scsh-conservatory
/
scsh-0.5
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Added a bunch of new char-set stuff.

This commit is contained in:
shivers 1998-06-16 21:19:32 +00:00
parent ec63c53ee6
commit 54ca902c67
1 changed files with 130 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

149
doc/scsh-manual/strings.tex
View File

@ -576,12 +576,79 @@ is also frequently useful for expanding file-names.
Scsh provides a \ex{char-set} type for expressing sets of characters.
These sets are used by some of the delimited-input procedures
(section~\ref{sec:field-reader}).
The character set package that scsh uses was taken from Project Mac's
MIT Scheme.
Scsh's character set package was adapted and extended from
Project Mac's MIT Scheme package.
Note that the character type used in the current implementation corresponds
to the ASCII character set---but you would be wise not to build this
assumption into your code if you can help it.\footnote{
Actually, it's slightly uglier than that, albeit somewhat more
useful. The current character type corresponds to an eight-bit
superset of ASCII. The \ex{ascii->char} and \ex{char->ascii}
functions will preserve this eighth bit. However, none of the
the high 128 characters appear in any of the standard character
sets defined in section~\ref{sec:std-csets}, except for
\ex{char-set:full}. If someone would email the authors a listing
of the full Latin-1 definition, we'll be happy to upgrade these
sets' definitions to make them Latin-1 compliant.}
\defun{char-set?}{x}\boolean
\begin{desc}
Returns true if the object \var{x} is a character set.
Is the object \var{x} a character set?
\end{desc}
\defun{char-set=}{cs1 cs2}\boolean
\begin{desc}
Are the character sets \var{cs1} and \var{cs2} equal?
\end{desc}
\defun{char-set<=}{cs1 cs2}\boolean
\begin{desc}
Returns true if character set \var{cs1} is a subset of character set \var{cs2}.
\end{desc}
\defun{reduce-char-set}{kons knil cs}\object
\begin{desc}
This is the fundamental iterator for character sets.
Reduces the function \var{kons} across the character set \var{cs} using
initial state value \var{knil}.
That is, if \var{cs} is the empty set, the procedure returns \var{knil}.
Otherwise, some element \var{c} of \var{cs} is chosen; let \var{cs'} be
the remaining, unchosen characters.
The procedure returns
\begin{tightcode}
(reduce-char-set \var{kons} (\var{kons} \var{c} \var{knil}) \var{cs'})\end{tightcode}
For example, we could define \ex{char-set-members} (see below)
as
\begin{tightcode}
(lambda (cs) (reduce-char-set cons '() cs))\end{tightcode}
\end{desc}
\subsection{Side effects}
\defun{set-char-set!}{cs char in?}{\undefined}
\begin{desc}
This side-effects character set \var{cs}.
If \var{in?} is true, character \var{char} is added to the set.
Otherwise, it is deleted from the set.
Use of this procedure is deprecated, since it could damage other procedures
that retain pointers to existing character sets.
You should use \ex{set-char-set!} in contexts where it is guaranteed that
there are no other pointers to the character set being modified.
(For example, functions that create character sets can use this function
to efficiently construct the character set, after which time the set is
used in a pure-functional, shared manner.)
\end{desc}
\defun{char-set-for-each}{p cs}{\undefined}
\begin{desc}
Apply procedure \var{p} to each character in the character set \var{cs}.
Note that the order in which \var{p} is applied to the characters in the
set is not specified, and may even change from application to application.
\end{desc}
\defun{copy-char-set}{cs}{char-set}
\begin{desc}
Returns a copy of the character set \var{cs}.
\end{desc}
\subsection{Creating character sets}
@ -634,46 +701,90 @@ of R4RS procedures.
We sought to escape the dilemma by shifting to a new name.}
\end{desc}
\defun{char-set-size}{cs}\integer
\begin{desc}
Returns the number of elements in character set \var{cs}.
\end{desc}
\subsection{Character set algebra}
\defun {char-set-invert}{char-set}{char-set}
\defunx{char-set-union}{\vari{char-set}1 \vari{char-set}2}{char-set}
\defunx{char-set-intersection}{\vari{char-set}1 \vari{char-set}2}{char-set}
\defunx{char-set-difference}{\vari{char-set}1 \vari{char-set}2}{char-set}
\defunx{char-set-union}{\vari{char-set}1\ldots}{char-set}
\defunx{char-set-intersection}{\vari{char-set}1 \vari{char-set}2\ldots}{char-set}
\defunx{char-set-difference}{\vari{char-set}1 \vari{char-set}2\ldots}{char-set}
\begin{desc}
These procedures implement set complement, union, intersection, and difference
for character sets.
The union, intersection, and difference operations are n-ary, associating
to the left; the difference function requires at least one argument, while
union and intersection may be applied to zero arguments.
\end{desc}
\subsection{Standard character sets}
\label{sec:std-csets}
Several character sets are predefined for convenience:
\begin{center}
\newcommand{\entry}[1]{\ex{#1}\index{#1}}
\begin{tabular}{|ll|}
\hline
\entry{char-set:upper-case} & A--Z \\
\entry{char-set:lower-case} & a--z \\
\entry{char-set:numeric} & 0--9 \\
\entry{char-set:whitespace} & space, newline, tab, linefeed, page,
return \\
\entry{char-set:not-whitespace} & Complement of \ex{char-set:whitespace} \\
\entry{char-set:alphabetic} & A--Z and a--z \\
\entry{char-set:alphabetic} & Alphabetic chars \\
\entry{char-set:lower-case} & Lower-case alphabetic chars \\
\entry{char-set:upper-case} & Upper-case alphabetic chars \\
\entry{char-set:numeric} & Decimal digits: 0--9 \\
\entry{char-set:alphanumeric} & Alphabetic or numeric \\
\entry{char-set:graphic} & Printing characters and space \\
\entry{char-set:graphic} & Printing characters except space \\
\entry{char-set:printing} & Printing characters including space \\
\entry{char-set:whitespace} & Whitespace characters \\
\entry{char-set:blank} & Blank characters \\
\entry{char-set:control} & Control characters \\
\entry{char-set:punctuation} & Punctuation characters \\
\entry{char-set:hex-digit} & A hexadecimal digit: 0--9, A--F, a--f \\
\entry{char-set:ascii} & A character in the ASCII set. \\
\entry{char-set:empty} & Empty set \\
\entry{char-set:full} & All characters \\
\hline
\end{tabular}
\end{center}
The first twelve of these correspond to the character classes defined in
Posix.
Note that there may be characters in \ex{char-set:alphabetic} that are
neither upper or lower case---this might occur in implementations that
use a character type richer than ASCII, such as Unicode.
A ``graphic character'' is one that would put ink on your page.
While the exact composition of these sets may vary depending upon the
character type provided by the Scheme system upon which scsh is running,
here are the definitions for some of the sets in an ASCII character set:
\begin{center}
\newcommand{\entry}[1]{\ex{#1}\index{#1}}
\begin{tabular}{|ll|}
\hline
char-set:alphabetic & A--Z and a--z \\
char-set:lower-case & a--z \\
char-set:upper-case & A--Z \\
char-set:graphic & Alphanumeric + punctuation \\
char-set:whitespace & Space, newline, tab, page,
vertical tab, carriage return \\
char-set:blank & Space and tab \\
char-set:control & ASCII 0--31 and 127 \\
char-set:punctuation & \verb|!"#$%&'()*+,-./:;<=>|\verb#?@[\]^_`{|}~# \\
\hline
\end{tabular}
\end{center}
\defun {char-upper-case?}\character\boolean
\defun {char-alphabetic?}\character\boolean
\defunx{char-lower-case?}\character\boolean
\defunx{char-upper-case?}\character\boolean
\defunx{char-numeric? }\character\boolean
\defunx{char-whitespace?}\character\boolean
\defunx{char-alphabetic?}\character\boolean
\defunx{char-alphanumeric?}\character\boolean
\defunx{char-graphic?}\character\boolean
\defunx{char-printing?}\character\boolean
\defunx{char-whitespace?}\character\boolean
\defunx{char-blank?}\character\boolean
\defunx{char-control?}\character\boolean
\defunx{char-punctuation?}\character\boolean
\defunx{char-hex-digit?}\character\boolean
\defunx{char-ascii?}\character\boolean
\begin{desc}
These predicates are defined in terms of the above character sets.
\end{desc}