Package org.eclipse.rdf4j.common.net

Class ParsedIRI

java.lang.Object

org.eclipse.rdf4j.common.net.ParsedIRI

All Implemented Interfaces:

Serializable, Cloneable

public class ParsedIRI
extends Object
implements Cloneable, Serializable

Represents an Internationalized Resource Identifier (IRI) reference.

Aside from some minor deviations noted below, an instance of this class represents a IRI reference as defined by RFC 3987: Internationalized Resource Identifiers (IRI): IRI Syntax. This class provides constructors for creating IRI instances from their components or by parsing their string forms, methods for accessing the various components of an instance, and methods for normalizing, resolving, and relativizing IRI instances. Instances of this class are immutable.

An IRI instance has the following seven components in string form has the syntax

[scheme:][//[user-info@]host[:port]][path][?query][#fragment]

In a given instance any particular component is either undefined or defined with a distinct value. Undefined string components are represented by null, while undefined integer components are represented by -1. A string component may be defined to have the empty string as its value; this is not equivalent to that component being undefined.

Whether a particular component is or is not defined in an instance depends upon the type of the IRI being represented. An absolute IRI has a scheme component. An opaque IRI has a scheme, a scheme-specific part, and possibly a fragment, but has no other components. A hierarchical IRI always has a path (though it may be empty) and a scheme-specific-part (which at least contains the path), and may have any of the other components.

IRIs, URIs, URLs, and URNs

IRIs are meant to replace URIs in identifying resources for protocols, formats, and software components that use a UCS-based character repertoire.

Internationalized Resource Identifier (IRI) is a complement to the Uniform Resource Identifier (URI). An IRI is a sequence of characters from the Universal Character Set (Unicode/ISO 10646). A mapping from IRIs to URIs is defined using toASCIIString(), which means that IRIs can be used instead of URIs, where appropriate, to identify resources. While all URIs are also IRIs, the normalize() method can be used to convert a URI back into a normalized IRI.

A URI is a uniform resource identifier while a URL is a uniform resource locator. Hence every URL is a URI, abstractly speaking, but not every URI is a URL. This is because there is another subcategory of URIs, uniform resource names (URNs), which name resources but do not specify how to locate them. The mailto, news, and isbn URIs shown above are examples of URNs.

Deviations

jar: This implementation treats the first colon as part of the scheme if the scheme starts with "jar:". For example the IRI jar:http://www.foo.com/bar/jar.jar!/baz/entry.txt is parsed with the scheme jar:http and the path /bar/jar.jar!/baz/entry.txt.

Since:

2.3

Author:

James Leigh

See Also:

• RFC 3987: Internationalized Resource Identifiers (IRIs)
• RFC 3986: Uniform Resource Identifiers (URI): Generic Syntax
• Serialized Form

Constructor Summary

Constructors

Constructor	Description
ParsedIRI(String iri)	Constructs a ParsedIRI by parsing the given string.
ParsedIRI(String scheme, String userInfo, String host, int port, String path, String query, String fragment)	Constructs a hierarchical IRI from the given components.

Method Summary

Modifier and Type	Method	Description
static ParsedIRI	create(String str)	Creates a ParsedIRI by parsing the given string.
boolean	equals(Object obj)	Tests this IRI for simple string comparison with another object.
String	getFragment()	Returns the raw fragment component of this IRI after the hash.
String	getHost()	Returns the host component of this IRI.
String	getPath()	Returns the raw path component of this IRI.
int	getPort()	Returns the port number of this IRI.
String	getQuery()	Returns the raw query component of this IRI after the first question mark.
String	getScheme()	Returns the scheme component of this IRI.
String	getUserInfo()	Returns the raw user-information component of this IRI.
int	hashCode()
boolean	isAbsolute()	Tells whether or not this IRI is absolute.
boolean	isOpaque()	Tells whether or not this IRI is opaque.
ParsedIRI	normalize()	Normalizes this IRI's components.
String	relativize(String iri)	Relativizes the given IRI against this ParsedIRI.
ParsedIRI	relativize(ParsedIRI absolute)	Relativizes the given IRI against this ParsedIRI.
String	resolve(String iri)	Resolves the given IRI against this ParsedIRI.
ParsedIRI	resolve(ParsedIRI relative)	Resolves the given IRI against this ParsedIRI.
String	toASCIIString()	Returns the content of this IRI as a US-ASCII string.
String	toString()	Returns the content of this IRI as a string.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

ParsedIRI

public ParsedIRI(String iri)
          throws URISyntaxException

Constructs a ParsedIRI by parsing the given string.

Parameters:

iri - The string to be parsed into a IRI

Throws:

NullPointerException - If iri is null

URISyntaxException - If the given string violates RFC 3987, as augmented by the above deviations

ParsedIRI

public ParsedIRI(String scheme,
 String userInfo,
 String host,
 int port,
 String path,
 String query,
 String fragment)

Constructs a hierarchical IRI from the given components.

This constructor first builds a IRI string from the given components according to the rules specified in RFC 3987

Parameters:

scheme - Scheme name

userInfo - User name and authorization information

host - Host name

port - Port number

path - Path

query - Query

fragment - Fragment

Method Details

create

public static ParsedIRI create(String str)

Creates a ParsedIRI by parsing the given string.

This convenience factory method works as if by invoking the ParsedIRI(String) constructor; any URISyntaxException thrown by the constructor is caught and the error code point is percent encoded. This process is repeated until a syntactically valid IRI is formed or a IllegalArgumentException is thrown.

This method is provided for use in situations where it is known that the given string is an IRI, even if it is not completely syntactically valid, for example a IRI constants declared within in a program. The constructors, which throw URISyntaxException directly, should be used situations where a IRI is being constructed from user input or from some other source that may be prone to errors.

Parameters:

str - The string to be parsed into an IRI

Returns:

The new ParsedIRI

Throws:

NullPointerException - If str is null

IllegalArgumentException - If the given string could not be converted into an IRI

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Tests this IRI for simple string comparison with another object.

If two IRI strings are identical, then it is safe to conclude that they are equivalent. However, even if the IRI strings are not identical the IRIs might still be equivalent. Further comparison can be made using the normalize() forms.

Overrides:

equals in class Object

Parameters:

obj - The object to which this object is to be compared

Returns:

true if the given object is a ParsedIRI that represents the same IRI

toString

public String toString()

Returns the content of this IRI as a string.

If this URI was created by invoking one of the constructors in this class then a string equivalent to the original input string, or to the string computed from the originally-given components, as appropriate, is returned. Otherwise this IRI was created by normalization, resolution, or relativization, and so a string is constructed from this IRI's components according to the rules specified in RFC 3987

Overrides:

toString in class Object

Returns:

The string form of this IRI

toASCIIString

public String toASCIIString()

Returns the content of this IRI as a US-ASCII string.

If this IRI only contains 8bit characters then an invocation of this method will return the same value as an invocation of the toString method. Otherwise this method works as if by encoding the host via RFC 3490 and all other components by percent encoding their UTF-8 values.

Returns:

The string form of this IRI, encoded as needed so that it only contains characters in the US-ASCII charset

isAbsolute

public boolean isAbsolute()

Tells whether or not this IRI is absolute.

Returns:

true if, and only if, this IRI has a scheme component

isOpaque

public boolean isOpaque()

Tells whether or not this IRI is opaque.

A IRI is opaque if, and only if, it is absolute and its path part does not begin with a slash character ('/'). An opaque IRI has a scheme, a path, and possibly a query or fragment; all other components (userInfo, host, and port) are undefined.

Returns:

true if, and only if, this IRI is absolute and its path does not start with a slash

getScheme

public String getScheme()

Returns the scheme component of this IRI.

The scheme component of a IRI, if defined, only contains characters in the alphanum category and in the string "-.+", unless the scheme starts with "jar:", in which case it may also contain one colon. A scheme always starts with an alpha character.

The scheme component of a IRI cannot contain escaped octets.

Returns:

The scheme component of this IRI, or null if the scheme is undefined

getUserInfo

public String getUserInfo()

Returns the raw user-information component of this IRI.

Returns:

The raw user-information component of this IRI, or null if the user information is undefined

getHost

public String getHost()

Returns the host component of this IRI.

Returns:

The host component of this IRI, or null if the host is undefined

getPort

public int getPort()

Returns the port number of this IRI.

The port component of a IRI, if defined, is a non-negative integer.

Returns:

The port component of this IRI, or -1 if the port is undefined

getPath

public String getPath()

Returns the raw path component of this IRI.

Returns:

The path component of this IRI (never null)

getQuery

public String getQuery()

Returns the raw query component of this IRI after the first question mark.

The query component of a IRI, if defined, only contains legal IRI characters.

Returns:

The raw query component of this IRI, or null if the IRI does not contain a question mark

getFragment

public String getFragment()

Returns the raw fragment component of this IRI after the hash.

The fragment component of a IRI, if defined, only contains legal IRI characters and does not contain a hash.

Returns:

The raw fragment component of this IRI, or null if the IRI does not contain a hash

normalize

public ParsedIRI normalize()

Normalizes this IRI's components.

Because IRIs exist to identify resources, presumably they should be considered equivalent when they identify the same resource. However, this definition of equivalence is not of much practical use, as there is no way for an implementation to compare two resources unless it has full knowledge or control of them. Therefore, IRI normalization is designed to minimize false negatives while strictly avoiding false positives.

Case Normalization the hexadecimal digits within a percent-encoding triplet (e.g., "%3a" versus "%3A") are case-insensitive and are normalized to use uppercase letters for the digits A - F. The scheme and host are case insensitive and are normalized to lowercase.

Character Normalization The Unicode Standard defines various equivalences between sequences of characters for various purposes. Unicode Standard Annex defines various Normalization Forms for these equivalences and is applied to the IRI components.

Percent-Encoding Normalization decodes any percent-encoded octet sequence that corresponds to an unreserved character anywhere in the IRI.

Path Segment Normalization is the process of removing unnecessary "." and ".." segments from the path component of a hierarchical IRI. Each "." segment is simply removed. A ".." segment is removed only if it is preceded by a non-".." segment or the start of the path.

HTTP(S) Scheme Normalization if the port uses the default port number or not given it is set to undefined. An empty path is replaced with "/".

File Scheme Normalization if the host is "localhost" or empty it is set to undefined.

Internationalized Domain Name Normalization of the host component to Unicode.

Returns:

normalized IRI

resolve

public String resolve(String iri)

Resolves the given IRI against this ParsedIRI.

Parameters:

iri - The IRI to be resolved against this ParsedIRI

Returns:

The resulting IRI

Throws:

NullPointerException - If relative is null

See Also:

• resolve(ParsedIRI)

resolve

public ParsedIRI resolve(ParsedIRI relative)

Resolves the given IRI against this ParsedIRI.

Resolution is the process of resolving one IRI against another, base IRI. The resulting IRI is constructed from components of both IRIs in the manner specified by RFC 3986, taking components from the base IRI for those not specified in the original. For hierarchical IRIs, the path of the original is resolved against the path of the base and then normalized.

If the given IRI is already absolute, or if this IRI is opaque, then the given IRI is returned.

If the given URI's fragment component is defined, its path component is empty, and its scheme, authority, and query components are undefined, then a URI with the given fragment but with all other components equal to those of this URI is returned. This allows an IRI representing a standalone fragment reference, such as "#foo", to be usefully resolved against a base IRI.

Otherwise this method constructs a new hierarchical IRI in a manner consistent with RFC 3987

The result of this method is absolute if, and only if, either this IRI is absolute or the given IRI is absolute.

Parameters:

relative - The IRI to be resolved against this ParsedIRI

Returns:

The resulting IRI

Throws:

NullPointerException - If relative is null

relativize

public String relativize(String iri)

Relativizes the given IRI against this ParsedIRI.

Parameters:

iri - The IRI to be relativized against this ParsedIRI

Returns:

The resulting IRI

Throws:

NullPointerException - If absolute is null

See Also:

• relativize(ParsedIRI)

relativize

public ParsedIRI relativize(ParsedIRI absolute)

Relativizes the given IRI against this ParsedIRI.

Relativization is the inverse of resolution. This operation is often useful when constructing a document containing IRIs that must be made relative to the base IRI of the document wherever possible.

The relativization of the given URI against this URI is computed as follows:

1. If either this IRI or the given IRI are opaque, or if the scheme and authority components of the two IRIs are not identical, or if the path of this IRI is not a prefix of the path of the given URI, then the given IRI is returned.

2. Otherwise a new relative hierarchical IRI is constructed with query and fragment components taken from the given IRI and with a path component computed by removing this IRI's path from the beginning of the given IRI's path.

Parameters:

absolute - The IRI to be relativized against this ParsedIRI

Returns:

The resulting IRI

Throws:

NullPointerException - If absolute is null