com.crashnote.core.model.data.PackageTrie.jav Maven / Gradle / Ivy

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///**
// * Copyright (C) 2011 - 101loops.com 
// *
// * Licensed 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.
// */
//package com.crashnote.core.model.data;
//
///**
// * FROM WIKIPEDIA:
// * "A trie, or prefix tree, is an ordered tree data structure that is used to store an associative
// * array where the keys are usually strings. Unlike a binary search tree, no node in the tree
// * stores the key associated with that node; instead, its position in the tree shows what key
// * it is associated with. All the descendants of a node have a common prefix of the string
// * associated with that node, and the root is associated with the empty string."
// * 
// * This 'package' trie stores each part from a package path (e.g. org - apache - tomcat) in a node,
// * this way a package can be found very quickly.
// */
//public class PackageTrie {
//
//    private final Node root;
//
//    // SETUP =====================================================================================
//
//    public PackageTrie() {
//        root = new Node("");
//    }
//
//    // INTERFACE ==================================================================================
//
//    public final void add(final String path) {
//        addPckg(path.split("\\."));
//    }
//
//    public final String find(final String path) {
//        return findPckg(path.split("\\."));
//    }
//
//    public final boolean has(final String path) {
//        return find(path) != null;
//    }
//
//    // INTERNALS ==================================================================================
//
//    private void addPckg(final String[] pckgs) {
//        int offset = 0;
//        Node root = this.root, last = null, next = root.child, parent = null;
//        while (root != null) {
//            last = null;
//            parent = root;
//            final String p = pckgs[offset];
//            while (next != null) {
//                final int comp = next.value.compareTo(p);
//                if (comp == 0) { // match found, add remaining word to this node
//                    root = next;
//                    next = root.child;
//                    offset++;
//                    break;
//                } else if (comp < 0) { // not found yet, continue searching
//                    last = next;
//                    next = next.next;
//                } else { // won't find it anymore
//                    root = null;
//                    break;
//                }
//            }
//            if (parent == root) break;
//        }
//
//        if (offset < pckgs.length) {
//            // create a new node
//            Node node = new Node(pckgs[offset]);
//            if (last == null) { // insert at the beginning of the list
//                parent.child = node;
//                node.next = next;
//            } else { // insert between last and next
//                last.next = node;
//                node.next = next;
//            }
//
//            // add remaining items
//            for (int i = offset + 1; i < pckgs.length; i++) {
//                node.child = new Node(pckgs[i]);
//                node = node.child;
//            }
//        }
//    }
//
//    private String findPckg(final String[] pckgs) {
//        int offset = 0;
//        final StringBuilder sb = new StringBuilder();
//        Node root = this.root;
//        while (root != null && offset < pckgs.length) {
//            final String p = pckgs[offset];
//            Node next = root.child;
//            root = null;
//            while (next != null) {
//                final int comp = next.value.compareTo(p);
//                if (comp < 0) next = next.next;
//                else if (comp == 0) {
//                    sb.append(".").append(next.value);
//                    root = next;
//                    next = null;
//                    offset++;
//                } else return null;
//            }
//            if (root != null && root.isLast()) return sb.toString().substring(1);
//        }
//        return null;
//    }
//
//    private final class Node {
//
//        public String value;
//        public Node child;
//        public Node next;
//
//        public Node(final String value) {
//            this.value = value;
//            child = null;
//            next = null;
//        }
//
//        public final boolean isLast() {
//            return child == null;
//        }
//    }
//
//}