libpkgconf: fragment: allow for overriding the default fragment rendering behaviour

libpkgconf/fragment.c

@@ -440,20 +440,8 @@ pkgconf_fragment_len(const pkgconf_fragment_t *frag, bool escape)
 	return len;
 }
 
-/*
+static size_t
- * !doc
+fragment_render_len(const pkgconf_list_t *list, bool escape)
- *
- * .. c:function:: size_t pkgconf_fragment_render_len(const pkgconf_list_t *list)
- *
- *    Calculates the required memory to store a `fragment list` when rendered as a string.
- *
- *    :param pkgconf_list_t* list: The `fragment list` being rendered.
- *    :param bool escape: Whether or not to escape special shell characters.
- *    :return: the amount of bytes required to represent the `fragment list` when rendered
- *    :rtype: size_t
- */
-size_t
-pkgconf_fragment_render_len(const pkgconf_list_t *list, bool escape)
 {
 	size_t out = 1;		/* trailing nul */
 	pkgconf_node_t *node;
@@ -467,21 +455,8 @@ pkgconf_fragment_render_len(const pkgconf_list_t *list, bool escape)
 	return out;
 }
 
-/*
+static void
- * !doc
+fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t buflen, bool escape)
- *
- * .. c:function:: void pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t buflen)
- *
- *    Renders a `fragment list` into a buffer.
- *
- *    :param pkgconf_list_t* list: The `fragment list` being rendered.
- *    :param char* buf: The buffer to render the fragment list into.
- *    :param size_t buflen: The length of the buffer.
- *    :param bool escape: Whether or not to escape special shell characters.
- *    :return: nothing
- */
-void
-pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t buflen, bool escape)
 {
 	pkgconf_node_t *node;
 	char *bptr = buf;
@@ -520,6 +495,52 @@ pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t buflen
 	*bptr = '\0';
 }
 
+static const pkgconf_fragment_render_ops_t default_render_ops = {
+	.render_len = fragment_render_len,
+	.render_buf = fragment_render_buf
+};
+
+/*
+ * !doc
+ *
+ * .. c:function:: size_t pkgconf_fragment_render_len(const pkgconf_list_t *list, bool escape, const pkgconf_fragment_render_ops_t *ops)
+ *
+ *    Calculates the required memory to store a `fragment list` when rendered as a string.
+ *
+ *    :param pkgconf_list_t* list: The `fragment list` being rendered.
+ *    :param bool escape: Whether or not to escape special shell characters.
+ *    :param pkgconf_fragment_render_ops_t* ops: An optional ops structure to use for custom renderers, else ``NULL``.
+ *    :return: the amount of bytes required to represent the `fragment list` when rendered
+ *    :rtype: size_t
+ */
+size_t
+pkgconf_fragment_render_len(const pkgconf_list_t *list, bool escape, const pkgconf_fragment_render_ops_t *ops)
+{
+	ops = ops != NULL ? ops : &default_render_ops;
+	return ops->render_len(list, escape);
+}
+
+/*
+ * !doc
+ *
+ * .. c:function:: void pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t buflen, bool escape, const pkgconf_fragment_render_ops_t *ops)
+ *
+ *    Renders a `fragment list` into a buffer.
+ *
+ *    :param pkgconf_list_t* list: The `fragment list` being rendered.
+ *    :param char* buf: The buffer to render the fragment list into.
+ *    :param size_t buflen: The length of the buffer.
+ *    :param bool escape: Whether or not to escape special shell characters.
+ *    :param pkgconf_fragment_render_ops_t* ops: An optional ops structure to use for custom renderers, else ``NULL``.
+ *    :return: nothing
+ */
+void
+pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t buflen, bool escape, const pkgconf_fragment_render_ops_t *ops)
+{
+	ops = ops != NULL ? ops : &default_render_ops;
+	return ops->render_buf(list, buf, buflen, escape);
+}
+
 /*
  * !doc
  *
@@ -529,16 +550,17 @@ pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t buflen
  *
  *    :param pkgconf_list_t* list: The `fragment list` being rendered.
  *    :param bool escape: Whether or not to escape special shell characters.
+ *    :param pkgconf_fragment_render_ops_t* ops: An optional ops structure to use for custom renderers, else ``NULL``.
  *    :return: An allocated string containing the rendered `fragment list`.
  *    :rtype: char *
  */
 char *
-pkgconf_fragment_render(const pkgconf_list_t *list, bool escape)
+pkgconf_fragment_render(const pkgconf_list_t *list, bool escape, const pkgconf_fragment_render_ops_t *ops)
 {
-	size_t buflen = pkgconf_fragment_render_len(list, escape);
+	size_t buflen = pkgconf_fragment_render_len(list, escape, ops);
 	char *buf = calloc(1, buflen);
 
-	pkgconf_fragment_render_buf(list, buf, buflen, escape);
+	pkgconf_fragment_render_buf(list, buf, buflen, escape, ops);
 
 	return buf;
 }

libpkgconf/libpkgconf.h

@@ -275,6 +275,11 @@ PKGCONF_API int pkgconf_argv_split(const char *src, int *argc, char ***argv);
 PKGCONF_API void pkgconf_argv_free(char **argv);
 
 /* fragment.c */
+typedef struct pkgconf_fragment_render_ops_ {
+	size_t (*render_len)(const pkgconf_list_t *list, bool escape);
+	void (*render_buf)(const pkgconf_list_t *list, char *buf, size_t len, bool escape);
+} pkgconf_fragment_render_ops_t;
+
 typedef bool (*pkgconf_fragment_filter_func_t)(const pkgconf_client_t *client, const pkgconf_fragment_t *frag, void *data);
 PKGCONF_API bool pkgconf_fragment_parse(const pkgconf_client_t *client, pkgconf_list_t *list, pkgconf_list_t *vars, const char *value);
 PKGCONF_API void pkgconf_fragment_add(const pkgconf_client_t *client, pkgconf_list_t *list, const char *string);
@@ -282,9 +287,9 @@ PKGCONF_API void pkgconf_fragment_copy(const pkgconf_client_t *client, pkgconf_l
 PKGCONF_API void pkgconf_fragment_delete(pkgconf_list_t *list, pkgconf_fragment_t *node);
 PKGCONF_API void pkgconf_fragment_free(pkgconf_list_t *list);
 PKGCONF_API void pkgconf_fragment_filter(const pkgconf_client_t *client, pkgconf_list_t *dest, pkgconf_list_t *src, pkgconf_fragment_filter_func_t filter_func, void *data);
-PKGCONF_API size_t pkgconf_fragment_render_len(const pkgconf_list_t *list, bool escape);
+PKGCONF_API size_t pkgconf_fragment_render_len(const pkgconf_list_t *list, bool escape, const pkgconf_fragment_render_ops_t *ops);
-PKGCONF_API void pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t len, bool escape);
+PKGCONF_API void pkgconf_fragment_render_buf(const pkgconf_list_t *list, char *buf, size_t len, bool escape, const pkgconf_fragment_render_ops_t *ops);
-PKGCONF_API char *pkgconf_fragment_render(const pkgconf_list_t *list, bool escape);
+PKGCONF_API char *pkgconf_fragment_render(const pkgconf_list_t *list, bool escape, const pkgconf_fragment_render_ops_t *ops);
 PKGCONF_API bool pkgconf_fragment_has_system_dir(const pkgconf_client_t *client, const pkgconf_fragment_t *frag);
 
 /* fileio.c */

main.c

@@ -65,6 +65,7 @@
 #define PKG_EXISTS			(((uint64_t) 1) << 40)
 
 static pkgconf_client_t pkg_client;
+static const pkgconf_fragment_render_ops_t *want_render_ops = NULL;
 
 static uint64_t want_flags;
 static int maximum_traverse_depth = 2000;
@@ -393,7 +394,7 @@ apply_env_var(const char *prefix, pkgconf_client_t *client, pkgconf_pkg_t *world
 	if (filtered_list.head == NULL)
 		goto out;
 
-	render_buf = pkgconf_fragment_render(&filtered_list, true);
+	render_buf = pkgconf_fragment_render(&filtered_list, true, want_render_ops);
 	printf("%s='%s'\n", prefix, render_buf);
 	free(render_buf);
 
@@ -443,7 +444,7 @@ apply_cflags(pkgconf_client_t *client, pkgconf_pkg_t *world, void *unused, int m
 	if (filtered_list.head == NULL)
 		goto out;
 
-	render_buf = pkgconf_fragment_render(&filtered_list, true);
+	render_buf = pkgconf_fragment_render(&filtered_list, true, want_render_ops);
 	printf("%s", render_buf);
 	free(render_buf);
 
@@ -472,7 +473,7 @@ apply_libs(pkgconf_client_t *client, pkgconf_pkg_t *world, void *unused, int max
 	if (filtered_list.head == NULL)
 		goto out;
 
-	render_buf = pkgconf_fragment_render(&filtered_list, true);
+	render_buf = pkgconf_fragment_render(&filtered_list, true, want_render_ops);
 	printf("%s", render_buf);
 	free(render_buf);