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