source: project/wiki/eggref/4/uri-generic @ 15481

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Note changes in 2.31 and 2.32

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1[[tags: eggs]]
2[[toc:]]
3
4== uri-generic
5
6=== Description
7
8The {{uri-generic}} library contains procedures for parsing and
9manipulation of Uniform Resource Identifiers
10([[http://tools.ietf.org/html/rfc3986|RFC 3986]]). It is intended to
11conform more closely to the RFC, and uses combinator parsing and
12character classes rather than regular expressions.
13
14This library should be considered to be a ''basis'' for creating
15scheme-specific URI parser libraries. This library only parses
16the generic components from a URI.  Any specific library can
17further parse subcomponents. For this reason, encoding and decoding
18of percent-encoded characters is not done automatically.
19This should be handled by specific URI scheme implementations.
20
21=== Library Procedures
22
23==== Constructors and predicates
24
25As specified in section 2.3 of RFC 3986, URI constructors
26automatically decode percent-encoded octets in the range of unreserved
27characters. This means that the following holds true:
28
29 (equal? (uri-reference "http://example.com/foo-bar")
30         (uri-reference "http://example.com/foo%2Dbar"))  => #t
31
32<procedure>(uri-reference STRING) => URI</procedure>
33
34A URI reference is either a URI or a relative reference (RFC 3986,
35Section 4.1).  If the given string's prefix does not match the syntax
36of a scheme followed by a colon separator, then the given string is
37parsed as a relative reference.
38
39<procedure>(uri-reference? URI) => BOOL</procedure>
40
41Is the given object a URI reference?  '''All objects created by
42URI-generic constructors are URI references'''; they are either URIs
43or relative references.  The constructors below are just more strict
44checking versions of {{uri-reference}}.  They all create
45URI references.
46
47<procedure>(absolute-uri STRING) => URI</procedure>
48
49Parses the given string as an absolute URI, in which no fragments are
50allowed.  If no URI scheme is found, or a fragment is detected, this
51raises an error.
52
53Absolute URIs are defined by RFC 3986 as non-relative URI references
54without a fragment (RFC 3986, Section 4.2).  Absolute URIs can be used
55as a base URI to resolve a relative-ref against, using
56{{uri-relative-to}} (see below).
57
58<procedure>(absolute-uri? URI) => BOOL</procedure>
59
60Is the given object an absolute URI?
61
62<procedure>(uri? URI) => BOOL</procedure>
63
64Is the given object a URI?  URIs are all URI references that include
65a scheme part.  The other type of URI references are relative
66references.
67
68<procedure>(relative-ref? URI) => BOOL</procedure>
69
70Is the given object a relative reference?  Relative references are
71defined by RFC 3986 as URI references which are not URIs; they contain
72no URI scheme and can be resolved against an absolute URI to obtain
73a complete URI using {{uri-relative-to}}.
74
75<procedure>(uri-path-absolute? URI) => BOOL</procedure>
76
77Is the {{URI}}'s path component an absolute path?
78
79<procedure>(uri-path-relative? URI) => BOOL</procedure>
80
81Is the {{URI}}'s path component a relative path?
82
83==== Attribute accessors
84
85* <procedure>(uri-authority URI) => URI-AUTH</procedure>
86* <procedure>(uri-scheme URI) => SYMBOL</procedure>
87* <procedure>(uri-path URI) => LIST</procedure>
88* <procedure>(uri-query URI) => STRING</procedure>
89* <procedure>(uri-fragment) URI => STRING</procedure>
90* <procedure>(uri-host URI) => STRING</procedure>
91* <procedure>(uri-port URI) => INTEGER</procedure>
92* <procedure>(uri-username URI) => STRING</procedure>
93* <procedure>(uri-password URI) => STRING</procedure>
94* <procedure>(authority? URI-AUTH) => BOOL</procedure>
95* <procedure>(authority-host URI-AUTH) => STRING</procedure>
96* <procedure>(authority-port URI-AUTH) => INTEGER</procedure>
97* <procedure>(authority-username URI-AUTH) => STRING</procedure>
98* <procedure>(authority-password URI-AUTH) => STRING</procedure>
99
100If a component is not defined in the given URI, then the corresponding
101accessor returns {{#f}}.
102
103* <procedure>(update-uri URI #!key authority scheme path query fragment host port username password) => URI</procedure>
104* <procedure>(update-authority URI-AUTH #!key host port username password) => URI</procedure>
105
106Update the specified keys in the URI or URI-AUTH object in a
107functional way (ie, it creates a new copy with the modifications).
108
109==== String and List Representations
110
111<procedure>(uri->string URI USERINFO) => STRING</procedure>
112
113Reconstructs the given URI into a string; uses a supplied function
114{{LAMBDA USERNAME PASSWORD -> STRING}} to map the userinfo part of the
115URI
116
117<procedure>(uri->list URI USERINFO) => LIST</procedure>
118
119Returns a list of the form {{(SCHEME SPECIFIC FRAGMENT)}};
120{{SPECIFIC}} is of the form {{(AUTHORITY PATH QUERY)}}.
121
122==== Reference Resolution
123
124<procedure>(uri-relative-to URI URI) => URI</procedure>
125
126Resolve the first URI as a reference relative to the second URI,
127returning a new URI (RFC 3986, Section 5.2.2).
128
129<procedure>(uri-relative-from URI URI) => URI</procedure>
130
131Constructs a new, possibly relative, URI which represents the location
132of the first URI with respect to the second URI.
133
134<examples>
135<example>
136<init>(use uri-generic)</init>
137<expr>(uri->string (uri-relative-to (uri-reference "../qux") (uri-reference "http://example.com/foo/bar/")))</expr>
138<result>"http://example.com/foo/qux"</result>
139</example>
140<example>
141<init>(use uri-generic)</init>
142<expr>(uri->string (uri-relative-from (uri-reference "http://example.com/foo/qux") (uri-reference "http://example.com/foo/bar/")))</expr>
143<result>"../qux"</result>
144</example>
145</examples>
146
147==== String encoding and decoding
148
149<procedure>(uri-encode-string STRING [CHAR-SET]) => STRING</procedure>
150
151Returns the percent-encoded form of the given string.  The optional
152char-set argument controls which characters should be encoded.
153It defaults to the complement of {{char-set:uri-unreserved}}. This is
154always safe, but often overly careful; it is allowed to leave certain
155characters unquoted depending on the context.
156
157<procedure>(uri-decode-string STRING [CHAR-SET]) => STRING</procedure>
158
159Returns the decoded form of the given string.  The optional char-set
160argument controls which characters should be decoded.  It defaults to
161{{char-set:full}}.
162
163
164==== Normalization 
165
166<procedure>(uri-normalize-case URI) => URI</procedure>
167
168URI case normalization (RFC 3986 section 6.2.2.1)
169
170<procedure>(uri-normalize-path-segments URI) => URI</procedure>
171
172URI path segment normalization (RFC 3986 section 6.2.2.3)
173
174
175==== Character sets
176
177As a convenience for sub-parsers or other special-purpose URI handling
178code, there are a couple of character sets exported by uri-generic.
179
180<constant>char-set:gen-delims</constant>
181
182Generic delimiters.
183  gen-delims  =  ":" / "/" / "?" / "#" / "[" / "]" / "@"
184
185<constant>char-set:sub-delims</constant>
186
187Sub-delimiters.
188  sub-delims  =  "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
189
190<constant>char-set:uri-reserved</constant>
191
192The union of {{gen-delims}} and {{sub-delims}}; all reserved URI characters.
193  reserved    =  gen-delims / sub-delims
194
195<constant>char-set:uri-unreserved</constant>
196
197All unreserved characters that are allowed in a URI.
198  unreserved  =  ALPHA / DIGIT / "-" / "." / "_" / "~"
199
200Note that this is _not_ the complement of {{char-set:uri-reserved}}!
201There are several characters (even printable, noncontrol characters)
202which are not allowed at all in a URI.
203
204
205=== Requires
206
207* [[matchable]]
208* [[defstruct]]
209
210=== Version History
211
212* 2.32 Empty absolute path directly followed by query is now properly recognised as an URI reference.
213* 2.31 Return {{#f}} in constructors if unconsumed input remains after parsing
214* 2.3 Add predicates uri-path-relative? and uri-path-absolute?
215* 2.2 Improvements to uri->string.
216* 2.1 Add new predicates for URIs, absolute URIs and relative references. Fix absolute-uri so it raises a condition when passing in a non-absolute uri string, instead of returning a string with the error. Also throw an error if a fragment is detected in the string.
217* 2.0 Export char-sets, add char-set arg to uri-encode/uri-decode,
218       do not decode query args as x-www-form-urlencoded, change path
219       representation.  Lots of bugfixes.
220* 1.12 Fix relative path normalization when original path ends in a slash, remove consecutive slashes from paths in URIs
221* 1.11 Added accessors for the authority components, functional update procedures. Fixed case-normalization.
222* 1.10 Fixed edge case in {{uri-relative-to}} with empty path in base uri,
223       fixed {{uri->string}} for URIs with query args, fixed {{uri->string}}
224       to not add an extraneous slash after authority in case of empty path.
225* 1.9 Fixed bug in uri-encode-string with reserved characters, added
226      tests for decoding and encoding [Peter Bex]
227* 1.8 Added uri-encode-string and uri-decode-string.
228      URI constructors now perform automatic normalization
229      of percent-encoded unreserved characters. [suggested by Peter Bex]
230* 1.6 Added error message about missing scheme in absolute-uri.
231* trunk Small bugfix in absolute-uri. [Peter Bex]
232* 1.5 Bug fixes in uri->string and absolute-uri. [reported by Peter Bex]
233* 1.3 Ported to Hygienic Chicken and the [[test]] egg [Peter Bex]
234* 1.2 Now using defstruct instead of define-record [suggested by Peter Bex]
235* 1.1 Added utf8 compatibility
236* 1.0 Initial Release
237
238=== License
239
240Based on the
241[[http://www.ninebynine.org/Software/ReadMe-URI-Haskell.txt|Haskell
242URI library]] by Graham Klyne <gk@ninebynine.org>.
243
244
245  Copyright 2008-2009 Ivan Raikov, Peter Bex.
246  All rights reserved.
247 
248  Redistribution and use in source and binary forms, with or without
249  modification, are permitted provided that the following conditions are
250  met:
251 
252  Redistributions of source code must retain the above copyright
253  notice, this list of conditions and the following disclaimer.
254 
255  Redistributions in binary form must reproduce the above copyright
256  notice, this list of conditions and the following disclaimer in the
257  documentation and/or other materials provided with the distribution.
258 
259  Neither the name of the author nor the names of its contributors may
260  be used to endorse or promote products derived from this software
261  without specific prior written permission.
262 
263  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
264  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
265  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
266  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
267  COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
268  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
269  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
270  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
271  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
272  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
273  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
274  OF THE POSSIBILITY OF SUCH DAMAGE.
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