/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.atlas.lib;
import org.apache.jena.atlas.AtlasException ;
import org.apache.jena.atlas.io.AWriter ;
import org.apache.jena.atlas.io.OutputUtils ;
import org.apache.jena.atlas.io.StringWriterI ;
/** String escape utilities */
public class EscapeStr
{
/*
* Escape characters in a string according to Turtle rules.
*/
public static String stringEsc(String s) {
AWriter w = new StringWriterI() ;
stringEsc(w, s, Chars.CH_QUOTE2, true, CharSpace.UTF8) ;
return w.toString() ;
}
/** Write a string - basic escaping, no quote escaping. */
public static void stringEsc(AWriter out, String s, boolean asciiOnly) {
int len = s.length() ;
for (int i = 0; i < len; i++) {
char c = s.charAt(i);
// \\ Escape always possible.
if (c == '\\') {
out.print('\\') ;
out.print(c) ;
continue ;
}
switch(c) {
case '\n': out.print("\\n"); continue;
case '\t': out.print("\\t"); continue;
case '\r': out.print("\\r"); continue;
case '\f': out.print("\\f"); continue;
default: // Drop through
}
if ( !asciiOnly )
out.print(c);
else
writeCharAsASCII(out, c) ;
}
}
public static void stringEsc(AWriter out, String s, char quoteChar, boolean singleLineString) {
stringEsc(out, s, quoteChar, singleLineString, CharSpace.UTF8);
}
public static void stringEsc(AWriter out, String s, char quoteChar, boolean singleLineString, CharSpace charSpace) {
boolean ascii = ( CharSpace.ASCII == charSpace ) ;
int len = s.length() ;
int quotesInARow = 0 ;
for (int i = 0; i < len; i++) {
char c = s.charAt(i);
// \\ Escape always possible.
if (c == '\\') {
out.print('\\') ;
out.print(c) ;
continue ;
}
if ( ! singleLineString ) {
// Multiline string.
if ( c == quoteChar ) {
quotesInARow++ ;
if ( quotesInARow == 3 ) {
out.print("\\");
out.print(quoteChar);
quotesInARow = 0;
continue;
}
} else {
quotesInARow = 0 ;
}
} else {
if ( c == quoteChar ) {
out.print("\\"); out.print(c) ; continue ;
}
switch(c) {
case '\n': out.print("\\n"); continue;
case '\t': out.print("\\t"); continue;
case '\r': out.print("\\r"); continue;
case '\f': out.print("\\f"); continue;
default: // Drop through
}
}
if ( !ascii )
out.print(c);
else
writeCharAsASCII(out, c) ;
}
}
/** Write a string with Unicode to ASCII conversion using \-u escapes */
public static void writeASCII(AWriter out, String s) {
int len = s.length() ;
for (int i = 0; i < len; i++) {
char c = s.charAt(i);
writeCharAsASCII(out, c);
}
}
/** Write a character with Unicode to ASCII conversion using \-u escapes */
public static void writeCharAsASCII(AWriter out, char c) {
if ( c >= 32 && c < 127 )
out.print(c);
else {
// Outside the charset range.
// Does not cover beyond 16 bits codepoints directly
// (i.e. \U escapes) but Java keeps these as surrogate
// pairs and will print as characters
out.print("\\u") ;
OutputUtils.printHex(out, c, 4) ;
}
}
// Utilities to remove escapes
/** Replace \ escapes (\\u, \t, \n etc) in a string */
public static String unescapeStr(String s)
{ return unescapeStr(s, '\\') ; }
/** Replace \ escapes (\\u, \t, \n etc) in a string */
public static String unescapeStr(String s, char escapeChar)
{ return unescape(s, escapeChar, false) ; }
// Main worker function for unescaping strings.
public static String unescape(String s, char escape, boolean pointCodeOnly) {
int i = s.indexOf(escape) ;
if ( i == -1 )
return s ;
// Dump the initial part straight into the string buffer
StringBuilder sb = new StringBuilder(s.substring(0,i)) ;
for ( ; i < s.length() ; i++ )
{
char ch = s.charAt(i) ;
if ( ch != escape )
{
sb.append(ch) ;
continue ;
}
// Escape
if ( i >= s.length()-1 )
throw new AtlasException("Illegal escape at end of string") ;
char ch2 = s.charAt(i+1) ;
i = i + 1 ;
// \\u and \\U
if ( ch2 == 'u' )
{
// i points to the \ so i+6 is next character
if ( i+4 >= s.length() )
throw new AtlasException("\\u escape too short") ;
int x = Hex.hexStringToInt(s, i+1, 4) ;
sb.append((char)x) ;
// Jump 1 2 3 4 -- already skipped \ and u
i = i+4 ;
continue ;
}
if ( ch2 == 'U' )
{
// i points to the \ so i+6 is next character
if ( i+8 >= s.length() )
throw new AtlasException("\\U escape too short") ;
int x = Hex.hexStringToInt(s, i+1, 8) ;
// Convert to UTF-16 codepoint pair.
sb.append((char)x) ;
// Jump 1 2 3 4 5 6 7 8 -- already skipped \ and u
i = i+8 ;
continue ;
}
// Are we doing just point code escapes?
// If so, \X-anything else is legal as a literal "\" and "X"
if ( pointCodeOnly )
{
sb.append('\\') ;
sb.append(ch2) ;
i = i + 1 ;
continue ;
}
// Not just codepoints. Must be a legal escape.
char ch3 = 0 ;
switch (ch2)
{
case 'n': ch3 = '\n' ; break ;
case 't': ch3 = '\t' ; break ;
case 'r': ch3 = '\r' ; break ;
case 'b': ch3 = '\b' ; break ;
case 'f': ch3 = '\f' ; break ;
case '\'': ch3 = '\'' ; break ;
case '\"': ch3 = '\"' ; break ;
case '\\': ch3 = '\\' ; break ;
default:
throw new AtlasException("Unknown escape: \\"+ch2) ;
}
sb.append(ch3) ;
}
return sb.toString() ;
}
}