org.eclipse.rdf4j.model.util.URIUtil Maven / Gradle / Ivy
Show all versions of rdf4j-model Show documentation
/*******************************************************************************
* 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.model.util;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Arrays;
import java.util.Set;
import java.util.regex.Pattern;
import org.eclipse.rdf4j.common.text.ASCIIUtil;
/**
* Utility functions for working with {@link URI URIs}.
*
* @author Arjohn Kampman
*/
public class URIUtil {
/**
* Reserved characters: their usage within the URI component is limited to their reserved purpose. If the data for a
* URI component would conflict with the reserved purpose, then the conflicting data must be escaped before forming
* the URI. http://www.isi.edu/in-notes/rfc2396.txt section 2.2.
*/
private static final Set reserved = Set.of(';', '/', '?', ':', '@', '&', '=', '+', '$', ',');
/**
* Punctuation mark characters, which are part of the set of unreserved chars and therefore allowed to occur in
* unescaped form. See http://www.isi.edu/in-notes/rfc2396.txt
*/
private static final Set mark = Set.of('-', '_', '.', '!', '~', '*', '\'', '(', ')');
/**
* Regular expression pattern for matching unicode control characters.
*/
private static final Pattern unicodeControlCharPattern = Pattern.compile(".*[\u0000-\u001F\u007F-\u009F].*");
/**
* Finds the index of the first local name character in an (non-relative) URI. This index is determined by the
* following the following steps:
*
* - Find the first occurrence of the '#' character,
*
- If this fails, find the last occurrence of the '/' character,
*
- If this fails, find the last occurrence of the ':' character.
*
- Add 1 to the found index and return this value.
*
* Note that the third step should never fail as every legal (non-relative) URI contains at least one ':' character
* to seperate the scheme from the rest of the URI. If this fails anyway, the method will throw an
* {@link IllegalArgumentException}.
*
* @param uri A URI string.
* @return The index of the first local name character in the URI string. Note that this index does not reference an
* actual character if the algorithm determines that there is not local name. In that case, the return index
* is equal to the length of the URI string.
* @throws IllegalArgumentException If the supplied URI string doesn't contain any of the separator characters.
* Every legal (non-relative) URI contains at least one ':' character to seperate
* the scheme from the rest of the URI.
*/
public static int getLocalNameIndex(String uri) {
int separatorIdx = uri.indexOf('#');
if (separatorIdx < 0) {
separatorIdx = uri.lastIndexOf('/');
}
if (separatorIdx < 0) {
separatorIdx = uri.lastIndexOf(':');
}
if (separatorIdx < 0) {
throw new IllegalArgumentException("No separator character founds in URI: " + uri);
}
return separatorIdx + 1;
}
/**
* Checks whether the URI consisting of the specified namespace and local name has been split correctly according to
* the URI splitting rules specified in {@link URI}.
*
* @param namespace The URI's namespace, must not be null.
* @param localName The URI's local name, must not be null.
* @return true if the specified URI has been correctly split into a namespace and local name,
* false otherwise.
* @see URI
* @see #getLocalNameIndex(String)
*/
public static boolean isCorrectURISplit(String namespace, String localName) {
assert namespace != null : "namespace must not be null";
assert localName != null : "localName must not be null";
if (namespace.length() == 0) {
return false;
}
int nsLength = namespace.length();
char lastNsChar = namespace.charAt(nsLength - 1);
if (lastNsChar == '#') {
// correct split if namespace has no other '#'
return namespace.lastIndexOf('#', nsLength - 2) == -1 && localName.indexOf('#') == -1;
} else if (lastNsChar == '/') {
// correct split if local name has no '/' and URI contains no '#'
return localName.indexOf('/') == -1 && localName.indexOf('#') == -1 && namespace.indexOf('#') == -1;
} else if (lastNsChar == ':') {
// correct split if local name has no ':' and URI contains no '#' or
// '/'
return localName.indexOf(':') == -1 && localName.indexOf('#') == -1 && localName.indexOf('/') == -1
&& namespace.indexOf('#') == -1 && namespace.indexOf('/') == -1;
}
return false;
}
/**
* Verifies that the supplied string is a valid RDF (1.0) URI reference, as defined in
* section 6.4 of the RDF
* Concepts and Abstract Syntax specification (RDF 1.0 Recommendation of February 10, 2004).
*
* An RDF URI reference is valid if it is a Unicode string that:
*
* - does not contain any control characters ( #x00 - #x1F, #x7F-#x9F)
*
- and would produce a valid URI character sequence (per RFC2396 , section 2.1) representing an absolute URI
* with optional fragment identifier when subjected to the encoding described below
*
* The encoding consists of:
*
* - encoding the Unicode string as UTF-8, giving a sequence of octet values.
*
- %-escaping octets that do not correspond to permitted US-ASCII characters.
*
*
* @param uriRef a string representing an RDF URI reference.
* @return true iff the supplied string is a syntactically valid RDF URI reference, false
* otherwise.
* @see section 6.4 of the RDF
* Concepts and Abstract Syntax specification
* @see RFC 3986
* @see RFC 2396
*/
public static boolean isValidURIReference(String uriRef) {
// check that string contains no Unicode control characters.
boolean valid = !unicodeControlCharPattern.matcher(uriRef).matches();
if (valid) {
// check that proper encoding/escaping would yield a valid absolute
// RFC 2396 URI
final String escaped = escapeExcludedChars(uriRef);
try {
/*
* NOTE we use java.net.URI parsing to check compliance to the RFC, which is almost, but not completely,
* in alignment with RFC 2396, and has not been updated for compatibility with RFC 3986. See the
* java.net.URI javadoc ( https://docs.oracle.com/javase/8/docs/api/java/net/URI.html ) for details."
*/
final java.net.URI uri = new java.net.URI(escaped);
valid = uri.isAbsolute();
} catch (URISyntaxException e) {
valid = false;
}
}
return valid;
}
/**
* Escapes any character that is not either reserved or in the legal range of unreserved characters, according to
* RFC 2396.
*
* @param unescaped a (relative or absolute) uri reference.
* @return a (relative or absolute) uri reference with all characters that can not appear as-is in a URI %-escaped.
* @see RFC 2396
*/
private static String escapeExcludedChars(String unescaped) {
final StringBuilder escaped = new StringBuilder();
for (int i = 0; i < unescaped.length(); i++) {
char c = unescaped.charAt(i);
if (!isUnreserved(c) && !reserved.contains(c)) {
escaped.append("%" + Integer.toHexString((int) c));
} else {
escaped.append(c);
}
}
return escaped.toString();
}
/**
* A character is unreserved according to RFC 2396 if it is either an alphanumeric char or a punctuation mark.
*/
private static boolean isUnreserved(char c) {
final int n = (int) c;
// check if alphanumeric
boolean unreserved = (47 < n && n < 58) || (96 < n && n < 123) || (64 < n && n < 91);
if (!unreserved) {
// check if punctuation mark
unreserved = mark.contains(c);
}
return unreserved;
}
/**
* Checks whether the specified name is allowed as the local name part of an IRI according to the SPARQL 1.1/Turtle
* 1.1 spec.
*
* @param name the candidate local name
* @return true if it is a local name
*/
public static boolean isValidLocalName(String name) {
// Empty names are legal
if (name.length() == 0) {
return true;
}
if (!isPN_CHARS_U(name.charAt(0)) && name.charAt(0) != ':' && !ASCIIUtil.isNumber(name.charAt(0))
&& !isPLX_START(name)) {
return false;
}
if (!isNameStartChar(name.charAt(0))) {
return false;
}
for (int i = 1; i < name.length(); i++) {
if (!isNameChar(name.charAt(i))) {
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) {
return false;
}
}
return true;
}
/**
* 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 | '_'
*/
private static boolean isPN_CHARS_U(int codePoint) {
return isPN_CHARS_BASE(codePoint) || codePoint == '_';
}
private 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;
}
private 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;
}
private 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;
}
private static final char[] LOCAL_ESCAPED_CHARS = new char[] { '_', '~', '.', '-', '!', '$', '&', '\'', '(', ')',
'*', '+', ',', ';', '=', '/', '?', '#', '@', '%' };
/**
* 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]
*/
private 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 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.
*/
private 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.
*/
private static boolean isNameChar(int codePoint) {
return isPN_CHARS(codePoint) || codePoint == '.' || codePoint == ':' | 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]
*/
private 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;
}
}