111 lines
4.1 KiB
Java
111 lines
4.1 KiB
Java
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/*
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* Janino - An embedded Java[TM] compiler
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*
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* Copyright (c) 2001-2010, Arno Unkrig
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
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* following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
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* following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
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* following disclaimer in the documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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package org.codehaus.janino;
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import java.io.FilterReader;
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import java.io.IOException;
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import java.io.Reader;
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/**
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* A {@link FilterReader} that unescapes the "Unicode Escapes" as described in JLS7 3.10.6.
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* <p>
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* Notice that it is possible to formulate invalid escape sequences, e.g. "\u123g" ("g" is not a valid hex
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* character). This is handled by throwing a {@link java.lang.RuntimeException}-derived {@link
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* org.codehaus.janino.UnicodeUnescapeException}.
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*/
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public
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class UnicodeUnescapeReader extends FilterReader {
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public
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UnicodeUnescapeReader(Reader in) { super(in); }
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/**
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* Override {@link FilterReader#read()}.
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*
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* @throws UnicodeUnescapeException Invalid escape sequence encountered
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*/
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@Override public int
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read() throws IOException {
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int c;
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// Read next character.
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if (this.unreadChar == -1) {
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c = this.in.read();
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} else {
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c = this.unreadChar;
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this.unreadChar = -1;
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}
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// Check for backslash-u escape sequence, preceeded with an even number
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// of backslashes.
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if (c != '\\' || this.oddPrecedingBackslashes) {
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this.oddPrecedingBackslashes = false;
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return c;
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}
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// Read one character ahead and check if it is a "u".
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c = this.in.read();
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if (c != 'u') {
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this.unreadChar = c;
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this.oddPrecedingBackslashes = true;
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return '\\';
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}
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// Skip redundant "u"s.
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do {
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c = this.in.read();
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if (c == -1) throw new UnicodeUnescapeException("Incomplete escape sequence");
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} while (c == 'u');
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// Decode escape sequence.
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char[] ca = new char[4];
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ca[0] = (char) c;
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if (this.in.read(ca, 1, 3) != 3) throw new UnicodeUnescapeException("Incomplete escape sequence");
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try {
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return 0xffff & Integer.parseInt(new String(ca), 16);
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} catch (NumberFormatException ex) {
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throw new UnicodeUnescapeException("Invalid escape sequence \"\\u" + new String(ca) + "\"", ex);
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}
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}
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/** Overrides {@link FilterReader#read(char[], int, int)}. */
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@Override public int
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read(char[] cbuf, int off, int len) throws IOException {
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if (len == 0) return 0;
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int res = 0;
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do {
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int c = this.read();
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if (c == -1) break;
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cbuf[off++] = (char) c;
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} while (++res < len);
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return res == 0 ? -1 : res;
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}
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private int unreadChar = -1; // -1 == none
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private boolean oddPrecedingBackslashes;
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}
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