1bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor/* 21d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Copyright (C) 2008 The Guava Authors 3bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 4bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * Licensed under the Apache License, Version 2.0 (the "License"); 5bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * you may not use this file except in compliance with the License. 6bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * You may obtain a copy of the License at 7bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 8bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * http://www.apache.org/licenses/LICENSE-2.0 9bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 10bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * Unless required by applicable law or agreed to in writing, software 11bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * distributed under the License is distributed on an "AS IS" BASIS, 12bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * See the License for the specific language governing permissions and 14bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * limitations under the License. 15bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor */ 16bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 17bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorpackage com.google.common.io; 18bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 19bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport com.google.common.base.Preconditions; 20bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 21bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport java.io.IOException; 221d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertimport java.io.Reader; 23bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorimport java.util.Iterator; 24bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 257dd252788645e940eada959bdde927426e2531c9Paul Duffinimport javax.annotation.Nullable; 267dd252788645e940eada959bdde927426e2531c9Paul Duffin 27bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor/** 281d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * A {@link Reader} that concatenates multiple readers. 29bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * 30bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * @author Bin Zhu 311d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @since 1.0 32bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor */ 33bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnorclass MultiReader extends Reader { 340888a09821a98ac0680fad765217302858e70fa4Paul Duffin private final Iterator<? extends CharSource> it; 35bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private Reader current; 36bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 370888a09821a98ac0680fad765217302858e70fa4Paul Duffin MultiReader(Iterator<? extends CharSource> readers) throws IOException { 38bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor this.it = readers; 39bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor advance(); 40bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 41bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 42bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor /** 43bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor * Closes the current reader and opens the next one, if any. 44bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor */ 45bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor private void advance() throws IOException { 46bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor close(); 47bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor if (it.hasNext()) { 480888a09821a98ac0680fad765217302858e70fa4Paul Duffin current = it.next().openStream(); 49bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 50bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 51bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 520888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public int read(@Nullable char cbuf[], int off, int len) throws IOException { 53bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor if (current == null) { 54bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor return -1; 55bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 56bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor int result = current.read(cbuf, off, len); 57bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor if (result == -1) { 58bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor advance(); 59bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor return read(cbuf, off, len); 60bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 61bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor return result; 62bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 63bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 640888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public long skip(long n) throws IOException { 65bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor Preconditions.checkArgument(n >= 0, "n is negative"); 66bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor if (n > 0) { 67bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor while (current != null) { 68bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor long result = current.skip(n); 69bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor if (result > 0) { 70bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor return result; 71bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 72bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor advance(); 73bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 74bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 75bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor return 0; 76bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 77bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 780888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public boolean ready() throws IOException { 79bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor return (current != null) && current.ready(); 80bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 81bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor 820888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public void close() throws IOException { 83bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor if (current != null) { 84bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor try { 85bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor current.close(); 86bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } finally { 87bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor current = null; 88bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 89bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 90bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor } 91bfe2dd089341dcb4c1fb65a5b6b077ad0ebbf6dcDan Egnor} 92