+	}
+
+	while (n != NULL) {
+		err = dom_node_get_node_type(n, &type);
+		if (err != DOM_NO_ERR) {
+			dom_node_unref(n);
+			return CSS_OK;
+		}
+
+		if (type == DOM_ELEMENT_NODE) {
+			/* We found a sibling node that is also an
+			   element and that's all we wanted. */
+			*sibling = n;
+			dom_node_unref(n);
+			return CSS_OK;
+		}
+
+		/* This sibling node was not an element; move on to
+		   the previous sibling */
+		err = dom_node_get_previous_sibling(n, &prev);
+		if (err != DOM_NO_ERR) {
+			dom_node_unref(n);
+			return CSS_OK;
+		}
+
+		dom_node_unref(n);
+		n = prev;
+	}
+
+	return CSS_OK;
+}