PREREX(1) PREREX(1)
NAME
prerex - interactive editor of prerequisite-chart descriptions
SYNOPSIS
prerex [ options ] [ basefile[.tex] [ chartfile[.tex] ] ]
DESCRIPTION
prerex is an interactive program for editing prerequisite-chart de-
scriptions in the prerex(5) format. The user does not normally have to
be familiar with details of the format. The editor supports add, re-
move, cut-and-paste, and edit operations on diagram elements, and ver-
tical or horizontal shifts of a list of specified elements, all the el-
ements in a rectangular region, or the entire diagram. The edited dia-
gram may be saved, re-processed, and viewed in a PDF viewer, without
exiting the editor. Alternatively, vprerex(1) will open a prerex(1)
window and display the corresponding PDF file alongside.
TERMINOLOGY
A prerequisite chart consists of several course boxes, linked by ar-
rows. Courses are either half or full, and may be required or optional
(or neither). Each course box contains a course code (upper left cor-
ner), a course title (lower half), and timetable information (upper
right corner). An arrow is either a prerequisite (solid), a corequi-
site (dotted), or recommended (dashed). When a conventional arrow
would be inappropriate, a mini course just above a target box may be
used. A line of text may have been placed anywhere in the chart.
In some implementations of the prerex(5) format, (some) arrows may be
curved and by default have non-zero curvature. The curvature of indi-
vidual arrows may be edited using the prerex(1) editor. Negative cur-
vatures are supported. To modify the default curvature (or set it to
zero), see prerex.sty(7).
COORDINATE SYSTEM
A conventional two-dimensional coordinate system is used to specify the
locations of diagram elements; the origin (where x = 0 and y = 0) is at
the lower-left corner of the diagram. For convenience, a coordinate
grid is normally displayed in the background while a diagram is being
edited.
The coordinates of a box, mini, or text-line are those of its centre
point. An arrow is described by the coordinates of the centre points
of its source and target boxes/minis/text-lines.
The notation x0,y0:x1,y1 denotes all the nodes (course boxes, minis,
texts) in the rectangle whose northwest and southeast corners are at
coordinates x0,y0 and x1,y1.
USAGE
If prerex is invoked on one existing file, a back-up copy is made of
it, the x,y coordinate grid is turned on, the file is processed by us-
ing a system call to pdflatex(1), and then the user gets a command sum-
mary and an interactive prompt of the form
file.tex>
If no file argument is given on the command line, the user is prompted
to supply a file name. In either case, if the file name provided does
not have a .tex extension, .tex is appended to it.
If the file.tex file named does not already exist, a new "empty" chart
file with that name is created, and then it is processed as above.
If a second filename is provided, the first filename is treated as the
base file of a LaTeX document and the second as an included file that
contains the chart environment to be edited. This allows more than one
document to share an included chart file and allows more than one chart
to be included in a single document.
The user may enter commands at the interactive command prompt as fol-
lows:
box x,y edit a course box at x,y, if necessary, creating a
new course box there
mini x,y edit a mini at x,y, if necessary, creating a new mini
there
text x,y edit a text-line at x,y, if necessary, creating a new
text-line there
arrow x0,y0,x1,y1 edit an arrow from x0,y0 to x1,y1, if necessary, cre-
ating a new such arrow
cut xi,yi ... (temporarily) remove the box, mini, or text at xi,yi
(including arrows into/out of the box/mini/text)
paste [x,y] re-insert most recently cut but not yet pasted box,
mini, or text at x,y (including arrows into/out of
the box/mini/text), or at the original coordinates if
x,y omitted
xchange x0,y0 x1,y1
exchange the box, mini or text at x0,y0 with that at
x1,y1. This is implemented as a sequence of two cuts
followed by two pastes to the same points.
delete [ x,y | x0,y0,x1,y1 | x0,y0:x1,y1 ] ...
remove the specified boxes, minis, texts, or arrows
(including automatically all arrows into/out of each
box/mini/text)
undo undo the most recent editing command (not already un-
done)
shift [-]s [ x,y | x0,y0:x1,y1 ] ...
move specified diagram elements x units right [left];
if no elements are specified, the whole diagram is
shifted
raise [-]r [ x,y | x0,y0:x1,y1 ] ...
move specified diagram elements y units up [down]; if
no elements are specified, the whole diagram is
raised
write, ! save to the current chartfile.tex and process the
chart by calling pdflatex(1) on the base file.
quit, exit, x, ^D turn off the coordinate grid, restore write-access,
save to the current chartfile.tex, process the base
file and exit.
!cmd restore write access to chartfile.tex, execute shell
command cmd, re-load and re-process the base file (in
case the command changed anything), and remove write-
access.
Backup copy the current chartfile.tex to the back-up file
.chartfile.tex; equivalent to !cp chartfile.tex
.chartfile.tex
Restore delete the current chartfile.tex and editing buffer,
and replace them using the current back-up in .chart-
file.tex.
grid [y/n] turn on/off coordinate-grid background
help, ? print a command summary
After most editing commands, the editing buffer is automatically saved
to chartfile.tex and the basefile is processed; the cut and paste com-
mands are exceptions: saving and processing take place only when all
outstanding cuts have been pasted. Saving and processing can be forced
by using the write (or !) command, or suppressed for all commands (ex-
cept write and !) by appending a ";" to the command immediately prior
to entering it. To exit the editor without saving to the current
chartfile.tex, use quit; (.i.e., quit followed by a semi-colon) or a
similar combination. Starting in Version 3.8, ^C and other interrupts
result in the editing buffer being saved to chartfile.tex before the
editor is exited.
OPTIONS
-v output program name and version number, and quit
-h output usage summary and quit
NOTES
The main difference between mini and text is in the maximum lengths for
the text displayed; the latter allows a full line of text, not merely a
course code. Also a text-line does not have an associated URI (when the
grid is off). The text "line" may actually be displayed as a paragraph
by using a LaTeX \parbox.
To save the current state of chartfile.tex, use Backup or a comparable
shell command. A history list of interpreted commands is maintained
and is accessible using the up-arrow key.
If processing of the chart fails, prerex will attempt to display the
LaTeX error message from the log file. The chart file can be fixed us-
ing a conventional text editor or LaTeX-oriented editor. LaTeX pro-
cessing should fail only if there is an initial problem or if ill-
formed LaTeX markup has been inserted into a text field.
Any (non-empty) prefix of a command suffices; for example, q, qu, or
qui may be used instead of quit. Some of the commands will begin a di-
alogue with the user in order to fill in or modify properties; the
prompts should be self-explanatory.
Since version 5.5, prerex no longer automatically calls a PDF viewer
(because it may be embedded in an instance of vprerex(1) which already
provides a PDF display). If prerex is being used by itself, a PDF
viewer may be invoked using the !cmd shell-escape mechanism. Also,
prerex no longer interacts with the user until a PDF file is available;
this is for use with vprerex(1). For example, if the .tex file is ini-
tially read-only, prerex aborts.
FILES
A LaTeX style file prerex.sty(7) that implements the macro calls de-
fined by the prerex(5) format must be available to [pdf]latex(1) to
process the chart file. Before any editing is allowed, chartfile.tex
is copied to .chartfile.tex as a backup.
ENVIRONMENT
The most convenient viewing program to use with prerex is one like
gv(1), gsview(1), kghostview(1), kpdf(1) or okular(1) that may be con-
figured to "watch" the pdf file and re-load the display automatically
when the file changes. evince(1) has a Reload button and xpdf(1) sup-
ports re-loading using the keystroke "R", but re-loading is much less
convenient with acroread(1) and gpdf(1), which may have to be re-
started.
Recent versions of some PDF viewers show the URIs of hyperlinks in a
tooltip or in the status bar; this mechanism is used by some implemen-
tations of prerex.sty(7) to allow display of the coordinates of a box,
mini, text-line, or arrow when the mouse hovers over it (while the co-
ordinate grid is on and the relevant chart file is presumably being
edited).
The prerex package at http://www.ctan.org/tex-archive/graphics/prerex/
has source code for vprerex(1), a GUI front-end for prerex which is
prerex-enabled.
BUGS
prerex analyzes chart files without using TeX; thus, macro calls are
not expanded, and anything in the chart file before or after the
(first) \begin{chart} ... \end{chart} environment is ignored (but pre-
served) by the editor. Lines that begin with "%" within the chart en-
vironment are preserved but other comments within the chart environment
are not preserved and may interfere with command parsing.
From version 5.6, prerex no longer supports the latex -> dvips ->
ps2pdf toolchain as an option.
AUTHOR
R. D. Tennent (rdt@cs.queensu.ca)
DEPENDENCIES
prerex uses the editline(3) library if available and the GNU read-
line(3) and history(3) libraries otherwise.
SEE ALSO
acroread(1), evince(1), gpdf(1), gsview(1), gv(1), kghostview(1),
kpdf(1), okular(1), pdflatex(1), prerex(5), prerex.sty(7), pre-
viewer(1), vprerex(1), xpdf(1).
prerex-6.8.0 2019-11-15 PREREX(1)
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