aoqi@0: /*
aoqi@0:  * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package com.sun.tools.javac.util;
aoqi@0: 
aoqi@0: import java.lang.reflect.Array;
aoqi@0: import java.util.ArrayList;
aoqi@0: import java.util.Collection;
aoqi@0: import java.util.Collections;
aoqi@0: import java.util.Iterator;
aoqi@0: import java.util.AbstractCollection;
aoqi@0: import java.util.ListIterator;
aoqi@0: import java.util.NoSuchElementException;
aoqi@0: 
aoqi@0: /** A class for generic linked lists. Links are supposed to be
aoqi@0:  *  immutable, the only exception being the incremental construction of
aoqi@0:  *  lists via ListBuffers.  List is the main container class in
aoqi@0:  *  GJC. Most data structures and algorithms in GJC use lists rather
aoqi@0:  *  than arrays.
aoqi@0:  *
aoqi@0:  *  <p>Lists are always trailed by a sentinel element, whose head and tail
aoqi@0:  *  are both null.
aoqi@0:  *
aoqi@0:  *  <p><b>This is NOT part of any supported API.
aoqi@0:  *  If you write code that depends on this, you do so at your own risk.
aoqi@0:  *  This code and its internal interfaces are subject to change or
aoqi@0:  *  deletion without notice.</b>
aoqi@0:  */
aoqi@0: public class List<A> extends AbstractCollection<A> implements java.util.List<A> {
aoqi@0: 
aoqi@0:     /** The first element of the list, supposed to be immutable.
aoqi@0:      */
aoqi@0:     public A head;
aoqi@0: 
aoqi@0:     /** The remainder of the list except for its first element, supposed
aoqi@0:      *  to be immutable.
aoqi@0:      */
aoqi@0:     //@Deprecated
aoqi@0:     public List<A> tail;
aoqi@0: 
aoqi@0:     /** Construct a list given its head and tail.
aoqi@0:      */
aoqi@0:     List(A head, List<A> tail) {
aoqi@0:         this.tail = tail;
aoqi@0:         this.head = head;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Construct an empty list.
aoqi@0:      */
aoqi@0:     @SuppressWarnings("unchecked")
aoqi@0:     public static <A> List<A> nil() {
aoqi@0:         return (List<A>)EMPTY_LIST;
aoqi@0:     }
aoqi@0: 
aoqi@0:     private static final List<?> EMPTY_LIST = new List<Object>(null,null) {
aoqi@0:         public List<Object> setTail(List<Object> tail) {
aoqi@0:             throw new UnsupportedOperationException();
aoqi@0:         }
aoqi@0:         public boolean isEmpty() {
aoqi@0:             return true;
aoqi@0:         }
aoqi@0:     };
aoqi@0: 
aoqi@0:     /** Returns the list obtained from 'l' after removing all elements 'elem'
aoqi@0:      */
aoqi@0:     public static <A> List<A> filter(List<A> l, A elem) {
aoqi@0:         Assert.checkNonNull(elem);
aoqi@0:         List<A> res = List.nil();
aoqi@0:         for (A a : l) {
aoqi@0:             if (a != null && !a.equals(elem)) {
aoqi@0:                 res = res.prepend(a);
aoqi@0:             }
aoqi@0:         }
aoqi@0:         return res.reverse();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public List<A> intersect(List<A> that) {
aoqi@0:         ListBuffer<A> buf = new ListBuffer<>();
aoqi@0:         for (A el : this) {
aoqi@0:             if (that.contains(el)) {
aoqi@0:                 buf.append(el);
aoqi@0:             }
aoqi@0:         }
aoqi@0:         return buf.toList();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public List<A> diff(List<A> that) {
aoqi@0:         ListBuffer<A> buf = new ListBuffer<>();
aoqi@0:         for (A el : this) {
aoqi@0:             if (!that.contains(el)) {
aoqi@0:                 buf.append(el);
aoqi@0:             }
aoqi@0:         }
aoqi@0:         return buf.toList();
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Create a new list from the first {@code n} elements of this list
aoqi@0:      */
aoqi@0:     public List<A> take(int n) {
aoqi@0:         ListBuffer<A> buf = new ListBuffer<>();
aoqi@0:         int count = 0;
aoqi@0:         for (A el : this) {
aoqi@0:             if (count++ == n) break;
aoqi@0:             buf.append(el);
aoqi@0:         }
aoqi@0:         return buf.toList();
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Construct a list consisting of given element.
aoqi@0:      */
aoqi@0:     public static <A> List<A> of(A x1) {
aoqi@0:         return new List<A>(x1, List.<A>nil());
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Construct a list consisting of given elements.
aoqi@0:      */
aoqi@0:     public static <A> List<A> of(A x1, A x2) {
aoqi@0:         return new List<A>(x1, of(x2));
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Construct a list consisting of given elements.
aoqi@0:      */
aoqi@0:     public static <A> List<A> of(A x1, A x2, A x3) {
aoqi@0:         return new List<A>(x1, of(x2, x3));
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Construct a list consisting of given elements.
aoqi@0:      */
aoqi@0:     @SuppressWarnings({"varargs", "unchecked"})
aoqi@0:     public static <A> List<A> of(A x1, A x2, A x3, A... rest) {
aoqi@0:         return new List<A>(x1, new List<A>(x2, new List<A>(x3, from(rest))));
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Construct a list consisting all elements of given array.
aoqi@0:      * @param array an array; if {@code null} return an empty list
aoqi@0:      */
aoqi@0:     public static <A> List<A> from(A[] array) {
aoqi@0:         List<A> xs = nil();
aoqi@0:         if (array != null)
aoqi@0:             for (int i = array.length - 1; i >= 0; i--)
aoqi@0:                 xs = new List<A>(array[i], xs);
aoqi@0:         return xs;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public static <A> List<A> from(Iterable<? extends A> coll) {
aoqi@0:         ListBuffer<A> xs = new ListBuffer<>();
aoqi@0:         for (A a : coll) {
aoqi@0:             xs.append(a);
aoqi@0:         }
aoqi@0:         return xs.toList();
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Construct a list consisting of a given number of identical elements.
aoqi@0:      *  @param len    The number of elements in the list.
aoqi@0:      *  @param init   The value of each element.
aoqi@0:      */
aoqi@0:     @Deprecated
aoqi@0:     public static <A> List<A> fill(int len, A init) {
aoqi@0:         List<A> l = nil();
aoqi@0:         for (int i = 0; i < len; i++) l = new List<A>(init, l);
aoqi@0:         return l;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Does list have no elements?
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public boolean isEmpty() {
aoqi@0:         return tail == null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Does list have elements?
aoqi@0:      */
aoqi@0:     //@Deprecated
aoqi@0:     public boolean nonEmpty() {
aoqi@0:         return tail != null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Return the number of elements in this list.
aoqi@0:      */
aoqi@0:     //@Deprecated
aoqi@0:     public int length() {
aoqi@0:         List<A> l = this;
aoqi@0:         int len = 0;
aoqi@0:         while (l.tail != null) {
aoqi@0:             l = l.tail;
aoqi@0:             len++;
aoqi@0:         }
aoqi@0:         return len;
aoqi@0:     }
aoqi@0:     @Override
aoqi@0:     public int size() {
aoqi@0:         return length();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public List<A> setTail(List<A> tail) {
aoqi@0:         this.tail = tail;
aoqi@0:         return tail;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Prepend given element to front of list, forming and returning
aoqi@0:      *  a new list.
aoqi@0:      */
aoqi@0:     public List<A> prepend(A x) {
aoqi@0:         return new List<A>(x, this);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Prepend given list of elements to front of list, forming and returning
aoqi@0:      *  a new list.
aoqi@0:      */
aoqi@0:     public List<A> prependList(List<A> xs) {
aoqi@0:         if (this.isEmpty()) return xs;
aoqi@0:         if (xs.isEmpty()) return this;
aoqi@0:         if (xs.tail.isEmpty()) return prepend(xs.head);
aoqi@0:         // return this.prependList(xs.tail).prepend(xs.head);
aoqi@0:         List<A> result = this;
aoqi@0:         List<A> rev = xs.reverse();
aoqi@0:         Assert.check(rev != xs);
aoqi@0:         // since xs.reverse() returned a new list, we can reuse the
aoqi@0:         // individual List objects, instead of allocating new ones.
aoqi@0:         while (rev.nonEmpty()) {
aoqi@0:             List<A> h = rev;
aoqi@0:             rev = rev.tail;
aoqi@0:             h.setTail(result);
aoqi@0:             result = h;
aoqi@0:         }
aoqi@0:         return result;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Reverse list.
aoqi@0:      * If the list is empty or a singleton, then the same list is returned.
aoqi@0:      * Otherwise a new list is formed.
aoqi@0:      */
aoqi@0:     public List<A> reverse() {
aoqi@0:         // if it is empty or a singleton, return itself
aoqi@0:         if (isEmpty() || tail.isEmpty())
aoqi@0:             return this;
aoqi@0: 
aoqi@0:         List<A> rev = nil();
aoqi@0:         for (List<A> l = this; l.nonEmpty(); l = l.tail)
aoqi@0:             rev = new List<A>(l.head, rev);
aoqi@0:         return rev;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Append given element at length, forming and returning
aoqi@0:      *  a new list.
aoqi@0:      */
aoqi@0:     public List<A> append(A x) {
aoqi@0:         return of(x).prependList(this);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Append given list at length, forming and returning
aoqi@0:      *  a new list.
aoqi@0:      */
aoqi@0:     public List<A> appendList(List<A> x) {
aoqi@0:         return x.prependList(this);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Append given list buffer at length, forming and returning a new
aoqi@0:      * list.
aoqi@0:      */
aoqi@0:     public List<A> appendList(ListBuffer<A> x) {
aoqi@0:         return appendList(x.toList());
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Copy successive elements of this list into given vector until
aoqi@0:      *  list is exhausted or end of vector is reached.
aoqi@0:      */
aoqi@0:     @Override @SuppressWarnings("unchecked")
aoqi@0:     public <T> T[] toArray(T[] vec) {
aoqi@0:         int i = 0;
aoqi@0:         List<A> l = this;
aoqi@0:         Object[] dest = vec;
aoqi@0:         while (l.nonEmpty() && i < vec.length) {
aoqi@0:             dest[i] = l.head;
aoqi@0:             l = l.tail;
aoqi@0:             i++;
aoqi@0:         }
aoqi@0:         if (l.isEmpty()) {
aoqi@0:             if (i < vec.length)
aoqi@0:                 vec[i] = null;
aoqi@0:             return vec;
aoqi@0:         }
aoqi@0: 
aoqi@0:         vec = (T[])Array.newInstance(vec.getClass().getComponentType(), size());
aoqi@0:         return toArray(vec);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public Object[] toArray() {
aoqi@0:         return toArray(new Object[size()]);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Form a string listing all elements with given separator character.
aoqi@0:      */
aoqi@0:     public String toString(String sep) {
aoqi@0:         if (isEmpty()) {
aoqi@0:             return "";
aoqi@0:         } else {
aoqi@0:             StringBuilder buf = new StringBuilder();
aoqi@0:             buf.append(head);
aoqi@0:             for (List<A> l = tail; l.nonEmpty(); l = l.tail) {
aoqi@0:                 buf.append(sep);
aoqi@0:                 buf.append(l.head);
aoqi@0:             }
aoqi@0:             return buf.toString();
aoqi@0:         }
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Form a string listing all elements with comma as the separator character.
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public String toString() {
aoqi@0:         return toString(",");
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Compute a hash code, overrides Object
aoqi@0:      *  @see java.util.List#hashCode
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public int hashCode() {
aoqi@0:         List<A> l = this;
aoqi@0:         int h = 1;
aoqi@0:         while (l.tail != null) {
aoqi@0:             h = h * 31 + (l.head == null ? 0 : l.head.hashCode());
aoqi@0:             l = l.tail;
aoqi@0:         }
aoqi@0:         return h;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Is this list the same as other list?
aoqi@0:      *  @see java.util.List#equals
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public boolean equals(Object other) {
aoqi@0:         if (other instanceof List<?>)
aoqi@0:             return equals(this, (List<?>)other);
aoqi@0:         if (other instanceof java.util.List<?>) {
aoqi@0:             List<A> t = this;
aoqi@0:             Iterator<?> oIter = ((java.util.List<?>) other).iterator();
aoqi@0:             while (t.tail != null && oIter.hasNext()) {
aoqi@0:                 Object o = oIter.next();
aoqi@0:                 if ( !(t.head == null ? o == null : t.head.equals(o)))
aoqi@0:                     return false;
aoqi@0:                 t = t.tail;
aoqi@0:             }
aoqi@0:             return (t.isEmpty() && !oIter.hasNext());
aoqi@0:         }
aoqi@0:         return false;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Are the two lists the same?
aoqi@0:      */
aoqi@0:     public static boolean equals(List<?> xs, List<?> ys) {
aoqi@0:         while (xs.tail != null && ys.tail != null) {
aoqi@0:             if (xs.head == null) {
aoqi@0:                 if (ys.head != null) return false;
aoqi@0:             } else {
aoqi@0:                 if (!xs.head.equals(ys.head)) return false;
aoqi@0:             }
aoqi@0:             xs = xs.tail;
aoqi@0:             ys = ys.tail;
aoqi@0:         }
aoqi@0:         return xs.tail == null && ys.tail == null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Does the list contain the specified element?
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public boolean contains(Object x) {
aoqi@0:         List<A> l = this;
aoqi@0:         while (l.tail != null) {
aoqi@0:             if (x == null) {
aoqi@0:                 if (l.head == null) return true;
aoqi@0:             } else {
aoqi@0:                 if (l.head.equals(x)) return true;
aoqi@0:             }
aoqi@0:             l = l.tail;
aoqi@0:         }
aoqi@0:         return false;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** The last element in the list, if any, or null.
aoqi@0:      */
aoqi@0:     public A last() {
aoqi@0:         A last = null;
aoqi@0:         List<A> t = this;
aoqi@0:         while (t.tail != null) {
aoqi@0:             last = t.head;
aoqi@0:             t = t.tail;
aoqi@0:         }
aoqi@0:         return last;
aoqi@0:     }
aoqi@0: 
aoqi@0:     @SuppressWarnings("unchecked")
aoqi@0:     public static <T> List<T> convert(Class<T> klass, List<?> list) {
aoqi@0:         if (list == null)
aoqi@0:             return null;
aoqi@0:         for (Object o : list)
aoqi@0:             klass.cast(o);
aoqi@0:         return (List<T>)list;
aoqi@0:     }
aoqi@0: 
aoqi@0:     private static final Iterator<?> EMPTYITERATOR = new Iterator<Object>() {
aoqi@0:             public boolean hasNext() {
aoqi@0:                 return false;
aoqi@0:             }
aoqi@0:             public Object next() {
aoqi@0:                 throw new java.util.NoSuchElementException();
aoqi@0:             }
aoqi@0:             public void remove() {
aoqi@0:                 throw new UnsupportedOperationException();
aoqi@0:             }
aoqi@0:         };
aoqi@0: 
aoqi@0:     @SuppressWarnings("unchecked")
aoqi@0:     private static <A> Iterator<A> emptyIterator() {
aoqi@0:         return (Iterator<A>)EMPTYITERATOR;
aoqi@0:     }
aoqi@0: 
aoqi@0:     @Override
aoqi@0:     public Iterator<A> iterator() {
aoqi@0:         if (tail == null)
aoqi@0:             return emptyIterator();
aoqi@0:         return new Iterator<A>() {
aoqi@0:             List<A> elems = List.this;
aoqi@0:             public boolean hasNext() {
aoqi@0:                 return elems.tail != null;
aoqi@0:             }
aoqi@0:             public A next() {
aoqi@0:                 if (elems.tail == null)
aoqi@0:                     throw new NoSuchElementException();
aoqi@0:                 A result = elems.head;
aoqi@0:                 elems = elems.tail;
aoqi@0:                 return result;
aoqi@0:             }
aoqi@0:             public void remove() {
aoqi@0:                 throw new UnsupportedOperationException();
aoqi@0:             }
aoqi@0:         };
aoqi@0:     }
aoqi@0: 
aoqi@0:     public A get(int index) {
aoqi@0:         if (index < 0)
aoqi@0:             throw new IndexOutOfBoundsException(String.valueOf(index));
aoqi@0: 
aoqi@0:         List<A> l = this;
aoqi@0:         for (int i = index; i-- > 0 && !l.isEmpty(); l = l.tail)
aoqi@0:             ;
aoqi@0: 
aoqi@0:         if (l.isEmpty())
aoqi@0:             throw new IndexOutOfBoundsException("Index: " + index + ", " +
aoqi@0:                                                 "Size: " + size());
aoqi@0:         return l.head;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean addAll(int index, Collection<? extends A> c) {
aoqi@0:         if (c.isEmpty())
aoqi@0:             return false;
aoqi@0:         throw new UnsupportedOperationException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public A set(int index, A element) {
aoqi@0:         throw new UnsupportedOperationException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public void add(int index, A element) {
aoqi@0:         throw new UnsupportedOperationException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public A remove(int index) {
aoqi@0:         throw new UnsupportedOperationException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public int indexOf(Object o) {
aoqi@0:         int i = 0;
aoqi@0:         for (List<A> l = this; l.tail != null; l = l.tail, i++) {
aoqi@0:             if (l.head == null ? o == null : l.head.equals(o))
aoqi@0:                 return i;
aoqi@0:         }
aoqi@0:         return -1;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public int lastIndexOf(Object o) {
aoqi@0:         int last = -1;
aoqi@0:         int i = 0;
aoqi@0:         for (List<A> l = this; l.tail != null; l = l.tail, i++) {
aoqi@0:             if (l.head == null ? o == null : l.head.equals(o))
aoqi@0:                 last = i;
aoqi@0:         }
aoqi@0:         return last;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public ListIterator<A> listIterator() {
aoqi@0:         return Collections.unmodifiableList(new ArrayList<A>(this)).listIterator();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public ListIterator<A> listIterator(int index) {
aoqi@0:         return Collections.unmodifiableList(new ArrayList<A>(this)).listIterator(index);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public java.util.List<A> subList(int fromIndex, int toIndex) {
aoqi@0:         if  (fromIndex < 0 || toIndex > size() || fromIndex > toIndex)
aoqi@0:             throw new IllegalArgumentException();
aoqi@0: 
aoqi@0:         ArrayList<A> a = new ArrayList<A>(toIndex - fromIndex);
aoqi@0:         int i = 0;
aoqi@0:         for (List<A> l = this; l.tail != null; l = l.tail, i++) {
aoqi@0:             if (i == toIndex)
aoqi@0:                 break;
aoqi@0:             if (i >= fromIndex)
aoqi@0:                 a.add(l.head);
aoqi@0:         }
aoqi@0: 
aoqi@0:         return Collections.unmodifiableList(a);
aoqi@0:     }
aoqi@0: }