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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/* $Rev$ $Date$ */
#ifndef tuscany_tree_hpp
#define tuscany_tree_hpp
/**
* Functions to work with trees.
*/
#include "stream.hpp"
#include "string.hpp"
#include "function.hpp"
#include "list.hpp"
#include "monad.hpp"
#include "value.hpp"
namespace tuscany {
/**
* Make a tree from a leaf and two branches.
*/
template<typename T> const list<T> mktree(const T& e, const list<T>& left, const list<T>& right) {
return mklist<T>(e, left, right);
}
/**
* Find a leaf with the given key in a tree.
*/
template<typename T> const list<T> assoctree(const T& k, const list<T>& tree) {
if (isNil(tree))
return tree;
if (k == car<T>(car(tree)))
return car(tree);
if (k < car<T>(car(tree)))
return assoctree<T>(k, cadr(tree));
return assoctree<T>(k, caddr(tree));
}
/**
* Construct a new tree from a leaf and a tree.
*/
template<typename T> const list<T> constree(const T& e, const list<T>& tree) {
if (isNil(tree))
return mktree(e, list<T>(), list<T>());
if (e == car(tree))
return tree;
if (e < car(tree))
return mktree<T>(car(tree), constree<T>(e, cadr(tree)), caddr(tree));
return mktree<T>(car(tree), cadr(tree), constree<T>(e, caddr(tree)));
}
/**
* Make a tree from an unordered list of leaves.
*/
template<typename T> const list<T> mktree(const list<T>& l) {
if (isNil(l))
return l;
return constree(car(l), mktree(cdr(l)));
}
/**
* Convert a tree to an ordered list of leaves.
*/
template<typename T> const list<T> flatten(const list<T>& tree) {
if (isNil(tree))
return tree;
return append<T>(flatten<T>(cadr(tree)), cons<T>(car(tree), flatten<T>(caddr(tree))));
}
/**
* Sort a list.
*/
template<typename T> const list<T> sort(const list<T>& l) {
return flatten(mktree(l));
}
/**
* Make a balanced tree from an ordered list of leaves.
*/
template<typename T> const list<T> btreeHelper(const list<T>& elements, const size_t n) {
if (n == 0)
return cons<T>(list<T>(), elements);
const size_t leftSize = (n - 1) / 2; {
const list<T> leftResult = btreeHelper<T>(elements, leftSize); {
const list<T> leftTree = car(leftResult);
const list<T> nonLeftElements = cdr(leftResult);
const size_t rightSize = n - (leftSize + 1); {
const T thisEntry = car(nonLeftElements);
const list<T> rightResult = btreeHelper<T>(cdr(nonLeftElements), rightSize); {
const list<T> rightTree = car(rightResult);
const list<T> remainingElements = cdr(rightResult); {
return cons<T>(mktree<T>(thisEntry, leftTree, rightTree), remainingElements);
}
}
}
}
}
}
template<typename T> const list<T> mkbtree(const list<T>& elements) {
return car(btreeHelper<T>(elements, length(elements)));
}
}
#endif /* tuscany_tree_hpp */
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