ref: 2459e34d77e2e21ef829c0dfaafd99433899494f
dir: /man/2/w3c-uris/
.TH W3C-URIS 2
.SH NAME
w3c-uris \- uniform resource identifiers
.SH SYNOPSIS
.EX
include "uris.m";
uris := load URIs URIs->PATH;
URI: import uris;
URI: adt
{
scheme: string;
userinfo: string; # authority, part I
host: string; # authority, part II
port: string; # authority, part III
path: string; # starts with / if absolute
query: string; # includes ? if not nil
fragment: string; # includes # if not nil
parse: fn(s: string): ref URI;
text: fn(u: self ref URI): string;
addbase: fn(base: self ref URI, rel: ref URI): ref URI;
authority: fn(u: self ref URI): string;
copy: fn(u: self ref URI): ref URI;
eq: fn(u: self ref URI, v: ref URI): int;
hasauthority: fn(u: self ref URI): int;
isabsolute: fn(u: self ref URI): int;
nodots: fn(u: self ref URI): ref URI;
userpw: fn(u: self ref URI): (string, string);
};
init: fn();
dec: fn(s: string): string;
enc: fn(s: string, safe: string): string;
.EE
.SH DESCRIPTION
.B URIs
supports the `generic syntax' for `Uniform' Resource Identifiers (URIs), defined by RFC3986.
Each URI can have up to five components in the general syntax:
.IP
.IB scheme :
.BI // authority / path
.BI ? query
.BI # fragment
.PP
where each component is optional, and can have scheme-specific substructure.
For instance, in the
.BR ftp ,
.B http
schemes, and perhaps others, the
.I authority
component has the further syntax:
.IP
.IB userinfo @ host : port
.PP
The set of characters allowed in most components is also scheme-specific, as is their interpretation, and indeed the
interpretation of the component itself.
.PP
.B Init
must be called before any other operation in the module.
.PP
.B URI
represents a parse of a URI into its components, where the
.I authority
has been further split into the scheme-specific but common triple of
.IR userinfo ,
.I host
and
.IR port .
(The function
.B URI.authority
will reproduce the original
.I authority
component if required.)
The
.B query
field starts with the
.RB ` ? '
character that introduces the
.I query
component, so that an empty query is represented by the string
\f5"?"\fP, and the absence of a query component is represented by a nil value.
The
.B fragment
field is handled in a similar way with its delimiting
.RB ` # '.
The fields representing the other components do not include the delimiters in the syntax,
and all but
.B query
have percent-encoded characters decoded.
(The query string is an exception because the set of characters to escape is application-specific.
See below for decoding and encoding functions.)
.B URI
provides the following operations:
.TP
.BI parse( s )
Return a
.B URI
value representing the results of parsing string
.I s
as a URI.
There is no error return.
The component values have percent-escapes decoded as discussed above.
The scheme name is converted to lower case.
.TP
.IB u .text()
Return the textual representation of
.I u
in the generic syntax,
adding percent-encoding as required to prevent characters
being misinterpreted as delimiters.
.TP
.IB u .addbase( b )
Resolves URI reference
.I u
with respect to a base URI
.IR b ,
including resolving all
.RB ` . '
and
.RB ` .. '
segments in the URI's path,
and returns the resulting
.B URI
value.
If
.I u
is an absolute URI reference or
.I b
is nil, the result is the same as
.I u
except that all
.RB ` . '
and
.RB ` .. '
segments have been resolved in the resulting path, and leading
instances of them removed.
.TP
.IB u .authority()
Returns the text of the
.I authority
component of
.IR u ,
in the generic syntax,
created from its
.BR userinfo ,
.B host
and
.B port
components.
.TP
.IB u .copy()
Return a reference to an independent copy of
.IR u .
.TP
.IB u .eq( v )
Returns true if
.I u
and
.I v
are textually equal in all components except
.BR fragment .
Note that
.I u
and
.I v
are assumed to be in a canonical form for the scheme and application.
.TP
.IB u .eqf( v )
Returns true if
.I u
and
.I v
are textually equal in all components including
.BR fragment .
.TP
.IB u .hasauthority()
Returns true if any of the authority subcomponents of
.I u
are not nil; returns false otherwise.
.TP
.IB u .isabsolute()
Returns true if
.I u
has a
.I scheme
component; returns false otherwise.
.TP
.IB u .nodots()
Returns a new
.B URI
value in which all
.RB ` . '
and
.RB ` .. '
segments have been resolved (equivalent to
.IB u .addbase(nil)\c
).
.TP
.IB u .userpw()
Returns a tuple
.BI ( username,\ password )
derived from parsing the
.I userinfo
subcomponent of
.I authority
using the deprecated but depressingly still common convention that
.I userinfo
has the syntax ``\fIusername\fP\f5:\fP\fIpassword\fP''.
.PP
A reserved or otherwise special character that appears in a URI component must be
encoded using a sequence of one or more strings of the form
.BI % xx
where
.I xx
is the hexadecimal value of one byte of the character's encoding in
.IR utf (6).
A string
.I s
containing such encodings can be decoded by the function
.BR dec .
A string
.I s
can be encoded by
.BR enc ,
where the parameter
.I safe
lists the characters that need not be escaped (where
.I safe
may be nil or empty).
These functions are normally only needed to decode and encode the values of
.BR URI.query ,
because
.B URI.parse
and
.B URI.text
above decode and encode the other fields.
.SH SOURCE
.B /appl/lib/w3c/uris.b
.SH SEE ALSO
.IR charon (1),
.IR httpd (8)