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<h2>21. PIC Reference
<a name="21. PIC Reference"></a>
</h2>
<p style="margin-top: 1em">This is an annotated grammar of
<b>pic</b>.</p>
<h3>21.1. Lexical Items
<a name="21.1. Lexical Items"></a>
</h3>
<p style="margin-top: 1em">In general, <b>pic</b> is a
free-format, token-oriented language that ignores whitespace
outside strings. But certain lines and constructs are
specially interpreted at the lexical level:</p>
<p style="margin-top: 1em">A comment begins with <b>#</b>
and continues to <b>\n</b> (comments may also follow text in
a line). A line beginning with a period or backslash may be
interpreted as text to be passed through to the
post-processor, depending on command-line options. An
end-of-line backslash is interpreted as a request to
continue the line; the backslash and following newline are
ignored.</p>
<p style="margin-left:28%; margin-top: 1em">Here are the
grammar terminals:</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em"><small>INT</small></p></td>
<td width="4%"></td>
<td width="44%">
<p style="margin-top: 1em">A positive integer.</p></td>
<td width="34%">
</td></tr>
</table>
<p style="margin-left:28%; margin-top: 1em"><small>NUMBER</small></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%"></td>
<td width="2%"></td>
<td width="78%">
<p>A floating point numeric constant. May contain a decimal
point or be expressed in scientific notation in the style of
<i>printf</i>(3)&rsquo;s %e escape. A trailing
&lsquo;i&rsquo; or &lsquo;I&rsquo; (indicating the unit
&lsquo;inch&rsquo;) is ignored.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em"><small>TEXT</small></p></td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em">A string enclosed in double
quotes. A double quote within <small>TEXT</small> must be
preceded by a backslash. Instead of <small>TEXT</small> you
can use</p></td></tr>
</table>
<p style="margin-left:46%; margin-top: 1em">sprintf ( TEXT
[, &lt;expr&gt; ...] )</p>
<p style="margin-left:37%; margin-top: 1em">except after
the &lsquo;until&rsquo; and &lsquo;last&rsquo; keywords, and
after all ordinal keywords (&lsquo;th&rsquo; and
friends).</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="18%">
<p style="margin-top: 1em"><small>VARIABLE</small></p></td>
<td width="71%">
</td></tr>
</table>
<p style="margin-left:37%;">A string starting with a
character from the set [a-z], optionally followed by one or
more characters of the set [a-zA-Z0-9_]. (Values of
variables are preserved across pictures.)</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="11%">
<p style="margin-top: 1em"><small>LABEL</small></p></td>
<td width="78%">
<p style="margin-top: 1em">A string starting with a
character from the set [A-Z], optionally followed by one or
more characters of the set [a-zA-Z0-9_].</p></td></tr>
</table>
<p style="margin-left:28%; margin-top: 1em"><small>COMMAND-LINE</small></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="78%">
<p>A line starting with a command character
(&lsquo;.&rsquo; in groff mode, &lsquo;\&rsquo; in TeX
mode).</p> </td></tr>
</table>
<p style="margin-left:28%; margin-top: 1em"><small>BALANCED-TEXT</small></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="78%">
<p>A string either enclosed by &lsquo;{&rsquo; and
&lsquo;}&rsquo; or with <i>X</i> and <i>X</i>, where
<i>X</i> doesn&rsquo;t occur in the string.</p></td></tr>
</table>
<p style="margin-left:28%; margin-top: 1em"><small>BALANCED-BODY</small></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="78%">
<p>Delimiters as in <small>BALANCED-TEXT</small> ; the body
is interpreted as
&lsquo;<b>&lang;command&rang;...</b>&rsquo;.</p> </td></tr>
</table>
<p style="margin-left:28%; margin-top: 1em"><small>FILENAME</small></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="78%">
<p>The name of a file. This has the same semantics as
<small>TEXT</small> .</p></td></tr>
</table>
<p style="margin-left:28%; margin-top: 1em"><small>MACRONAME</small></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="57%">
<p>Either <small>VARIABLE</small> or <small>LABEL</small>
.</p> </td>
<td width="21%">
</td></tr>
</table>
<h3>21.2. Semi-Formal Grammar
<a name="21.2. Semi-Formal Grammar"></a>
</h3>
<p style="margin-top: 1em">Tokens not enclosed in
&lang;&rang; are literals, except:</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="4%">
<p style="margin-top: 1em">1.</p></td>
<td width="7%"></td>
<td width="89%">
<p style="margin-top: 1em"><b>\n</b> is a newline.</p></td></tr>
<tr valign="top" align="left">
<td width="4%">
<p style="margin-top: 1em">2.</p></td>
<td width="7%"></td>
<td width="89%">
<p style="margin-top: 1em">Three dots is a suffix meaning
&lsquo;replace with 0 or more repetitions of the preceding
element(s).</p> </td></tr>
<tr valign="top" align="left">
<td width="4%">
<p style="margin-top: 1em">3.</p></td>
<td width="7%"></td>
<td width="89%">
<p style="margin-top: 1em">An enclosure in square brackets
has its usual meaning of &lsquo;this clause is
optional&rsquo;.</p> </td></tr>
<tr valign="top" align="left">
<td width="4%">
<p style="margin-top: 1em">4.</p></td>
<td width="7%"></td>
<td width="89%">
<p style="margin-top: 1em">Square-bracket-enclosed portions
within tokens are optional. Thus, &lsquo;h[eigh]t&rsquo;
matches either &lsquo;height&rsquo; or &lsquo;ht&rsquo;.</p></td></tr>
</table>
<p style="margin-top: 1em">If one of these special tokens
has to be referred to literally, it is surrounded with
single quotes.</p>
<p style="margin-top: 1em">The top-level <b>pic</b> object
is a picture.</p>
<p style="margin-left:28%; margin-top: 1em">&lt;picture&gt;
::= <br>
.PS [NUMBER [NUMBER]]\n <br>
&lt;statement&gt; ... <br>
.PE \n</p>
<p style="margin-top: 1em">The arguments, if present,
represent the width and height of the picture, causing
<b>pic</b> to attempt to scale it to the given dimensions in
inches. In no case, however, the X and Y&nbsp;dimensions of
the picture exceed the values of the style variables
<b>maxpswid</b> and <b>maxpsheight</b> (which default to the
normal 8.5i by 11i page size).</p>
<p style="margin-top: 1em">If the ending &lsquo;.PE&rsquo;
is replaced by &lsquo;.PF&rsquo; or &lsquo;.PY&rsquo;, the
page vertical position is restored to its value at the time
&lsquo;.PS&rsquo; was encountered. Another alternate form of
invocation is &lsquo;.PS&nbsp;&lt; <small>FILENAME</small>
&rsquo;, which replaces the &lsquo;.PS&rsquo; line with a
file to be interpreted by <b>pic</b> (but this feature is
deprecated).</p>
<p style="margin-top: 1em">The &lsquo;.PS&rsquo;,
&lsquo;.PE&rsquo;, &lsquo;.PF&rsquo;, and &lsquo;.PY&rsquo;
macros to perform centering and scaling are normally
supplied by the post-processor.</p>
<p style="margin-top: 1em">In the following, either
&lsquo;|&rsquo; or a new line starts an alternative.</p>
<p style="margin-left:28%; margin-top: 1em">&lt;statement&gt;
::= <br>
&lt;command&gt; ; <br>
&lt;command&gt; \n <br>
&lt;command&gt; ::= <br>
&lt;primitive&gt; [&lt;attribute&gt;] <br>
LABEL : [;] &lt;command&gt; <br>
LABEL : [;] &lt;command&gt; [&lt;position&gt;] <br>
{ &lt;command&gt; ... } <br>
VARIABLE [:] = &lt;any-expr&gt; <br>
figname = MACRONAME <br>
up | down | left | right <br>
COMMAND-LINE <br>
command &lt;print-arg&gt; ... <br>
print &lt;print-arg&gt; ... <br>
sh BALANCED-TEXT <br>
copy FILENAME <br>
copy [FILENAME] thru MACRONAME [until TEXT] <br>
copy [FILENAME] thru BALANCED-BODY [until TEXT] <br>
for VARIABLE = &lt;expr&gt; to &lt;expr&gt; [by [*]
&lt;expr&gt;] do BALANCED-BODY <br>
if &lt;any-expr&gt; then BALANCED-BODY [else BALANCED-BODY]
<br>
reset [VARIABLE [[,] VARIABLE ...]] <br>
&lt;print-arg&gt; ::= <br>
TEXT <br>
&lt;expr&gt; <br>
&lt;position&gt;</p>
<p style="margin-top: 1em">The current position and
direction are saved on entry to a <br>
&lsquo;{&nbsp;...&nbsp;}&rsquo; construction and restored on
exit from it.</p>
<p style="margin-top: 1em">Note that in &lsquo;if&rsquo;
constructions, newlines can only occur in
<small>BALANCED-BODY</small> . This means that</p>
<p style="margin-left:28%; margin-top: 1em">if <br>
{ ... } <br>
else <br>
{ ... }</p>
<p style="margin-top: 1em">fails. You have to use the
braces on the same line as the keywords:</p>
<p style="margin-left:28%; margin-top: 1em">if { <br>
... <br>
} else { <br>
... <br>
}</p>
<p style="margin-top: 1em">This restriction doesn&rsquo;t
hold for the body after the &lsquo;do&rsquo; in a
&lsquo;for&rsquo; construction.</p>
<p style="margin-top: 1em">At the beginning of each
picture, &lsquo;figname&rsquo; is reset to the vbox name
&lsquo;graph&rsquo;; this command has only a meaning in TeX
mode. While the grammar rules allow digits and the
underscore in the value of &lsquo;figname&rsquo;, TeX
normally accepts uppercase and lowercase letters only as box
names (you have to use &lsquo;\csname&rsquo; if you really
need to circumvent this limitation).</p>
<p style="margin-left:28%; margin-top: 1em">&lt;any-expr&gt;
::= <br>
&lt;expr&gt; <br>
&lt;text-expr&gt; <br>
&lt;any-expr&gt; &lt;logical-op&gt; &lt;any-expr&gt; <br>
! &lt;any-expr&gt; <br>
&lt;logical-op&gt; ::= <br>
== | != | &amp;&amp; | &rsquo;||&rsquo; <br>
&lt;text-expr&gt; ::= <br>
TEXT == TEXT <br>
TEXT != TEXT</p>
<p style="margin-top: 1em">Logical operators are handled
specially by <b>pic</b> since they can deal with text
strings also. <b>pic</b> uses <i>strcmp</i>(3) to test for
equality of strings; an empty string is considered as
&lsquo;false&rsquo; for &lsquo;&amp;&amp;&rsquo; and
&lsquo;||&rsquo;.</p>
<p style="margin-left:28%; margin-top: 1em">&lt;primitive&gt;
::= <br>
box # closed object &mdash; rectangle <br>
circle # closed object &mdash; circle <br>
ellipse # closed object &mdash; ellipse <br>
polygon # closed object &mdash; polygon <br>
arc # open object &mdash; quarter-circle <br>
line # open object &mdash; line <br>
arrow # open object &mdash; line with arrowhead <br>
spline # open object &mdash; spline curve <br>
move <br>
TEXT TEXT ... # text within invisible box <br>
plot &lt;expr&gt; TEXT # formatted text <br>
&rsquo;[&rsquo; &lt;command&gt; ... &rsquo;]&rsquo;</p>
<p style="margin-top: 1em">Drawn objects within
&lsquo;[&nbsp;...&nbsp;]&rsquo; are treated as a single
composite object with a rectangular shape (that of the
bounding box of all the elements). Variable and label
assignments within a block are local to the block. Current
direction of motion is restored to the value at start of
block upon exit. Position is <i>not</i> restored (unlike
&lsquo;{&nbsp;}&rsquo;); instead, the current position
becomes the exit position for the current direction on the
block&rsquo;s bounding box.</p>
<p style="margin-left:28%; margin-top: 1em">&lt;attribute&gt;
::= <br>
h[eigh]t &lt;expr&gt; # set height of closed figure <br>
wid[th] &lt;expr&gt; # set width of closed figure <br>
rad[ius] &lt;expr&gt; # set radius of circle/arc <br>
diam[eter] &lt;expr&gt; # set diameter of circle/arc <br>
up [&lt;expr&gt;] # move up <br>
down [&lt;expr&gt;] # move down <br>
left [&lt;expr&gt;] # move left <br>
right [&lt;expr&gt;] # move right <br>
from &lt;position&gt; # set from position of open figure
<br>
to &lt;position&gt; # set to position of open figure <br>
at &lt;position&gt; # set center of open figure <br>
with &lt;path&gt; # fix corner/named point at specified
location <br>
with &lt;position&gt; # fix position of object at specified
location <br>
by &lt;expr-pair&gt; # set object&rsquo;s attachment point
<br>
then # sequential segment composition <br>
dotted [&lt;expr&gt;] # set dotted line style <br>
dashed [&lt;expr&gt;] # set dashed line style <br>
thick[ness] &lt;expr&gt; # set thickness of lines <br>
chop [&lt;expr&gt;] # chop end(s) of segment <br>
&rsquo;-&gt;&rsquo; | &rsquo;&lt;-&rsquo; |
&rsquo;&lt;-&gt;&rsquo; # decorate with arrows <br>
invis[ible] # make primitive invisible <br>
solid # set solid line style <br>
fill[ed] [&lt;expr&gt;] # fill closed figure with optional
density <br>
xscaled &lt;expr&gt; # slant box into x direction <br>
yscaled &lt;expr&gt; # slant box into y direction <br>
colo[u]r[ed] TEXT # set fill and outline color for figure
<br>
outline[d] TEXT # set outline color for figure <br>
shaded TEXT # set fill color for figure <br>
same # copy size of previous object <br>
cw | ccw # set orientation of curves <br>
ljust | rjust # adjust text horizontally <br>
above | below # adjust text vertically <br>
aligned # align parallel to object <br>
TEXT TEXT ... # text within object <br>
&lt;expr&gt; # motion in the current direction</p>
<p style="margin-top: 1em">Missing attributes are supplied
from defaults; inappropriate ones are silently ignored. For
lines, splines, and arcs, height and width refer to
arrowhead size.</p>
<p style="margin-top: 1em">The &lsquo;at&rsquo; primitive
sets the center of the current object. The
&lsquo;with&rsquo; attribute fixes the specified feature of
the given object to a specified location. (Note that
&lsquo;with&rsquo; is incorrectly described in the Kernighan
paper.)</p>
<p style="margin-top: 1em">The &lsquo;by&rsquo; primitive
is not documented in the tutorial portion of the Kernighan
paper, and should probably be considered unreliable.</p>
<p style="margin-top: 1em">The primitive
&lsquo;arrow&rsquo; is a synonym for
&lsquo;line&nbsp;-&gt;&rsquo;.</p>
<p style="margin-top: 1em">Text is normally an attribute of
some object, in which case successive strings are vertically
stacked and centered on the object&rsquo;s center by
default. Standalone text is treated as though placed in an
invisible box.</p>
<p style="margin-top: 1em">A text item consists of a string
or sprintf-expression, optionally followed by positioning
information. Text (or strings specified with
&lsquo;sprintf&rsquo;) may contain font changes, size
changes, and local motions, provided those changes are
undone before the end of the current item. Text may also
contain \-escapes denoting special characters. The base font
and specific set of escapes supported is implementation
dependent, but supported escapes always include the
following:</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="18%">
<p style="margin-top: 1em">\fR, \f1</p></td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em">Set Roman style (the
default)</p> </td></tr>
<tr valign="top" align="left">
<td width="18%">
<p style="margin-top: 1em">\fI, \f2</p></td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em">Set Italic style</p></td></tr>
<tr valign="top" align="left">
<td width="18%">
<p style="margin-top: 1em">\fB, \f3</p></td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em">Set Bold style</p></td></tr>
<tr valign="top" align="left">
<td width="18%">
<p style="margin-top: 1em">\fP</p></td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em">Revert to previous style; only
works one level deep, does not stack.</p></td></tr>
</table>
<p style="margin-top: 1em">Color names are dependent on the
pic implementation, but in all modern versions color names
recognized by the X&nbsp;window system are supported.</p>
<p style="margin-top: 1em">A position is an (x,y)
coordinate pair. There are lots of different ways to specify
positions:</p>
<p style="margin-left:28%; margin-top: 1em">&lt;position&gt;
::= <br>
&lt;position-not-place&gt; <br>
&lt;place&gt; <br>
( &lt;position&gt; ) <br>
&lt;position-not-place&gt; ::= <br>
&lt;expr-pair&gt; <br>
&lt;position&gt; + &lt;expr-pair&gt; <br>
&lt;position&gt; - &lt;expr-pair&gt; <br>
( &lt;position&gt; , &lt;position&gt; ) <br>
&lt;expr&gt; [of the way] between &lt;position&gt; and
&lt;position&gt; <br>
&lt;expr&gt; &rsquo;&lt;&rsquo; &lt;position&gt; ,
&lt;position&gt; &rsquo;&gt;&rsquo; <br>
&lt;expr-pair&gt; ::= <br>
&lt;expr&gt; , &lt;expr&gt; <br>
( expr-pair ) <br>
&lt;place&gt; ::= <br>
&lt;label&gt; <br>
&lt;label&gt; &lt;corner&gt; <br>
&lt;label&gt; &lt;reference-point&gt; <br>
&lt;corner&gt; [of] &lt;label&gt; <br>
&lt;reference-point&gt; of &lt;label&gt; <br>
Here <br>
&lt;label&gt; ::= <br>
LABEL [. LABEL ...] <br>
&lt;nth-primitive&gt; <br>
&lt;corner&gt; ::= <br>
.n | .e | .w | .s <br>
.ne | .se | .nw | .sw <br>
.c[enter] | .start | .end <br>
.t[op] | .b[ot[tom]] | .l[eft] | .r[ight] <br>
left | right | &lt;top-of&gt; | &lt;bottom-of&gt; <br>
&lt;north-of&gt; | &lt;south-of&gt; | &lt;east-of&gt; |
&lt;west-of&gt; <br>
&lt;center-of&gt; | &lt;start-of&gt; | &lt;end-of&gt; <br>
upper left | lower left | upper right | lower right <br>
&lt;reference-point&gt; ::= <br>
.v[er[tex]] &lt;expr&gt; <br>
.v[er[tex]] ` &lt;expr&gt; ' <br>
.mid[point] &lt;expr&gt; <br>
.mid[point] ` &lt;expr&gt; ' <br>
&lt;<i>xxx</i>-of&gt; ::= <i><br>
xxx</i> # followed by &lsquo;of&rsquo; <br>
&lt;nth-primitive&gt; ::= <br>
&lt;ordinal&gt; &lt;object-type&gt; <br>
[&lt;ordinal&gt;] last &lt;object-type&gt; <br>
&lt;ordinal&gt; ::= <br>
INT th <br>
INT st | INT nd | INT rd <br>
` &lt;any-expr&gt; 'th <br>
&lt;object-type&gt; ::= <br>
box <br>
circle <br>
ellipse <br>
polygon <br>
arc <br>
line <br>
arrow <br>
spline <br>
&rsquo;[]&rsquo; <br>
TEXT</p>
<p style="margin-top: 1em">As Kernighan notes, &ldquo;since
barbarisms like <b>1th</b> and <b>3th</b> are barbaric,
synonyms like <b>1st</b> and <b>3rd</b> are accepted as
well.&rdquo; Objects of a given type are numbered from 1
upward in order of declaration; the <b>last</b> modifier
counts backward.</p>
<p style="margin-top: 1em">The &ldquo;'th&rdquo; form
(which allows you to select a previous object with an
expression, as opposed to a numeric literal) is not
documented in DWB&rsquo;s <i>pic</i>(1).</p>
<p style="margin-top: 1em">The &lang;<i>xxx</i>-of&rang;
rule is special: The lexical parser checks whether
<i>xxx</i> is followed by the token &lsquo;of&rsquo; without
eliminating it so that the grammar parser can still see
&lsquo;of&rsquo;. Valid examples of specifying a place with
corner and label are thus</p>
<p style="margin-left:28%; margin-top: 1em">A .n <br>
.n of A <br>
.n A <br>
north of A</p>
<p style="margin-top: 1em">while</p>
<p style="margin-left:28%; margin-top: 1em">north A <br>
A north</p>
<p style="margin-top: 1em">both cause a syntax error. (DWB
<b>pic</b> also allows the weird form
&lsquo;A&nbsp;north&nbsp;of&rsquo;.)</p>
<p style="margin-top: 1em">Here the special rules for the
&lsquo;with&rsquo; keyword using a path:</p>
<p style="margin-left:28%; margin-top: 1em">&lt;path&gt;
::= <br>
&lt;relative-path&gt; <br>
( &lt;relative-path&gt; , &lt;relative-path&gt; ) <br>
&lt;relative-path&gt; ::= <br>
&lt;corner&gt; <br>
. LABEL [. LABEL ...] [&lt;corner&gt;]</p>
<p style="margin-top: 1em">The following style variables
control output:</p>
<p align="center"><img src="img/pic-53.png" alt="Image img/pic-53.png"></p>
<p style="margin-top: 1em">Any of these can be set by
assignment, or reset using the <b>reset</b> statement. Style
variables assigned within &lsquo;[&nbsp;]&rsquo; blocks are
restored to their beginning-of-block value on exit;
top-level assignments persist across pictures. Dimensions
are divided by <b>scale</b> on output.</p>
<p style="margin-top: 1em">All <b>pic</b> expressions are
evaluated in floating point; units are always inches (a
trailing &lsquo;i&rsquo; or &lsquo;I&rsquo; is ignored).
Expressions have the following simple grammar, with
semantics very similar to C&nbsp;expressions:</p>
<p style="margin-left:28%; margin-top: 1em">&lt; <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
: <br>
: <br>
= <br>
V <br>
A <br>
R <br>
I <br>
A <br>
B <br>
L <br>
E <br>
N <br>
U <br>
M <br>
B <br>
E <br>
R <br>
&lt; <br>
p <br>
l <br>
a <br>
c <br>
e <br>
&gt; <br>
&lt; <br>
p <br>
l <br>
a <br>
c <br>
e <br>
- <br>
a <br>
t <br>
t <br>
r <br>
i <br>
b <br>
u <br>
t <br>
e <br>
&gt; <br>
&lt; <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
&lt; <br>
o <br>
p <br>
&gt; <br>
&lt; <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
- <br>
&lt; <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
( <br>
&lt; <br>
a <br>
n <br>
y <br>
- <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
) <br>
! <br>
&lt; <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
&lt; <br>
f <br>
u <br>
n <br>
c <br>
1 <br>
&gt; <br>
( <br>
&lt; <br>
a <br>
n <br>
y <br>
- <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
) <br>
&lt; <br>
f <br>
u <br>
n <br>
c <br>
2 <br>
&gt; <br>
( <br>
&lt; <br>
a <br>
n <br>
y <br>
- <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
, <br>
&lt; <br>
a <br>
n <br>
y <br>
- <br>
e <br>
x <br>
p <br>
r <br>
&gt; <br>
) <br>
r <br>
a <br>
n <br>
d <br>
( <br>
) <br>
&lt;place-attribute&gt; <br>
.x | .y | .h[eigh]t | .wid[th] | .rad <br>
&lt;op&gt; ::= <br>
+ | - | * | / | % | ˆ | &rsquo;&lt;&rsquo; |
&rsquo;&gt;&rsquo; | &rsquo;&lt;=&rsquo; |
&rsquo;&gt;=&rsquo; <br>
&lt;func1&gt; ::= <br>
sin | cos | log | exp | sqrt | int | rand | srand <br>
&lt;func2&gt; ::= <br>
atan2 | max | min</p>
<p style="margin-top: 1em">Both <b>exp</b> and <b>log</b>
are base 10; <b>int</b> does integer truncation; and
<b>rand()</b> returns a random number in [0-1).</p>
<p style="margin-top: 1em">There are <b>define</b> and
<b>undef</b> statements which are not part of the grammar
(they behave as pre-processor macros to the language). These
may be used to define pseudo-functions.</p>
<p style="margin-left:28%; margin-top: 1em"><b>define</b>
<i>name</i> <b>{</b> <i>replacement-text</i> <b>}</b></p>
<p style="margin-top: 1em">This defines <i>name</i> as a
macro to be replaced by the replacement text (not including
the braces). The macro may be called as</p>
<p style="margin-left:28%; margin-top: 1em"><i>name</i><b>(</b><i>arg1,
arg2, ..., argn</i><b>)</b></p>
<p style="margin-top: 1em">The arguments (if any) are
substituted for tokens $1, $2 ... $n appearing in the
replacement text. To undefine a macro, say <b>undef</b>
<i>name</i>, specifying the name to be undefined.</p>
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