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<title>[pre.h] Preprocessing Facility</title>
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<h1><font color="#008B8B">[pre.h] Preprocessing Facility</font></h1>
<h2><font color="#008B8B"><a href="styx.html">contents</a></font></h2><br>
<br><a href="standard.htm">#include "standard.h"</a>
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<br><pre>
This module, [pre], realises a simple text processor. It supports the
usage of macros which will be expanded during processing - by the result
of the corresponding special replacement functions.
The following rules describes the source text format:
Text :: Literal
:: "&&"
:: "&" MacroName "&"
:: "&" "IF" FlagName "&" Text
["&" "ELSE" "&" Text]
"&" "FI" "&"
:: Text Text
Literal :: Each printable ASCII-character beside "&", additionally "\n" und "\f".
MacroName :: (Literal-"&"-" "-"\n"-"\f")+ .
Beside that the reserved words "IF","ELSE","FI" are not allowed.
FlagName :: like MacroName; MacroName and FlagName must be disjunct sets.
Now the interpretation can be specified as follows:
A literal identifies itself, i.e. will be taken as is.
'&&' will be expanded to '&'.
'&MacroName&' forces the call of the corresponding evaluation function to output
the replacement text for the macro. The left border is the column with the first "&".
With the IF-THEN-ELSE-FI construction conditional generation becomes possible.
FlagName refers to the corresponding boolean evaluation function. On true the text
after '&IF FlagName& will be processed, otherwise the optional '&ELSE&'-part.
Internally the following generalisation of the grammar will be used:
Text :: Literal
:: "&&"
:: "&" MacroName "&"
:: "&" KeyWord [FlagName] "&"
:: Text Text
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<td bgcolor="#FFF8DC" align=left><pre>void <b>PRE_dfnMacro</b>(c_string MacroName, void (* Macro)())</pre>
<td bgcolor="#FFF0F5" align=left> defines macro with name 'MacroName' and meaning 'Macro' <br>
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<td bgcolor="#FFF8DC" align=left><pre>void <b>PRE_dfnFlag</b>(c_string FlagName, int (* Flag)())</pre>
<td bgcolor="#FFF0F5" align=left> defines flag with name 'FlagName' and meaning 'Flag' <br>
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<td bgcolor="#FFF8DC" align=left><pre>void <b>PRE_Process</b>(c_string environ, c_string file, c_string ext, FILE *fileout)</pre>
<td bgcolor="#FFF0F5" align=left> preprocesses module [$'environ'/'file''ext'] to file 'fileout' <br>
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<td bgcolor="#FFF8DC" align=left><pre>void <b>PRE_init</b>(void)</pre>
<td bgcolor="#FFF0F5" align=left>enter the preprocessor module
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<td bgcolor="#FFF8DC" align=left><pre>void <b>PRE_quit</b>(void)</pre>
<td bgcolor="#FFF0F5" align=left>leave the preprocessor module
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<td bgcolor="#FFF8DC" align=left><pre>int <b>PRE_tColumnNo</b>(void)</pre>
<td bgcolor="#FFF0F5" align=left>column number of current token
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