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95 lines
3.9 KiB
C++
95 lines
3.9 KiB
C++
// Copyright 2009, Google Inc. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// 3. Neither the name of Google Inc. nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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// EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// WARNING: THE VISITOR API IMPLEMENTED IN THIS CLASS IS EXPERIMENTAL AND
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// SUBJECT TO CHANGE WITHOUT WARNING.
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#ifndef KML_DOM_VISITOR_DRIVER_H__
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#define KML_DOM_VISITOR_DRIVER_H__
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#include "kml/base/util.h"
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#include "kml/dom/kml_ptr.h"
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#include "kml/dom/visitor.h"
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namespace kmldom {
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// A visitor driver controls the flow of a visitation over the dom element
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// hierarchy. There is typically expected to be only a single driver for each
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// visitation and currently there is not concept of chaining drivers (though
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// visitors themselves could be chained within a single 'multi driver').
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class VisitorDriver {
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protected:
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VisitorDriver();
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virtual ~VisitorDriver();
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public:
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// Handles the visitation of the subtree of elements rooted at the given
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// element. This method is invoked either by the user to initiate a visitation
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// or in response to a call to AcceptChildren() for an element.
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//
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// Typically when a driver visits an element it will, in some order:
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// - call accept() on the given element for some set of visitors
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// - call acceptChildren() on the given element, passing itself
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// However there is no requirement that either of these actually occur and
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// the driver is free to implement whatever semantics it chooses.
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virtual void Visit(const ElementPtr& element) = 0;
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LIBKML_DISALLOW_EVIL_CONSTRUCTORS(VisitorDriver);
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};
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// A simple driver implementation that invokes a single visitor in pre-order
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// traversal of an element hierarchy. The visitor will visit each element in a
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// hierarchy before that element's children are visited.
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class SimplePreorderDriver : public VisitorDriver {
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public:
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explicit SimplePreorderDriver(Visitor* visitor);
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virtual ~SimplePreorderDriver();
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virtual void Visit(const ElementPtr& element);
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private:
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Visitor* visitor_;
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LIBKML_DISALLOW_EVIL_CONSTRUCTORS(SimplePreorderDriver);
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};
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// A simple driver implementation that invokes a single visitor in post-order
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// traversal of an element hierarchy. The visitor will visit each element in a
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// hierarchy after that element's children have been visited.
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class SimplePostorderDriver : public VisitorDriver {
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public:
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explicit SimplePostorderDriver(Visitor* visitor);
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virtual ~SimplePostorderDriver();
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virtual void Visit(const ElementPtr& element);
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private:
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Visitor* visitor_;
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LIBKML_DISALLOW_EVIL_CONSTRUCTORS(SimplePostorderDriver);
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};
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} // namespace kmldom
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#endif // KML_DOM_VISITOR_DRIVER_H__
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