'\"
'\" Generated from file 'page_pluginmgr\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2007 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>
'\"
.TH "page_pluginmgr" n 1\&.0 tcllib "Parser generator tools"
.\" The -*- nroff -*- definitions below are for supplemental macros used
.\" in Tcl/Tk manual entries.
.\"
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.\"	omitted, defaults to "options". The options follow on successive
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.if t .wh -1.3i ^B
.nr ^l \n(.l
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.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
.\}
.el \{\
.br
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\&\\$1	\\fI\\$2\\fP
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\&\\fI\\$1\\fP
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..
.AS Tcl_Interp Tcl_CreateInterp in/out
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.mk ^y
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.if n \l'\\n(.lu\(ul'
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.ie n \l'\\n(^lu\(ul'
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.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
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.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
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.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
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.RE
.sp
..
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.de SO
'ie '\\$1'' .ds So \\fBoptions\\fR
'el .ds So \\fB\\$1\\fR
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
.\"	# SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\*(So manual entry for details on the standard options.
..
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.de OP
.LP
.nf
.ta 4c
Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
.IP
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..
.BS
.SH NAME
page_pluginmgr \- page plugin manager
.SH SYNOPSIS
package require \fBpage::pluginmgr ?0\&.3?\fR
.sp
package require \fBfileutil\fR
.sp
\fB::page::pluginmgr::reportvia\fR \fIcmd\fR
.sp
\fB::page::pluginmgr::report\fR \fIlevel\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fB::page::pluginmgr::log\fR \fIcmd\fR
.sp
\fB::page::pluginmgr::configuration\fR \fIname\fR
.sp
\fB::page::pluginmgr::reader\fR \fIname\fR
.sp
\fB::page::pluginmgr::rconfigure\fR \fIdict\fR
.sp
\fB::page::pluginmgr::rtimeable\fR
.sp
\fB::page::pluginmgr::rtime\fR
.sp
\fB::page::pluginmgr::rgettime\fR
.sp
\fB::page::pluginmgr::rhelp\fR
.sp
\fB::page::pluginmgr::rlabel\fR
.sp
\fB::page::pluginmgr::read\fR \fIread\fR \fIeof\fR ?\fIcomplete\fR?
.sp
\fIread\fR \fInum\fR
.sp
\fIeof\fR
.sp
\fIdone\fR
.sp
\fB::page::pluginmgr::writer\fR \fIname\fR
.sp
\fB::page::pluginmgr::wconfigure\fR \fIdict\fR
.sp
\fB::page::pluginmgr::wtimeable\fR
.sp
\fB::page::pluginmgr::wtime\fR
.sp
\fB::page::pluginmgr::wgettime\fR
.sp
\fB::page::pluginmgr::whelp\fR
.sp
\fB::page::pluginmgr::wlabel\fR
.sp
\fB::page::pluginmgr::write\fR \fIchan\fR \fIdata\fR
.sp
\fB::page::pluginmgr::transform\fR \fIname\fR
.sp
\fB::page::pluginmgr::tconfigure\fR \fIid\fR \fIdict\fR
.sp
\fB::page::pluginmgr::ttimeable\fR \fIid\fR
.sp
\fB::page::pluginmgr::ttime\fR \fIid\fR
.sp
\fB::page::pluginmgr::tgettime\fR \fIid\fR
.sp
\fB::page::pluginmgr::thelp\fR \fIid\fR
.sp
\fB::page::pluginmgr::tlabel\fR \fIid\fR
.sp
\fB::page::pluginmgr::transform_do\fR \fIid\fR \fIdata\fR
.sp
\fBpage_cdefinition\fR
.sp
\fBpage_rfeature\fR \fIname\fR
.sp
\fBpage_rtime\fR
.sp
\fBpage_rgettime\fR
.sp
\fBpage_rlabel\fR
.sp
\fBpage_rhelp\fR
.sp
\fBpage_roptions\fR
.sp
\fBpage_rconfigure\fR \fIoption\fR \fIvalue\fR
.sp
\fBpage_rrun\fR
.sp
\fBpage_read\fR \fInum\fR
.sp
\fBpage_read_done\fR
.sp
\fBpage_eof\fR
.sp
\fBpage_info\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_warning\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_error\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_log_info\fR \fItext\fR
.sp
\fBpage_log_warning\fR \fItext\fR
.sp
\fBpage_log_error\fR \fItext\fR
.sp
\fBpage_wfeature\fR
.sp
\fBpage_wtime\fR
.sp
\fBpage_wgettime\fR
.sp
\fBpage_wlabel\fR
.sp
\fBpage_whelp\fR
.sp
\fBpage_woptions\fR
.sp
\fBpage_wconfigure\fR \fIoption\fR \fIvalue\fR
.sp
\fBpage_wrun\fR \fIchan\fR \fIdata\fR
.sp
\fBpage_info\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_warning\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_error\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_log_info\fR \fItext\fR
.sp
\fBpage_log_warning\fR \fItext\fR
.sp
\fBpage_log_error\fR \fItext\fR
.sp
\fBpage_tfeature\fR
.sp
\fBpage_ttime\fR
.sp
\fBpage_tgettime\fR
.sp
\fBpage_tlabel\fR
.sp
\fBpage_thelp\fR
.sp
\fBpage_toptions\fR
.sp
\fBpage_tconfigure\fR \fIoption\fR \fIvalue\fR
.sp
\fBpage_trun\fR \fIchan\fR \fIdata\fR
.sp
\fBpage_info\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_warning\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_error\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
.sp
\fBpage_log_info\fR \fItext\fR
.sp
\fBpage_log_warning\fR \fItext\fR
.sp
\fBpage_log_error\fR \fItext\fR
.sp
.BE
.SH DESCRIPTION
.PP
This package provides the plugin manager central to the \fBpage\fR
application\&. It manages the various reader, writer, configuration, and
transformation plugins which actually process the text (read,
transform, and write)\&.
.PP
All plugins are loaded into slave interpreters specially prepared for
them\&. While implemented using packages they need this special
environment and are not usable in a plain interpreter, like
tclsh\&. Because of that they are only described in general terms in
section \fBPREDEFINED PLUGINS\fR, and not documented as regular
packages\&. It is expected that they follow the APIs specified in the
sections
.IP [1]
\fBCONFIG PLUGIN API\fR
.IP [2]
\fBREADER PLUGIN API\fR
.IP [3]
\fBWRITER PLUGIN API\fR
.IP [4]
\fBTRANSFORM PLUGIN API\fR
.PP
as per their type\&.
.SH API
.TP
\fB::page::pluginmgr::reportvia\fR \fIcmd\fR
This command defines the callback command used by
\fB::page::pluginmgr::report\fR (see below) to report input errors and
warnings\&. The default is to write such reports to the standard error
channel\&.
.TP
\fB::page::pluginmgr::report\fR \fIlevel\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
This command is used to report input errors and warnings\&. By default
such reports are written to the standard error\&. This can be changed by
setting a user-specific callback command with
\fB::page::pluginmgr::reportvia\fR (see above)\&.
.sp
The arguments \fIlevel\fR and \fItext\fR specify both the importance
of the message, and the message itself\&. For the former see the package
\fBlogger\fR for the allowed values\&.
.sp
The optional argument \fIfrom\fR and \fIto\fR can be used by the
caller to indicate the location (or range) in the input where the
reported problem occured\&. Each is a list containing two elements, the
line and the column in the input, in this order\&.
.TP
\fB::page::pluginmgr::log\fR \fIcmd\fR
This command defines a log callback command to be used by loaded
plugins for the reporting of internal errors, warnings, and general
information\&. Specifying the empty string as callback disables logging\&.
.sp
Note: The \fIcmd\fR has to be created by the \fBlogger\fR package,
or follow the same API as such\&.
.sp
The command returns the empty string as its result\&.
.TP
\fB::page::pluginmgr::configuration\fR \fIname\fR
This command loads the named configuration plugin, retrieves the
options encoded in it, and then immediately unloads it again\&.
.sp
If the \fIname\fR is the path to a file, then this files will be tried
to be loaded as a plugin first, and, if that fails, opened and its
contents read as a list of options and their arguments, separated by
spaces, tabs and newlines, possibly quotes with single and double
quotes\&.
.sp
See section \fBCONFIG PLUGIN API\fR for the API expected of
configuration plugins\&.
.sp
The result of the command is the list of options retrieved\&.
.TP
\fB::page::pluginmgr::reader\fR \fIname\fR
This command loads the named reader plugin and initializes it\&. The
result of the command is a list of options the plugin understands\&.
.sp
Only a single reader plugin can be loaded\&. Loading another reader
plugin causes the previously loaded reader plugin to be de-initialized
and unloaded\&.
.sp
See section \fBREADER PLUGIN API\fR for the API expected of
reader plugins\&.
.TP
\fB::page::pluginmgr::rconfigure\fR \fIdict\fR
This commands configures the loaded reader plugin\&. The options and
their values are provided as a Tcl dictionary\&. The result of the
command is the empty string\&.
.TP
\fB::page::pluginmgr::rtimeable\fR
This commands checks if the loaded reader plugin is able to collect
timing statistics\&. The result of the command is a boolean flag\&. The
result is \fBtrue\fR if the plugin can be timed, and \fBfalse\fR
otherwise\&.
.TP
\fB::page::pluginmgr::rtime\fR
This command activates the collection of timing statistics in the
loaded reader plugin\&.
.TP
\fB::page::pluginmgr::rgettime\fR
This command retrieves the collected timing statistics of the loaded
reader plugin after it was executed\&.
.TP
\fB::page::pluginmgr::rhelp\fR
This command retrieves the help string of the loaded reader
plugin\&. This is expected to be in \fIdoctools\fR format\&.
.TP
\fB::page::pluginmgr::rlabel\fR
This command retrieves the human-readable name of the loaded reader
plugin\&.
.TP
\fB::page::pluginmgr::read\fR \fIread\fR \fIeof\fR ?\fIcomplete\fR?
This command invokes the loaded reader plugin to process the input,
and returns the results of the plugin as its own result\&. The input is
accessible through the callback commands \fIread\fR, and \fIeof\fR\&. The
optional \fIdone\fR can be used to intrecept when the plugin has
completed its processing\&. All arguments are command prefixes\&.
.sp
The plugin will invoke the various callbacks in the following
situations:
.RS
.TP
\fIread\fR \fInum\fR
is invoked whenever input to process is needed, with the number of
characters/bytes it asks for\&. The result is expected to be the input
the plugin is in need of\&.
.TP
\fIeof\fR
is invoked by the plugin to check if the input has reached the of the
stream\&. The result is expected to be a boolean flag, \fBtrue\fR when
the input has hit EOF, and \fBfalse\fR otherwise\&.
.TP
\fIdone\fR
is invoked when the plugin has completed the processing of the input\&.
.RE
.TP
\fB::page::pluginmgr::writer\fR \fIname\fR
This command loads the named writer plugin and initializes it\&. The
result of the command is a list of options the plugin understands\&.
.sp
Only a single reader plugin can be loaded\&. Loading another reader
plugin causes the previously loaded reader plugin to be de-initialized
and unloaded\&.
.sp
See section \fBWRITER PLUGIN API\fR for the API expected of
writer plugins\&.
.TP
\fB::page::pluginmgr::wconfigure\fR \fIdict\fR
This commands configures the loaded writer plugin\&. The options and
their values are provided as a Tcl dictionary\&. The result of the
command is the empty string\&.
.TP
\fB::page::pluginmgr::wtimeable\fR
This commands checks if the loaded writer plugin is able to measure
execution times\&. The result of the command is a boolean flag\&. The
result is \fBtrue\fR if the plugin can be timed, and \fBfalse\fR
otherwise\&.
.TP
\fB::page::pluginmgr::wtime\fR
This command activates the collection of timing statistics in the
loaded writer plugin\&.
.TP
\fB::page::pluginmgr::wgettime\fR
This command retrieves the collected timing statistics of the loaded
writer plugin after it was executed\&.
.TP
\fB::page::pluginmgr::whelp\fR
This command retrieves the help string of the loaded writer
plugin\&. This is expected to be in \fIdoctools\fR format\&.
.TP
\fB::page::pluginmgr::wlabel\fR
This command retrieves the human-readable name of the loaded writer
plugin\&.
.TP
\fB::page::pluginmgr::write\fR \fIchan\fR \fIdata\fR
The loaded writer plugin is invoked to generate the output\&. It is
given the \fIdata\fR to generate the outpout from, and the Tcl handle
\fIchan\fR of the channel to write the generated output to\&. The
command returns th empty string as its result\&.
.TP
\fB::page::pluginmgr::transform\fR \fIname\fR
This command loads the named transformation plugin and initializes
it\&. The result of the command is a 2-element list containing the
plugin id and a list of options the plugin understands, in this order\&.
.sp
Multiple transformations plugins can be loaded and are identified by
handles\&.
.sp
See section \fBTRANSFORM PLUGIN API\fR for the API expected of
transformation plugins\&.
.TP
\fB::page::pluginmgr::tconfigure\fR \fIid\fR \fIdict\fR
This commands configures the identified transformation plugin\&. The
options and their values are provided as a Tcl dictionary\&. The result
of the command is the empty string\&.
.TP
\fB::page::pluginmgr::ttimeable\fR \fIid\fR
This commands checks if the identified transformation plugin is able
to collect timing statistics\&. The result of the command is a boolean
flag\&. The result is \fBtrue\fR if the plugin can be timed, and
\fBfalse\fR otherwise\&.
.TP
\fB::page::pluginmgr::ttime\fR \fIid\fR
This command activates the collection of timing statistics in the
identified transformation plugin\&.
.TP
\fB::page::pluginmgr::tgettime\fR \fIid\fR
This command retrieves the collected timing statistics of the
identified transformation plugin after it was executed\&.
.TP
\fB::page::pluginmgr::thelp\fR \fIid\fR
This command retrieves the help string of the identified
transformation plugin\&. This is expected to be in \fIdoctools\fR
format\&.
.TP
\fB::page::pluginmgr::tlabel\fR \fIid\fR
This command retrieves the human-readable name of the identified
transformation plugin\&.
.TP
\fB::page::pluginmgr::transform_do\fR \fIid\fR \fIdata\fR
The identified transformation plugin is invoked to process the
specified \fIdata\fR\&. The result of the plugin is returned as the
result of the command\&.
.PP
.SH "CONFIG PLUGIN API"
Configuration plugins are expected to provide a single command,
described below\&.
.PP
.TP
\fBpage_cdefinition\fR
This command of a configuration plugin is called by the plugin manager
to execute it\&. Its result has to be a list of options and values to
process\&.
.PP
.PP
Configuration plugins do not expect the environment to provide any
special commands\&.
.PP
It is expected that a configuration plugin \fBFOO\fR is implemented
by the package \fBpage::config::\fBFOO\fR\fR\&.
.PP
Configuration plugins are loaded, executed, and unloaded in one step,
they are not kept in memory\&. The command for doing this is
\fB::page::pluginmgr::configuration\fR\&.
.SH "READER PLUGIN API"
Reader plugins are expected to provide the following commands,
described below\&.
.PP
.TP
\fBpage_rfeature\fR \fIname\fR
This command takes a feature \fIname\fR and returns a boolean flag
indicating whether the feature is supported by the plugin, or not\&.
The result has to be \fBtrue\fR if the feature is supported, and
\fBfalse\fR otherwise\&.
.sp
See section \fBFEATURES\fR for the possible features the plugin
manager will ask for\&.
.TP
\fBpage_rtime\fR
This command is invoked to activate the collection of timing
statistics\&.
.TP
\fBpage_rgettime\fR
This command is invoked to retrieve the collected timing statistics\&.
.TP
\fBpage_rlabel\fR
This command is invoked to retrieve a human-readable label for the
plugin\&.
.TP
\fBpage_rhelp\fR
This command is invoked to retrieve a help text for plugin\&. The text
is expected to be in \fIdoctools\fR format\&.
.TP
\fBpage_roptions\fR
This command is invoked to retrieve the options understood by the
plugin\&.
.TP
\fBpage_rconfigure\fR \fIoption\fR \fIvalue\fR
This command is invoked to reconfigure the plugin, specifically the
given \fIoption\fR is set to the new \fIvalue\fR\&.
.TP
\fBpage_rrun\fR
This command is invoked to process the input stream per the current
plugin configuration\&.  The result of the command is the result of the
processing\&.
.PP
.PP
Reader plugins expect the environment to provide the following special
commands\&.
.TP
\fBpage_read\fR \fInum\fR
This command is invoked to read \fInum\fR characters/bytes from the
input\&. Its result has to be read characters/bytes\&.
.TP
\fBpage_read_done\fR
This command is invoked to signal that the plugin has completed the
processing of the input\&.
.TP
\fBpage_eof\fR
This command is invoked to check if the input stream has reached its
end\&. Its result has to be a boolean flag, \fBtrue\fR when the input
has reached the end, \fBfalse\fR otherwise\&.
.TP
\fBpage_info\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report some information to the user\&. May indicate a
location or range in the input\&. Each piece of location data, if
provided, is a 2-element list containing line and column numbers\&.
.TP
\fBpage_warning\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report a warning to the user\&. May indicate a location or
range in the input\&. Each piece of location data, if provided, is a
2-element list containing line and column numbers\&.
.TP
\fBpage_error\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report an error to the user\&. May indicate a location or
range in the input\&. Each piece of location data, if provided, is a
2-element list containing line and column numbers\&.
.TP
\fBpage_log_info\fR \fItext\fR
Invoked to report some internal information\&.
.TP
\fBpage_log_warning\fR \fItext\fR
Invoked to report an internal warning\&.
.TP
\fBpage_log_error\fR \fItext\fR
Invoked to report an internal error\&.
.PP
.PP
It is expected that a reader plugin \fBFOO\fR is implemented
by the package \fBpage::reader::\fBFOO\fR\fR\&.
.PP
Reader plugins are loaded by the command
\fB::page::pluginmgr::reader\fR\&. At most one reader plugin can be kept
in memory\&.
.SH "WRITER PLUGIN API"
Writer plugins are expected to provide the following commands,
described below\&.
.PP
.TP
\fBpage_wfeature\fR
This command takes a feature \fIname\fR and returns a boolean flag
indicating whether the feature is supported by the plugin, or not\&.
The result has to be \fBtrue\fR if the feature is supported, and
\fBfalse\fR otherwise\&.
.sp
See section \fBFEATURES\fR for the possible features the plugin
manager will ask for\&.
.TP
\fBpage_wtime\fR
This command is invoked to activate the collection of timing
statistics\&.
.TP
\fBpage_wgettime\fR
This command is invoked to retrieve the collected timing statistics\&.
.TP
\fBpage_wlabel\fR
This command is invoked to retrieve a human-readable label for the
plugin\&.
.TP
\fBpage_whelp\fR
This command is invoked to retrieve a help text for plugin\&. The text
is expected to be in \fIdoctools\fR format\&.
.TP
\fBpage_woptions\fR
This command is invoked to retrieve the options understood by the
plugin\&.
.TP
\fBpage_wconfigure\fR \fIoption\fR \fIvalue\fR
This command is invoked to reconfigure the plugin, specifically the
given \fIoption\fR is set to the new \fIvalue\fR\&.
.TP
\fBpage_wrun\fR \fIchan\fR \fIdata\fR
This command is invoked to process the specified \fIdata\fR and write
it to the output stream \fIchan\fR\&. The latter is a Tcl channel handle
opened for writing\&. The result of the command is the empty string\&.
.PP
.PP
Writer plugins expect the environment to provide the following special
commands\&.
.TP
\fBpage_info\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report some information to the user\&. May indicate a
location or range in the input\&. Each piece of location data, if
provided, is a 2-element list containing line and column numbers\&.
.TP
\fBpage_warning\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report a warning to the user\&. May indicate a location or
range in the input\&. Each piece of location data, if provided, is a
2-element list containing line and column numbers\&.
.TP
\fBpage_error\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report an error to the user\&. May indicate a location or
range in the input\&. Each piece of location data, if provided, is a
2-element list containing line and column numbers\&.
.TP
\fBpage_log_info\fR \fItext\fR
Invoked to report some internal information\&.
.TP
\fBpage_log_warning\fR \fItext\fR
Invoked to report an internal warning\&.
.TP
\fBpage_log_error\fR \fItext\fR
Invoked to report an internal error\&.
.PP
.PP
It is expected that a writer plugin \fBFOO\fR is implemented
by the package \fBpage::writer::\fBFOO\fR\fR\&.
.PP
Writer plugins are loaded by the command
\fB::page::pluginmgr::writer\fR\&. At most one writer plugin can be kept
in memory\&.
.SH "TRANSFORM PLUGIN API" page::transform::*
Transformation plugins are expected to provide the following commands,
described below\&.
.PP
.TP
\fBpage_tfeature\fR
This command takes a feature \fIname\fR and returns a boolean flag
indicating whether the feature is supported by the plugin, or not\&.
The result has to be \fBtrue\fR if the feature is supported, and
\fBfalse\fR otherwise\&.
.sp
See section \fBFEATURES\fR for the possible features the plugin
manager will ask for\&.
.TP
\fBpage_ttime\fR
This command is invoked to activate the collection of timing
statistics\&.
.TP
\fBpage_tgettime\fR
This command is invoked to retrieve the collected timing statistics\&.
.TP
\fBpage_tlabel\fR
This command is invoked to retrieve a human-readable label for the
plugin\&.
.TP
\fBpage_thelp\fR
This command is invoked to retrieve a help text for plugin\&. The text
is expected to be in \fIdoctools\fR format\&.
.TP
\fBpage_toptions\fR
This command is invoked to retrieve the options understood by the
plugin\&.
.TP
\fBpage_tconfigure\fR \fIoption\fR \fIvalue\fR
This command is invoked to reconfigure the plugin, specifically the
given \fIoption\fR is set to the new \fIvalue\fR\&.
.TP
\fBpage_trun\fR \fIchan\fR \fIdata\fR
This command is invoked to process the specified \fIdata\fR and write
it to the output stream \fIchan\fR\&. The latter is a Tcl channel handle
opened for writing\&. The result of the command is the empty string\&.
.PP
.PP
Transformation plugins expect the environment to provide the following
special commands\&.
.TP
\fBpage_info\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report some information to the user\&. May indicate a
location or range in the input\&. Each piece of location data, if
provided, is a 2-element list containing line and column numbers\&.
.TP
\fBpage_warning\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report a warning to the user\&. May indicate a location or
range in the input\&. Each piece of location data, if provided, is a
2-element list containing line and column numbers\&.
.TP
\fBpage_error\fR \fItext\fR ?\fIfrom\fR ?\fIto\fR??
Invoked to report an error to the user\&. May indicate a location or
range in the input\&. Each piece of location data, if provided, is a
2-element list containing line and column numbers\&.
.TP
\fBpage_log_info\fR \fItext\fR
Invoked to report some internal information\&.
.TP
\fBpage_log_warning\fR \fItext\fR
Invoked to report an internal warning\&.
.TP
\fBpage_log_error\fR \fItext\fR
Invoked to report an internal error\&.
.PP
.PP
It is expected that a transformation plugin \fBFOO\fR is implemented
by the package \fBpage::transform::\fBFOO\fR\fR\&.
.PP
Transformation plugins are loaded by the command
\fB::page::pluginmgr::transform\fR\&. More than one transformation
plugin can be kept in memory\&.
.SH "PREDEFINED PLUGINS"
The following predefined plugins are known, i\&.e\&. provided by the page
module\&.
.TP
Configuration
.RS
.TP
peg
Returns a set of options to configure the \fBpage\fR application
for the processing of a PEG grammar and the generation of ME code\&. See
the packages \fBgrammar_peg\fR, \fBgrammar_me\fR and relations
for more details\&.
.RE
.TP
Reader
.RS
.TP
hb
Expects a so-called \fIhalf-baked PEG container\fR as input and
returns the equivalent abstract syntax tree\&. See the writer plugin
\fIhb\fR for the plugin generating this type of input\&.
.TP
lemon
Expects a grammar specification as understood by Richar Hipp's LEMON
parser generator and returns an abstract syntax tree for it\&.
.TP
peg
Expects a grammar specification in the form of a parsing expression
grammar (PEG) and returns an abstract syntax tree for it\&.
.TP
ser
Expect the serialized form of a parsing expression grammar as
generated by the package \fBgrammar::peg\fR as input, converts it
into an equivalent abstract syntax tree and returns that\&.
.TP
treeser
Expects the serialized form of a tree as generated by the package
\fBstruct::tree\fR as input and returns it, after validation\&.
.RE
.TP
Writer
.RS
.TP
hb
Expects an abstract syntax tree for a parsing expression grammar as
input and writes it out in the form of a so-called
\fIhalf-baked PEG container\fR\&.
.TP
identity
Takes any input and writes it as is\&.
.TP
mecpu
Expects symbolic assembler code for the MatchEngine CPU (See the
package \fBgrammar::me::cpu\fR and relatives) and writes it out as
Tcl code for a parser\&.
.TP
me
Expects an abstract syntax tree for a parsing expression grammar as
input and writes it out as Tcl code for the MatchEngine (See the
package \fBgrammar::me\fR and relatives) which parses input in
that grammar\&.
.TP
null
Takes any input and writes nothing\&. The logical equivalent of
/dev/null\&.
.TP
peg
Expects an abstract syntax tree for a parsing expression grammar as
input and writes it out in the form of a canonical PEG which can be
read by the reader plugin \fIpeg\fR\&.
.TP
ser
Expects an abstract syntax tree for a parsing expression grammar as
input and writes it out as a serialized PEG container which can be
read by the reader plugin \fIser\fR\&.
.TP
tpc
Expects an abstract syntax tree for a parsing expression grammar as
input and writes it out as Tcl code initializing a PEG container as
provided by the package \fBgrammar::peg\fR\&.
.TP
tree
Takes any serialized tree (per package \fBstruct::tree\fR) as
input and writes it out in a generic indented format\&.
.RE
.TP
Transformation
.RS
.TP
mecpu
Takes an abstract syntax tree for a parsing expression grammer as
input, generates symbolic assembler code for the MatchEngine CPU, and
returns that as its result (See the package \fBgrammar::me::cpu\fR
and relatives)\&.
.TP
reachable
Takes an abstract syntax tree for a parsing expression grammer as
input, performs a reachability analysis, and returns the modified and
annotated tree\&.
.TP
realizable
Takes an abstract syntax tree for a parsing expression grammer as
input, performs an analysis of realizability, and returns the modified
and annotated tree\&.
.RE
.PP
.SH FEATURES
The plugin manager currently checks the plugins for only one feature,
\fBtimeable\fR\&. A plugin supporting this feature is assumed to be
able to collect timing statistics on request\&.
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIpage\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH KEYWORDS
page, parser generator, text processing
.SH CATEGORY
Page Parser Generator
.SH COPYRIGHT
.nf
Copyright (c) 2007 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>

.fi
