slice(1)
NAME
Slice -- Extract pre-defined slices from an ASCII file
SYNOPSIS
slice [-v] [-y outputpolicy] [-o sliceterm:outputfile[@chmodcmd][#outputpolicy] ..] [inputfile] slice [-V] [-h]
VERSION
1.3.8 (10-Feb-2002)
DESCRIPTION
Input Principle
The slice program reads inputfile (or from STDIN if inputfile is not
given or equal ``"-"'') and divides its already prepared ASCII contents
into possibly overlapping areas, called slices. These slices are
determined by enclosing blocks defined by begin and end delimiters
which have to be already in the file. These block delimiters use the
syntax
[NAME: ... :NAME]
or alternatively (if there is no misinterpretation possible, i.e. no
overlapping or stacked slices)
[NAME: ... :]
The NAME identifier has to match against the regular expression
``"[_A-Z0-9]+"'', i.e. NAME is a string consisting only of uppercase
letters, digits or underscore characters.
There can be as many such slice definitions as you like and there can
be more than one slice with the same name. The resulting slice is the
union of all equal named slices. Actually use this to spread a big
slice over disjunct peaces of inputfile.
Output Selection Scheme
The final output data gets calculated by a slice term consisting of
slice names and set theory operators. The following syntax is
recognized (in order of LR(1) grammar parsing) for slice terms:
SLICE_TERM ::= "NAME"
The slice NAME itself. This name has to match against the regex
``"[_A-Z0-9*{}]+"''. Here two cases are possible: "NAME" is either
a plain slice name consisting only of uppercase letters, digits or
an underscore character. Or it is a wildcarded slice name indicated
by an asterisk character.
The first variant just expands to the union of all slices named
exactly "NAME". The second variant expands to the union of all
slices which match against the wildcard pattern "NAME". Here the
asterisk has the semantical meaning of none or any number of
characters. There is one special case, when the asterisk is
immediately followed by characters enclosed within braces, it means
none or any number of characters, but not this sequence of
characters.
SLICE_TERM ::= "!NAME" | "~NAME"
The complement of slice NAME (i.e. ALL\NAME).
In formula: {x in ALL: x not in NAME}
SLICE_TERM ::= "NAME1xNAME2", "NAME1^NAME2"
The exclusive-or relation between slice NAME1 and slice NAME2. In
set theory also called symmetric difference:
(NAME1uNAME2)\(NAME1nNAME2) or alternatively
(NAME1n!NAME2)u(!NAME1nNAME2).
In formula: {x in ALL: (x in NAME1 or x in NAME2) and not (x in
NAME1 and x in NAME2)}.
SLICE_TERM ::= "NAME1\NAME2", "NAME1-NAME2"
The difference of slice NAME1 and slice NAME2, i.e. NAME1 minus
NAME2.
In formula: {x in ALL: x in NAME1 and x not in NAME2}
SLICE_TERM ::= "NAME1nNAME2" | "NAME1%NAME2"
The intersection of slice NAME1 and slice NAME2.
In formula: {x in ALL: x in NAME1 and x in NAME2}
SLICE_TERM ::= "NAME1uNAME2", "NAME1+NAME2"
The union of slice NAME1 and slice NAME2.
In formula: {x in ALL: x in NAME1 or x in NAME2}
SLICE_TERM ::= "(" SLICE_TERM ")"
A grouped slice term. Use this to force a different order of
evaluation. By default, all operators are left-associative, except
complement which is right-associative. Operators are listed below
from lowest to highest precedence:
- u x n !
Advanced Selection: Slice Levels
Because slices can be overlapping and stacked, a definition level is
assigned to each slice while the input is parsed. These levels range
from 1 to the maximum encountered (the level 0 is the whole file, i.e.
"ALL"). When a slice begins, it is assigned the lowest free level,
beginning with level 1. As long as one level is in use, it cannot be
assigned again until the end delimiter of the corresponding slice is
seen.
An example:
[A:[B::B]:A][C:[D:[E::C]:D][F::E]:F]
3 E-----------E
2 B--B D--------D
1 A--------A C--------C F-----F
0
Here slice A is assigned level 1. Then B is assigned level 2 because
level 1 is still in use by A. Then the end of B is reached, level 2 is
freed. Then the end of A is reached and level 1 is also free now, so C
is assigned level 1 again. Now only level 1 is in use, so D is assigned
level 2. Then E is assigned level 3. Then the end of C is seen and
level 1 freed. Then the end of D is seen and level 2 is freed. Now F
begins and because only level 3 is in use, it gets level 1 assigned.
Then the end of E frees level 3 and the end of F frees level 1. Finally
no levels are still in use. This indicates that the slicing is correct.
If there are any used levels left at the end of this process this
indicates an input error and slice responds with an error message
displaying the still open slices.
This complicated level mechanism is needed for granular set operations
where particular slices should be included or excluded only. So, to
make life easier, a few pseudo-slices are automatically defined:
"DEFn"
The union of all user-defined slices at exactly level n (0 <= n <=
oo).
"UNDEFn"
The union of all non-user-defined slices at exactly level n (0 <= n
<= oo). This actually is just "!DEFn".
"DEF"
The union of all user-defined slices at all levels, beginning at
level 1. This actually is the union of all "DEFn" slices.
"UNDEF"
The union of all non-user-defined slices at all levels, beginning
with 1. This actually is just "!DEF".
"ALL"
The whole file. This actually is just "UNDEF0", because at level 0
there are no user defined slices, so all is undefined.
NAME"@"
This is the slice NAME minus the union of all "DEFn" slices with
min(NAME) <= n <= oo. Here min(NAME) is the lowest level plus one
where NAME ever occurred. You can read this as ``NAME without all
other slices at higher levels which overwrite it''. This sounds a
little bit crazy, but actually is the most important construct. Try
to understand it or your slice terms become very complicated.
OPTIONS
[-y outputpolicy]
This flag changes output policy depending on events: "u" when an
undefined set is encountered, "w" for an unmatched wildcard set,
"z" when output is empty and "s" if it only consists of whitespace
characters. Each letter is followed by a digit telling which
action is bound to such events: 0 to ignore such events, 1 to
display a warning message and continue, 2 to skip concerned file
and continue, and 3 to abort with an error message.
This flag consists of one or more events specifications, and
default is "u0w0s0z0".
[-o sliceterm:outputfile[@chmodcmd][#outputpolicy] ..]
This redirects the output to a file. Usually the whole file will be
send to "STDOUT" (same as "ALL:-"). You can use this option more
than once to output to more than one file while the corresponding
sliceterm determines which output data will be included into each
output file.
The optional chmodcmd string is intended for specifying options for
the chmod command, which is applied to outputfile after writing.
For instance use ``"a+r"'' to make sure the file is readable by a
webserver of ``"u+x"'' to create a file with the execution bit set
(usually used for SSI files on a webserver with the "XBitHack"
option available).
The optional outputpolicy string allows changing output policy for
only this output file without changing its global meaning. See
above for information on output policy.
Be careful here: When you use parenthesis or asterisks inside
sliceterm you have to make sure it is really passed to slice this
way, i.e. usually you have to escape these characters from
interpolation by the used shell. Do this either by adding
backslashes in front of these characters or just surround the
complete option argument with single quotes ('').
-v This sets verbose mode where some processing information will be
given on the console for debugging purpose.
-V Displays the version identification string.
-h Displays the usage page.
SPECIAL FEATURE
Sometimes it can be very useful to be able to provide command line
options directly within the input file, for instance to setup one or
more -o options. For this slice recognizes lines of the form
%!slice OPTIONS
in the input file and automatically adds OPTIONS to the argument line
options. These lines have to start in column 0.
Example:
%!slice -oTOC:contents.txt
EXAMPLE
Assume the following simple multi-language article file article.src,
written in HTML:
<html>
<head>
<title>[EN:Titlepage:][DE:Titelseite:]</title>
</head>
<body>
<center>
<h1>[EN:The Title itself:][DE:Der Titel selbst:]</h1>
</center>
<blockquote>
[EN:...English Abstract...:]
[DE:...Deutsche Zusammenfassung...:]
</blockquote>
[EN:...English Text...:]
[DE:...Deutscher Text...:]
</body>
</html>
The command
slice -o ENuUNDEF:article.html.en -o DEuUNDEF:article.html.de
then creates the following to files:
article.html.en:
<html>
<head>
<title>Titlepage</title>
</head>
<body>
<center>
<h1>The Title itself</h1>
</center>
<blockquote>
...English Abstract...
</blockquote>
...English Text...
</body>
</html>
article.html.de:
<html>
<head>
<title>Titelseite</title>
</head>
<body>
<center>
<h1>Der Titel selbst</h1>
</center>
<blockquote>
...Deutsche Zusammenfassung...
</blockquote>
...Deutscher Text...
</body>
</html>
RESTRICTION
The current implementation only handles anonymous end delimiters
``":]"'' correct in clear cases where no mis-interpretation is
possible, i.e. when no overlapping occurs. For instance in
...[A:...[B:...:A]...:]...
the end delimiter is not correctly assign to the `B' slice. So, be
careful when using anonymous end delimiters in overlapping situations.
Pure stacking like
...[A:...[B:...:]...:]...
is allowed and handled correctly, but only when you interpret this as
...[A:...[B:...:B]...:A]...
COPYRIGHT
Copyright (c) 1997-2002 Ralf S. Engelschall.
Copyright (c) 1999-2002 Denis Barbier.
SEEALSO
Slice Home: http://www.engelschall.com/sw/slice/
AUTHORS
Ralf S. Engelschall
rse@engelschall.com
www.engelschall.com
Denis Barbier
barbier@engelschall.com
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