page(n) 1.0 "Development Tools"
page - Parser Generator
TABLE OF CONTENTS
SYNOPSIS
DESCRIPTION
COMMAND LINE
OPERATION
OPTIONS
PLUGINS
PLUGIN LOCATIONS
SEE ALSO
KEYWORDS
COPYRIGHT
The application described by this document, page, is actually
not just a parser generator, as the name implies, but a generic tool
for the execution of arbitrary transformations on texts.
Its genericity comes through the use of plugins for reading,
transforming, and writing data, and the predefined set of plugins
provided by Tcllib is for the generation of memoizing recursive
descent parsers (aka packrat parsers) from grammar
specifications (Parsing Expression Grammars).
page is written on top of the package
page::pluginmgr, wrapping its functionality into a command
line based application. All the other page::* packages are
plugin and/or supporting packages for the generation of parsers. The
parsers themselves are based on the packages grammar::peg,
grammar::peg::interp, and grammar::mengine.
- page ?options...? ?input ?output??
-
This is general form for calling page. The application will
read the contents of the file input, process them under the
control of the specified options, and then write the result to
the file output.
If input is the string - the data to process will be
read from stdin instead of a file. Analogously the result will
be written to stdout instead of a file if output is the
string -. A missing output or input specification causes the
application to assume -.
The detailed specifications of the recognized options are
provided in section OPTIONS.
- path input (in)
-
This argument specifies the path to the file to be processed by the
application, or -. The last value causes the application to
read the text from stdin. Otherwise it has to exist, and be
readable. If the argument is missing - is assumed.
- path output (in)
-
This argument specifies where to write the generated text. It can be
the path to a file, or -. The last value causes the
application to write the generated documented to stdout.
If the file output does not exist then
[file dirname $output] has to exist and must be a writable
directory, as the application will create the fileto write to.
If the argument is missing - is assumed.
... reading ... transforming ... writing - plugins - pipeline ...
This section describes all the options available to the user of the
application. Options are always processed in order. I.e. of both
--help and --version are specified the option
encountered first has precedence.
Unknown options specified before any of the options -rd,
-wr, or -tr will cause processing to abort with an
error. Unknown options coming in between these options, or after the
last of them are assumed to always take a single argument and are
associated with the last plugin option coming before them. They will
be checked after all the relevant plugins, and thus the options they
understand, are known. I.e. such unknown options cause error if and
only if the plugin option they are associated with does not understand
them, and was not superceded by a plugin option coming after.
Default options are used if and only if the command line did not
contain any options at all. They will set the application up as a
PEG-based parser generator. The exact list of options is
And now the recognized options and their arguments, if they have any:
- --help
-
- -h
-
- -?
-
When one of these options is found on the command line all arguments
coming before or after are ignored. The application will print a short
description of the recognized options and exit.
- --version
-
- -V
-
When one of these options is found on the command line all arguments
coming before or after are ignored. The application will print its
own revision and exit.
- -P
-
This option signals the application to activate visual feedback while
reading the input.
- -T
-
This option signals the application to collect statistics while
reading the input and to print them after reading has completed,
before processing started.
- -D
-
This option signals the application to activate logging in the Safe
base, for the debugging of problems with plugins.
- -r parser
-
- -rd parser
-
- --reader parser
-
These options specify the plugin the application has to use for
reading the input. If the options are used multiple times the
last one will be used.
- -w generator
-
- -wr generator
-
- --writer generator
-
These options specify the plugin the application has to use for
generating and writing the final output. If the options are used
multiple times the last one will be used.
- -t process
-
- -tr process
-
- --transform process
-
These options specify a plugin to run on the input. In contrast to
readers and writers each use will not supersede previous
uses, but add each chosen plugin to a list of transformations, either
at the front, or the end, per the last seen use of either option
-p or -a. The initial default is to append the new
transformations.
- -a
-
- --append
-
These options signal the application that all following
transformations should be added at the end of the list of
transformations.
- -p
-
- --prepend
-
These options signal the application that all following
transformations should be added at the beginning of the list of
transformations.
- --reset
-
This option signals the application to clear the list of
transformations. This is necessary to wipe out the default
transformations used.
- -c file
-
- --configuration file
-
This option causes the application to load a configuration file and/or
plugin. This is a plugin which in essence provides a pre-defined set
of commandline options. They are processed exactly as if they have
been specified in place of the option and its arguments. This means
that unknown options found at the beginning of the configuration file
are associated with the last plugin, even if that plugin was specified
before the configuration file itself. Conversely, unknown options
coming after the configuration file can be associated with a plugin
specified in the file.
If the argument is a file which cannot be loaded as a plugin the
application will assume that its contents are a list of options and
their arguments, separated by space, tabs, and newlines. Options and
argumentes containing spaces can be quoted via double-quotes (") and
quotes ('). The quote character can be specified within in a quoted
string by doubling it. Newlines in a quoted string are accepted as is.
page makes use of four different types of plugins, namely:
readers, writers, transformations, and configurations. Here we provide
only a basic introduction on how to use them from page. The
exact APIs provided to and expected from the plugins can be found in
the documentation for page::pluginmgr, for those who wish to
write their own plugins.
Plugins are specified as arguments to the options -r,
-w, -t, -c, and their equivalent longer
forms. See the section OPTIONS for reference.
Each such argument will be first treated as the name of a file and
this file is loaded as the plugin. If however there is no file with
that name, then it will be translated into the name of a package, and
this package is then loaded. For each type of plugins the package
management searches not only the regular paths, but a set application-
and type-specific paths as well. Please see the section
PLUGIN LOCATIONS for a listing of all paths and their
sources.
- -c name
-
Configurations. The name of the package for the plugin name is
"page::config::name".
We have one predefined plugin:
- peg
-
It sets the application up as a parser generator accepting parsing
expression grammars and writing a packrat parser in Tcl. The actual
arguments it specifies are:
|
--reset
--append
--reader peg
--transform reach
--transform use
--writer me
|
- -r name
-
Readers. The name of the package for the plugin name is
"page::reader::name".
We have five predefined plugins:
- peg
-
Interprets the input as a parsing expression grammar (PEG) and
generates a tree representation for it. Both the syntax of PEGs and
the structure of the tree representation are explained in their own
manpages.
- hb
-
Interprets the input as Tcl code as generated by the writer plugin
hb and generates its tree representation.
- ser
-
Interprets the input as the serialization of a PEG, as generated by
the writer plugin ser, using the package
grammar::peg.
- lemon
-
Interprets the input as a grammar specification as understood by
Richard Hipp's LEMON parser generator and generates a tree
representation for it. Both the input syntax and the structure of the
tree representation are explained in their own manpages.
- treeser
-
Interprets the input as the serialization of a
struct::tree. It is validated as such,
but nothing else. It is not assumed to
be the tree representation of a grammar.
- -w name
-
Writers. The name of the package for the plugin name is
"page::writer::name".
We have eight predefined plugins:
- identity
-
Simply writes the incoming data as it is, without making any
changes. This is good for inspecting the raw result of a reader or
transformation.
- null
-
Generates nothing, and ignores the incoming data structure.
- tree
-
Assumes that the incoming data structure is a struct::tree
and generates an indented textual representation of all nodes, their
parental relationships, and their attribute information.
- peg
-
Assumes that the incoming data structure is a tree representation of a
PEG or other other grammar and writes it out as a PEG. The
result is nicely formatted and partially simplified (strings as
sequences of characters). A pretty printer in essence, but can also be
used to obtain a canonical representation of the input grammar.
- tpc
-
Assumes that the incoming data structure is a tree representation of a
PEG or other other grammar and writes out Tcl code defining a
package which defines a grammar::peg object containing the
grammar when it is loaded into an interpreter.
- hb
-
This is like the writer plugin tpc, but it writes only the
statements which define stat expression and grammar rules. The code
making the result a package is left out.
- ser
-
Assumes that the incoming data structure is a tree representation of a
PEG or other other grammar, transforms it internally into a
grammar::peg object and writes out its serialization.
- me
-
Assumes that the incoming data structure is a tree representation of a
PEG or other other grammar and writes out Tcl code defining a
package which implements a memoizing recursive descent parser based on
the match engine (ME) provided by the package grammar::mengine.
- -t name
-
Transformers. The name of the package for the plugin name is
"page::transform::name".
We have two predefined plugins:
- reach
-
Assumes that the incoming data structure is a tree representation of a
PEG or other other grammar. It determines which nonterminal
symbols and rules are reachable from start-symbol/expression. All
nonterminal symbols which were not reached are removed.
- use
-
Assumes that the incoming data structure is a tree representation of a
PEG or other other grammar. It determines which nonterminal
symbols and rules are able to generate a finite sequences of
terminal symbols (in the sense for a Context Free Grammar). All
nonterminal symbols which were not deemed useful in this sense are
removed.
The application-specific paths searched by page either are,
or come from:
- The directory "~/.page/plugin"
- The environment variable PAGE_PLUGINS
- The registry entry HKEY_LOCAL_MACHINE\SOFTWARE\PAGE\PLUGINS
- The registry entry HKEY_CURRENT_USER\SOFTWARE\PAGE\PLUGINS
The type-specific paths searched by page either are, or come
from:
- The directory "~/.page/plugin/<TYPE>"
- The environment variable PAGE_<TYPE>_PLUGINS
- The registry entry HKEY_LOCAL_MACHINE\SOFTWARE\PAGE\<TYPE>\PLUGINS
- The registry entry HKEY_CURRENT_USER\SOFTWARE\PAGE\<TYPE>\PLUGINS
Where the placeholder <TYPE> is always one of the values below,
properly capitalized.
- reader
- writer
- transform
- config
The registry entries are specific to the Windows(tm) platform, all
other platforms will ignore them.
The contents of both environment variables and registry entries are
interpreted as a list of paths, with the elements separated by either
colon (Unix), or semicolon (Windows).
page::pluginmgr
parser generator, text processing
Copyright © 2005 Andreas Kupries <andreas_kupries@users.sourceforge.net>