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<P><FONT SIZE="5">6 Tangle</FONT><BR>
<P>If the scanner, parser, and analyser have successfully
(i.e. with no errors, severe errors, or fatal errors)
completed, and the Tangle option (<SAMP>+O</SAMP>) is turned on
(it is by default), then the Tangle component of FunnelWeb
is invoked to generate the product files specified in the
<SAMP>@O</SAMP> macros of the input file.
<P>The operation of Tangle is very simple. Each
<SAMP>@O</SAMP> macro is expanded and written to a file of the
same name. As there are a finite number of macros, and the
analyser guarantees that the macro structure is
non-recursive, Tangle is guaranteed to terminate.
<P>Three remaining points are worth mentioning.
<P>
<UL>
<LI> Tangle expands macros using blank indentation unless
the user has specified otherwise in an indentation pragma in
the input file.
<LI> Tangle keeps track of the length of the lines that
it is writing and issues an error if any line of any product
file that it generates is longer than the maximum. The
maximum is the minimum of a value defaulted or specified in
the input file, and the value (if any) provided by the
<SAMP>+w</SAMP> command line argument.
<LI> If there is more than one macro definition of the
same name, then each such definition must have a different
library level (<SAMP>@L</SAMP>). Tangle uses the macro
definition that has the lowest library level and ignores
the others completely.
</UL>
<P><BR><FONT SIZE="4"><STRONG>Memory Use During Tangling</STRONG></FONT><BR>
<P>When FunnelWeb executes, it reads each input file (the
main input file and any include files) into memory where
they are kept for the duration of the run. This means that
there must be room in memory for all of the input files.
This approach is necessary to support FunnelWeb's
unrestricted forward referencing.
<P>In contrast, there is no requirement that there be
enough memory to hold the product files, as these are
written to disk sequentially during their expansion.
Furthermore, FunnelWeb does not expand the values of actual
parameters in memory.
<P>This means that, so long as the input files fit in
memory, your product files can be arbitrarily large. You can
also pass arbitrary large arguments to FunnelWeb macros.
<P>
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