| /* |
| * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package jdk.nashorn.internal.parser; |
| |
| /** |
| * Utility for scanning thru a char array. |
| * |
| */ |
| public class Scanner { |
| /** Characters to scan. */ |
| protected final char[] content; |
| |
| /** Position in content. */ |
| protected int position; |
| |
| /** Scan limit. */ |
| protected final int limit; |
| |
| /** Current line number. */ |
| protected int line; |
| |
| /** Current character in stream */ |
| protected char ch0; |
| /** 1 character lookahead */ |
| protected char ch1; |
| /** 2 character lookahead */ |
| protected char ch2; |
| /** 3 character lookahead */ |
| protected char ch3; |
| |
| /** |
| * Constructor |
| * |
| * @param content content to scan |
| * @param line start line number |
| * @param start position index in content where to start |
| * @param length length of input |
| */ |
| protected Scanner(final char[] content, final int line, final int start, final int length) { |
| this.content = content; |
| this.position = start; |
| this.limit = start + length; |
| this.line = line; |
| |
| reset(position); |
| } |
| |
| /** |
| * Constructor |
| * |
| * Scan content from beginning to end. Content given as a string |
| * |
| * @param content content to scan |
| */ |
| protected Scanner(final String content) { |
| this(content.toCharArray(), 0, 0, content.length()); |
| } |
| |
| /** |
| * Copy constructor |
| * |
| * @param scanner scanner |
| * @param state state, the state is a tuple {position, limit, line} only visible internally |
| */ |
| Scanner(final Scanner scanner, final State state) { |
| content = scanner.content; |
| position = state.position; |
| limit = state.limit; |
| line = state.line; |
| |
| reset(position); |
| } |
| |
| /** |
| * Information needed to restore previous state. |
| */ |
| static class State { |
| /** Position in content. */ |
| public final int position; |
| |
| /** Scan limit. */ |
| public int limit; |
| |
| /** Current line number. */ |
| public final int line; |
| |
| State(final int position, final int limit, final int line) { |
| this.position = position; |
| this.limit = limit; |
| this.line = line; |
| } |
| |
| /** |
| * Change the limit for a new scanner. |
| * @param limit New limit. |
| */ |
| void setLimit(final int limit) { |
| this.limit = limit; |
| } |
| |
| boolean isEmpty() { |
| return position == limit; |
| } |
| } |
| |
| /** |
| * Save the state of the scan. |
| * @return Captured state. |
| */ |
| State saveState() { |
| return new State(position, limit, line); |
| } |
| |
| /** |
| * Restore the state of the scan. |
| * @param state Captured state. |
| */ |
| void restoreState(final State state) { |
| position = state.position; |
| line = state.line; |
| |
| reset(position); |
| } |
| |
| /** |
| * Returns true of scanner is at end of input |
| * @return true if no more input |
| */ |
| protected final boolean atEOF() { |
| return position == limit; |
| } |
| |
| /** |
| * Get the ith character from the content. |
| * @param i Index of character. |
| * @return ith character or '\0' if beyond limit. |
| */ |
| protected final char charAt(final int i) { |
| // Get a character from the content, '\0' if beyond the end of file. |
| return i < limit ? content[i] : '\0'; |
| } |
| |
| /** |
| * Reset to a character position. |
| * @param i Position in content. |
| */ |
| protected final void reset(final int i) { |
| ch0 = charAt(i); |
| ch1 = charAt(i + 1); |
| ch2 = charAt(i + 2); |
| ch3 = charAt(i + 3); |
| position = i < limit? i : limit; |
| } |
| |
| /** |
| * Skip ahead a number of characters. |
| * @param n Number of characters to skip. |
| */ |
| protected final void skip(final int n) { |
| if (n == 1 && !atEOF()) { |
| ch0 = ch1; |
| ch1 = ch2; |
| ch2 = ch3; |
| ch3 = charAt(position + 4); |
| position++; |
| } else if (n != 0) { |
| reset(position + n); |
| } |
| } |
| } |