|
|
Эта страница руководства для версии 10.9 Mac OS XЕсли Вы выполняете различную версию Mac OS X, просматриваете документацию локально:
Читать страницы руководстваСтраницы руководства предназначаются как справочник для людей, уже понимающих технологию.
|
pt::peg::export(n) Parser Tools pt::peg::export(n)
____________________________________________________________________________________________________________
NAME
pt::peg::export - PEG Export
SYNOPSIS
package require Tcl 8.5
package require snit
package require configuration
package require pt::peg
package require pluginmgr
package require pt::peg::export ?1?
::pt::peg::export objectName
objectName method ?arg arg ...?
objectName destroy
objectName export serial serial ?format?
objectName export object object ?format?
objectName configuration names
objectName configuration get
objectName configuration set name ?value?
objectName configuration unset pattern...
____________________________________________________________________________________________________________
DESCRIPTION
Are you lost ? Do you have trouble understanding this document ? In that case please read the over-view overview
view provided by the Introduction to Parser Tools. This document is the entrypoint to the whole sys-tem system
tem the current package is a part of.
This package provides a manager for parsing expression grammars, with each instance handling a set of
plugins for the export of them to other formats, i.e. their conversion to, for example nroff, HTML,
etc.
It resides in the Export section of the Core Layer of Parser Tools, and is one of the three pillars
the management of parsing expression grammars resides on.
IMAGE: arch_core_export
The other two pillars are, as shown above
[1] PEG Import, and
[2] PEG Storage
For information about the data structure which is the major input to the manager objects provided by
this package see the section PEG serialization format.
The plugin system of this class is based on the package pluginmgr, and configured to look for plugins
using
[1] the environment variable GRAMMAR_PEG_EXPORT_PLUGINS,
[2] the environment variable GRAMMAR_PEG_PLUGINS,
[3] the environment variable GRAMMAR_PLUGINS,
[4] the path "~/.grammar/peg/export/plugin"
[5] the path "~/.grammar/peg/plugin"
[6] the path "~/.grammar/plugin"
[7] the path "~/.grammar/peg/export/plugins"
[8] the path "~/.grammar/peg/plugins"
[9] the path "~/.grammar/plugins"
[10] the registry entry "HKEY_CURRENT_USER\SOFTWARE\GRAMMAR\PEG\EXPORT\PLUGINS"
[11] the registry entry "HKEY_CURRENT_USER\SOFTWARE\GRAMMAR\PEG\PLUGINS"
[12] the registry entry "HKEY_CURRENT_USER\SOFTWARE\GRAMMAR\PLUGINS"
The last three are used only when the package is run on a machine using the Windows(tm) operating
system.
The whole system is delivered with three predefined export plugins, namely
container
See PEG Export Plugin. To CONTAINER format for details.
json See PEG Export Plugin. To JSON format for details.
peg See PEG Export Plugin. To PEG format for details.
For readers wishing to write their own export plugin for some format, i.e. plugin writers, reading
and understanding the Parser Tools Export API specification is an absolute necessity, as it documents
the interaction between this package and its plugins in detail.
API
PACKAGE COMMANDS
::pt::peg::export objectName
This command creates a new export manager object with an associated Tcl command whose name is
objectName. This object command is explained in full detail in the sections Object command and
Object methods. The object command will be created under the current namespace if the object-Name objectName
Name is not fully qualified, and in the specified namespace otherwise.
OBJECT COMMAND
All objects created by the ::pt::peg::export command have the following general form:
objectName method ?arg arg ...?
The method method and its arg'uments determine the exact behavior of the command. See section
Object methods for the detailed specifications.
OBJECT METHODS
objectName destroy
This method destroys the object it is invoked for.
objectName export serial serial ?format?
This method takes the canonical serialization of a parsing expression grammar stored in serial
and converts it to the specified format, using the export plugin for the format. This will
fail with an error if no plugin could be found for the format. The string generated by the
conversion process is returned as the result of this method.
If no format is specified the method defaults to text.
The specification of what a canonical serialization is can be found in the section PEG serial-ization serialization
ization format.
The plugin has to conform to the interface documented in the Parser Tools Export API specifi-cation. specification.
cation.
objectName export object object ?format?
This method is a convenient wrapper around the export serial method described by the previous
item. It expects that object is an object command supporting a serialize method returning the
canonical serialization of a parsing expression grammar. It invokes that method, feeds the
result into export serial and returns the resulting string as its own result.
objectName configuration names
This method returns a list containing the names of all configuration options currently known
to the object.
objectName configuration get
This method returns a dictionary containing the names and values of all configuration options
currently known to the object.
objectName configuration set name ?value?
This method sets the configuration option name to the specified value and returns the new
value of the option.
If no value is specified it simply returns the current value, without changing it.
Note that these configuration options and their values are simply passed to a plugin when the
actual export is performed. It is the plugin which checks the validity, not the manager.
objectName configuration unset pattern...
This method unsets all configuration options matching the specified glob patterns. If no pat-tern pattern
tern is specified it will unset all currently defined configuration options.
PEG SERIALIZATION FORMAT
Here we specify the format used by the Parser Tools to serialize Parsing Expression Grammars as
immutable values for transport, comparison, etc.
We distinguish between regular and canonical serializations. While a PEG may have more than one reg-ular regular
ular serialization only exactly one of them will be canonical.
regular serialization
[1] The serialization of any PEG is a nested Tcl dictionary.
[2] This dictionary holds a single key, pt::grammar::peg, and its value. This value holds
the contents of the grammar.
[3] The contents of the grammar are a Tcl dictionary holding the set of nonterminal symbols
and the starting expression. The relevant keys and their values are
rules The value is a Tcl dictionary whose keys are the names of the nonterminal sym-bols symbols
bols known to the grammar.
[1] Each nonterminal symbol may occur only once.
[2] The empty string is not a legal nonterminal symbol.
[3] The value for each symbol is a Tcl dictionary itself. The relevant keys
and their values in this dictionary are
is The value is the serialization of the parsing expression describ-ing describing
ing the symbols sentennial structure, as specified in the section
PE serialization format.
mode The value can be one of three values specifying how a parser
should handle the semantic value produced by the symbol.
value The semantic value of the nonterminal symbol is an abstract
syntax tree consisting of a single node node for the non-terminal nonterminal
terminal itself, which has the ASTs of the symbol's right
hand side as its children.
leaf The semantic value of the nonterminal symbol is an abstract
syntax tree consisting of a single node node for the non-terminal, nonterminal,
terminal, without any children. Any ASTs generated by the
symbol's right hand side are discarded.
void The nonterminal has no semantic value. Any ASTs generated
by the symbol's right hand side are discarded (as well).
start The value is the serialization of the start parsing expression of the grammar,
as specified in the section PE serialization format.
[4] The terminal symbols of the grammar are specified implicitly as the set of all terminal
symbols used in the start expression and on the RHS of the grammar rules.
canonical serialization
The canonical serialization of a grammar has the format as specified in the previous item, and
then additionally satisfies the constraints below, which make it unique among all the possible
serializations of this grammar.
[1] The keys found in all the nested Tcl dictionaries are sorted in ascending dictionary
order, as generated by Tcl's builtin command lsort -increasing -dict.
[2] The string representation of the value is the canonical representation of a Tcl dictio-nary. dictionary.
nary. I.e. it does not contain superfluous whitespace.
EXAMPLE
Assuming the following PEG for simple mathematical expressions
PEG calculator (Expression)
Digit <- '0'/'1'/'2'/'3'/'4'/'5'/'6'/'7'/'8'/'9' ;
Sign <- '-' / '+' ;
Number <- Sign? Digit+ ;
Expression <- '(' Expression ')' / (Factor (MulOp Factor)*) ;
MulOp <- '*' / '/' ;
Factor <- Term (AddOp Term)* ;
AddOp <- '+'/'-' ;
Term <- Number ;
END;
then its canonical serialization (except for whitespace) is
pt::grammar::peg {
rules {
AddOp {is {/ {t -} {t +}} mode value}
Digit {is {/ {t 0} {t 1} {t 2} {t 3} {t 4} {t 5} {t 6} {t 7} {t 8} {t 9}} mode value}
Expression {is {/ {x {t (} {n Expression} {t )}} {x {n Factor} {* {x {n MulOp} {n Factor}}}}} mode value}
Factor {is {x {n Term} {* {x {n AddOp} {n Term}}}} mode value}
MulOp {is {/ {t *} {t /}} mode value}
Number {is {x {? {n Sign}} {+ {n Digit}}} mode value}
Sign {is {/ {t -} {t +}} mode value}
Term {is {n Number} mode value}
}
start {n Expression}
}
PE SERIALIZATION FORMAT
Here we specify the format used by the Parser Tools to serialize Parsing Expressions as immutable
values for transport, comparison, etc.
We distinguish between regular and canonical serializations. While a parsing expression may have
more than one regular serialization only exactly one of them will be canonical.
Regular serialization
Atomic Parsing Expressions
[1] The string epsilon is an atomic parsing expression. It matches the empty string.
[2] The string dot is an atomic parsing expression. It matches any character.
[3] The string alnum is an atomic parsing expression. It matches any Unicode alpha-
bet or digit character. This is a custom extension of PEs based on Tcl's builtin
command string is.
[4] The string alpha is an atomic parsing expression. It matches any Unicode alpha-bet alphabet
bet character. This is a custom extension of PEs based on Tcl's builtin command
string is.
[5] The string ascii is an atomic parsing expression. It matches any Unicode charac-ter character
ter below U0080. This is a custom extension of PEs based on Tcl's builtin com-mand command
mand string is.
[6] The string control is an atomic parsing expression. It matches any Unicode con-trol control
trol character. This is a custom extension of PEs based on Tcl's builtin command
string is.
[7] The string digit is an atomic parsing expression. It matches any Unicode digit
character. Note that this includes characters outside of the [0..9] range. This
is a custom extension of PEs based on Tcl's builtin command string is.
[8] The string graph is an atomic parsing expression. It matches any Unicode print-ing printing
ing character, except for space. This is a custom extension of PEs based on
Tcl's builtin command string is.
[9] The string lower is an atomic parsing expression. It matches any Unicode lower-case lowercase
case alphabet character. This is a custom extension of PEs based on Tcl's
builtin command string is.
[10] The string print is an atomic parsing expression. It matches any Unicode print-ing printing
ing character, including space. This is a custom extension of PEs based on Tcl's
builtin command string is.
[11] The string punct is an atomic parsing expression. It matches any Unicode punctu-ation punctuation
ation character. This is a custom extension of PEs based on Tcl's builtin com-mand command
mand string is.
[12] The string space is an atomic parsing expression. It matches any Unicode space
character. This is a custom extension of PEs based on Tcl's builtin command
string is.
[13] The string upper is an atomic parsing expression. It matches any Unicode upper-case uppercase
case alphabet character. This is a custom extension of PEs based on Tcl's
builtin command string is.
[14] The string wordchar is an atomic parsing expression. It matches any Unicode word
character. This is any alphanumeric character (see alnum), and any connector
punctuation characters (e.g. underscore). This is a custom extension of PEs
based on Tcl's builtin command string is.
[15] The string xdigit is an atomic parsing expression. It matches any hexadecimal
digit character. This is a custom extension of PEs based on Tcl's builtin com-mand command
mand string is.
[16] The string ddigit is an atomic parsing expression. It matches any decimal digit
character. This is a custom extension of PEs based on Tcl's builtin command reg-exp. regexp.
exp.
[17] The expression [list t x] is an atomic parsing expression. It matches the termi-nal terminal
nal string x.
[18] The expression [list n A] is an atomic parsing expression. It matches the non-terminal nonterminal
terminal A.
Combined Parsing Expressions
[1] For parsing expressions e1, e2, ... the result of [list / e1 e2 ... ] is a pars-ing parsing
ing expression as well. This is the ordered choice, aka prioritized choice.
[2] For parsing expressions e1, e2, ... the result of [list x e1 e2 ... ] is a pars-ing parsing
ing expression as well. This is the sequence.
[3] For a parsing expression e the result of [list * e] is a parsing expression as
well. This is the kleene closure, describing zero or more repetitions.
[4] For a parsing expression e the result of [list + e] is a parsing expression as
well. This is the positive kleene closure, describing one or more repetitions.
[5] For a parsing expression e the result of [list & e] is a parsing expression as
well. This is the and lookahead predicate.
[6] For a parsing expression e the result of [list ! e] is a parsing expression as
well. This is the not lookahead predicate.
[7] For a parsing expression e the result of [list ? e] is a parsing expression as
well. This is the optional input.
Canonical serialization
The canonical serialization of a parsing expression has the format as specified in the previ-ous previous
ous item, and then additionally satisfies the constraints below, which make it unique among
all the possible serializations of this parsing expression.
[1] The string representation of the value is the canonical representation of a pure Tcl
list. I.e. it does not contain superfluous whitespace.
[2] Terminals are not encoded as ranges (where start and end of the range are identical).
EXAMPLE
Assuming the parsing expression shown on the right-hand side of the rule
Expression <- '(' Expression ')'
/ Factor (MulOp Factor)*
then its canonical serialization (except for whitespace) is
{/ {x {t (} {n Expression} {t )}} {x {n Factor} {* {x {n MulOp} {n Factor}}}}}
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems.
Please report such in the category pt of the Tcllib SF Trackers [http://source -
forge.net/tracker/? group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
KEYWORDS
EBNF, LL(k), PEG, TDPL, context-free languages, expression, grammar, matching, parser, parsing
expression, parsing expression grammar, push down automaton, recursive descent, state, top-down pars-ing parsing
ing languages, transducer
CATEGORY
Parsing and Grammars
COPYRIGHT
Copyright (c) 2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>
pt 1 pt::peg::export(n)
|
Сообщение о проблемах
Способ сообщить о проблеме с этой страницей руководства зависит от типа проблемы:
- Ошибки содержания
- Ошибки отчета в содержании этой документации со ссылками на отзыв ниже.
- Отчеты об ошибках
- Сообщите об ошибках в функциональности описанного инструмента или API через Генератор отчетов Ошибки.
- Форматирование проблем
- Отчет, форматирующий ошибки в интерактивной версии этих страниц со ссылками на отзыв ниже.