org.eclipse.rdf4j.rio.turtle.TurtleUtil Maven / Gradle / Ivy
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/*******************************************************************************
* Copyright (c) 2015 Eclipse RDF4J contributors, Aduna, and others.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Distribution License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*******************************************************************************/
package org.eclipse.rdf4j.rio.turtle;
import java.util.Arrays;
import org.eclipse.rdf4j.common.text.ASCIIUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Utility methods for Turtle encoding/decoding.
*
* @see Turtle: Terse RDF Triple Language
*/
public class TurtleUtil {
private static final Logger logger = LoggerFactory.getLogger(TurtleUtil.class);
public static final char[] LOCAL_ESCAPED_CHARS = new char[] { '_', '~', '.', '-', '!', '$', '&', '\'', '(', ')',
'*', '+', ',', ';', '=', '/', '?', '#', '@', '%' };
static {
// sorting array to allow simple binary search for char lookup.
Arrays.sort(LOCAL_ESCAPED_CHARS);
}
/**
* Tries to find an index where the supplied URI can be split into a namespace and a local name that comply with the
* serialization constraints of the Turtle format.
*
* @param uri The URI to split.
* @return The index where the supplied URI can be split, or -1 if the URI cannot be split.
*/
public static int findURISplitIndex(String uri) {
int uriLength = uri.length();
int idx = uriLength - 1;
// Search last character that is not a name character
for (; idx >= 0; idx--) {
if (!TurtleUtil.isNameChar(uri.charAt(idx))) {
// Found a non-name character
break;
}
}
idx++;
// Local names need to start with a 'nameStartChar', skip characters
// that are not nameStartChar's.
for (; idx < uriLength; idx++) {
if (TurtleUtil.isNameStartChar(uri.charAt(idx))) {
break;
}
}
// Last character cannot be a period
if (!TurtleUtil.isNameEndChar(uri.charAt(uriLength - 1))) {
return -1;
}
if (idx > 0 && idx < uriLength) {
// A valid split index has been found
return idx;
}
// No valid local name has been found
return -1;
}
/**
* Check if the supplied code point represents a whitespace character
*
* @param codePoint a Unicode code point
* @return true if the supplied code point represents a whitespace character, false
* otherwise.
*/
public static boolean isWhitespace(int codePoint) {
// Whitespace character are space, tab, newline and carriage return:
return codePoint == 0x20 || codePoint == 0x9 || codePoint == 0xA || codePoint == 0xD;
}
/**
* Check if the supplied code point represents a valid prefixed name base character.
*
* From Turtle Spec:
*
* http://www.w3.org/TR/turtle/#grammar-production-PN_CHARS_BASE
*
* [163s] PN_CHARS_BASE ::= [A-Z] | [a-z] | [#x00C0-#x00D6] | [#x00D8-#x00F6] | [#x00F8-#x02FF] | [#x0370-#x037D] |
* [#x037F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF] | [#xF900-#xFDCF] |
* [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]
*/
public static boolean isPN_CHARS_BASE(int codePoint) {
return ASCIIUtil.isLetter(codePoint) || codePoint >= 0x00C0 && codePoint <= 0x00D6
|| codePoint >= 0x00D8 && codePoint <= 0x00F6 || codePoint >= 0x00F8 && codePoint <= 0x02FF
|| codePoint >= 0x0370 && codePoint <= 0x037D || codePoint >= 0x037F && codePoint <= 0x1FFF
|| codePoint >= 0x200C && codePoint <= 0x200D || codePoint >= 0x2070 && codePoint <= 0x218F
|| codePoint >= 0x2C00 && codePoint <= 0x2FEF || codePoint >= 0x3001 && codePoint <= 0xD7FF
|| codePoint >= 0xF900 && codePoint <= 0xFDCF || codePoint >= 0xFDF0 && codePoint <= 0xFFFD
|| codePoint >= 0x10000 && codePoint <= 0xEFFFF;
}
/**
* Check if the supplied code point represents either a valid prefixed name base character or an underscore.
*
* From Turtle Spec:
*
* http://www.w3.org/TR/turtle/#grammar-production-PN_CHARS_U
*
* [164s] PN_CHARS_U ::= PN_CHARS_BASE | '_'
*/
public static boolean isPN_CHARS_U(int codePoint) {
return isPN_CHARS_BASE(codePoint) || codePoint == '_';
}
/**
* Check if the supplied code point represents a valid prefixed name character.
*
* From Turtle Spec:
*
* http://www.w3.org/TR/turtle/#grammar-production-PN_CHARS
*
* [166s] PN_CHARS ::= PN_CHARS_U | '-' | [0-9] | #x00B7 | [#x0300-#x036F] | [#x203F-#x2040]
*/
public static boolean isPN_CHARS(int codePoint) {
return isPN_CHARS_U(codePoint) || ASCIIUtil.isNumber(codePoint) || codePoint == '-' || codePoint == 0x00B7
|| codePoint >= 0x0300 && codePoint <= 0x036F || codePoint >= 0x203F && codePoint <= 0x2040;
}
/**
* Check if the supplied code point represents a valid prefixed name start character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid prefixed name start char, false
* otherwise.
*/
public static boolean isPrefixStartChar(int codePoint) {
return isPN_CHARS_BASE(codePoint);
}
/**
* Check if the supplied code point represents a valid start character for a blank node label.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid blank node label start char,
* false otherwise.
*/
public static boolean isBLANK_NODE_LABEL_StartChar(int codePoint) {
return isPN_CHARS_U(codePoint) || ASCIIUtil.isNumber(codePoint);
}
/**
* Check if the supplied code point represents a valid blank node label character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid blank node label char, false
* otherwise.
*/
public static boolean isBLANK_NODE_LABEL_Char(int codePoint) {
return isPN_CHARS(codePoint) || codePoint == '.';
}
/**
* Check if the supplied code point represents a valid blank node label end character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid blank node label end char,
* false otherwise.
*/
public static boolean isBLANK_NODE_LABEL_EndChar(int codePoint) {
return isPN_CHARS(codePoint);
}
/**
* Check if the supplied code point represents a valid name start character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid name start char, false
* otherwise.
*/
public static boolean isNameStartChar(int codePoint) {
return isPN_CHARS_U(codePoint) || codePoint == ':' || ASCIIUtil.isNumber(codePoint) || codePoint == '\\'
|| codePoint == '%';
}
/**
* Check if the supplied code point represents a valid name character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid name char, false otherwise.
*/
public static boolean isNameChar(int codePoint) {
return isPN_CHARS(codePoint) || codePoint == '.' || codePoint == ':' | codePoint == '\\' || codePoint == '%';
}
/**
* Check if the supplied code point represents a valid name end character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid name end char, false
* otherwise.
*/
public static boolean isNameEndChar(int codePoint) {
return isPN_CHARS(codePoint) || codePoint == ':';
}
/**
* Check if the supplied code point represents a valid local escaped character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid local escaped char, false
* otherwise.
*/
public static boolean isLocalEscapedChar(int codePoint) {
return Arrays.binarySearch(LOCAL_ESCAPED_CHARS, (char) codePoint) > -1;
}
/**
* Check if the supplied code point represents a valid prefix character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid prefix char, false
* otherwise.
*/
public static boolean isPrefixChar(int codePoint) {
return isPN_CHARS_BASE(codePoint) || isPN_CHARS(codePoint) || codePoint == '.';
}
/**
* Check if the supplied code point represents a valid language tag start character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid language tag start char,
* false otherwise.
*/
public static boolean isLanguageStartChar(int codePoint) {
return ASCIIUtil.isLetter(codePoint);
}
/**
* Check if the supplied code point represents a valid language tag character.
*
* @param codePoint a Unicode code point.
* @return true if the supplied code point represents a valid language tag char, false
* otherwise.
*/
public static boolean isLanguageChar(int codePoint) {
return ASCIIUtil.isLetter(codePoint) || ASCIIUtil.isNumber(codePoint) || codePoint == '-';
}
/**
* Checks if the supplied prefix string is a valid Turtle namespace prefix. From Turtle Spec:
*
* http://www.w3.org/TR/turtle/#grammar-production-PN_PREFIX
*
* [167s] PN_PREFIX ::= PN_CHARS_BASE ((PN_CHARS | '.')* PN_CHARS)?
*
* @param prefix a prefix string.
* @return true if the supplied prefix conforms to Turtle grammar rules
*/
public static boolean isPN_PREFIX(String prefix) {
// Empty prefixes are not legal, they should always have a colon
if (prefix.isEmpty()) {
logger.debug("PN_PREFIX was not valid (empty)");
return false;
}
if (!isPN_CHARS_BASE(prefix.charAt(0))) {
logger.debug("PN_PREFIX was not valid (start character invalid) i=0 nextchar={} prefix=", prefix.charAt(0),
prefix);
return false;
}
final int numberOfCodePoints = prefix.codePointCount(0, prefix.length());
for (int i = 1; i < numberOfCodePoints; i++) {
final int codePoint = prefix.codePointAt(i);
if (!isPN_CHARS(codePoint) || (codePoint == '.' && i < (numberOfCodePoints - 1))) {
logger.debug(
"PN_PREFIX was not valid (intermediate character invalid) i=" + i + " nextchar={} prefix={}",
Character.toChars(codePoint), prefix);
return false;
}
// Check if the percent encoding was less than two characters from the
// end of the prefix, in which case it is invalid
if (codePoint == '%' && (prefix.length() - i) < 2) {
logger.debug("PN_PREFIX was not valid (percent encoding) i=" + i + " nextchar={} prefix={}",
Character.toChars(codePoint), prefix);
return false;
}
if (Character.isHighSurrogate((char) codePoint)) {
// surrogate pair, skip second member in char sequence.
i++;
}
}
return true;
}
public static boolean isPLX_START(String name) {
if (name.length() >= 3 && isPERCENT(name.substring(0, 3))) {
return true;
}
if (name.length() >= 2 && isPN_LOCAL_ESC(name.substring(0, 2))) {
return true;
}
return false;
}
public static boolean isPERCENT(String name) {
if (name.length() != 3) {
return false;
}
if (name.charAt(0) != '%') {
return false;
}
if (!ASCIIUtil.isHex(name.charAt(1)) || !ASCIIUtil.isHex(name.charAt(2))) {
return false;
}
return true;
}
public static boolean isPLX_INTERNAL(String name) {
if (name.length() == 3 && isPERCENT(name)) {
return true;
}
if (name.length() == 2 && isPN_LOCAL_ESC(name)) {
return true;
}
return false;
}
public static boolean isPN_LOCAL_ESC(String name) {
if (name.length() != 2) {
return false;
}
if (!name.startsWith("\\")) {
return false;
}
if (!(Arrays.binarySearch(LOCAL_ESCAPED_CHARS, name.charAt(1)) > -1)) {
return false;
}
return true;
}
public static boolean isPN_LOCAL(String name) {
// Empty names are legal
if (name.isEmpty()) {
return true;
}
if (!isPN_CHARS_U(name.charAt(0)) && name.charAt(0) != ':' && !ASCIIUtil.isNumber(name.charAt(0))
&& !isPLX_START(name)) {
logger.debug("PN_LOCAL was not valid (start characters invalid) i=" + 0 + " nextchar="
+ name.charAt(0) + " name=" + name);
return false;
}
if (!isNameStartChar(name.charAt(0))) {
logger.debug("name was not valid (start character invalid) i=" + 0 + " nextchar=" + name.charAt(0)
+ " name=" + name);
return false;
}
for (int i = 1; i < name.length(); i++) {
if (!isNameChar(name.charAt(i))) {
logger.debug("name was not valid (intermediate character invalid) i=" + i + " nextchar="
+ name.charAt(i) + " name=" + name);
return false;
}
// Check if the percent encoding was less than two characters from the
// end of the prefix, in which case it is invalid
if (name.charAt(i) == '%' && (name.length() - i) < 3) {
logger.debug("name was not valid (short percent escape) i=" + i + " nextchar=" + name.charAt(i)
+ " name=" + name);
return false;
}
}
return true;
}
// public static boolean isLegalName(String name) {
// return isPN_LOCAL(name);
// }
/**
* Encodes the supplied string for inclusion as a 'normal' string in a Turtle document.
*
* @param s
* @return encoded string
*/
public static String encodeString(String s) {
s = s.replace("\\", "\\\\");
s = s.replace("\t", "\\t");
s = s.replace("\n", "\\n");
s = s.replace("\r", "\\r");
s = s.replace("\"", "\\\"");
return s;
}
/**
* Encodes the supplied string for inclusion as a long string in a Turtle document.
*
* @param s
* @return encoded long string
*/
public static String encodeLongString(String s) {
// TODO: not all double quotes need to be escaped. It suffices to encode
// the ones that form sequences of 3 or more double quotes, and the ones
// at the end of a string.
s = s.replace("\\", "\\\\");
s = s.replace("\"", "\\\"");
return s;
}
/**
* Encodes the supplied string for inclusion as a (relative) URI in a Turtle document.
*
* @param s
*/
@Deprecated
public static String encodeURIString(String s) {
s = s.replace("\\", "\\u005C");
s = s.replace("\t", "\\u0009");
s = s.replace("\n", "\\u000A");
s = s.replace("\r", "\\u000D");
s = s.replace("\"", "\\u0022");
s = s.replace("`", "\\u0060");
s = s.replace("^", "\\u005E");
s = s.replace("|", "\\u007C");
s = s.replace("<", "\\u003C");
s = s.replace(">", "\\u003E");
s = s.replace(" ", "\\u0020");
return s;
}
public static boolean isValidPrefixedName(String s) {
if (s == null || s.isEmpty()) {
return false;
}
if (!isPN_CHARS_BASE(s.codePointAt(0))) {
return false;
}
return s.codePoints() //
.skip(1) // Skip the first code point
.allMatch(TurtleUtil::isPN_CHARS);
}
/**
* Decodes an encoded Turtle string. Any \-escape sequences are substituted with their decoded value.
*
* @param s An encoded Turtle string.
* @return The unencoded string.
* @throws IllegalArgumentException If the supplied string is not a correctly encoded Turtle string.
**/
public static String decodeString(String s) {
int backSlashIdx = s.indexOf('\\');
if (backSlashIdx == -1) {
// No escaped characters found
return s;
}
int startIdx = 0;
int sLength = s.length();
StringBuilder sb = new StringBuilder(sLength);
while (backSlashIdx != -1) {
sb.append(s.substring(startIdx, backSlashIdx));
if (backSlashIdx + 1 >= sLength) {
throw new IllegalArgumentException("Unescaped backslash in: " + s);
}
char c = s.charAt(backSlashIdx + 1);
if (c == 't') {
sb.append('\t');
startIdx = backSlashIdx + 2;
} else if (c == 'b') {
sb.append('\b');
startIdx = backSlashIdx + 2;
} else if (c == 'n') {
sb.append('\n');
startIdx = backSlashIdx + 2;
} else if (c == 'r') {
sb.append('\r');
startIdx = backSlashIdx + 2;
} else if (c == 'f') {
sb.append('\f');
startIdx = backSlashIdx + 2;
} else if (c == '"') {
sb.append('"');
startIdx = backSlashIdx + 2;
} else if (c == '\'') {
sb.append('\'');
startIdx = backSlashIdx + 2;
} else if (c == '>') {
sb.append('>');
startIdx = backSlashIdx + 2;
} else if (c == '\\') {
sb.append('\\');
startIdx = backSlashIdx + 2;
} else if (c == 'u') {
// \\uxxxx
if (backSlashIdx + 5 >= sLength) {
throw new IllegalArgumentException("Incomplete Unicode escape sequence in: " + s);
}
String xx = s.substring(backSlashIdx + 2, backSlashIdx + 6);
try {
final int codePoint = Integer.parseInt(xx, 16);
sb.append(Character.toChars(codePoint));
startIdx = backSlashIdx + 6;
} catch (NumberFormatException e) {
throw new IllegalArgumentException("Illegal Unicode escape sequence '\\u" + xx + "' in: " + s);
}
} else if (c == 'U') {
// \\Uxxxxxxxx
if (backSlashIdx + 9 >= sLength) {
throw new IllegalArgumentException("Incomplete Unicode escape sequence in: " + s);
}
String xx = s.substring(backSlashIdx + 2, backSlashIdx + 10);
try {
final int codePoint = Integer.parseInt(xx, 16);
sb.append(Character.toChars(codePoint));
startIdx = backSlashIdx + 10;
} catch (NumberFormatException e) {
throw new IllegalArgumentException("Illegal Unicode escape sequence '\\U" + xx + "' in: " + s);
}
} else {
throw new IllegalArgumentException("Unescaped backslash in: " + s);
}
backSlashIdx = s.indexOf('\\', startIdx);
}
sb.append(s.substring(startIdx));
return sb.toString();
}
}