Tue, 16 Jun 2009 10:46:37 +0100
6638712: Inference with wildcard types causes selection of inapplicable method
Summary: Added global sanity check in order to make sure that return type inference does not violate bounds constraints
Reviewed-by: jjg
duke@1 | 1 | /* |
duke@1 | 2 | * Copyright 2002-2003 Sun Microsystems, Inc. All Rights Reserved. |
duke@1 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@1 | 4 | * |
duke@1 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@1 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@1 | 7 | * published by the Free Software Foundation. |
duke@1 | 8 | * |
duke@1 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@1 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@1 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@1 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@1 | 13 | * accompanied this code). |
duke@1 | 14 | * |
duke@1 | 15 | * You should have received a copy of the GNU General Public License version |
duke@1 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@1 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@1 | 18 | * |
duke@1 | 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
duke@1 | 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
duke@1 | 21 | * have any questions. |
duke@1 | 22 | */ |
duke@1 | 23 | |
duke@1 | 24 | class List<A> { |
duke@1 | 25 | |
duke@1 | 26 | /** The first element of the list, supposed to be immutable. |
duke@1 | 27 | */ |
duke@1 | 28 | public A head; |
duke@1 | 29 | |
duke@1 | 30 | /** The remainder of the list except for its first element, supposed |
duke@1 | 31 | * to be immutable. |
duke@1 | 32 | */ |
duke@1 | 33 | public List<A> tail; |
duke@1 | 34 | |
duke@1 | 35 | /** Construct a list given its head and tail. |
duke@1 | 36 | */ |
duke@1 | 37 | public List(A head, List<A> tail) { |
duke@1 | 38 | this.tail = tail; |
duke@1 | 39 | this.head = head; |
duke@1 | 40 | } |
duke@1 | 41 | |
duke@1 | 42 | /** Construct an empty list. |
duke@1 | 43 | */ |
duke@1 | 44 | public List() { |
duke@1 | 45 | this(null, null); |
duke@1 | 46 | } |
duke@1 | 47 | |
duke@1 | 48 | /** Construct a list consisting of given element. |
duke@1 | 49 | */ |
duke@1 | 50 | public static <A> List<A> make(A x1) { |
duke@1 | 51 | return new List<A>(x1, new List<A>()); |
duke@1 | 52 | } |
duke@1 | 53 | |
duke@1 | 54 | /** Construct a list consisting of given elements. |
duke@1 | 55 | */ |
duke@1 | 56 | public static <A> List<A> make(A x1, A x2) { |
duke@1 | 57 | return new List<A>(x1, new List<A>(x2, new List<A>())); |
duke@1 | 58 | } |
duke@1 | 59 | |
duke@1 | 60 | /** Construct a list consisting of given elements. |
duke@1 | 61 | */ |
duke@1 | 62 | public static <A> List<A> make(A x1, A x2, A x3) { |
duke@1 | 63 | return new List<A>(x1, new List<A>(x2, new List<A>(x3, new List<A>()))); |
duke@1 | 64 | } |
duke@1 | 65 | |
duke@1 | 66 | /** Construct a list consisting all elements of given array. |
duke@1 | 67 | */ |
duke@1 | 68 | public static <A> List<A> make(A[] vec) { |
duke@1 | 69 | List<A> xs = new List<A>(); |
duke@1 | 70 | for (int i = vec.length - 1; i >= 0; i--) |
duke@1 | 71 | xs = new List<A>(vec[i], xs); |
duke@1 | 72 | return xs; |
duke@1 | 73 | } |
duke@1 | 74 | |
duke@1 | 75 | /** Construct a list consisting of a given number of identical elements. |
duke@1 | 76 | * @param len The number of elements in the list. |
duke@1 | 77 | * @param init The value of each element. |
duke@1 | 78 | */ |
duke@1 | 79 | public static <A> List<A> make(int len, A init) { |
duke@1 | 80 | List<A> l = new List<A>(); |
duke@1 | 81 | for (int i = 0; i < len; i++) l = new List<A>(init, l); |
duke@1 | 82 | return l; |
duke@1 | 83 | } |
duke@1 | 84 | |
duke@1 | 85 | /** Does list have no elements? |
duke@1 | 86 | */ |
duke@1 | 87 | public boolean isEmpty() { |
duke@1 | 88 | return tail == null; |
duke@1 | 89 | } |
duke@1 | 90 | |
duke@1 | 91 | /** Does list have elements? |
duke@1 | 92 | */ |
duke@1 | 93 | public boolean nonEmpty() { |
duke@1 | 94 | return tail != null; |
duke@1 | 95 | } |
duke@1 | 96 | |
duke@1 | 97 | /** Return the number of elements in this list. |
duke@1 | 98 | */ |
duke@1 | 99 | public int length() { |
duke@1 | 100 | List<A> l = this; |
duke@1 | 101 | int len = 0; |
duke@1 | 102 | while (l.tail != null) { |
duke@1 | 103 | l = l.tail; |
duke@1 | 104 | len++; |
duke@1 | 105 | } |
duke@1 | 106 | return len; |
duke@1 | 107 | } |
duke@1 | 108 | |
duke@1 | 109 | /** Prepend given element to front of list, forming and returning |
duke@1 | 110 | * a new list. |
duke@1 | 111 | */ |
duke@1 | 112 | public List<A> prepend(A x) { |
duke@1 | 113 | return new List<A>(x, this); |
duke@1 | 114 | } |
duke@1 | 115 | |
duke@1 | 116 | /** Prepend given list of elements to front of list, forming and returning |
duke@1 | 117 | * a new list. |
duke@1 | 118 | */ |
duke@1 | 119 | public List<A> prependList(List<A> xs) { |
duke@1 | 120 | if (this.isEmpty()) return xs; |
duke@1 | 121 | else if (xs.isEmpty()) return this; |
duke@1 | 122 | else return this.prependList(xs.tail).prepend(xs.head); |
duke@1 | 123 | } |
duke@1 | 124 | |
duke@1 | 125 | /** Reverse list, forming and returning a new list. |
duke@1 | 126 | */ |
duke@1 | 127 | public List<A> reverse() { |
duke@1 | 128 | List<A> rev = new List<A>(); |
duke@1 | 129 | for (List<A> l = this; l.nonEmpty(); l = l.tail) |
duke@1 | 130 | rev = new List<A>(l.head, rev); |
duke@1 | 131 | return rev; |
duke@1 | 132 | } |
duke@1 | 133 | |
duke@1 | 134 | /** Append given element at length, forming and returning |
duke@1 | 135 | * a new list. |
duke@1 | 136 | */ |
duke@1 | 137 | public List<A> append(A x) { |
duke@1 | 138 | return make(x).prependList(this); |
duke@1 | 139 | } |
duke@1 | 140 | |
duke@1 | 141 | /** Append given list at length, forming and returning |
duke@1 | 142 | * a new list. |
duke@1 | 143 | */ |
duke@1 | 144 | public List<A> appendList(List<A> x) { |
duke@1 | 145 | return x.prependList(this); |
duke@1 | 146 | } |
duke@1 | 147 | |
duke@1 | 148 | /** Copy successive elements of this list into given vector until |
duke@1 | 149 | * list is exhausted or end of vector is reached. |
duke@1 | 150 | */ |
duke@1 | 151 | public A[] toArray(A[] vec) { |
duke@1 | 152 | int i = 0; |
duke@1 | 153 | List<A> l = this; |
duke@1 | 154 | while (l.nonEmpty() && i < vec.length) { |
duke@1 | 155 | vec[i] = l.head; |
duke@1 | 156 | l = l.tail; |
duke@1 | 157 | i++; |
duke@1 | 158 | } |
duke@1 | 159 | return vec; |
duke@1 | 160 | } |
duke@1 | 161 | |
duke@1 | 162 | /** Form a string listing all elements with given separator character. |
duke@1 | 163 | */ |
duke@1 | 164 | public String toString(String sep) { |
duke@1 | 165 | if (isEmpty()) { |
duke@1 | 166 | return ""; |
duke@1 | 167 | } else { |
duke@1 | 168 | StringBuffer buf = new StringBuffer(); |
duke@1 | 169 | buf.append(((Object)head).toString()); |
duke@1 | 170 | for (List<A> l = tail; l.nonEmpty(); l = l.tail) { |
duke@1 | 171 | buf.append(sep); |
duke@1 | 172 | buf.append(((Object)l.head).toString()); |
duke@1 | 173 | } |
duke@1 | 174 | return buf.toString(); |
duke@1 | 175 | } |
duke@1 | 176 | } |
duke@1 | 177 | |
duke@1 | 178 | /** Form a string listing all elements with comma as the separator character. |
duke@1 | 179 | */ |
duke@1 | 180 | public String toString() { |
duke@1 | 181 | return toString(","); |
duke@1 | 182 | } |
duke@1 | 183 | |
duke@1 | 184 | /** Compute a hash code, overrides Object |
duke@1 | 185 | */ |
duke@1 | 186 | public int hashCode() { |
duke@1 | 187 | List<A> l = this; |
duke@1 | 188 | int h = 0; |
duke@1 | 189 | while (l.tail != null) { |
duke@1 | 190 | h = h * 41 + (head != null ? head.hashCode() : 0); |
duke@1 | 191 | l = l.tail; |
duke@1 | 192 | } |
duke@1 | 193 | return h; |
duke@1 | 194 | } |
duke@1 | 195 | |
duke@1 | 196 | /** Is this list the same as other list? |
duke@1 | 197 | */ |
duke@1 | 198 | public boolean equals(Object other) { |
duke@1 | 199 | return other instanceof List && equals(this, (List)other); |
duke@1 | 200 | } |
duke@1 | 201 | |
duke@1 | 202 | /** Are the two lists the same? |
duke@1 | 203 | */ |
duke@1 | 204 | public static boolean equals(List xs, List ys) { |
duke@1 | 205 | while (xs.tail != null && ys.tail != null) { |
duke@1 | 206 | if (xs.head == null) { |
duke@1 | 207 | if (ys.head != null) return false; |
duke@1 | 208 | } else { |
duke@1 | 209 | if (!xs.head.equals(ys.head)) return false; |
duke@1 | 210 | } |
duke@1 | 211 | xs = xs.tail; |
duke@1 | 212 | ys = ys.tail; |
duke@1 | 213 | } |
duke@1 | 214 | return xs.tail == null && ys.tail == null; |
duke@1 | 215 | } |
duke@1 | 216 | |
duke@1 | 217 | /** Does the list contain the specified element? |
duke@1 | 218 | */ |
duke@1 | 219 | public boolean contains(A x) { |
duke@1 | 220 | List<A> l = this; |
duke@1 | 221 | while (l.tail != null) { |
duke@1 | 222 | if (x == null) { |
duke@1 | 223 | if (l.head == null) return true; |
duke@1 | 224 | } else { |
duke@1 | 225 | if (x.equals(l.head)) return true; |
duke@1 | 226 | } |
duke@1 | 227 | l = l.tail; |
duke@1 | 228 | } |
duke@1 | 229 | return false; |
duke@1 | 230 | } |
duke@1 | 231 | |
duke@1 | 232 | } |