\n
", "
Table of Contents
\n", "") # also lame substitution("frac", "frac") substitution("sqrt", "frac") every substitution("ldots" | "cdots" | "vdots", "...") ignore("left") ignore("right") ignore("overline") substitution(":", " ") substitution(";", " ") ignore("!") @ The [[star]] procedure lets us define \verb+eqnarray+ and \verb+eqnarray*+ in one fell swoop. <<*>>= procedure star(cs) suspend cs | (cs || "*") end @ There are a gazillion symbols. I'll add them on demand. <
Abstract
", "") @ \subsubsection{Cross-reference} A more ambitious scheme would make labels anchor at preceding sectioning commands, but it's hard to see how to do that in one pass. Instead, I just use some conventional glyphs. I use special procedures for the cross-references so I can have an arrow pointing either forward or backward, depending on the direction of the reference. <
References
", "", "{") every cstab["cite" | "citeN" | "opencite" | "openciteN" | "citeyear"] := Ccite cstab["bibitem"] := Cbibitem ignore("newblock") ignore("nocite", "{") @ \subsubsection{Splitting the input} All input is ignored. Those things are in their own files. <") ignore("-") ignoreenv("sloppypar") ignore("sloppy") @ \subsubsection{Page breaking} I simulate forced page breaks by horizontal rules. <
") substitution("newpage", "
") substitution("clearpage", "
") ignore("enlargethispage", "*{") @ \subsubsection{Boxes} <
", "
", "[") every envblock(star("table"), "
", "
", "[") argblock("caption", "b") # captions in bold @ \subsubsection{{\tt tabbing} environment} I can't see how to do anything sensible with {\tt tabbing}. <
", "
") substitution("cr", "
") substitution("hrule", "
") substitution("vrule", "|") substitution("hrulefill", "------") ignore("hyphenation", "{") ignore("hbox") ignore("rlap") ignore("llap") ignore("vbox") ignore("vtop") ignore("hidewidth") ignore("message", "{") ignore("relax") ignore("null") ignore("offinterlineskip") ignore("omit") ignore("newdimen", "{") ignore("nobreak") <
>
return S
end
@
The basic action performed by the
[[S.text]] function is to accumulate converted text in [[S.the_text]].
[[S.text]] is usually [[accumulate_text]].
<<*>>=
procedure accumulate_text(S, text)
S.the_text ||:= text
return
end
<>=
, text, the_text
<>=
, accumulate_text, ""
<>=
S.text := accumulate_text
S.the_text := ""
@
[[emit_text]] just uses the current value of [[S.text]], provided we aren't
currently ignoring tokens.
Its primary use is to appear in closures, when we don't know what
[[S.text]] will be when the closure is executed.
<<*>>=
procedure emit_text(S, text)
return if \S.ignoring then "" else S.text(S, text)
end
<>=
, ignoring
<>=
, &null
<>=
S.ignoring := &null
@
Active characters are like control sequences.
The only one active by default is the~[[~]].
<<*>>=
global activetab, activeclosure
procedure do_activechar(S, c)
(activetab[c])(S, c, activeclosure[c])
return
end
<>=
activetab := table(unknown_cs)
activeclosure := table()
<>=
, activechars
<>=
, '~'
<>=
S.activechars := '~'
@
\subsection{Action and continuation hooks}
We provide hooks so that actions can be taken at various points.
The major ones are:
\begin{description}
\item[\tt newtext]
When the next string is passed in for conversion.
\item[open brace]
After the next open brace or begin environment.
\item[close brace]
Before the next close brace or end environment.
\end{description}
@
\subsubsection{{\tt newtext}}
[[newtext]] is a list of closures to be executed (actions to take)
when the next input comes.
<>=
, newtext
<>=
, []
<>=
S.newtext := []
@
A closure is simply a procedure with arguments.
<<*>>=
record closure(proc, args)
@
[[before_next_newtext]] and [[after_next_newtext]]
add to the list of actions to be taken (at the left and right, respectively).
<<*>>=
procedure before_next_newtext(S, proc, args)
push(S.newtext, closure(proc, args))
end
procedure after_next_newtext(S, proc, args)
put(S.newtext, closure(proc, args))
end
@
When taking the actions, be careful to avoid infinite loop, e.g., on empty lines.
<>=
l := S.newtext
S.newtext := []
while c := get(l) do
c.proc!c.args
@
Some control sequences temporarily override all actions to be taken on
a new input, using [[delay_newtext]].
[[undelay_newtext]] restores actions.
<<*>>=
procedure delay_newtext(S)
push(S.delayed_newtext, S.newtext)
S.newtext := []
return
end
procedure undelay_newtext(S)
S.newtext := \pop(S.delayed_newtext) |
{write(&errout, "This can't happen: no delayed_newtext"); &null[0]}
end
<>=
, delayed_newtext
<>=
, []
<>=
S.delayed_newtext := []
@
\subsubsection{Opening and closing groups}
There's only one list of actions to be taken at the next open,
but there's a whole stack of lists of actions to be taken at closes.
<>=
, open, closes
<>=
, [], []
<>=
every S.open | S.closes := []
<<*>>=
procedure after_next_open(S, proc, args)
return put(S.open, closure(proc, args))
end
procedure before_next_close(S, proc, args)
return push(S.closes[1], closure(proc, args)) # lost at top level
end
procedure after_next_close(S, proc, args)
return put(S.closes[1], closure(proc, args)) # lost at top level
end
<>=
push(S.closes, []) # fresh set of closing tasks
while c := get(S.open) do
c.proc!c.args
<>=
while c := get(S.closes[1]) do
c.proc!c.args
pop(S.closes)
<>=
procedure Cbegingroup(S, cs, cl)
<>
end
<>=
procedure Cendgroup(S, cs, cl)
<>
end
<>=
cstab["begingroup"] := Cbegingroup
cstab["endgroup"] := Cendgroup
cstab["bgroup"] := Cbegingroup
cstab["egroup"] := Cendgroup
@
\subsection{Handling control sequences and environments}
OK, to eat a control sequence, first scan it, then execute it using [[do_cs]].
[[S.csletters]] records the current set of ``letters'' for control
sequences (so we can interpret \verb+\makeatletter+).
<>=
cs := if pos(0) then ""
else if any(S.csletters) then tab(many(S.csletters))
else move(1)
if /S.ignoring | cs == ("else"|"fi") | cstab[cs] === (Ciffalse|Ciftrue) then
do_cs(S, cs)
else
&null # error("### Ignoring \\", cs)
<>=
, csletters
<>=
, &letters
<>=
S.csletters := &letters
@
To execute a control sequence, look up its procedure in [[cstab]],
and pass in the name of the control sequence, plus the closure
argument from [[csclosure]].
\label{cs-tables}
<<*>>=
global cstab, csclosure
procedure do_cs(S, cs)
tab(many(' \t')) # skip white space following CS
if pos(0) | any('\n') then before_next_newtext(S, skipblanks, [S])
(cstab[cs])(S, cs, csclosure[cs])
return
end
<>=
cstab := table(unknown_cs)
csclosure := table()
@
The default action for an unknown control sequence is [[unknown_cs]].
If the global [[show_unknowns]] is set we dump the control sequence into the
output in bold. We save the unknown sequences for later warning messages.
<<*>>=
global show_unknowns
procedure unknown_cs(S, cs, cl)
# if S.text === ignore_text then return # a bit of a hack -- should no longer be needed
if \show_unknowns then S.text(S, "\\" || cs || "")
if not member(unknown_set, cs) then {
write(\unknown_file, "Warning: unknown control sequence \\", cs)
insert(unknown_set, cs)
}
return
end
<>=
unknown_set := set()
<<*>>=
global cstab, csclosure, unknown_set
@
The control sequences \verb+\begin+ and \verb+\end+ are treated
specially,
so we can have a similar machinery for environments.
<<*>>=
global begintab, endtab, begincl, endcl
procedure do_begin(S, cs, cl)
(="{", env := tab(upto('}')), ="}") | error("botched \\begin{...}")
<>
(begintab[env])(S, env, begincl[env])
return
end
procedure do_end(S, cs, cl)
(="{", env := tab(upto('}')), ="}") | error("botched \\end{...}")
# write(&errout, "calling ", image(endtab[env]), " for \\end{", env, "}")
(endtab[env])(S, env, endcl[env])
<>
return
end
<>=
cstab["begin"] := do_begin
cstab["end"] := do_end
<>=
every begintab | endtab := table(unknown_env)
every begincl | endcl := table()
<<*>>=
procedure unknown_env(S, env, cl)
### if S.text === ignore_text then return # a bit of a hack # no longer needed
if \show_unknowns then S.text(S, "{" || env || "}")
if not member(unknown_envs, env) then {
write(\unknown_file, "Warning: unknown environment {", env, "}")
insert(unknown_envs, env)
}
return
end
<>=
unknown_envs := set()
<<*>>=
global unknown_envs
@
\subsection{Issuing warnings about unknown control sequences and environments}
<<*>>=
procedure warn_unknown(s, type, mark, rmark)
if *s > 0 then {
pushout("Unknown " || type || ": ")
every pushout(((\mark | "")\1) || !sort(s) || ((\rmark | "")\1) || " ")
pushout("\n")
}
end
<<*>>=
procedure pushout(s)
static col
initial col := 0
if find("\n", s) then
s ? {
pushout(tab(upto('\n')))
while ="\n" do {col := 0; write(&errout)}
pushout(tab(0))
}
else {
col +:= *s
if col >= 79 then {writes(&errout, "\n "); col := *s + 2}
writes(&errout, s)
}
return
end
@
\subsection{Procedures related to parsing {\TeX}}
\subsubsection{Comment-skipping}
This logic gobbles text into [[S.comment]]
until a newline is encountered, at which point it calls
[[Ccomment]] to format the comment.
All other new-text actions go on hold until the comment is over.
<>=
parse_dynamic_add(S)
delay_newtext(S)
eat_comment(S)
<<*>>=
procedure eat_comment(S)
S.comment ||:= tab(upto('\n') | 0)
if pos(0) then
before_next_newtext(S, eat_comment, [S])
else {
undelay_newtext(S)
Ccomment(S)
S.comment := ""
}
return
end
<>=
, comment
<>=
, ""
<>=
S.comment := ""
@
Verbatim text is a little bit like comment text---we keep swallowing
under special rules until we find a terminator.
There are at least three classes of rules:
\begin{itemize}
\item
Copy text, but escape the HTML specials.
This corresponds to an ordinary {\LaTeX} \texttt{verbatim}
environment.
\item
Copy text while changing nothing.
This correspondes to a \texttt{rawhtml} environment.
\item
Throw everything on the floor.
This corresponds to a \texttt{latexonly} environment.
\end{itemize}
We store an output method, a string that terminates the environment,
and possibly tag for an HTML wrapper around the environment.
<<*>>=
record verbatim_cl(output, terminator, html, translate_blank)
procedure verbatim(name, output, html)
begintab[name] := Cverbatim
begincl [name] := verbatim_cl(output, &null, html)
return
end
procedure Cverbatim(S, cs, cl)
if cl === begincl[cs] & /cl.terminator then
cl := begincl[cs] :=
verbatim_cl(cl.output, "\\end{" || cs || "}", cl.html, cl.translate_blank)
emit_text(S, tag(\cl.html))
delay_newtext(S)
do_verbatim(S, cl)
return
end
@
If we find the terminator, we're finished.
Otherwise, we swallow the whole input and make sure our action on next
input is to continue scanning.
<<*>>=
procedure do_verbatim(S, cl)
if cl.output(S, tab(find(cl.terminator)), cl) then {
=cl.terminator
emit_text(S, endtag(\cl.html))
undelay_newtext(S)
} else {
cl.output(S, tab(0), cl)
before_next_newtext(S, do_verbatim, [S, cl])
}
return
end
@
When writing verbatim text, we still have to convert HTML specials.
<<*>>=
procedure escape_HTML_specials(S, s, cl)
s ? {
while emit_text(S, tab(upto('&<>" '))) do
case move(1) of {
"\"" : emit_text(S, """)
"&" : emit_text(S, "&")
"<" : emit_text(S, "<")
">" : emit_text(S, ">")
" " : emit_text(S, if \cl.translate_blank then "·" else " ")
}
emit_text(S, tab(0))
}
return
end
@
The \verb+\verb+ control sequence's terminator is the first character
following \verb+\verb+.
<<*>>=
procedure Cverb(S, cs, cl)
Cverbatim(S, cs, verbatim_cl(escape_HTML_specials, move(1), "tt", cl))
return
end
@
<<*>>=
procedure Cverbatiminput(S, cs, cl)
local filename, f, line
if ="{" & filename := tab(upto('}')) & ="}" then {
f := \open(filename) | { emit_text(S, "Could not read file ")
escape_HTML_specials(S, filename, cl)
emit_text(S, "")
return
}
emit_text(S, "\n\n")
while line := read(f) do {
escape_HTML_specials(S, line, cl)
emit_text(S, "\n")
}
emit_text(S, "\n")
close(f)
}
return
end
@
\subsubsection{Arguments}
It's occasionally necessary to collect the argument of a control
sequence.
[[csarg]] does the job.
<<*>>=
procedure csarg(S)
return 2(="{", tab(bal('}', '{', '}')), ="}") |
(optwhite(),
if ="\\" then
"\\" || (tab(many(S.csletters)) | move(1))
else
move(1))
end
@
[[csarg()]] works only if the whole
argument is in the same line; otherwise it only returns the opening curly
brace, `[[{]]'. Another problem with [[csarg()]] is that it does not cope with
[[%]] or [[\]] in the input (due to the use of the Icon function [[bal()]] to
balance curly brackets), as such a escaped or commented out curly brace is
handled incorrectly.
The solution provided here is not trivial. The problem is that if we have
`[[\foo{bar]]' in a line and the `[[baz}]]' is in another line then due to the
way how l2h works the Icon command associated with [[foo]] will have to
terminate before the `[[baz}]]' gets read, and as such cannot do anything
useful except register a callback to finish the job.
@
[[apply_arg(S, cl)]] scans an argument (preceded by optional
whitespace), then invokes the closure on that argument.
Its use should subsume [[csarg]], but that may take a while yet.
<<*>>=
@
[[apply_args(S, p, as, n]] scans [[n]] arguments from the
input, puts them in a list [[args]], then calls [[p!(as ||| args)]].
This is a bit weak, because we really want to turn off comment
skipping for some arguments.
N.B. the arguments are \emph{not} converted.
<<*>>=
procedure apply_args(S, p, as, args_wanted)
delay_newtext(S)
do_apply_args(S, closure(p, as), args_wanted, [], "", 0)
return
end
procedure do_apply_args(S, cl, wanted_count, args_seen, current_arg, brace_depth)
local open_comment
# invariant : we have an open brace
# pushtrace("APPLY")
while *args_seen < wanted_count & not pos(0) do {
while *args_seen < wanted_count & brace_depth = 0 & not pos(0) do {
tab(many(' \t\n'))
case c := move(1) of {
"\\" : put(args_seen, "\\" ||
if pos(0) then ""
else if any(S.csletters) then tab(many(S.csletters))
else move(1))
"{" : { current_arg := "" ; brace_depth := 1 }
"}" : { error("Insufficient arguments to macro ", macro.name) }
"%" : if tab(upto('\n')) then ="\n" else open_comment := tab(0)
default : put(args_seen, c)
}
}
while brace_depth > 0 & not pos(0) do {
current_arg ||:= tab(upto('\\{}%') | 0)
case move(1) of {
"%" : if tab(upto('\n')) then ="\n" else open_comment := tab(0)
"\\" : current_arg ||:= "\\" ||
if pos(0) then ""
else if any(S.csletters) then tab(many(S.csletters))
else move(1)
"{" : { current_arg ||:= "{" ; brace_depth +:= 1 }
"}" : { brace_depth -:= 1
if brace_depth > 0 then
current_arg ||:= "}"
else {
put(args_seen, current_arg)
current_arg := ""
}
}
}
}
}
if *args_seen = wanted_count then {
undelay_newtext(S)
cl.proc ! (cl.args ||| args_seen)
} else if \open_comment then {
delay_newtext(S)
before_next_newtext(S, skip_comment_and_continue,
[S, closure(do_apply_args, [S, cl, wanted_count, args_seen,
current_arg, brace_depth])])
} else
before_next_newtext(S, do_apply_args, [S, cl, wanted_count, args_seen,
current_arg, brace_depth])
# poptrace()
return
end
<<*>>=
procedure skip_comment_and_continue(S, cl)
tab(upto('\n') | 0)
if pos(0) then
before_next_newtext(S, skip_comment_and_continue, [S, cl])
else {
="\n"
undelay_newtext(S)
# >
}
return
end
@
\subsubsection{Misc specials}
Ampersands are covered in the table section (\ref{tabular}).
@
The dollar sign is for entering and exiting math mode:
<>=
if /S.ignoring then
if ="$" then
if S.mode == "M" then { Cdisplaymath_end(S); S.mode := "V" }
else { Cdisplaymath(S); S.mode := "M" }
else
if S.mode == "M" then { Cmath_end(S); S.mode := "H" }
else { Cmath(S); S.mode := "M" }
@
Newlines emit themselves, plus start skipping blanks until they get to
some nonblank text.
We have to identify a blank line so we can insert a paragraph marker.
<>=
emit_text(S, "\n")
if /S.ignoring then Cnewline(S)
<<*>>=
procedure Cnewline(S)
tab(many(' \t'))
if match("\n") then implicit_paragraph(S)
if pos(0) then before_next_newtext(S, Cnewline, [S])
end
@
Other procedures might want to skip white space, which includes
newlines, but we don't want to miss a paragraph.
<<*>>=
procedure skipblanks(S)
tab(many(' \t'))
if ="\n" then Cnewline(S)
else if pos(0) then before_next_newtext(S, skipblanks, [S])
end
@
Paragraphs count only in horizontal or math mode (and they better not
happen in math mode!).
<<*>>=
procedure implicit_paragraph(S, cs, cl)
if S.mode ~== "V" then {
S.mode := "V"
Cparagraph(S)
}
cs_ignore(S, cs, \cl)
end
@
Here's a real hack. I use it to stop skipping blanks when the noweb
filter sees text quoted by [[[[...]]]].
That text is never converted, but we don't want to skip blanks that
follow it.
<<*>>=
procedure stop_skipping(S)
while S.newtext[1].proc === (Cnewline|skipblanks) do pop(S.newtext)
end
@
\subsubsection{Items}
For items, we actually want to do something with the optional arguments,
namely, convert them.
We wrap them in braces so that any font changes and so on will be
appropriately limited in their effects.
<<*>>=
record item_cl(before, after, ifnone)
procedure Citem(S, cs, cl)
if pos(0) then
after_next_newtext(S, Citem, [S, cs, cl])
else if ="[" then {
delay_newtext(S)
with_upto_bracket(S, "", convert_bracketed, cl)
} else {
skipblanks(S)
emit_text(S, cl[1].ifnone)
\liststack[1] := \liststack[1] + 1
}
end
<<*>>=
procedure convert_bracketed(S, contents, cl)
emit_text(S, cl[1].before ||
convert(converter("H"), "{" || contents || "}") ||
cl[1].after)
optwhite()
end
<<*>>=
global liststack, suspendstack
<>=
liststack := []
# write(&errout, "Initialized liststack")
suspendstack := []
<>=
cstab["suspend"] := Csuspend
cstab["resume"] := Cresume
<<*>>=
procedure listenv(env, html)
begintab[env] := Clist
begincl[env] := html
endtab[env] := Clist_end
endcl[env] := html
end
procedure push_item_closure(cs)
push(csclosure["item"],
if cs == "description" then item_cl("", " ", " ")
else item_cl("", "--", " "))
end
procedure Clist(S, cs, cl)
push(liststack, 1)
push_item_closure(cs)
emit_text(S, tag(cl))
end
procedure Cresume(S, cs, cl)
local n, env
(="{", env := tab(upto('}')), ="}") | error("botched \\resume{...}")
n := pop(suspendstack) | error("\\resume not balanced by corresponding \\suspend")
push(liststack, n)
push_item_closure(env)
if env == "enumerate" then
emit_text(S, tag(begincl[env] || " start=\"" || n || "\""))
else
emit_text(S, tag(begincl[env]))
end
procedure Clist_end(S, cs, cl)
emit_text(S, endtag(cl))
pop(csclosure["item"])
pop(liststack)
end
procedure Csuspend(S, cs, cl)
local env
(="{", env := tab(upto('}')), ="}") | error("botched \\suspend{...}")
emit_text(S, endtag(endcl[env]))
pop(csclosure["item"])
push(suspendstack, pop(liststack))
end
@
\subsubsection{Labels and references}
These could be done by [[argblock]], except I want to make it possible to have
different text depending on whether the references point forward or backward.
<<*>>=
global labels_seen
procedure Clabel(S, cs, cl)
initial /labels_seen := set()
insert(labels_seen, l := csarg(S)) | fail
emit_text(S, "[*]")
end
procedure Cref(S, cs, cl)
local prefix, prefix_tag
initial /labels_seen := set()
prefix_tag := (\cl)[1] | ""
prefix := (\cl)[2] | ""
l := prefix || csarg(S) | fail
emit_text(S, prefix_tag || "[" ||
(if member(labels_seen, l) then "<-" else "->") || "]")
end
@
\subsubsection{Citations}
The important thing about a citation key is that it makes a hot line
to the appropriate item in the bibliography.
[[Ccite]] and [[Cbibitem]] work together to make it happen.
Optional arg might contain blanks, so it might be split, but
I assume the citation key isn't split between inputs.
<<*>>=
procedure Ccite(S, cs, cl, bracketed_text)
if ="[" then {
delay_newtext(S)
with_upto_bracket(S, "", do_cite, cl)
} else
do_cite(S, &null, cl)
end
procedure do_cite(S, commentary, cl)
local key
if \commentary then
optwhite()
if pos(0) then before_next_newtext(S, do_cite, [S, commentary, cl])
else {
key := csarg(S)
\commentary := convert(converter("H"), "{" || \commentary || "}")
emit_text(S, "[cite ")
key ? {
while k := tab(upto(",")) & ="," do
emit_text(S, "" || k || ", ")
if k := tab(0) then
emit_text(S, "" || k || "")
}
emit_text(S, ", " || \commentary || "")
emit_text(S, "]")
}
end
<<*>>=
procedure Cbibitem(S, cs, cl)
local label, key
static counter
initial counter := 0
if ="[" then {
delay_newtext(S)
with_upto_bracket(S, "", finish_bibitem, [])
} else {
label := "[" || (counter +:= 1) || "]"
apply_args(S, do_bibitem_key, [S, label], 1)
}
end
procedure do_bibitem_key(S, label, key)
return emit_text(S, "" || label || " ")
end
procedure finish_bibitem(S, contents, args)
local key, label
optwhite()
label := convert(converter("H"), "{" || contents || "}")
key := apply_args(S, do_bibitem_key, [S, label], 1)
end
@
\subsubsection{Conditionals}
The idea here is that an \verb+\if+$\cdots$ control sequence will conditionally
ignore text, and that \verb+\fi+ restores the previous state.
To keep track of state, we have an ``if stack'' that records what
[[S.text]] should be upon encountering \verb+\else+ and \verb+\fi+.
<>=
, ifstack
<>=
, []
<>=
if *S.ifstack > 0 then S.ifstack := [] # keeps GC down
@
What's on the ifstack is
<<*>>=
record ifrec(on_else, on_fi)
@ It's possible that one day this code will need to be updated to delay
new-text actions (and to do God knows what if
new-text actions have already been delayed).
@
Every \verb+\if+$\cdots$ is equivalent either to \verb+\iffalse+
of \verb+\iftrue+, so we begin by defining those, as well as \verb+\else+
and \verb+\fi+
<<*>>=
procedure Ciffalse(S, cs, cl)
#error("### \\", cs, " -> false (S.ignoring === ", image(S.ignoring) ? {="procedure "; tab(0)}, ")")
push(S.ifstack, ifrec(S.ignoring, S.ignoring))
S.ignoring := 1
end
procedure Ciftrue(S, cs, cl)
#error("### \\", cs, " -> true (S.ignoring === ", image(S.ignoring) ? {="procedure "; tab(0)}, ")")
push(S.ifstack, ifrec(1, S.ignoring))
end
procedure Celse(S, cs, cl)
S.ignoring := S.ifstack[1].on_else
#error("### \\else -> S.ignoring === ", image(S.ignoring) ? {="procedure "; tab(0)})
end
procedure Cfi(S, cs, cl)
S.ignoring := S.ifstack[1].on_fi
#error("### \\fi -> S.ignoring === ", image(S.ignoring) ? {="procedure "; tab(0)})
pop(S.ifstack)
end
@
Now, all that's left is to handle \verb+\newif+.
This part is all boilerplate.
<<*>>=
procedure Cnewif(S, cs, cl)
local newif, newcs
tab(many(' \t\n'))
if pos(0) then
after_next_newtext(S, Cnewif, [S, cs, cl])
else {
newif := csarg(S)
newif ?
if ="\\if" & newcs := tab(many(S.csletters)) & pos(0) then {
<>
} else
error("\\newif argument botch: " || newif)
}
end
@
And here we do the real work:
<>=
cstab[newcs || "false"] := Csetif
cstab[newcs || "true"] := Csetif
cstab["if" || newcs] := Ciffalse
<<*>>=
procedure Csetif(S, cs, cl)
local base, tag
if cs ? (base := tab(find("true"|"false")), tag := =("true"|"false"), pos(0)) then {
cstab["if" || base] := if tag == "true" then Ciftrue else Ciffalse
} else {
error("This can't happen --- setif botch (not urgent)")
}
end
@
\subsection{Upper case}
This is a very simple implementation of [[\uppercase]]: it requires to
have all of its argument immediately.
<<*>>=
procedure Cuppercase(S, cs, cl)
l := map(csarg(S), &lcase, &ucase) | fail
emit_text(S, l)
end
<>=
cstab["uppercase"] := Cuppercase
@
\subsection{HTML support for array and tabular environments}
We handle tables by using [[S.text]] to implement a little state machine.
There are only two states: waiting to start a new cell, and the
ordinary state of converting text.
The rest of the state information is held in a list of [[table_info]]
records that tell us what to expect for the next cell.
<<*>>=
record table_info(index, # number of this cell in the row
alignment, # the alignment of this cell
width, # how many columns this cell will span
alignments, # default alignments for this table
brace_depth, # size of S.closes after start of cell
cell_text) # value of S.text to use to scan this cell
@ This state could conceivably be extended to include pre- and
post-content for each cell, \`a la plain {\TeX}'s [[\halign]] or the
{\LaTeX} [[<{}]] and [[>{}]] directives, but for now I won't bother.
I should probably also add a [[rows_taken]] field and use it to
implement [[multirow]] support.
@
Here's a stack that keeps track of all currently active tabular environments.
<>=
, tables
<>=
, []
<>=
S.tables := []
@
Accumulating text forces the transition between states.
While I'm at it, I update the state for the next cell.
<<*>>=
procedure start_table_cell(S, text)
local this, attributes
text ? {
tab(many(' \t\n'))
if pos(0) then return
}
# write(&errout, "starting cell with ", image(text))
this := S.tables[1] | fatal("starting cell with no current table")
S.text := this.cell_text
if /(\this).brace_depth then write(&errout, "starting table cell, ", image(this), " has null brace depth")
# use this to start the current cell
if this.index = 1 then emit_text(S, "")
attributes := \this.alignment | aligneq("top")
if this.width > 1 then attributes ||:= " colspan=" || this.width
emit_text(S, "")
# now update state for the next cell
this.index +:= this.width # advance to next cell
this.alignment := this.alignments[this.index] | &null
this.width := 1
# can't set cell_text until we hit &
<>
emit_text(S, text)
return
end
@
Hitting an ampersand closes and opens groups, and it advances to the
next cell.
<<*>>=
procedure ampersand(S)
local this
this := S.tables[1]
<>
if /this then
emit_text(S, " --- ")
else {
emit_text(S, "") # be sure cell gets started, even if empty
emit_text(S, "")
if S.text ~=== start_table_cell then
this.cell_text := S.text
S.text := start_table_cell
this.brace_depth := *S.closes + 1 # will open at start of cell
#write(&errout, "set brace depth for ", image(this))
}
tab(many(' \t\n'))
## write(&errout, " past &, text = ", image(S.text), ", next = ",
## image(&subject[&pos:0]))
return
end
@
The double backslash is the end of a row, unless it's buried in braces
or there's no table.
We have to be careful about ignoring a square bracket, because if the
[[\\]] is at the end of a line, we won't know until we see the newline
that it's not a bracket, and we don't see the newline until we get the
next text.
We therefore must use a continuation-passing style for this ignore.
<<*>>=
procedure Cbackback(S, cs, cl)
local this
this := S.tables[1]
cs_ignore(S, cs, "[", Cbackback_continue, [S, this])
end
procedure Cbackback_continue(S, this)
#if /(\this).brace_depth then write(&errout, image(this), " has null brace depth")
if /this | *S.closes > this.brace_depth then { # ordinary \\
S.text(S, "
")
} else { # row terminator
## write(&errout, "ending row with ", image(&subject[&pos:0]))
emit_text(S, "") # be sure cell gets started, even if empty
<>
emit_text(S, " \n")
tab(many(' \t\n'))
if S.text ~=== start_table_cell then
this.cell_text := S.text
this.index := 1
this.alignment := this.alignments[this.index] | &null
this.width := 1
S.text := start_table_cell
this.brace_depth := *S.closes + 1 # about to open
}
end
@
A horizontal line disappears if it's in a table.
<<*>>=
procedure Chline(S, cs, cl)
if \S.tables[1] then return
else emit_text(S, "
")
return
end
@
An [[\end{tabular}]] terminates the whole affair.
If we're at the beginning of a row, things are easy.
Otherwise, we terminate the current row first.
<<*>>=
procedure Ctabular_end(S, cs, cl)
local this
if S.text ~=== start_table_cell | S.tables[1].index > 1 then {# row in progress
emit_text(S, "") # be sure cell gets started, even if empty
<>
emit_text(S, "")
}
if S.text === start_table_cell then # abort it
S.text := S.tables[1].cell_text
emit_text(S, "")
xxx := pop(S.tables)
#write(&errout, "popped ", image(xxx))
return
end
@
Finally, the setup of the table itself:
<<*>>=
procedure Ctabular(S, cs, cl)
cs_ignore(S, cs, cl, Ctabular_continue, [S])
return
end
procedure Ctabular_continue(S)
a := csarg() # alignment
#write(&errout, "Alignment ", a)
emit_text(S, if upto('|', a) then "" else "")
emit_text(S, "")
a := alignments(a)
emit_text(S, "")
push(S.tables, table_info(1, a[1] | "l", 1, a, *S.closes+1, S.text))
#write(&errout, "pushed ", image(S.tables[1]))
S.text := start_table_cell
optwhite()
return
end
@ Earlier, the initial value of [[S.tables[1].brace_depth]] was
[[&null]], but when we had alignment of \verb+{c}+, it was never
getting set, so I'm setting it on startup, even though I'm not sure if
that's really right.
<<*>>=
procedure tabular(env, ignore)
begintab[env] := Ctabular
begincl[env] := ignore
endtab[env] := Ctabular_end
endcl[env] := ignore
end
@
We figure alignments using the tricks in the {\LaTeX} book.
<<*>>=
procedure aligneq(a)
return " align=\"" || a || "\""
end
procedure valigneq(a)
return " valign=\"" || a || "\""
end
procedure alignments(s)
a := []
s ? {
while not pos(0) do
case move(1) of {
"l" | "X" | "Y" | "p" :
{ put(a, aligneq("left") || valigneq("top")); skip_bracket() }
"c" : put(a, aligneq("center"))
"r" : put(a, aligneq("right"))
"m" : { put(a, aligneq("left") || valigneq("center")); skip_bracket() }
"b" : { put(a, aligneq("left") || valigneq("bottom")); skip_bracket() }
"@" | "<" | ">" | "!" : skip_bracket()
"|" : &null
default : &null # unrecognized...
}
}
return a
end
<<*>>=
procedure skip_bracket()
if ="{" then {
n := 1
while n > 0 & not pos(0) do {
tab(upto('{}\\') | 0)
case move(1) of {
"{" : n +:= 1
"}" : n -:= 1
"\\" : move(1)
}
}
}
return
end
@
[[\multicolumn]] changes the width and alignment of the current cell.
[[\multispan]] changes only the width.
<<*>>=
procedure Cmulticolumn(S, cs, cl)
local this
this := S.tables[1]
n := integer(csarg()) | error("\\multicolumn or \\multispan not followed by integer")
if cs == "multicolumn" then a := alignments(csarg())
# write(&errout, "\\", cs, " n = ", n, ", a = ", (\a)[1] | "???",
# ", text = ", image(S.text))
if /this then return # \multicolumn without table?
this.width := n
this.alignment := (\a)[1]
return
end
procedure Cspan(S, cs, cl)
(\S.tables[1]).width +:= 1
return
end
@
<<*>>=
procedure Cnoalign(S, cs, cl)
apply_args(S, finish_noalign, [S], 1)
return
end
procedure finish_noalign(S, arg)
return if \S.ignoring then "" else
accumulate_text(S, "
" || convert(converter("V"), "{" || arg || "}") || "
")
end
@
\subsection{Reading and converting auxiliary {\LaTeX} files}
<<*>>=
procedure auxfile(cs, ext, placeholder, header, trailer, ignore)
cstab[cs] := Cauxfile
csclosure[cs] := aux_cl(ext, placeholder, header, trailer, \ignore | "")
end
@
[[Cauxfile]] succeeds if it finds a file, fails otherwise.
<<*>>=
record aux_cl(ext, placeholder, header, trailer, ignore)
procedure Cauxfile(S, cs, cl)
local auxfile, T
if auxfile := open(basename(\curfile) || "." || cl.ext) then {
T := converter("V")
Cmakeatletter(T)
S.text(S, \cl.header)
while line := read(auxfile) do
S.text(S, convert(T, line || "\n"))
close(auxfile)
S.text(S, \cl.trailer)
} else {
S.text(S, \cl.placeholder)
}
cs_ignore(S, cs, cl.ignore)
if \auxfile then return
end
<<*>>=
procedure basename(name)
reverse(name) ? {
tab(upto('.')) & ="."
return reverse(tab(0))
}
end
@
\subsubsection{Table of contents}
We can build a table of contents by reading the .toc file.
Sadly, I haven't figured out how to get hot links yet.
<>=
cstab["contentsline"] := Ccontentsline
<<*>>=
procedure Ctableofcontents(S, cs, cl)
S.mode := "V"
Cauxfile(S, cs, cl)
set_toclevel(S)
end
@
[[set_toclevel]] manages the starting and ending of lists.
With no level argument, it resets the toc to the initial level.
<<*>>=
procedure set_toclevel(S, l)
static toclevel, initiallevel
if /initiallevel := \l then
S.text(S, "")
if /l := \initiallevel then
S.text(S, "
")
if /l then return # never set a level
/toclevel := l
while toclevel < l do {
S.text(S, "")
toclevel +:= 1
}
while toclevel > l do {
S.text(S, "
")
toclevel -:= 1
}
return
end
@
Assume one table of contents per converted document.
<<*>>=
procedure Ccontentsline(S, cs, cl)
local type, level
static leveltab
initial { <> }
l := \leveltab[csarg()] | fail
if l > \countertab["tocdepth"] then
cs_ignore(S, cs, "{{") # skip this one
else {
set_toclevel(S, l)
S.text(S, "")
after_next_open(S, after_next_close, [S, cs_ignore, [S, cs, "{"]])
}
end
<>=
l := ["part", "chapter", "section", "subsection", "subsubsection",
"paragraph", "subparagraph"]
leveltab := table()
every i := 1 to *l do
leveltab[l[i]] := i - 2 # making section level 1
@
\subsubsection{Counters}
<<*>>=
global countertab
procedure Csetcounter(S, cs, cl)
local counter
(counter := csarg(), countertab[counter] := integer(csarg())) |
cs_ignore(S, cs, "{{")
end
<>=
countertab := table()
@
\subsubsection{Accents}
This info is taken from the HTML RFC, section entitled
``ISO Latin~1 character entities.''
<<*>>=
global accent_name, accent_valid
<>=
accent_name := table()
accent_valid := table('')
accent_name ["`"] := "grave"
accent_valid["`"] := 'AEIOUaeiou'
accent_name ["'"] := "acute"
accent_valid["'"] := 'AEIOUYaeiouy'
accent_name ["^"] := "circ"
accent_valid["^"] := 'AEIOUaeiou'
accent_name ["hat"] := "circ"
accent_valid["hat"] := 'AEIOUaeiou'
accent_name ["\""] := "uml"
accent_valid["\""] := 'AEIOUaeiouy'
accent_name ["~"] := "tilde"
accent_valid["~"] := 'ANOano'
accent_name ["="] := "bar"
accent_name ["."] := "dot"
accent_name ["u"] := "u"
accent_name ["v"] := "v"
accent_name ["H"] := "H"
accent_name ["t"] := "t"
accent_name ["c"] := "cedil"
accent_valid["c"] := 'Cc'
accent_name ["d"] := "underdot"
accent_name ["b"] := "underbar"
@
Initialization calls [[accent]] to indicate that a control
sequence represents an accent.
In fact, [[accent]] is called on all keys of [[accent_name]].
<<*>>=
procedure accent(cs)
cstab[cs] := Caccent
end
procedure Caccent(S, cs, cl)
static warned
initial warned := table()
arg := csarg(S) | return
if arg == "\\i" then arg := "i"
if arg == "\\j" then arg := "j"
if *arg = 1 & any(accent_valid[cs], arg) then
S.text(S, "&" || arg || accent_name[cs] || ";")
else {
<>
S.text(S, arg)
}
end
<>=
/warned[cs] := set()
if not member(warned[cs], arg) then {
write(&errout, "Warning: Can't handle \\", cs, " with arg `", arg, "'")
insert(warned[cs], arg)
}
@
\subsection{Font changes}
A font change changes the font until the next close, when we need to emit
the appropriate end tag.
<<*>>=
procedure fontchange(tex, html)
cstab[tex] := Cfontchange
csclosure[tex] := html
end
<<*>>=
procedure Cfontchange(S, tex, html)
S.text(S, tag(html))
before_next_close(S, emit_text, [S, endtag(html)])
end
@
\section{Implementations of declaratives}
\label{imp-decl}
\subsection{Ignoring stuff}
There are several different kinds of things that can be ignored:
ordinary arguments,
balanced-brace arguments, optional arguments, assignments (which may
include dimensions), stars, and parenthesized coordinates.
We ignore a sequence of these things by supplying a template to
[[ignore]], in which each character stands for something to be ignored.
We've already seen examples of these things in Section~\ref{cs-decls}.
We can ignore arguments of control sequences or environments.
In either case, [[cs_ignore]] does the work.
<<*>>=
procedure ignore(cs, template)
/template := ""
cstab[cs] := cs_ignore
csclosure[cs] := template
end
procedure ignoreenv(env, template)
/template := ""
begintab[env] := cs_ignore
begincl[env] := template
endtab[env] := do_nothing
end
@
Because ignoring may span many inputs, all [[cs_ignore]] does is set things
up to call [[do_ignore]].
The major setup is replacing [[S.text]] with a function that does nothing.
Oh, and it converts an integer template
into that many arguments, for historical reasons.
<<*>>=
procedure cs_ignore(S, cs, template, proc, args)
local saved_ignore
saved_ignore := S.ignoring
S.ignoring := 1
if type(template) == "integer" then template := repl("{", template)
return do_ignore(S, template, saved_ignore, proc, args)
end
@
Some things are easily ignored (partly because we assume they don't
span inputs). For others, we have special procedures.
The brace-ignoring stuff uses the open and close hooks, because braces
can be nested deeply.
If non-null, [[proc]] is applied to [[args]] after everything is ignored.
<<*>>=
procedure do_ignore(S, template, saved_ignore, proc, args)
if *template > 0 then
if optwhite() & pos(0) then
after_next_newtext(S, do_ignore, [S, template, saved_ignore, proc, args])
else
case template[1] of {
"{" : { S.ignoring := 1
after_next_open(S, ignore_til_close,
[S, template[2:0], saved_ignore, proc, args])
}
"A" : { csarg(S) # had better be in one input
do_ignore(S, template[2:0], saved_ignore, proc, args)
}
"[" : if optwhite() & ="[" then {
delay_newtext(S)
with_upto_bracket(S, "", ignore_bracket_plus,
[S, template[2:0], saved_ignore, proc, args])
} else
do_ignore(S, template[2:0], saved_ignore, proc, args)
"C" : # a total cheat, means ``copy optional arg''
if optwhite() & ="[" then {
S.ignoring := &null
delay_newtext(S)
with_upto_bracket(S, "", copy_bracket_plus,
[S, template[2:0], saved_ignore, proc, args])
} else
do_ignore(S, template[2:0], saved_ignore, proc, args)
"=" : { delay_newtext(S)
eat_assignment(S, do_ignore, [S, template[2:0], saved_ignore, proc,args])
}
"*" : { (="*", optwhite())
do_ignore(S, template[2:0], saved_ignore, proc, args)
}
"(" : { (="(", tab(upto(')')), =")", optwhite())
do_ignore(S, template[2:0], saved_ignore, proc, args)
}
}
else {
S.ignoring := saved_ignore
(\proc)!(\args)
}
end
procedure ignore_til_close(S, template, saved_ignore, proc, args)
before_next_close(S, do_ignore, [S, template, saved_ignore, proc, args])
end
@
Finally, at the end of an ignored environment, do nothing.
<<*>>=
procedure do_nothing(S, cs, cl)
return
end
@
\subsubsection{Parsing bracketed (optional) arguments}
We may have to deal with optional arguments that are split across lines.
We pass in a continuation for the bracket.
This is a lot like gobbling to a newline, which we had to do with a comment.
As in the other case, we do something stupid if the bracket is
protected (e.g. by a backslash or comment char).
<<*>>=
procedure with_upto_bracket(S, bracketed_text, proc, args)
bracketed_text ||:= tab(upto(']') | 0)
if pos(0) then
before_next_newtext(S, with_upto_bracket, [S, bracketed_text, proc, args])
else {
="]"
undelay_newtext(S)
(\proc)(S, bracketed_text, args)
}
return
end
@
To ignore brackets:
<<*>>=
procedure ignore_bracket_plus(S, contents, args)
# contents are ignored
do_ignore!args
end
@ and to copy them
<<*>>=
procedure copy_bracket_plus(S, contents, args)
local should_ignore
should_ignore := args[3] | fail # saved_ignore arg to do_ignore
if /should_ignore then
S.text(S, convert(converter("H"), "{" || contents || "}"))
do_ignore!args
end
@
\subsubsection{Ignoring assignments}
Assignments are tricky because they might involve numbers, control
sequences, dimensions, or even glue.
We approximate the syntax from page 275 in the \TeX book.
<<*>>=
procedure eat_assignment(S, proc, args)
static decimal_chars, hex_chars, oct_chars
initial {
decimal_chars := &digits ++ '.,+-'
hex_chars := &digits ++ 'abcdefABCDEF'
oct_chars := '0124567'
}
optwhite()
="=" # so what if we swallow multiple = signs
optwhite()
if pos(0) then {
before_next_newtext(S, eat_assignment, [S, proc, args])
return
} else if glue() then { # finished
} else if any(decimal_chars) then {
tab(many(decimal_chars))
optwhite()
if ="\\" then
tab(many(S.csletters)) | move(1)
# else assume assignment of the form \hangafter=2
} else if ="\"" then {
tab(many(hex_chars)) & optwhite()
} else if ="\'" then {
tab(many(oct_chars)) & optwhite()
} else if =("\\"|"`\\") then
tab(many(S.csletters)) | move(1)
undelay_newtext(S)
(\proc)!args
end
<<*>>=
procedure dimen()
static decimal_chars
initial decimal_chars := &digits ++ '.,'
suspend (optwhite(),
if any('+-') then (move(1), optwhite()) else "",
tab(many(decimal_chars)), optwhite(),
(="true", optwhite()) | &null,
=("em"|"ex"|"pt"|"pc"|"in"|"bp"|"cm"|"mm"|"dd"|"cc"|"sp"|"mu"))
end
<<*>>=
procedure glue()
suspend (dimen(),
(optwhite(), ="plus", dimen()) | "",
(optwhite(), ="minus", dimen()) | "")
end
@
\subsection{Substitution}
\subsubsection{Simple substitution for a single control sequence}
Even simple substitution isn't so simple, because in addition to the
HTML that we substitute for the {\TeX}, we can also supply a template
of stuff to be ignored (like the optional argument to \verb+\\+).
<<*>>=
procedure substitution(tex, html, ignore_template)
# ignore mode for now
cstab[tex] := Cemit_ig
csclosure[tex] := emit_ig_cl(html, \ignore_template | "")
end
@
The closure contains HTML to be written and a template to be ignored.
<<*>>=
record emit_ig_cl(html, template)
procedure Cemit_ig(S, cs, cl)
emit_text(S, cl.html)
if *cl.template > 0 then
cs_ignore(S, cs, cl.template)
end
@
\subsubsection{Substitution for active characters}
<<*>>=
procedure activesubst(char, html, ignore_template)
local S
# ignore mode for now
activetab[char] := Cemit_ig
activeclosure[char] := emit_ig_cl(html, \ignore_template | "")
S := \dynamic_add_hack | return
if upto(S.activechars, char) then return # already active
if S.activechars ++:= cset(char) then {
before_next_close(S, delete_active_char, [S, char])
} else impossible("ugh")
return
end
procedure delete_active_char(S, char)
S.activechars --:= char
return
end
@
\subsubsection{Substitution for environments}
The [[envblock]] procedure has two forms:
\begin{itemize}
\item
{}[[envblock(]]{\it environment}, {\it tag}[[)]] simply uses
begin- and end-{\it tag} in place of the environment.
\item
{}[[envblock(]]{\it environment}, {\it left}, {\it right}, {\it
ignore}[[)]]
puts the {\it left} text at the beginning of the environment, the {\it
right} text at the end, plus at the beginning of the environment it
ignores the arguments described by {\it ignore}.
\end{itemize}
It's easier to implement than to describe.
<<*>>=
procedure envblock(env, left, right, ignore_template)
/ignore_template := ""
begintab[env] := Cemit_ig
begincl[env] := emit_ig_cl(if /right then tag(left) else left, ignore_template)
endtab[env] := Cemit
endcl[env] := if /right then endtag(left) else right
end
@ [[Cemit]] emits text with nothing to ignore.
<<*>>=
procedure Cemit(S, cs, cl)
S.text(S, cl)
end
@
\subsubsection{Substitution around arguments of control sequences}
These substitutions place tags at the beginning and end of arguments
to control sequences, instead of surrounding the contents of an
environment.
For example, they specify how to convert [[\section{...}]] to
[[...
]] and so forth.
The calling convention is as for [[envblock]].
<<*>>=
record blockpair(left, right, ignore)
procedure argblock(tex, html, right, ignore)
# called as is envblock
/ignore := ""
cstab[tex] := Cblock
csclosure[tex] :=
if /right then blockpair (tag(html), endtag(html), ignore)
else blockpair (html, right, ignore)
end
@ There is a fine point; control sequences labelled with [[argblockv]]
should put the converter into vertical mode.
<<*>>=
procedure argblockv(tex, html, right, ignore)
argblock(tex, html, right, ignore)
cstab[tex] := CblockV
end
<<*>>=
procedure Cblock(S, cs, cl, done_ignoring)
if /done_ignoring & *cl.ignore > 0 then {
cs_ignore(S, cs, cl.ignore, Cblock, [S, cs, cl, 1])
} else if pos(0) then {
after_next_newtext(S, do_cs, [S, cs, cl])
} else if match("{") then {
S.text(S, cl.left)
after_next_open(S, before_next_close, [S, emit_text, [S, cl.right]])
} else {
# S.text(S, cl.left || csarg(S) || cl.right)
apply_args(S, Cblock_continue, [S, cl], 1)
}
return
end
procedure Cblock_continue(S, cl, title)
S.text (S, cl.left || title || cl.right)
return
end
<<*>>=
procedure CblockV(S, cs, cl)
S.mode := "V"
Cblock(S, cs, cl)
return
end
@
\subsubsection{Macro substitution}
I'm taking the plunge and describing a ghastly macro language.
Macros have arguments, a body, and an optional terminal mode.
The final mode, if non-null, is the mode to which the conversion
engine should be set.
<<*>>=
record macro_defn(name, arg_count, body, mode)
@ The body is a list of items, where an item may be a raw argument, a
converted argument, or a string.
<<*>>=
record raw_arg(number)
record converted_arg(number, mode)
@
<<*>>=
procedure expand_macro(S, macro, args)
every a := !macro.body do
case type(a) of {
"string" : emit_text(S, a)
"raw_arg" : emit_text(S, args[a.number]) | impossible("missing arg")
"converted_arg" : S.text(S, convert(S, "{" || args[a.number] || "}"))
}
# poptrace()
return
end
#link pushtrace
@
Scan arguments and hope comments in arguments just work out. Ha ha.
<<*>>=
procedure do_macro(S, macro, args_seen, current_arg, brace_depth)
# invariant : we have an open brace
# write(&errout, "scanning args for macro ", macro.name)
# write(&errout, "seen ", *args_seen, " want ", macro.arg_count)
while *args_seen < macro.arg_count & not pos(0) do {
while *args_seen < macro.arg_count & brace_depth = 0 & not pos(0) do {
# write(&errout, "seen ", *args_seen, " want ", macro.arg_count,
# " current ", image(current_arg), " braces ", brace_depth)
tab(many(' \t\n'))
case c := move(1) of {
"\\" : put(args_seen, "\\" ||
if pos(0) then ""
else if any(S.csletters) then tab(many(S.csletters))
else move(1))
"{" : { current_arg := "" ; brace_depth := 1 }
"}" : { error("Insufficient arguments to macro ", macro.name) }
default : put(args_seen, c)
}
}
while brace_depth > 0 & not pos(0) do {
# write(&errout, "seen ", *args_seen, " want ", macro.arg_count,
# " current ", image(current_arg), " braces ", brace_depth)
current_arg ||:= tab(upto('\\{}') | 0)
case move(1) of {
"\\" : current_arg ||:= "\\" ||
if pos(0) then ""
else if any(S.csletters) then tab(many(S.csletters))
else move(1)
"{" : { current_arg ||:= "{" ; brace_depth +:= 1 }
"}" : { brace_depth -:= 1
if brace_depth > 0 then
current_arg ||:= "}"
else {
put(args_seen, current_arg)
current_arg := ""
}
}
}
}
}
# write(&errout, "seen ", *args_seen, " want ", macro.arg_count,
# " current ", image(current_arg), " braces ", brace_depth)
if *args_seen = macro.arg_count then {
# write(&errout, "Arguments for macro ", macro.name, ":")
# every write(&errout, "\t", image(!args_seen))
expand_macro(S, macro, args_seen)
undelay_newtext(S)
} else
before_next_newtext(S, do_macro, [S, macro, args_seen, current_arg, brace_depth])
return
end
@
<<*>>=
procedure Cmacro(S, cs, cl)
# pushtrace("MACRO")
delay_newtext(S)
# apply_args(S, closure(expand_macro, [cl]), cl.arg_count)
do_macro(S, cl, [], "", 0)
return
end
@
Now, a {\TeX}-like macro facility in which [[#]] is used for converted
parameters and [[#$]] for raw ones.
<<*>>=
procedure macro(name, arg_count, body, mode)
m := macro_defn(name, arg_count, parse_body(body), mode)
cstab[name] := Cmacro
csclosure[name] := m
return
end
procedure begin_macro(env, arg_count, body, mode)
m := macro_defn(env, arg_count, parse_body(body), mode)
begintab[env] := Cmacro
begincl[env] := m
return
end
procedure parse_body(body)
b := []
body ? {
put(b, tab(upto('#') | 0))
while ="#" do {
put(b, ="#" | (="$", raw_arg(argnum())) | converted_arg(argnum())) |
error("malformed macro arg #", tab(0))
put(b, tab(upto('#') | 0))
}
}
return b
end
procedure argnum()
if any(&digits) then return integer(move(1)) else fail
end
@
And the dynamic version\ldots
<<*>>=
procedure l2h_macro(name, count, body[])
count := integer(count) |
return error("must give # of arguments to l2h macro ", name)
s := ""
every s ||:= " " || (1(b := !body, type(b) == "string"))
s := s[2:0] # strip leading space if any
return macro(name, count, s)
end
@
<<*>>=
procedure l2h_environment(env, count, body[])
count := integer(count) |
return error("must give # of arguments to l2h environment ", env)
s := ""
every s ||:= " " || (1(b := !body, type(b) == "string"))
s := s[2:0] # strip leading space if any
return begin_macro(env, count, s)
end
@
\subsection{Table environments}
For tables, we not only have an HTML tag, we also supply some text
for the ampersand.
[[args]] is a template describing the arguments to the environment,
which are ignored.
<<*>>=
record table_closure(args, amp, open, close)
procedure table_env(env, args, amp, open, close)
begintab[env] := Ctable
begincl[env] := table_closure(args, amp,
if /close then tag(\open) | &null else open,
if /close then endtag(\open) | &null else close)
endtab[env] := Ctable_end
endcl[env] := []
end
<<*>>=
procedure Ctable(S, env, cl)
local amp
## amp := S.ampersand
## S.ampersand := cl.amp
S.text(S, \cl.open)
push(endcl[env], amp)
cs_ignore(S, env, cl.args)
end
procedure Ctable_end(S, env, cl)
# S.ampersand := pop(cl)
S.text(S, \begincl[env].close)
end
@
\subsection{Postscript}
<<*>>=
procedure Cepsfig(S, cs, cl)
apply_args(S, do_epsfig, [S], 1)
end
procedure do_epsfig(S, arg)
local args
args := []
arg ?
while not pos(0) do {
tab(many(' \t\n'))
put(args, eqsplit(tab(upto(',') | 0)))
}
if a := !args & a.name == ("file"|"figure") then
emit_text(S, "[PostScript figure " ||
a.value || "]")
else
emit_text(S, "[Ill-understood PostScript figure]")
end
record apair(name, value)
procedure eqsplit(s)
p := apair()
s ? (p.name := tab(upto('=')), ="=", p.value := tab(0))
return p
end
@
<<*>>=
procedure Cincludegraphics(S, cs, cl)
local saved_ignore
saved_ignore := S.ignoring
S.ignoring := 1
do_ignore(S, "[", saved_ignore, apply_args, [S, do_includegraphics, [S], 1])
end
procedure do_includegraphics(S, arg)
local base, ext
if arg ? (base := tab(find(ext := ".ps" | ".eps" | ".epsi")), =ext, pos(0)) then
emit_text(S, "[PostScript figure " ||
arg || "]")
else if arg ? (base := tab(find(ext := ".png" | ".gif" | ".jpg")), =ext, pos(0)) then
emit_text(S, " || )
")
else
emit_text(S, "[Ill-understood graphics]")
end
@
\subsection{Control-sequence assignment}
This procedure is available to be used for dynamic assignment.
One day we might use it to parse \verb+\let+ as well.
<<*>>=
procedure let(lhs, rhs)
cstab[lhs] := cstab[rhs]
csclosure[lhs] := csclosure[rhs]
end
procedure let_closure(lhs, cl[])
csclosure[lhs] := if *cl = 1 then cl[1] else cl
end
procedure letenv(lhs, rhs)
begintab[lhs] := begintab[rhs]
endtab[lhs] := endtab[rhs]
begincl[lhs] := begincl[rhs]
endcl[lhs] := endcl[rhs]
end
@
\section{HTML formatting}
\label{html-format}
First, generic procedures used to create beginning and ending tags.
<<*>>=
procedure tag(html)
return "<" || html || ">"
end
procedure endtag(html)
return ""
end
@
Next, a gazillion formatting procedures.
<<*>>=
procedure Ccomment(S)
if *S.comment > 0 then {
S.text(S, "")
}
S.comment := ""
return
end
<<*>>=
procedure Cparagraph(S)
S.text(S, "")
end
<<*>>=
procedure Cmath(S)
<>
S.text(S, "")
end
procedure Cmath_end(S)
S.text(S, "")
<>
end
<<*>>=
procedure Cdisplaymath(S)
<>
S.text(S, "")
end
procedure Cdisplaymath_end(S)
S.text(S, "
")
<>
end
<<*>>=
procedure Cmakeatletter(S)
S.csletters ++:= '@'
end
procedure Cmakeatother(S)
S.csletters --:= '@'
end
@
Approximate \verb+\kill+ by eliminating text.
<<*>>=
procedure Ckill(S, cs, cl)
S.the_text := ""
end
@
\section{Support for adding control sequences dynamically}
The idea is to use formal comments of the form:
\begin{quote}
\verb+% l2h function arg arg ...+
\end{quote}
These comments have the same effect as the procedure calls in
the chunk [[<>]].
@
Our first step is to create a table with the names of the functions we
recognize.
Ordinarly this table would be distributed, but I created it after the
fact with a little quick Unix pipeline.
<<*>>=
global csfunctions
<>=
csfunctions := table()
<>=
csfunctions["argblock"] := argblock
csfunctions["argblockv"] := argblockv
csfunctions["envblock"] := envblock
csfunctions["fontchange"] := fontchange
csfunctions["ignore"] := ignore
csfunctions["ignoreenv"] := ignoreenv
csfunctions["let"] := let
csfunctions["letenv"] := letenv
csfunctions["listenv"] := listenv
csfunctions["substitution"] := substitution
csfunctions["activesubst"] := activesubst
csfunctions["closure"] := let_closure
csfunctions["let_closure"] := let_closure
csfunctions["newcommand"] := l2h_macro
csfunctions["macro"] := l2h_macro
csfunctions["environment"] := l2h_environment
csfunctions["tabular"] := tabular
@
Now, the tough issue is how to parse arguments. I'm going to try the
following initial strategy: arguments are separated by spaces.
To put a space within an argument, use \verb+#+. There is no way to
put a \verb+#+ within an argument.
<<*>>=
global dynamic_add_hack
procedure parse_dynamic_add(S)
if (optwhite(), =("l2h"|"sl2h"), skipwhite(),
p := tab(upto(' \t')), <>,
skipwhite(), any(~'\n')) then {
a := []
while (any(~'\n'), l := tab(upto(' \t\n') | 0)) do {
put(a, if p === (l2h_macro|l2h_environment) then l else map(l, "#", " "))
skipwhite()
}
dynamic_add_hack := S
p!a
dynamic_add_hack := &null
return
}
end
<>=
((p := \csfunctions[p]) |
{ dynamic_warn(p); fail })
<<*>>=
procedure dynamic_warn(p)
static badprocs
initial badprocs := set()
if not member(badprocs, p) then {
write(&errout, "Warning: % l2h ", p, " not recognized -- ignored")
insert(badprocs, p)
}
end
@
\section{Miscellanous utilities}
[[optwhite]] skips and returns optional white space.
<<*>>=
procedure optwhite()
suspend tab(many(' \t')) | ""
end
@ [[skipwhite]] insists that there must be some white space.
<<*>>=
procedure skipwhite()
suspend tab(many(' \t'))
end
@
\section{Main program for a noweb filter}
First, this is how we use the converter as a noweb filter.
<>=
<<*>>
procedure main(args)
local line
errstatus := 0
every arg := !args do
case arg of {
"-show-unknowns" : show_unknowns := 1
"-html-quotes" : html_quotes := 1
default : fatal("unknown arg ", image(arg))
}
while line := read() do
apply(filter, line)
warn_unknown(\unknown_set, "control sequences", "\\")
warn_unknown(\unknown_envs, "environments", "{", "}")
if errstatus > 0 then
write("@fatal l2h Error occurred in l2h conversion")
exit(errstatus)
end
procedure apply(pass, line)
line ? (="@" & pass(tab(upto(' ')|0), if =" " then tab(0) else &null))
end
@
This is noweb filter machinery. I really ought to coordinate quoted text
with the converter (so it always shows up in the right place),
but so far I'm too lazy.
<>=
global curfile, curline
procedure filter(name, arg)
static S, code
initial S := converter("V")
### write(" mode ", S.mode)
case name of {
"begin" : {<>; if match("code ", arg) then code := 1}
"end" : {if match("docs ", arg) then <>
<>; code := &null; S.mode := "V"}
"quote" : { outtext("\0" ? convert(S)) }
"endquote" : { outtext("\1" ? convert(S)) }
"file" : {<>; curfile := arg; curline := 1}
"line" : {<>; curline := integer(arg)}
"defn" : { write("@", name, " ", convert_use_or_def(arg)) }
"use" : { write("@", name, " ", convert_use_or_def(arg)) }
"text" : {if \code then <> else outtext(arg ? convert(S)) }
"nl" : {if \code then <> else outtext("\n" ? convert(S)); curline +:= 1}
"fatal" : {<>; exit(1)}
default : {<>}
}
return
end
<>=
if S.mode ~== "V" then write("@text ")
@ A special function is needed to implement {\tt noweb}'s quoting
convention within chunk names.
<>=
procedure convert_use_or_def(s)
r := ""
s ? {
while r ||:= quickconv(tab(find("[["))) do {
(r ||:= ="[[") | fatal("impossible missing [[")
(r ||:= tab(find("]]")) || tab(many(']'))) |
fatal("impossible missing ]] in ", image(s))
}
return r || quickconv(tab(0))
}
end
procedure quickconv(s)
static C
initial C := converter("H")
return 1(("{" || s || "}" ? convert(C)), reset(C))
end
<>=
write("@", name, (" " || \arg) | "")
<>=
procedure outtext(s)
s ?
while not pos(0) do
if ="\n" then write("@nl")
else if ="\0" then write("@quote")
else if ="\1" then write("@endquote")
else write("@text ", tab(upto('\n\0\1') | 0))
return
end
<<*>>=
global errstatus
procedure error(args[])
errstatus := 1
return write!([&errout, (\curfile || ":") | "line ", curline, ": "] ||| args)
end
@
\section{Main program for a simple converter}
<>=
<<*>>
global curfile, curline
procedure convert_file(f)
static S
initial S := converter("V")
curline := 0
while line := read(f) do {
curline +:= 1
writes(convert(S, line || "\n"))
}
return
end
procedure main(args)
local warn
warn := 1
errstatus := 0
every arg := !args do
if arg[1] == "-" then
case arg of {
"-show-unknowns" : show_unknowns := 1
"-nowarn" : warn := &null
"-html-quotes" : html_quotes := 1
"-" : { curfile := arg; convert_file(&input) }
default : write(&errout, "Warning: unrecognized option ", arg)
}
else if f := open(curfile <- arg) then
convert_file(f)
else
write(&errout, "Error: Can't open file ", arg)
if /curfile then
convert_file(&input)
if \warn then {
warn_unknown(\unknown_set, "control sequences", "\\")
warn_unknown(\unknown_envs, "environments", "{", "}")
}
exit(errstatus)
end
@
<<*>>=
procedure fatal(L[])
write!(["@fatal l2h "] ||| L)
write!([&errout, "noweb error in l2h: "] ||| L)
exit(1)
end
@
<<*>>=
procedure rcsinfo ()
return "$Id: l2h.nw,v 1.24 2008/10/06 01:03:05 nr Exp nr $" ||
"$Name: v2_12 $"
end
@
\section{Chunks}
\nowebchunks
\begin{multicols}{2}[\section{Index}]
\nowebindex
\end{multicols}
@
\end{document}