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/* -*- c++ -*- */
/*
* Copyright © 2010 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#pragma once
#ifndef IR_HIERARCHICAL_VISITOR_H
#define IR_HIERARCHICAL_VISITOR_H
/**
* Enumeration values returned by visit methods to guide processing
*/
enum ir_visitor_status {
visit_continue, /**< Continue visiting as normal. */
visit_continue_with_parent, /**< Don't visit siblings, continue w/parent. */
visit_stop /**< Stop visiting immediately. */
};
/**
* Base class of hierarchical visitors of IR instruction trees
*
* Hierarchical visitors differ from traditional visitors in a couple of
* important ways. Rather than having a single \c visit method for each
* subclass in the composite, there are three kinds of visit methods.
* Leaf-node classes have a traditional \c visit method. Internal-node
* classes have a \c visit_enter method, which is invoked just before
* processing child nodes, and a \c visit_leave method which is invoked just
* after processing child nodes.
*
* In addition, each visit method and the \c accept methods in the composite
* have a return value which guides the navigation. Any of the visit methods
* can choose to continue visiting the tree as normal (by returning \c
* visit_continue), terminate visiting any further nodes immediately (by
* returning \c visit_stop), or stop visiting sibling nodes (by returning \c
* visit_continue_with_parent).
*
* These two changes combine to allow nagivation of children to be implemented
* in the composite's \c accept method. The \c accept method for a leaf-node
* class will simply call the \c visit method, as usual, and pass its return
* value on. The \c accept method for internal-node classes will call the \c
* visit_enter method, call the \c accpet method of each child node, and,
* finally, call the \c visit_leave method. If any of these return a value
* other that \c visit_continue, the correct action must be taken.
*
* The final benefit is that the hierarchical visitor base class need not be
* abstract. Default implementations of every \c visit, \c visit_enter, and
* \c visit_leave method can be provided. By default each of these methods
* simply returns \c visit_continue. This allows a significant reduction in
* derived class code.
*
* For more information about hierarchical visitors, see:
*
* http://c2.com/cgi/wiki?HierarchicalVisitorPattern
* http://c2.com/cgi/wiki?HierarchicalVisitorDiscussion
*/
class ir_hierarchical_visitor {
public:
/**
* \name Visit methods for leaf-node classes
*/
/*@{*/
virtual ir_visitor_status visit(class ir_variable *);
virtual ir_visitor_status visit(class ir_constant *);
virtual ir_visitor_status visit(class ir_loop_jump *);
/*@}*/
/**
* \name Visit methods for internal-node classes
*/
/*@{*/
virtual ir_visitor_status visit_enter(class ir_loop *);
virtual ir_visitor_status visit_leave(class ir_loop *);
virtual ir_visitor_status visit_enter(class ir_function_signature *);
virtual ir_visitor_status visit_leave(class ir_function_signature *);
virtual ir_visitor_status visit_enter(class ir_function *);
virtual ir_visitor_status visit_leave(class ir_function *);
virtual ir_visitor_status visit_enter(class ir_expression *);
virtual ir_visitor_status visit_leave(class ir_expression *);
virtual ir_visitor_status visit_enter(class ir_swizzle *);
virtual ir_visitor_status visit_leave(class ir_swizzle *);
virtual ir_visitor_status visit_enter(class ir_dereference *);
virtual ir_visitor_status visit_leave(class ir_dereference *);
virtual ir_visitor_status visit_enter(class ir_assignment *);
virtual ir_visitor_status visit_leave(class ir_assignment *);
virtual ir_visitor_status visit_enter(class ir_call *);
virtual ir_visitor_status visit_leave(class ir_call *);
virtual ir_visitor_status visit_enter(class ir_return *);
virtual ir_visitor_status visit_leave(class ir_return *);
virtual ir_visitor_status visit_enter(class ir_if *);
virtual ir_visitor_status visit_leave(class ir_if *);
/*@}*/
/**
* Utility function to process a linked list of instructions with a visitor
*/
void run(struct exec_list *instructions);
};
#endif /* IR_HIERARCHICAL_VISITOR_H */
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