Index: uspace/lib/bithenge/transform.h
===================================================================
--- uspace/lib/bithenge/transform.h	(revision 681a985970ab8032138c183df4d54034631009bb)
+++ uspace/lib/bithenge/transform.h	(revision 681a985970ab8032138c183df4d54034631009bb)
@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2012 Sean Bartell
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup bithenge
+ * @{
+ */
+/**
+ * @file
+ * Transforms.
+ */
+
+#ifndef BITHENGE_TRANSFORM_H_
+#define BITHENGE_TRANSFORM_H_
+
+#include "blob.h"
+#include "tree.h"
+
+/** A transform that creates a new tree from an old tree. */
+typedef struct {
+	/** @privatesection */
+	const struct bithenge_transform_ops *ops;
+	unsigned int refs;
+	int num_params;
+} bithenge_transform_t;
+
+/** Context and parameters used when applying transforms. */
+typedef struct bithenge_scope {
+	/** @privatesection */
+	unsigned int refs;
+	struct bithenge_scope *outer;
+	char *error;
+	bool barrier;
+	int num_params;
+	bithenge_node_t **params;
+	bithenge_node_t *current_node;
+	bithenge_node_t *in_node;
+} bithenge_scope_t;
+
+static inline void bithenge_scope_inc_ref(bithenge_scope_t *self) {
+	self->refs++;
+}
+
+/** Operations that may be provided by a transform. All transforms must provide
+ * apply and/or prefix_apply. To be used in struct transforms and repeat
+ * transforms, transforms must provide prefix_length and/or prefix_apply. */
+typedef struct bithenge_transform_ops {
+	/** @copydoc bithenge_transform_t::bithenge_transform_apply */
+	int (*apply)(bithenge_transform_t *self, bithenge_scope_t *scope,
+	    bithenge_node_t *in, bithenge_node_t **out);
+	/** @copydoc bithenge_transform_t::bithenge_transform_prefix_length */
+	int (*prefix_length)(bithenge_transform_t *self,
+	    bithenge_scope_t *scope, bithenge_blob_t *blob, aoff64_t *out);
+	/** @copydoc bithenge_transform_t::bithenge_transform_prefix_apply */
+	int (*prefix_apply)(bithenge_transform_t *self,
+	    bithenge_scope_t *scope, bithenge_blob_t *blob,
+	    bithenge_node_t **out_node, aoff64_t *out_size);
+	/** Destroy the transform.
+	 * @param self The transform. */
+	void (*destroy)(bithenge_transform_t *self);
+} bithenge_transform_ops_t;
+
+/** Get the number of parameters required by a transform. This number is used
+ * by the parser and param-wrapper. Takes ownership of nothing.
+ * @param self The transform.
+ * @return The number of parameters required. */
+static inline int bithenge_transform_num_params(bithenge_transform_t *self)
+{
+	assert(self);
+	return self->num_params;
+}
+
+/** Increment a transform's reference count.
+ * @param self The transform to reference. */
+static inline void bithenge_transform_inc_ref(bithenge_transform_t *self)
+{
+	assert(self);
+	self->refs++;
+}
+
+/** Decrement a transform's reference count and free it if appropriate.
+ * @param self The transform to dereference, or NULL. */
+static inline void bithenge_transform_dec_ref(bithenge_transform_t *self)
+{
+	if (!self)
+		return;
+	assert(self->ops);
+	assert(self->refs > 0);
+	if (--self->refs == 0)
+		self->ops->destroy(self);
+}
+
+/** A transform with a name. */
+typedef struct {
+	const char *name;
+	bithenge_transform_t *transform;
+} bithenge_named_transform_t;
+
+extern bithenge_transform_t bithenge_ascii_transform;
+extern bithenge_transform_t bithenge_bit_transform;
+extern bithenge_transform_t bithenge_bits_be_transform;
+extern bithenge_transform_t bithenge_bits_le_transform;
+extern bithenge_transform_t bithenge_invalid_transform;
+extern bithenge_transform_t bithenge_known_length_transform;
+extern bithenge_transform_t bithenge_nonzero_boolean_transform;
+extern bithenge_transform_t bithenge_uint8_transform;
+extern bithenge_transform_t bithenge_uint16le_transform;
+extern bithenge_transform_t bithenge_uint16be_transform;
+extern bithenge_transform_t bithenge_uint32le_transform;
+extern bithenge_transform_t bithenge_uint32be_transform;
+extern bithenge_transform_t bithenge_uint64le_transform;
+extern bithenge_transform_t bithenge_uint64be_transform;
+extern bithenge_transform_t bithenge_uint_le_transform;
+extern bithenge_transform_t bithenge_uint_be_transform;
+extern bithenge_transform_t bithenge_zero_terminated_transform;
+extern bithenge_named_transform_t *bithenge_primitive_transforms;
+
+int bithenge_init_transform(bithenge_transform_t *,
+    const bithenge_transform_ops_t *, int);
+int bithenge_transform_apply(bithenge_transform_t *, bithenge_scope_t *,
+    bithenge_node_t *, bithenge_node_t **);
+int bithenge_transform_prefix_length(bithenge_transform_t *,
+    bithenge_scope_t *, bithenge_blob_t *, aoff64_t *);
+int bithenge_transform_prefix_apply(bithenge_transform_t *, bithenge_scope_t *,
+    bithenge_blob_t *, bithenge_node_t **, aoff64_t *);
+int bithenge_new_barrier_transform(bithenge_transform_t **, int);
+int bithenge_barrier_transform_set_subtransform(bithenge_transform_t *,
+    bithenge_transform_t *);
+
+int bithenge_scope_new(bithenge_scope_t **, bithenge_scope_t *);
+void bithenge_scope_dec_ref(bithenge_scope_t *);
+bithenge_scope_t *bithenge_scope_outer(bithenge_scope_t *);
+const char *bithenge_scope_get_error(bithenge_scope_t *);
+int bithenge_scope_error(bithenge_scope_t *, const char *, ...);
+bithenge_node_t *bithenge_scope_get_current_node(bithenge_scope_t *);
+void bithenge_scope_set_current_node(bithenge_scope_t *, bithenge_node_t *);
+bithenge_node_t *bithenge_scope_in_node(bithenge_scope_t *);
+void bithenge_scope_set_in_node(bithenge_scope_t *, bithenge_node_t *);
+void bithenge_scope_set_barrier(bithenge_scope_t *);
+bool bithenge_scope_is_barrier(bithenge_scope_t *);
+int bithenge_scope_alloc_params(bithenge_scope_t *, int);
+int bithenge_scope_set_param(bithenge_scope_t *, int, bithenge_node_t *);
+int bithenge_scope_get_param(bithenge_scope_t *, int, bithenge_node_t **);
+
+#endif
+
+/** @}
+ */
