153 lines
4.7 KiB
Plaintext
153 lines
4.7 KiB
Plaintext
This file documents names specified in uri.scm.
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NOTES
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URIs are of following syntax:
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[scheme] : path [? search ] [# fragmentid]
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Parts in [] may be ommitted. The last part is usually referred to as
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fragid in this document.
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DEFINITIONS AND DESCRIPTIONS
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char-set
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uri-reserved
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A list of reserved characters (semicolon, slash, hash, question mark,
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double colon and space).
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procedure
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parse-uri uri-string --> (scheme, path, search, frag-id)
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Multiple-value return: scheme, path, search, frag-id, in this
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order. scheme, search and frag-id are either #f or a string. path is a
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nonempty list of strings. An empty path is a list containing the empty
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string. parse-uri tries to be tolerant of the various ways people
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build broken URIs out there on the Net (so it is not absolutely
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conform with RFC 1630).
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procedure
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unescape-uri string [start [end]] --> string
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Unescapes a string. This procedure should only be used *after* the url
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(!) was parsed, since unescaping may introduce characters that blow
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up the parse (that's why escape sequences are used in URIs ;).
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Escape-sequences are of following scheme: %hh where h is a hexadecimal
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digit. E.g. %20 is space (ASCII character 32).
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procedure
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hex-digit? character --> boolean
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Returns #t if character is a hexadecimal digit (i.e., one of 1-9, a-f,
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A-F), #f otherwise.
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procedure
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hexchar->int character --> number
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Translates the given character to an integer, p.e. (hexchar->int \#a)
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=> 10.
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procedure
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int->hexchar integer --> character
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Translates the given integer from range 1-15 into an hexadecimal
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character (uses uppercase letters), p.e. (int->hexchar 14) => E.
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char-set
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uri-escaped-chars
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A set of characters that are escaped in URIs. These are the following
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characters: dollar ($), minus (-), underscore (_), at (@), dot (.),
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and-sign (&), exclamation mark (!), asterisk (*), backslash (\),
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double quote ("), single quote ('), open brace ((), close brace ()),
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comma (,) plus (+) and all other characters that are neither letters
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nor digits (such as space and control characters).
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procedure
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escape-uri string [escaped-chars] --> string
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Escapes characters of string that are given with escaped-chars.
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escaped-chars default to uri-escaped-chars. Be careful with using this
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procedure to chunks of text with syntactically meaningful reserved
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characters (e.g., paths with URI slashes or colons) -- they'll be
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escaped, and lose their special meaning. E.g. it would be a mistake to
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apply escape-uri to "//lcs.mit.edu:8001/foo/bar.html" because the
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slashes and colons would be escaped. Note that esacpe-uri doesn't
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check this as it would lose his meaning.
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procedure
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resolve-uri cscheme cp scheme p --> (scheme, path)
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Sorry, I can't figure out what resolve-uri is inteded to do. Perhaps
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I find it out later.
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The code seems to have a bug: In the body of receive, there's a
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loop. j should, according to the comment, count sequential /. But j
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counts nothing in the body. Either zero is added ((lp (cdr cp-tail)
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(cons (car cp-tail) rhead) (+ j 0))) or j is set to 1 ((lp (cdr
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cp-tail) (cons (car cp-tail) rhead) 1))). Nevertheless, j is expected
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to reach value numsl that can be larger than one. So what? I am
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confused.
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procedure
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rev-append list-a list-b --> list
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Performs a (append (reverse list-a) list-b). The comment says it
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should be defined in a list package but I am wondering how often this
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will be used.
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procedure
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split-uri-path uri start end --> list
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Splits uri at /'s. Only the substring given with start (inclusive) and
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end (exclusive) is considered. Start and end - 1 have to be within the
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range of the uri-string. Otherwise an index-out-of-range exception
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will be raised. Example: (split-uri-path "foo/bar/colon" 4 11) ==>
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'("bar" "col")
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procedure
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simplify-uri-path path --> list
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Removes "." and ".." entries from path. The result is a (maybe empty)
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list representing a path that does not contain any "." or "..". The
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list can only be empty if the path did not start with "/" (for the
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rare occasion someone wants to simplify a relative path). The result
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is #f if the path tries to back up past root, for example by "/.." or
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"/foo/../.." or just "..". "//" may occur somewhere in the path
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referring to root but not being backed up.
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Examples:
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(simplify-uri-path (split-uri-path "/foo/bar/baz/.." 0 15))
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==> '("" "foo" "bar")
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(simplify-uri-path (split-uri-path "foo/bar/baz/../../.." 0 20))
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==> '()
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(simplify-uri-path (split-uri-path "/foo/../.." 0 10))
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==> #f ; tried to back up root
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(simplify-uri-path (split-uri-path "foo/bar//" 0 9))
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==> '("") ; "//" refers to root
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(simplify-uri-path (split-uri-path "foo/bar/" 0 8))
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==> '("") ; last "/" also refers to root
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(simplify-uri-path (split-uri-path "/foo/bar//baz/../.." 0 19))
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==> #f ; tries to back up root
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