{opt assets/VecTcLab*}
{opt assets/vfs* {libs/$arch/libtclvfs.so jni/tclvfs}}
{opt assets/vnc* {libs/$arch/libtkvnc.so jni/tkvnc}}
{opt assets/vqtcl* {libs/$arch/libvqtcl.so jni/tclkit}}
{opt assets/vu* {libs/$arch/libvu.so jni/vu}}
{opt assets/wibble*}
{opt assets/xotcl* {libs/$arch/libxotcl.so jni/xotcl}}

{opt assets/zbar* {libs/$arch/libzbar.so jni/ZBar}}
{opt assets/zint* {libs/$arch/libzint.so jni/zint}}

{opt assets/VecTcLab*}
{opt assets/vfs* {libs/$arch/libtclvfs.so jni/tclvfs}}
{opt assets/vnc* {libs/$arch/libtkvnc.so jni/tkvnc}}
{opt assets/vqtcl* {libs/$arch/libvqtcl.so jni/tclkit}}
{opt assets/vu* {libs/$arch/libvu.so jni/vu}}
{opt assets/wibble*}
{opt assets/xotcl* {libs/$arch/libxotcl.so jni/xotcl}}
{opt assets/yeti*}
{opt assets/zbar* {libs/$arch/libzbar.so jni/ZBar}}
{opt assets/zint* {libs/$arch/libzint.so jni/zint}}

This directory contains yeti and ylex, version 4c010893cd39.
Yeti is released under BSD license without any warranties.
Copyright (c) 2004 Frank Pilhofer, yeti@fpx.de
Copyright (c) 2013 Steve Havelka, steve@arieslabs.com

Original but vanished source:

https://bitbucket.org/smh377/yeti
https://bitbucket.org/smh377/yeti/get/4c010893cd39.zip

package ifneeded ylex 0.4.2 [list source [file join $dir ylex.tcl]]
package ifneeded yeti 0.4.2 [list source [file join $dir yeti.tcl]]

'\""
'\" Copyright (c) 2001 Frank Pilhofer"
'\""
'\".so man.macros"
.TH YETI n 0.4 yeti "Yet another Tcl Interpreter"
.BS
.SH NAME
Yeti \- Yet another Tcl Interpreter
.SH SYNOPSIS
.PD 0
\fBpackage require yeti ?0.4?\fR
.PD
.PP
.PD 0
\fByeti::yeti\fR \fIname\fR \fR?\fIoptions\fR?\fR
.PP
\fIname\fR \fBadd\fR \fIlhs\fR \fIrhs\fR \fR?\fIscript\fR?\fR
.PP
\fIname\fR \fBadd\fR \fIargs\fR
.PP
\fIname\fR \fBcode\fR \fItoken\fR \fIscript\fR
.PP
\fIname\fR \fBdump\fR
.PP
\fIname\fR \fBconfigure\fR \fB-name\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-start\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-verbose\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-verbout\fR \fR?\fIvalue\fR?\fR
.PD
.BE
.SH PARSER SYNOPSIS
.PP
.PD 0
\fIparserName\fR \fIobjName\fR \fR?\fIoptions\fR?\fR
.PP
\fIobjName\fR \fBparse\fR
.PP
\fIobjName\fR \fBstep\fR
.PP
\fIobjName\fR \fBreset\fR
.PP
\fIobjName\fR \fBconfigure\fR \fB-scanner\fR \fR?\fIobject\fR?\fR
.PP
\fIobjName\fR \fBconfigure\fR \fB-verbose\fR \fR?\fIvalue\fR?\fR
.PD
.SH DESCRIPTION
.PP
This manual page describes \fByeti\fR, a parser generator that is
modeled after the standard \fByacc\fR package (and its incarnation as
GNU \fBbison\fR), which is used to create parsers in the C programming
language.
.PP
Parsers are used to parse an input (a stream of terminals) according
to a \fIgrammar\fR. This grammar is defined by a number of
\fIrules\fR. \fByeti\fR supports a subclass of context-free grammars
named LALR(1), which is the class of context-free grammars that can be
parsed using a single lookahead token.
.PP
Rules in \fByeti\fR are written similar to the Backus-Naur Form
(BNF). Rules have a \fInon-terminal\fR as left-hand side (LHS) and a
list of non-terminals and \fIterminals\fR on the right-hand side
(RHS). Non-terminals are parsed according to these rules, while
terminals are read from the input. This way, all non-terminals are
ultimately decomposed into sequences of terminals. There may be
multiple rules with the same non-terminal on the LHS but different
RHSs. The RHS may be empty.
.PP
\fByeti\fR does not do the parsing by itself, rather it is used, quite
like \fByacc\fR, to generate parsers (by way of the \fBdump\fR
method). Generated parsers are \fB[incr Tcl]\fR classes that act
independently of \fByeti\fR, see the \fBParser\fR section below. These
parsers can be customized; you can use the \fBcode\fR method to add
user variables and methods to the class.
.SH COMMANDS
.TP
\fByeti::yeti\fR \fIname\fR \fR?\fIoptions\fR?\fR
Creates a new parser generator by the name of \fIname\fR. The new
parser generator has an empty set of rules. \fIoptions\fR can be used
to configure the parser generator's public variables, see the
\fIvariables\fR section below.
.SH METHODS
.TP
\fIname\fR \fBadd\fR \fIlhs\fR \fIrhs\fR \fR?\fIscript\fR?\fR
.PD 0
.TP
\fIname\fR \fBadd\fR \fIargs\fR
.PD
Adds new rules to the parser. In the first form, \fIlhs\fR is a
non-terminal, \fIrhs\fR is a (possibly empty) list of terminals and
non-terminals. If this rule is matched, \fIscript\fR is executed. In
the second form, \fIargs\fR is a list consisting of triplets, so the
number of elements must be divisible by three. Each triplet represents
a rule. The first element of each triplet is the \fIlhs\fR, the second
element is the \fIrhs\fR, and the third element is a
\fIscript\fR, as above. In the second and following triplets, \fB|\fR
(vertical bar, pipe symbol) can be used as \fIlhs\fR, referring to the
\fIlhs\fR of the previous rule. The minus sign \fB-\fR can be used for
\fIcode\fR to indicate that no script is associated with this rule. If
a rule is matched, its corresponding script is executed, see the
\fBscripts\fR section below.
.TP
\fIname\fR \fBcode\fR \fItoken\fR \fIscript\fR
Adds custom user code to the generated parser. \fItoken\fR must be one
of
.RS
.IP \fBconstructor\fR
Defines the class's constructor. The \fIscript\fR may have any of the
formats allowed by \fB[incr Tcl]\fR, without the \fBconstructor\fR
keyword.
.IP \fBdestructor\fR
Defines the body of the class's destructor.
.IP \fBerror\fR
Defines the body of the error handler that is called whenever an error
occurs, e.g. parse errors or errors executing a rule's
script. \fIscript\fR has access to the \fByyerrmsg\fR parameter, which
contains a string with a description of the error and its
cause. \fIscript\fR is supposed to inform the user of the problem. The
default implementations prints the message to the channel set in the
\fBverbout\fR variable. \fIscript\fR is expected to return normally;
the parser then returns from the current invocation with the original
error.
.IP \fBreset\fR
The \fIscript\fR is added to the body of the parser's \fIreset\fR
method.
.IP \fBreturndefault\fR
The \fIscript\fR is executed by the parser whenever the code
associated with a non-terminal is omitted or does not execute a
return. The result or return value of \fIscript\fR is used as the
value of the non-terminal. The default \fBreturndefault\fR script
returns the leftmost item on the RHS (\fB$1\fR). If \fIscript\fR is
set to empty string, the result of the code associated with a
non-terminal is used as its value even if return was not executed.
.IP \fBpublic\fR
.PD 0
.IP \fBprotected\fR
.IP \fBprivate\fR
Defines public, protected or private class members. The \fIscript\fR
may contain many different member definitions, like the respective
keywords in an \fB[incr Tcl]\fR class definition.
.PD
.RE
.TP
\fIname\fR \fBdump\fR
Returns a script containing the generated parser. This method is
called after all configuration options have been set and all rules
have been added; the parser generator object is usually deleted after
this method has been called. The returned script can be passed to
\fBeval\fR for instant usage, or saved to a file, from where it can
later be sourced without involvement of the parser generator.
.SH VARIABLES
.TP
\fIname\fR \fBconfigure\fR \fB-name\fR \fR?\fIvalue\fR?\fR
Defines the class name of the generated parser class. The default
value is \fBunnamed\fR.
.TP
\fIname\fR \fBconfigure\fR \fB-start\fR \fR?\fIvalue\fR?\fR
Defines the starting non-terminal for the parser. There must be at
least one rule with this starting non-terminal as the left hand
side. The default value is \fBstart\fR.
.TP
\fIname\fR \fBconfigure\fR \fB-verbose\fR \fR?\fIvalue\fR?\fR
If the value of the \fBverbose\fR variable is non-zero, the parser
prints some debug information about the generated parser, like the
state machines that are generated from the rule set.
.TP
\fIname\fR \fBconfigure\fR \fB-verbout\fR \fR?\fIvalue\fR?\fR
Sets the target channel for debug information. The default value is
\fBstderr\fR.
.SH NOTES
.PP
No checks are done whether all non-terminals are reachable. Also, no
checks are done to ensure that all non-terminals are defined, i.e.
there is at least one rule with the non-terminal as LHS.
.PP
Using uppercase names for terminals and lowercase names for
non-terminals is a common convention that is not enforced, and
\fByeti\fR assumes all undefined tokens to be terminals.
.PP
Set the \fIverbose\fR variable to a positive value to see warnings
about reduce/reduce conflicts. Shift/reduce conflicts are not
reported; \fByeti\fR always prefers shifts over reductions.
.SH PARSER USAGE
.PP
Parsers are independent of \fByeti\fR, their only dependency is on
\fB[incr Tcl]\fR.
.PP
Parsers read terminals from a \fIscanner\fR and try to match them
against the rule set. Starting from the \fBstart\fR non-terminal, the
parser looks for a rule that accepts the terminal. Whenever a rule is
matched, the script associated with the rule is executed. The values
for each element on the RHS are made available to the script in the
variables \fB$\fI<i>\fR, where \fI<i>\fR is the index of the item. The
script can use these values to compute its own result.
.PP
Values for terminals are read from the \fIscanner\fR, values for
non-terminals are the return values of the code associated with a rule
that produced the non-terminal. If the code does not execute a
\fBreturn\fR, or if there is no code associated with a rule, the
\fBreturndefault\fR script is executed to obtain the value of the
non-terminal. If the user did not override \fBreturndefault\fR, the
value of the leftmost item on the RHS (\fB$1\fR) is used as result
(see the example below).
.PP
Parsers are \fB[incr Tcl]\fR objects, so its usual rules of object
handling (e.g. deletion of parsers) apply.
.SH PARSER COMMANDS
.TP
\fIparserName\fR \fIobjName\fR \fR?\fIoptions\fR?\fR
Creates a new parser instance by the name of \fIobjName\fR.
\fIoptions\fR can be used to configure the parser's public variables,
see the \fIparser variables\fR section below.
.SH PARSER METHODS
.TP
\fIobjName\fR \fBparse\fR
Runs the parser. Tokens are read from the scanner as necessary and
matched against terminals. The parsing process runs to completion,
i.e. until a rule for the \fBstart\fR token has been executed and the
end of input has been reached. The value returned from the last rule
is returned as result of \fBparse\fR, but it is also very common for
parsers to leave data in variables rather than returning a result.
.TP
\fIobjName\fR \fBstep\fR
Single-steps the parser. One step is either the shifting of a token or
a reduction. This method may be useful e.g. to do other work in
parallel to the parsing. The method returns a list of length two; the
first element is the token just shifted or reduced, and the second
element is the associated data. Parsing is finished if the token
\fB__init__\fR has been reduced.
.TP
\fIobjName\fR \fBreset\fR
Resets the parser to the initial state, e.g. to start parsing new
input. The scanner must be reset or replaced separately.
.SH PARSER VARIABLES
.TP
\fIobjName\fR \fBconfigure\fR \fB-scanner\fR \fR?\fIobject\fR?\fR
The \fBscanner\fR variable holds the scanner from which terminals are
read. The scanner must be configured before parsing can begin. By
default, the scanner is not deleted; if desired, this can be done in
custom destructor code (see the parser generator's \fBcode\fR method).
.RS
.PP
\fIobject\fR must be a command; the parser calls this command
with \fBnext\fR as parameter whenever a new terminal needs to be
read. The value returned by the command is expected to be a list of
length one or two. The first item of this list is considered to be a
terminal, and the second item is considered to be the value associated
with this terminal. If the list has only one element, the value is
assumed to be the empty string. At the end of input, an empty string
shall be returned as terminal.
.PP
The \fBylex\fR package is designed to provide appropriate scanners for
parsing, but it is possible to use custom scanners as long as the
above rules are satisfied.
.RE
.TP
\fIobjName\fR \fBconfigure\fR \fB-verbose\fR \fR?\fIvalue\fR?\fR
If the value of the \fBverbose\fR variable is non-zero, the parser
prints debug information about the read tokens and matched rules to
standard output.
.TP
\fIobjName\fR \fBconfigure\fR \fB-verbout\fR \fR?\fIvalue\fR?\fR
Sets the target channel for debug information. The default value is
\fBstderr\fR.
.SH SCRIPTS
.PP
If a rule is matched, its corresponding script is executed in the
context of the parser. Scripts have access to the variables
\fB$\fI<i>\fR, which are set to the values associated with each
item on the RHS, where \fI<i>\fR is the index of the item. Numbering
items is left to right, starting with 1.
.PP
Scripts can execute \fBreturn\fR to set their return value, which will
then be associated with the rule's LHS. If a script does not execute
\fBreturn\fR, the value associated with the the leftmost item on the
RHS is used as the rule's value. If the RHS is empty, an empty string
is used.
.PP
\fByeti\fR reserves names with the \fByy\fR prefix, so scripts should
not use or access variables with this prefix. Also, a parser's public
methods and variables as seen above must be respected.
.SH EXAMPLE
.PP
Here's one simple but complete example of a parser that can parse
mathematical expressions, albeit limited to multiplications. The
scanner is not shown, but is expected to return the terminals written
in uppercase.
.PP
.PD 0
set pgen [yeti::yeti #auto -name MathParser]
.PP
$pgen add start {mult} {
.RS
.PP
puts "Result is $1"
.RE
.PP
}
.PP
$pgen add mult {number MULTIPLY number} {
.RS
.PP
return [expr {$1 * $3}]
.RE
.PP
}
.PP
$pgen add mult {number}
.PP
$pgen add number {INTEGER}
.PP
$pgen add number {OPEN mult CLOSE} {
.RS
.PP
return $2
.RE
.PP
}
.PP
eval [$pgen dump]
.PP
set mp [MathParser #auto -scanner $scanner]
.PP
puts "The result is [$mp parse]"
.PD
.PP
.SH KEYWORDS
parser, scanner

#
# ======================================================================
#
# YETI -- Yet anothEr Tcl Interpreter
#
# A yacc/bison like parser for Tcl
#
# Copyright (c) Frank Pilhofer, yeti@fpx.de
#
# ======================================================================
#
# CVS Version Tag: $Id: yeti.tcl,v 1.28 2004/07/06 00:11:03 fp Exp $
#

package require Tcl 8.0
package require struct 2.0
package require Itcl
package provide yeti 0.4.2

#
# ----------------------------------------------------------------------
# The Yeti parser
# ----------------------------------------------------------------------
#

namespace eval yeti {
    namespace import -force ::itcl::*
    class yeti {
	public variable verbose
	public variable verbout

	#
	# production rules
	#

	public variable start
	private variable productions
	private variable rules
	private variable codes
	private variable ruleno

	#
	# NFSM data
	#

	private variable nfsm
	private variable nfsminitstate
	private variable nfsmendstate
	private variable nfsmstateno

	#
	# DFSM data
	#

	private variable dfsm
	private variable dfsminitstate
	private variable dfsmendstate
	private variable dfsmstateno

	#
	# Mapping bettween the three
	#

	private variable nfsmstatetont
	private variable nfsmstatetodfsmstate
	private variable dfsmstatetonfsmstate

	#
	# We store the terminals that may follow a non-terminal. This
	# knowledge is useful to solve reduce/reduce conflicts by
	# looking at the lookahead.
	#

	private variable ntpostterminals

	#
	# cache
	#

	private variable equivalentstates
	private variable canntbeempty

	#
	# user code to be dumped
	#

	public variable name
	private variable usercode
	private variable userconstrcode
	private variable userdestrcode
	private variable usererrorcode
	private variable userresetcode
	private variable userreturndefaultcode {set yyretdata [append 1 {}]}

	#
	# ============================================================
	# Constructor and Destructor
	# ============================================================
	#

	constructor {args} {
	    set verbose 0
	    set ruleno 1
	    set dfsm ""
	    set nfsm ""
	    set verbout stderr
	    set name "unnamed"
	    set start "start"
	    eval $this configure $args
	}

	destructor {
	    if {$nfsm != ""} {
		catch {$nfsm destroy}
	    }
	    if {$dfsm != ""} {
		catch {$dfsm destroy}
	    }
	}

	public method add {args} {
	    if {[llength $args] == 1} {
		set args [lindex $args 0]
	    }

	    if {([llength $args] == 1) || \
		    ([llength $args] != 2 && ([llength $args] % 3) != 0)} {
		error "usage: $this add lhs rhs ?script?"
	    }

	    if {[llength $args] == 2} {
		set lhs [lindex $args 0]
		set rhs [lindex $args 1]
		lappend productions($lhs) [incr ruleno]
		set rules($ruleno) [list $lhs $rhs]
		return $ruleno
	    }

	    set lastlhs ""

	    foreach {lhs rhs code} $args {
		if {$lhs == "|"} {
		    set lhs $lastlhs
		}

		lappend productions($lhs) [incr ruleno]
		set rules($ruleno) [list $lhs $rhs]

		if {$code != "" && $code != "-"} {
		    set codes($ruleno) $code
		}

		set lastlhs $lhs
	    }

	    return $ruleno
	}

	public method code {type thecode} {
	    switch -- $type {
		public -
		private -
		protected {
		    lappend usercode $type $thecode
		}
		constructor {
		    set userconstrcode $thecode
		}
		destructor {
		    set userdestrcode $thecode
		}
		error {
		    set usererrorcode $thecode
		}
		reset {
		    set userresetcode $thecode
		}
		returndefault {
		    set userreturndefaultcode $thecode
		}
	    }
	}

	#
	# ============================================================
	# Build a Non-deterministic Finite State Machine from rules
	# ============================================================
	#

	private method BuildNFSM {} {
	    if {$nfsm != ""} {
		catch {$nfsm destroy}
		catch {unset equivalentstates}
		catch {unset canntbeempty}
		catch {unset nfsmstatetont}
	    }

	    set nfsm [::struct::graph nfsm$this]

	    #
	    # initially, assign state# to each non-terminal
	    #

	    set nfsmstateno 0

	    foreach nt [array names productions] {
		set ntstate($nt) [incr nfsmstateno]
		set nfsmstatetont($nfsmstateno) $nt

		$nfsm node insert $nfsmstateno
		$nfsm node set $nfsmstateno info [list]
		$nfsm node set $nfsmstateno reductions [list]
	    }

	    set nfsminitstate $ntstate(__init__)

	    #
	    # traverse all rules
	    #

	    foreach ruleno [array names rules] {
		set lhs [lindex $rules($ruleno) 0]
		set rhs [lindex $rules($ruleno) 1]

		#
		# create new state, make epsilon transition from
		# the non-terminal's state# to new state
		#

		$nfsm node insert [incr nfsmstateno]
		$nfsm node set $nfsmstateno info [list [list $ruleno 0]]
		$nfsm node set $nfsmstateno reductions [list]

		set arc [$nfsm arc insert $ntstate($lhs) $nfsmstateno]
		$nfsm arc set $arc token ""

		set laststate $nfsmstateno

		#
		# create new state for each step of RHS
		#

		for {set i 0} {$i < [llength $rhs]} {incr i} {
		    set token [lindex $rhs $i]

		    $nfsm node insert [incr nfsmstateno]
		    $nfsm node set $nfsmstateno info \
			    [list [list $ruleno [expr {$i+1}]]]
		    $nfsm node set $nfsmstateno reductions [list]

		    set arc [$nfsm arc insert $laststate $nfsmstateno]
		    $nfsm arc set $arc token $token

		    #
		    # If token is a non-terminal, make epsilon transition
		    # to non-terminal's state# so that this non-terminal
		    # can be read.
		    #
		    # However, don't do that if we're at index 0 and the
		    # non-terminal is our LHS. In that case, we're in the
		    # right state for reading this non-terminal already
		    # (via other rules). Adding a transition would cause
		    # a circle (via epsilon transitions).
		    #

		    if {($i != 0 || $token != $lhs) && \
			    [info exists productions($token)]} {
			set arc [$nfsm arc insert $laststate $ntstate($token)]
			$nfsm arc set $arc token ""
		    }

		    set laststate $nfsmstateno
		}

		#
		# mark the last state as a reduction state
		#

		$nfsm node set $laststate reductions [list $ruleno]

		#
		# if lhs is __init__, then this is our final state
		#

		if {$lhs == "__init__"} {
		    set nfsmendstate $laststate
		}
	    }
	}

	#
	# ============================================================
	# State Machine Helpers
	# ============================================================
	#

	#
	# Determine if the non-terminal can produce the empty string
	#

	private method CanNTBeEmpty {nt} {
	    if {[info exists canntbeempty($nt)]} {
		return $canntbeempty($nt)
	    }

	    if {![info exists productions($nt)]} {
		return 0
	    }

	    set canbeempty 0
	    set canntbeempty($nt) 1 ;# protection against infinite recursion

	    foreach rule $productions($nt) {
		set lhs [lindex $rules(rule) 0]
		set rhs [lindex $rules(rule) 1]

		for {set i 0} {$i < [llength $rhs]} {incr i} {
		    set token [lindex $rhs $i]

		    #
		    # if token is a terminal, this rule cannot be empty
		    #

		    if {![info exists productions($token)]} {
			break
		    }

		    #
		    # if token is the lhs, then ignore
		    #

		    if {$token == $lhs} {
			continue
		    }

		    if {![CanNTBeEmpty $token]} {
			break
		    }
		}

		#
		# if we could traverse the rule without finding a terminal,
		# then this rule can indeed produce the empty string
		#

		if {$i >= [llength $rhs]} {
		    set canbeempty 1
		    break
		}
	    }

	    set canntbeempty($nt) $canbeempty
	    return $canbeempty
	}

	#
	# Determine which states are reachable by epsilon transitions,
	# taking into account non-terminals that can produce an empty
	# string.
	#

	private method NFSMEpsilonTransitions {state {beenthere {}}} {
	    if {[info exists equivalentstates($state)]} {
		return $equivalentstates($state)
	    }

	    if {[lsearch -exact $beenthere $state] != -1} {
		error "error: infinite loop detected for NFSM state $state"
	    }

	    lappend beenthere $state
	    set resstates [list $state]

	    foreach arc [$nfsm arcs -out $state] {
		set token [$nfsm arc get $arc token]

		if {$token != ""} {
		    if {[info exists productions($token)]} {
			continue
		    }

		    if {![CanNTBeEmpty $token]} {
			continue
		    }
		}

		set newstate [$nfsm arc target $arc]
		lappend resstates $newstate

		foreach addstate [NFSMEpsilonTransitions $newstate $beenthere] {
		    lappend resstates $addstate
		}
	    }

	    set equivalentstates($state) [lsort -unique $resstates]
	    return $equivalentstates($state)
	}

	#
	# Collect terminals that can follow a non-terminal. This info
	# can be used to resolve reduce/reduce conflicts.
	#

	private method CollectPostTerminalsRek {nt {beenthere {}}} {
	    upvar ntpostfollows ntpostfollows
	    upvar temppostterminals temppostterminals

	    if {[info exists ntpostterminals($nt)]} {
		return $ntpostterminals($nt)
	    }

	    if {[lsearch -exact $beenthere $nt] != -1} {
		return [list]
	    }

	    lappend beenthere $nt

	    if {[info exists temppostterminals($nt)]} {
		set res $temppostterminals($nt)
	    } else {
		set res [list]
	    }

	    if {[info exists ntpostfollows($nt)]} {
		foreach follows $ntpostfollows($nt) {
		    foreach token [CollectPostTerminalsRek $follows $beenthere] {
			lappend res $token
		    }
		}
	    }

	    set ntpostterminals($nt) [lsort -unique $res]
	    return $res
	}

	private method CollectPostTerminals {} {
	    catch {unset ntpostterminals}

	    #
	    # Look at each arc in the graph, and see if it is marked with
	    # a non-terminal. If so, then see which terminals can be read
	    # in the target state.
	    #

	    foreach arc [$nfsm arcs] {
		set nt [$nfsm arc get $arc token]

		if {$nt == ""} {
		    continue
		}

		if {![info exists productions($nt)]} {
		    # terminal
		    continue
		}

		set ntstate [$nfsm arc target $arc]
		set ntstates [NFSMEpsilonTransitions $ntstate]

		foreach state $ntstates {
		    foreach arc [$nfsm arcs -out $state] {
			set token [$nfsm arc get $arc token]

			if {$token == ""} {
			    continue
			}

			if {[info exists productions($token)]} {
			    # non-terminal
			    continue
			}

			lappend temppostterminals($nt) $token
		    }

		    #
		    # If there is a reduction possible, then everything
		    # that can follow the LHS of the rule that is being
		    # reduced can also follow this nt.
		    #

		    foreach redux [$nfsm node get $state reductions] {
			set lhs [lindex $rules($redux) 0]
			lappend ntpostfollows($nt) $lhs
		    }
		}
	    }

	    lappend temppostterminals(__init__) "" ;# EOF

	    foreach nt [array names productions] {
		CollectPostTerminalsRek $nt
	    }

	    if {$verbose >= 4} {
		puts $verbout "CollectPostTerminals: lookahead terminals for reductions"

		foreach nt [array names productions] {
		    puts -nonewline $verbout "  lookaheads for reducing $nt:"
		    if {[llength $ntpostterminals($nt)] == 0} {
			puts $verbout " (none)"
		    } else {
			foreach lookahead $ntpostterminals($nt) {
			    if {$lookahead == ""} {
				puts -nonewline $verbout " (EOF)"
			    } else {
				puts -nonewline $verbout " $lookahead"
			    }
			}
			puts $verbout ""
		    }
		}

		puts $verbout ""
	    }
	}

	#
	# ============================================================
	# Build a Deterministic Finite State Machine from NFSM
	# ============================================================
	#

	#
	# Build up deterministic state dfsmstate from all of nfsmstates
	# by simulating all transitions from these states in parallel
	#

	private method BuildDFSMTransition {dfsmstate nfsmstates} {
	    #
	    # fill in state information for this dfsmstate from all of
	    # the nfsmstates
	    #

	    set dfsminfo [list]
	    set dfsmredux [list]

	    foreach nfsmstate $nfsmstates {
		foreach info [$nfsm node get $nfsmstate info] {
		    lappend dfsminfo $info
		}
		foreach redux [$nfsm node get $nfsmstate reductions] {
		    lappend dfsmredux $redux
		}
	    }

	    #
	    # initialize dfsmstate info
	    #

	    $dfsm node set $dfsmstate info $dfsminfo
	    $dfsm node set $dfsmstate reductions $dfsmredux

	    #
	    # map nfsmstates to dfsmstate
	    #

	    set nfsmstates [lsort -unique -integer $nfsmstates]
	    set dfsmstatetonfsmstate($dfsmstate) $nfsmstates
	    set nfsmstatetodfsmstate([join $nfsmstates ,]) $dfsmstate

	    foreach nfsmstate $nfsmstates {
		set nfsmstatetodfsmstate($nfsmstate) $dfsmstate
	    }

	    #
	    # collect all tokens that can be read in any of these states,
	    # and the states that we can enter by reading them
	    #
	    # allnfsmtokens: map(token) : list of nextstate
	    #

	    foreach arc [eval $nfsm arcs -out $nfsmstates] {
		set token [$nfsm arc get $arc token]

		if {$token == ""} {
		    continue
		}

		set newstate [$nfsm arc target $arc]
		set newstates [NFSMEpsilonTransitions $newstate]

		foreach nstate $newstates {
		    lappend allnfsmtokens($token) $nstate
		}
	    }

	    #
	    # create transitions for each of these tokens
	    #

	    foreach token [array names allnfsmtokens] {
		#
		# See if we already have a DFSM state that is equivalent to
		# all the NFSM states reachable by reading $token. If yes,
		# link to it, otherwise create a new one.
		#

		set allnfsmtokens($token) \
			[lsort -unique -integer $allnfsmtokens($token)]
		set allnfsmindex [join $allnfsmtokens($token) ,]

		if {[info exists nfsmstatetodfsmstate($allnfsmindex)]} {
		    set equivalentstate $nfsmstatetodfsmstate($allnfsmindex)
		} else {
		    set equivalentstate -1
		}

		if {$equivalentstate >= 0} {
		    #
		    # create transition to that state
		    #
		    set arc [$dfsm arc insert $dfsmstate $equivalentstate]
		    $dfsm arc set $arc token $token
		} else {
		    #
		    # else, create a new state, and simulate that state
		    #
		    $dfsm node insert [incr dfsmstateno]
		    set arc [$dfsm arc insert $dfsmstate $dfsmstateno]
		    $dfsm arc set $arc token $token
		    BuildDFSMTransition $dfsmstateno $allnfsmtokens($token)
		}
	    }
	}

	private method BuildDFSM {} {
	    #
	    # initialize DFSM building process
	    #

	    if {$dfsm != ""} {
		catch {$dfsm destroy}
		catch {unset nfsmstatetodfsmstate}
		catch {unset dfsmstatetonfsmstate}
	    }

	    set dfsm [::struct::graph dfsm$this]

	    set dfsmstateno 1
	    set dfsminitstate 1
	    $dfsm node insert 1

	    #
	    # Start DFSM building process by creating an initial state #1
	    # that represents all nodes that are reachable by epsilon
	    # transitions from the NFSM's initial state.
	    #

	    BuildDFSMTransition 1 [NFSMEpsilonTransitions $nfsminitstate]

	    #
	    # Check which DFSM state the NFSM's end state has been mapped to
	    #

	    if {![info exists nfsmstatetodfsmstate($nfsmendstate)]} {
		error "assertion failure: no dfsm state for end state $nfsmendstate"
	    }

	    set dfsmendstate $nfsmstatetodfsmstate($nfsmendstate)
	}

	#
	# ============================================================
	# Check for conflicts
	# ============================================================
	#

	#
	# check for reduce/reduce conflicts
	#

	private method CheckReduceReduce {} {
	    foreach state [$dfsm nodes] {
		set reductions [$dfsm node get $state reductions]

		if {[llength $reductions] <= 1} {
		    continue
		}

		#
		# multiple reductions possible here, check if their set
		# of lookaheads is disjunct
		#

		catch {unset testlookaheads}

		foreach redux $reductions {
		    set lhs [lindex $rules($redux) 0]
		    if {![info exists ntpostterminals($lhs)]} {
			continue
		    }
		    foreach lookahead $ntpostterminals($lhs) {
			if {[info exists testlookaheads($lookahead)]} {
			    if {$verbose} {
				puts $verbout "yeti: warning: reduce/reduce conflict in state $state ($lookahead)"
				DumpState $dfsm $state
			    }
			} else {
			    set testlookaheads($lookahead) 1
			}
		    }
		}

		catch {unset testlookaheads}
	    }
	}

	private method CheckShiftReduce {} {
	    foreach state [$dfsm nodes] {
		#
		# We have computed the reduction lookaheads (which
		# terminals could follow a non-terminal) in the
		# ntpostterminals array.
		#
		# Make sure that this state, where the reduction
		# may occur, does not offer an out arc that also
		# reads this token
		#

		catch {unset testlookaheads}

		set reductions [$dfsm node get $state reductions]

		foreach redux $reductions {
		    set lhs [lindex $rules($redux) 0]

		    if {![info exists ntpostterminals($lhs)]} {
			continue
		    }

		    foreach terminal $ntpostterminals($lhs) {
			set testlookaheads($terminal) $lhs
		    }
		}

		foreach arc [$dfsm arcs -out $state] {
		    set token [$dfsm arc get $arc token]

		    if {[info exists testlookaheads($token)]} {
			if {$verbose} {
			    puts $verbout "yeti: warning: shift/reduce conflict in state $state (shift $token, reduce $testlookaheads($token))"
			    DumpState $dfsm $state
			}
		    }
		}
	    }
	}

	private method CheckDFSM {} {
	    CheckReduceReduce
	    CheckShiftReduce
	}

	#
	# ============================================================
	# Debug: dump the state machines
	# ============================================================
	#

	private method DumpState {sm state} {
	    foreach info [$sm node get $state info] {
		set index [lindex $info 1]
		set ruleno [lindex $info 0]
		set rule $rules($ruleno)
		set lhs [lindex $rule 0]
		set rhs [lindex $rule 1]
		puts -nonewline $verbout "  $lhs -->"
		for {set i 0} {$i < $index} {incr i} {
		    puts -nonewline $verbout " "
		    puts -nonewline $verbout [lindex $rhs $i]
		}
		puts -nonewline $verbout " ."
		for {} {$i < [llength $rhs]} {incr i} {
		    puts -nonewline $verbout " "
		    puts -nonewline $verbout [lindex $rhs $i]
		}
		puts $verbout ""
	    }

	    if {[llength [$sm node get $state info]] > 0} {
		puts $verbout ""
	    }

	    foreach arc [$sm arcs -out $state] {
		set token [$sm arc get $arc token]
		if {$token == ""} {
		    puts -nonewline $verbout "  (epsilon): go to state"
		} else {
		    puts -nonewline $verbout "  $token: go to state"
		}
		set ts [$sm arc target $arc]
		puts -nonewline $verbout " "
		puts -nonewline $verbout $ts
		puts $verbout "."
	    }

	    if {[llength [$sm arcs -out $state]] > 0} {
		puts $verbout ""
	    }

	    set reductions [$sm node get $state reductions]

	    if {[llength $reductions] > 1} {
		foreach redux $reductions {
		    set lhs [lindex $rules($redux) 0]
		    if {[info exists ntpostterminals($lhs)]} {
			set lookaheads $ntpostterminals($lhs)
		    } else {
			set lookaheads [list "(default)"]
		    }
		    foreach lookahead $lookaheads {
			if {$lookahead == ""} {
			    set lookahead "(EOF)"
			}
			puts $verbout "  $lookahead: reduce using rule# $redux ($lhs)"
		    }
		}
	    } elseif {[llength $reductions] == 1} {
		set redux [lindex $reductions 0]
		set lhs [lindex $rules($redux) 0]
		puts $verbout "  (default): reduce using rule# $redux ($lhs)"
	    }

	    if {[llength $reductions] > 0} {
		puts $verbout ""
	    }
	}

	public method DumpNFSM {} {
	    puts -nonewline $verbout "NFSM: initial state $nfsminitstate, "
	    puts $verbout "final state $nfsmendstate"
	    foreach state [lsort -integer [$nfsm nodes]] {
		puts $verbout "NFSM State # $state:"
		if {[info exists nfsmstatetont($state)]} {
		    puts $verbout "  represents token $nfsmstatetont($state)"
		}
		DumpState $nfsm $state
	    }
	}

	public method DumpDFSM {} {
	    puts -nonewline $verbout "DFSM: initial state $dfsminitstate, "
	    puts $verbout "final state $dfsmendstate"
	    foreach state [lsort -integer [$dfsm nodes]] {
		puts $verbout "DFSM State # $state:"
		puts $verbout "  represents NFSM states $dfsmstatetonfsmstate($state)"
		puts $verbout ""
		DumpState $dfsm $state
	    }
	}

	#
	# ============================================================
	# Build State Machines
	# ============================================================
	#

	public method BuildSMS {} {
	    #
	    # Add initial rule __init__ -> $start
	    #

	    if {![info exists rules(0)]} {
		lappend productions(__init__) 0
		set rules(0) [list __init__ [list $start]]
	    }

	    #
	    # Build Non-deterministic Finite State Machine from rules
	    #

	    if {$nfsm == ""} {
		BuildNFSM
	    }

	    #
	    # Build Deterministic Finite State Machine from NFSM
	    #

	    CollectPostTerminals

	    if {$dfsm == ""} {
		BuildDFSM
	    }

	    #
	    # Check DFSM for conflicts
	    #

	    CheckDFSM

	    #
	    # Debug output
	    #

	    if {$verbose >= 3} {
		puts $verbout "-----"
		puts $verbout "NFSM:"
		puts $verbout "-----"
		DumpNFSM
	    }

	    if {$verbose >= 2} {
		puts $verbout "-----"
		puts $verbout "DFSM:"
		puts $verbout "-----"
		DumpDFSM
	    }
	}

	#
	# ============================================================
	# Dump generated Parser
	# ============================================================
	#

	public method dump {} {
	    #
	    # First, build DFSM if necessary
	    #

	    if {$dfsm == ""} {
		BuildSMS
	    }

	    #
	    # Create parser code
	    #

	    append data "itcl::class $name {\n"
	    append data "    public variable scanner \"\"\n"
	    append data "    public variable verbose 0\n"
	    append data "    public variable verbout stderr\n"
	    append data "    private variable yystate $dfsminitstate\n"
	    append data "    private variable yysstack {$dfsminitstate}\n"
	    append data "    private variable yydstack {}\n"
	    append data "    private variable yyreadnext 1\n"
	    append data "    private variable yylookahead\n"
	    append data "    private variable yyfinished 0\n"
	    append data "    private common yytrans\n"
	    append data "    private common yyredux\n"
	    append data "    private common yyrules\n"
	    append data "\n"

	    #
	    # yytrans: array($state,$token) -> newstate
	    #

	    append data "    array set yytrans {\n"

	    foreach state [lsort -integer [$dfsm nodes]] {
		foreach arc [$dfsm arcs -out $state] {
		    set token [$dfsm arc get $arc token]
		    set ts [$dfsm arc target $arc]
		    append data "        [list $state,$token] $ts\n"
		}
	    }

	    append data "    }\n"
	    append data "\n"

	    #
	    # yyredux: array($state,$token) -> ruleno
	    #          array($state)        -> ruleno
	    #

	    append data "    array set yyredux {\n"

	    foreach state [lsort -integer [$dfsm nodes]] {
		set reductions [$dfsm node get $state reductions]

		foreach redux $reductions {
		    set lhs [lindex $rules($redux) 0]
		    set count [expr {[llength $rules($redux)] - 1}]

		    if {[info exists ntpostterminals($lhs)] && \
			    [llength $reductions] > 1} {
			foreach lookahead $ntpostterminals($lhs) {
			    append data "        $state,$lookahead $redux\n"
			}
		    } else {
			append data "        $state $redux\n"
		    }
		}
	    }

	    append data "    }\n"
	    append data "\n"

	    #
	    # yyrules: array($ruleno) -> [list lhs rhs]
	    #

	    append data "    array set yyrules {\n"

	    foreach ruleno [lsort -integer [array names rules]] {
		set rule $rules($ruleno)
		set lhs [lindex $rule 0]
		set rhs [lindex $rule 1]
		append data "        $ruleno {$lhs {$rhs}}\n"
	    }

	    append data "    }\n"
	    append data "\n"

	    #
	    # user code
	    #

	    if {[info exists usercode]} {
		foreach {type thecode} $usercode {
		    append data "    $type {\n"
		    append data $thecode "\n"
		    append data "    }\n"
		    append data "\n"
		}
	    }

	    #
	    # constructor
	    #

	    if {[info exists userconstrcode]} {
		append data "    constructor " $userconstrcode "\n"
	    } else {
		append data "    constructor {args} {\n"
		append data "        eval \$this configure \$args\n"
		append data "    }\n"
		append data "    \n"
	    }

	    #
	    # destructor
	    #

	    if {[info exists userdestrcode]} {
		append data "    destructor " $userdestrcode "\n"
	    }

	    #
	    # reset
	    #

	    append data "    public method reset {} {\n"
	    append data "        if {\$verbose} {\n"
	    append data "            puts \$verbout \"$name: reset, entering state $dfsminitstate\"\n"
	    append data "        }\n"
	    append data "        set yystate $dfsminitstate\n"
	    append data "        set yysstack \[list \$yystate\]\n"
	    append data "        set yydstack \[list\]\n"
	    append data "        set yyreadnext 1\n"
	    append data "        set yyfinished 0\n"

	    if {[info exists userresetcode]} {
		append data "\n" $userresetcode "\n"
	    }

	    append data "    }\n"
	    append data "    \n"

	    #
	    # yyerror: overloadable error handling
	    #

	    append data "    protected method yyerror {yyerrmsg} {\n"

	    if {[info exists usererrorcode]} {
		append data $usererrorcode "\n"
	    } else {
		append data "        puts \$verbout \"$name: \$yyerrmsg\"\n"
	    }

	    append data "    }\n"
	    append data "    \n"

	    #
	    # yyshift: shift token and data
	    #

	    append data "    private method yyshift {yytoken yydata} {\n"
	    append data "        set yynewstate \$yytrans(\$yystate,\$yytoken)\n"
	    append data "        lappend yysstack \$yynewstate\n"
	    append data "        lappend yydstack \$yydata\n"
	    append data "        \n"
	    append data "        if {\$verbose} {\n"
	    append data "            puts \$verbout \"$name: shifting token \$yytoken, entering state \$yynewstate\"\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yystate \$yynewstate\n"
	    append data "    }\n"
	    append data "\n"

	    #
	    # yyreduce: execute a rule
	    #

	    append data "    private method yyreduce {yyruleno} {\n"
	    append data "        set yylhs \[lindex \$yyrules(\$yyruleno) 0\]\n"
	    append data "        set yyrhs \[lindex \$yyrules(\$yyruleno) 1\]\n"
	    append data "        set yycount \[llength \$yyrhs\]\n"
	    append data "        set yyssdepth \[llength \$yysstack\]\n"
	    append data "        set yydsdepth \[llength \$yydstack\]\n"
	    append data "        \n"
	    append data "        if {\$verbose} {\n"
	    append data "            puts -nonewline \$verbout \"$name: reducing rule # \$yyruleno: \$yylhs -->\"\n"
	    append data "            foreach yytoken \$yyrhs {\n"
	    append data "                puts -nonewline \$verbout \" \"\n"
	    append data "                puts -nonewline \$verbout \$yytoken\n"
	    append data "            }\n"
	    append data "            puts \$verbout \"\"\n"
	    append data "        }\n"
	    append data "\n"
	    append data "        for {set yyi 0} {\$yyi < \$yycount} {incr yyi} {\n"
	    append data "            set yyvarname \[expr {\$yyi + 1}\]\n"
	    append data "            set yyvarval  \[lindex \$yydstack \[expr {\$yydsdepth-\$yycount+\$yyi}\]\]\n"
	    append data "            set \$yyvarname \$yyvarval\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yyretcode \[catch {\n"
	    append data "            switch -- \$yyruleno {\n"
	    append data "                0 {\n"
	    append data "                    return \$1\n"
	    append data "                }\n"
	    foreach ruleno [lsort -integer [array names codes]] {
		append data "                $ruleno {\n"
		append data $codes($ruleno) "\n"
		append data "                }\n"
	    }
	    append data "            }\n"
	    append data "        } yyretdata\]\n"
	    append data "        \n"
	    if {$userreturndefaultcode ne {}} {
		append data "        if {\$yyretcode == 0} {\n"
		append data "            set yyretcode \[catch {\n"
		append data $userreturndefaultcode\n
		append data "            } yyretdata\]\n"
		append data "        }\n"
	    }
	    append data "        if {\$yyretcode == 1} {\n"
	    append data "            global errorInfo\n"
	    append data "            set yyerrmsg \"script for rule # \$yyruleno (\$yylhs --> \$yyrhs) failed: \$yyretdata\"\n"
	    append data "            yyerror \$yyerrmsg\n"
	    append data "            append errorInfo \"\\n    while executing script for rule # \$yyruleno (\$yylhs --> \$yyrhs)\"\n"
	    append data "            error \$yyerrmsg \$errorInfo\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yysstack \[lrange \$yysstack 0 \[expr {\$yyssdepth-\$yycount-1}\]\]\n"
	    append data "        set yydstack \[lrange \$yydstack 0 \[expr {\$yydsdepth-\$yycount-1}\]\]\n"
	    append data "        set yystate \[lindex \$yysstack end\]\n"
	    append data "        \n"
	    append data "        if {\$verbose} {\n"
	    append data "            puts \$verbout \"$name: entering state \$yystate\"\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        return \$yyretdata\n"
	    append data "    }\n"
	    append data "    \n"

	    #
	    # Single step
	    #

	    append data "    public method step {} {\n"
	    append data "        if {\$yyfinished} {\n"
	    append data "           error \"step beyond end of parse\"\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        if {\$yyreadnext} {\n"
	    append data "            set yylookahead \[\$scanner next\]\n"
	    append data "            set yyreadnext 0\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yyterm \[lindex \$yylookahead 0\]\n"
	    append data "        set yydata \[lindex \$yylookahead 1\]\n"
	    append data "        \n"
	    append data "        if {\[info exists yytrans(\$yystate,\$yyterm)\]} {\n"
	    append data "            yyshift \$yyterm \$yydata\n"
	    append data "            set yyreadnext 1\n"
	    append data "            return \[list \$yyterm \$yydata\]\n"
	    append data "        } elseif {\[info exists yyredux(\$yystate)\] || \\\n"
	    append data "                \[info exists yyredux(\$yystate,\$yyterm)\]} {\n"
	    append data "            if {\[info exists yyredux(\$yystate)\]} {\n"
	    append data "                set yyruleno \$yyredux(\$yystate)\n"
	    append data "            } else {\n"
	    append data "                set yyruleno \$yyredux(\$yystate,\$yyterm)\n"
	    append data "            }\n"
	    append data "            \n"
	    append data "            set yyreduxlhs \[lindex \$yyrules(\$yyruleno) 0\]\n"
	    append data "            set yyreduxdata \[yyreduce \$yyruleno\]\n"
	    append data "            \n"
	    append data "            if {\$yyreduxlhs == \"__init__\"} {\n"
	    append data "                set yyfinished 1\n"
	    append data "            } else {\n"
	    append data "                yyshift \$yyreduxlhs \$yyreduxdata\n"
	    append data "            }\n"
	    append data "            return \[list \$yyreduxlhs \$yyreduxdata\]\n"
	    append data "        } else {\n"
	    append data "            global errorInfo\n"
	    append data "            set yyerrmsg \"parse error reading \\\"\$yyterm\\\" in state \$yystate\"\n"
	    append data "            set errorInfo \$yyerrmsg\n"
	    append data "            append errorInfo \"\\n    expecting one of:\"\n"
	    append data "            foreach yylaname \[array names yytrans \$yystate,*\] {\n"
	    append data "                append errorInfo \"\\n        \" \[lindex \[split \$yylaname ,\] 1\]\n"
	    append data "            }\n"
	    append data "            yyerror \$yyerrmsg\n"
	    append data "            error \$yyerrmsg \$errorInfo\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        error \"oops: unreachable code\"\n"
	    append data "    }\n"
	    append data "    \n"

	    #
	    # Main parse method
	    #

	    append data "    public method parse {} {\n"
	    append data "        if {\$scanner == \"\"} {\n"
	    append data "            global errorInfo\n"
	    append data "            set yyerrmsg \"cannot start parsing without a scanner\"\n"
	    append data "            set errorInfo \$yyerrmsg\n"
	    append data "            yyerror \$yyerrmsg\n"
	    append data "            error \$yyerrmsg \$errorInfo\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        while {!\$yyfinished} {\n"
	    append data "            set yydata \[step\]\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        if {\[lindex \$yylookahead 0\] != \"\"} {\n"
	    append data "            global errorInfo\n"
	    append data "            set yyerrmsg \"parser finished, but not at EOF (lookahead: \[lindex \$yylookahead 0\])\"\n"
	    append data "            set errorInfo \$yyerrmsg\n"
	    append data "            yyerror \$yyerrmsg\n"
	    append data "            error \$yyerrmsg\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        return \[lindex \$yydata 1\]\n"
	    append data "    }\n"

	    #
	    # End of newly generated class
	    #

	    append data "}\n"
	    append data "\n"
	}
    }
}

'\""
'\" Copyright (c) 2001 Frank Pilhofer"
'\""
'\".so man.macros"
.TH YLEX n 0.4 ylex "Yeti Scanner"
.BS
.SH NAME
Ylex \- Yeti's Scanner
.SH SYNOPSIS
.PD 0
.PP
\fBpackage require ylex ?0.4?\fR
.PD
.PP
.PD 0
\fByeti::ylex\fR \fIname\fR
.PP
\fIname\fR \fBmacro\fR \fIname\fR \fIregex\fR ?\fI...\fI?
.PP
\fIname\fR \fBmacro\fR \fIargs\fR
.PP
\fIname\fR \fBadd\fR ?\fIoptions\fR? \fIregex\fR \fIscript\fR ?\fI...\fI?
.PP
\fIname\fR \fBadd\fR ?\fIoptions\fR? \fIargs\fR
.PP
\fIname\fR \fBcode\fR \fItoken\fR \fIscript\fR
.PP
\fIname\fR \fBdump\fR
.PP
\fIname\fR \fBconfigure\fR \fB-name\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-start\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-case\fR \fR?\fIvalue\fR?\fR
.PD
.BE
.SH SCANNER SYNOPSIS
.PP
.PD 0
\fIscannerName\fR \fIobjName\fR \fR?\fIoptions\fR?\fR
.PP
\fIname\fR \fBstart\fR \fIstring\fR
.PP
\fIname\fR \fBreset\fR
.PP
\fIname\fR \fBnext\fR
.PP
\fIname\fR \fBstep\fR
.PP
\fIname\fR \fBrun\fR
.PP
\fIname\fR \fBconfigure\fR \fB-case\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-yydata\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-verbose\fR \fR?\fIvalue\fR?\fR
.PP
\fIname\fR \fBconfigure\fR \fB-verbout\fR \fR?\fIvalue\fR?\fR
.PD
.BE
.SH DESCRIPTION
.PP
This manual page describes \fBylex\fR, a scanner generator that comes
with the \fByeti\fR package. \fBylex\fR is modeled after the standard
\fBlex\fR utility, which is used to create scanners in the C
programming language.
.PP
A scanner consists of a number of rules. Each rule associates a
regular expression with a Tcl script; this script is executed whenever
the regular expression is matched in the input. This code can either
act on its own, or it can generate a stream of tokens that can then be
evaluated outside of the scanner - e.g. in a parser.
.PP
\fBylex\fR does not do the scanning by itself, rather it is used,
quite like \fBlex\fR, to generate scanners (by way of the \fBdump\fR
method). Generated scanners are \fB[incr Tcl]\fR classes that act
independently of \fBylex\fR, see the \fBScanner\fR section
below. These scanners can be customized; you can use the \fBcode\fR
method to add user variables and methods to the class.
.SH COMMANDS
.TP
\fByeti::ylex\fR \fIname\fR
Creates a new scanner generator by the name of \fIname\fR. The new
scanner generator has an empty set of rules. \fIoptions\fR can be used
to configure the scanner generator's public variables, see the
\fIvariables\fR section below.
.SH METHODS
.PD 0
.TP
\fIname\fR \fBmacro\fR \fIname\fR \fIregex\fR ?\fI...\fI?
.TP
\fIname\fR \fBmacro\fR \fIargs\fR
.PD
Defines \fImacros\fR, which are regular expressions that are stored
for later use. Macros can be used in other macros or rules using their
name in angular brackets, e.g. \fI<digit>\fR would reference the
\fIdigit\fR macro. Macro names must be alphanumerical. In the first
form, the \fBmacro\fR method takes an even number of parameters. The
first parameter of each pair is the name, the second parameter is a
regular expression that may itself contain other macros. In the second
form, the method takes a list as single parameter, where this list is
composed as above of alternating names and regular expressions. The
second form may be more convenient to define multiple macros.
.TP
\fIname\fR \fBadd\fR ?\fIoptions\fR? \fIregex\fR \fIscript\fR ?\fI...\fI?
.PD 0
.TP
\fIname\fR \fBadd\fR ?\fIoptions\fR? \fIargs\fR
.PD
Adds new rules to the scanner. In the first form, the \fBadd\fR method
takes an even number of parameters (not counting options). The first
parameter of each pair is a regular expression, the second parameter
is a script. In the second form, the method takes a list as single
parameter (not counting options), where this list is composed as above
of alternating regular expressions and scripts.
.RS
.PP
Whenever the regular expression \fIregex\fR is matched in the input
string, its corresponding \fIscript\fR will be executed by the
scanner.
.PP
The following options are supported:
.IP "-nocase"
This option has the same meaning as on \fBregexp\fR. In matching this
rule, upper-case characters in the input will be treated as
lower-case.
.IP "-state \fIname\fR"
This rule will only be considered if the scanner is in the state
\fIname\fR. See below for more information.
.IP "-states \fInames\fR"
Same as above, but \fInames\fR is a list of state names in which the
rule is active.
.RE
.TP
\fIname\fR \fBcode\fR \fItoken\fR \fIscript\fR
Adds custom user code to the generated scanner. \fItoken\fR must be
one of
.RS
.IP \fBconstructor\fR
Defines the class's constructor. The \fIscript\fR may have any of the
formats allowed by \fB[incr Tcl]\fR, without the \fBconstructor\fR
keyword.
.IP \fBdestructor\fR
Defines the body of the class's destructor.
.IP \fBerror\fR
Defines the body of the error handler that is called whenever an error
occurs, e.g. errors executing a rule's
script. \fIscript\fR has access to the \fByyerrmsg\fR parameter, which
contains a string with a description of the error and its
cause. \fIscript\fR is supposed to inform the user of the problem. The
default implementations prints the message to the channel set in the
\fBverbout\fR variable. \fIscript\fR is expected to return normally;
the parser then returns from the current invocation with the original
error.
.IP \fBreset\fR
The \fIscript\fR is added to the body of the scanner's \fIreset\fR
method.
.IP \fBpublic\fR
.PD 0
.IP \fBprotected\fR
.IP \fBprivate\fR
Defines public, protected or private class members. The \fIscript\fR
may contain many different member definitions, like the respective
keywords in an \fB[incr Tcl]\fR class definition.
.PD
.RE
.TP
\fIname\fR \fBdump\fR
Returns a script containing the generated scanner. This method is
called after all configuration options have been set and all rules
have been added; the scanner generator object is usually deleted after
this method has been called. The returned script can be passed to
\fBeval\fR for instant usage, or saved to a file, from where it can
later be sourced without involvement of the scanner generator.
.SH VARIABLES
.TP
\fIname\fR \fBconfigure\fR \fB-name\fR \fR?\fIvalue\fR?\fR
Defines the class name of the generated scanner class. The default
value is \fBunnamed\fR.
.TP
\fIname\fR \fBconfigure\fR \fB-start\fR \fR?\fIvalue\fR?\fR
Defines the initial state for the scanner. Setting this variable is
only required if your scanner needs multiple states, and you are not
satisfied with the default of \fBINITIAL\fR.
.TP
\fIname\fR \fBconfigure\fR \fB-case\fR \fR?\fIvalue\fR?\fR
If set to 0 (zero), the generated scanner will be case-insensitive
(i.e. \fB-nocase\fR will be used on all calls to \fBregexp\fR). The
default value is 1 for a case-sensitive scanner. This setting can be
overridden on a rule-by-rule basis using the \fB-nocase\fR option upon
adding a rule.
.SH SCANNER USAGE
.PP
Scanners are independent of \fBylex\fR, their only dependency is on
\fB[incr Tcl]\fR.
.PP
A scanner reads its input from a string that must be set before
scanning can begin. The regular expressions (rules) are then
repeatedly matched against the current input position within this
string. If more than one regular expression matches text at a certain
position, the rule matching the most text is selected. If more than
one regular expression matches the same amount of text, the rule that
was added to the scanner generator first is selected. If a rule
matches, its associated \fIscript\fR is executed, and the read pointer
is moved beyond the match. Unmatched text in the input is ignored and
skipped.
.PP
Scanners are \fB[incr Tcl]\fR objects, so its usual rules of object
handling (e.g. deletion of scanners) apply.
.SH SCANNER COMMANDS
.TP
\fIscannerName\fR \fIobjName\fR \fR?\fIoptions\fR?\fR
Creates a new scanner instance by the name of \fIobjName\fR.
\fIoptions\fR can be used to configure the scanner's public variables,
see the \fIscanner variables\fR section below.
.SH SCANNER METHODS
.TP
\fIobjName\fR \fBstart\fR \fIstring\fR
Initializes the scanner to scan \fIstring\fR. Calling \fBstart\fR
implies \fBreset\fR.
.TP
\fIobjName\fR \fBreset\fR
Resets the scanner to the beginning of the input string, and resets
the state to the initial state. If you want to scan a different
string, you need not call \fBreset\fR but only \fBstart\fR.
.TP
\fIobjName\fR \fBnext\fR
Starts the scanning process. Regular expressions are matched, and
their scripts are executed. This repeats until a script executes
\fBreturn\fR or until end of input is reached. If a script executes
\fBreturn\fR, the script's return value is returned. At the end of
input, an empty string is returned.
.TP
\fIobjName\fR \fBstep\fR
Single-steps the parser. This method returns after a single match has
been done, regardless of whether its script executed \fBreturn\fR or
not. \fBstep\fR returns a list of length three. The first element of
this list is the number of the rule that was matched or -1 if at the
end of input. The second element is 1 if the script executed
\fBreturn\fR, 0 otherwise. The third element is the script's return
value if the script executed \fBreturn\fR, empty otherwise.
.TP
\fIobjName\fR \fBrun\fR
Runs the scanning process to completion. \fBnext\fR is repeatedly
called until the end of input has been reached. A list of all the
results returned from \fBnext\fR is returned.
.SH SCANNER VARIABLES
.TP
\fIobjName\fR \fBconfigure\fR \fB-case\fR \fR?\fIvalue\fR?\fR
If this variable is zero, then the \fB-nocase\fR option is
implicitly set for all rules. The default value is determined by the
setting of the \fBcase\fR variable in the scanner generator. Setting
this variable after scanning has started may yield unexpected results
because of cached data.
.TP
\fIobjName\fR \fBconfigure\fR \fB-yydata\fR \fR?\fIvalue\fR?\fR
This variable holds the input string. This variable is not meant to be
modified, but it can be conveniently configured upon object
creation. If that is done, there is no need to call the \fBstart\fR
method.
.TP
\fIobjName\fR \fBconfigure\fR \fB-yyindex\fR \fR?\fIvalue\fR?\fR
This variable holds the current index into the input string. This
variable is not meant to be set, but reading it may be useful
e.g. to determine the position that causes an error in a parser. After
an invocation \fBstep\fR or \fBnext\fR, \fByyindex\fR points to the
character after the current match.
.TP
\fIobjName\fR \fBconfigure\fR \fB-verbose\fR \fR?\fIvalue\fR?\fR
If this value is non-zero, the scanner prints debug information about
its processing. The larger \fBverbose\fR is, the more information is
printed (sensible values are 0 to 3). By default, no debug information
is printed.
.TP
\fIobjName\fR \fBconfigure\fR \fB-verbout\fR \fR?\fIvalue\fR?\fR
This variable contains the channel that is used for debug output. By
default, this is \fBstderr\fR.
.SH SCRIPTS
.PP
Scripts are executed in the context of the scanner. Scripts have
access to the following variables.
.TP
\fByytext\fR
This variable contains the text that was matched by the regular
expression.
.TP
\fByystate\fR
This variable contains the current state of the scanner. The script may
modify this variable to switch the scanner to a different state.
.TP
\fByystart\fR
The absolute index of the first character of the current match.
.TP
\fByyend\fR
The absolute index of the last character of the current match.
.TP
\fI<i>\fR
These variables (\fB$1\fR, \fB$2\fR ...) contain any subexpressions
matched by the regular expression.
.PP
\fBylex\fR reserves names with the \fByy\fR prefix, so scripts should
not use or access variables with this prefix other than those
documented here. Also, a scanner's public methods and variables as
seen above must be respected.
.SH STATES
.PP
Initially, a scanner is in the initial state as determined by the
\fBstart\fR variable of the scanner generator. Scripts can switch to a
different state by modifying the \fByystate\fR variable during
execution of a script. In each state, only a subset of all
rules will be considered, as determined by the \fB-state\fR or
\fB-states\fR options upon adding rules to the scanner generator; if
no such option was used when adding a rule, it will be active in all
states.
.SH NOTES
.PP
Unmatched text in the input is ignored. In order to throw an error
upon unmatched text, add a "catch-all" rule at the end of the rule
set (usually with the regular expression "." that matches any
character).
.PP
Subexpressions are available in the \fI$<i>\fR variables only when
using Tcl 8.3 or above.
.PP
It is illegal to have rules that match the empty string.
.SH TODO
.PP
There should be a means of reading data from elsewhere than a
string. It might be inconvenient to have all the input in
memory. However, that is not possible with the current regexp engine.
.PP
Maybe there should be the possibility to read a lex-like input file.
.SH KEYWORDS
scanner, parser, token

#
# ======================================================================
#
# YLEX -- Scanner for the Yeti Package
#
# A (f)lex-like parser for Tcl
#
# Copyright (c) Frank Pilhofer, yeti@fpx.de
#
# ======================================================================
#
# CVS Version Tag: $Id: ylex.tcl,v 1.8 2004/07/05 23:46:49 fp Exp $
#

package require Tcl 8.0
package require Itcl
package provide ylex 0.4.2

#
# ----------------------------------------------------------------------
# The Yeti Lexer
# ----------------------------------------------------------------------
#

namespace eval yeti {
    namespace import -force ::itcl::*
    class ylex {
	#
        # nocase:     whether we want -nocase on all regexps
	#

        public variable case
        public variable verbose
	public variable verbout
	public variable start

	#
	# ruleno:   integer for rule numbering
	# rules:    list of all active rules
	# regexs:   map rule# -> regular expression
	# igncase:  map rule# -> 1 if case should be ignored
	# codes:    map rule# -> user code to execute upon match
	# states:   map name -> list of active rules
	# macros:   map name  -> regular expression
	#

	private variable ruleno
	private variable rules
	private variable regexs
	private variable igncase
	private variable codes
	private variable states
	private variable macros

	#
	# user code to be dumped
	#

	public variable name
	private variable usercode
	private variable userconstrcode
	private variable userdestrcode
	private variable usererrorcode
	private variable userresetcode

	#
	# ============================================================
	# Constructor
	# ============================================================
	#

	constructor {args} {
	    set ruleno 0
	    set case 1
	    set verbose 0
	    set verbout stderr
	    set name "unnamed"
	    set start "INITIAL"
	    eval $this configure $args
	}

	#
	# ============================================================
	# Macro handling
	# ============================================================
	#

	private method substitute_macros {regex} {
	    #
	    # try to find {name} in regex
	    #

	    set hasmacro [regexp -indices {<[[:alnum:]_]+>} $regex found]

	    while {$hasmacro} {
		set begin [lindex $found 0]
		set end [lindex $found 1]
		set macroname [string range $regex \
			[expr {$begin + 1}] [expr {$end - 1}]]
		if {![info exists macros($macroname)]} {
		    error "undefined macro: $macroname"
		}

		#
		# substitute this macro
		#

		set regex [string replace $regex \
			$begin $end \
			"(?:$macros($macroname))"]

		#
		# repeat
		#

		set hasmacro [regexp -indices {<[[:alnum:]_]+>} $regex found]
	    }

	    return $regex
	}

	public method macro {args} {
	    #
	    # There may be a single list of names and regexs
	    #

	    if {[llength $args] == 1} {
		set args [lindex $args 0]
	    }

	    #
	    # Number of args must be positive and even
	    #

	    if {[llength $args] == 0 || ([llength $args] % 2) != 0} {
		error "usage: $this macro name regex ?name regex ...?"
	    }

	    foreach {macroname regex} $args {
		set macros($macroname) [substitute_macros $regex]

		if {$verbose > 1} {
		    puts $verbout "ylex: macro `$macroname' expands to `$macros($macroname)'"
		}
	    }
	}

	#
	# ============================================================
	# Rule handling
	# ============================================================
	#

	public method add {args} {
	    set doigncase 0

	    for {set i 0} {$i < [llength $args]} {incr i} {
		set arg [lindex $args $i]
		switch -glob -- $arg {
		    -nocase {
			set doigncase 1
		    }
		    -state {
			lappend thestates [lindex $args [incr i]]
		    }
		    -states {
			foreach thestate [lindex $args [incr i]] {
			    lappend thestates $thestate
			}
		    }
		    -- {
			incr i
			break
		    }
		    -* {
			error "illegal option: $arg"
		    }
		    default {
			break
		    }
		}
	    }

	    #
	    # One remaining argument can be a list of regexs and codes
	    #

	    if {$i+1 == [llength $args]} {
		set args [lindex $args $i]
		set i 0
	    }

	    #
	    # There must be an even, positive number of remaining args
	    #

	    if {$i >= [llength $args] || (([llength $args] - $i) % 2) != 0} {
		error "usage: $this add ?options? regex script ?regex script ...?"
	    }

	    for {} {$i < [llength $args]} {incr i} {
		set orig_regex [lindex $args $i]
		set code [lindex $args [incr i]]

		set regex [substitute_macros $orig_regex]

		#
		# check if regular expression is valid
		#

		if {[catch {regexp -- $regex "Hello World"}]} {
		    error "syntax error in regular expression `$regex'"
		}

		#
		# sanity check: the regular expression must not match the
		# empty string.
		#

		if {[regexp -- $regex ""]} {
		    error "regular expression `$regex' matches empty string"
		}

		#
		# check that there are no unbalanced unquoted braces
		#

		set quoted 0
		set brlevel 0

		for {set j 0} {$j < [string length $regex]} {incr j} {
		    set c [string index $regex $j]
		    if {$quoted} {
			set quoted 0
			continue
		    } elseif {[string equal $c "\\"]} {
			set quoted 1
			continue
		    } elseif {[string equal $c \{]} {
			incr brlevel
		    } elseif {[string equal $c \}]} {
			if {[incr brlevel -1] < 0} {
			    error "extra characters after close-brace in regular expression `$regex'"
			}
		    }
		}

		if {$brlevel != 0} {
		    error "missing close brace in regular expression `$regex'"
		}

		#
		# add to rule set
		#

		lappend rules [incr ruleno]
		set regexs($ruleno) $regex
		set igncase($ruleno) $doigncase

		if {[info exists thestates]} {
		    foreach thestate $thestates {
			lappend states($thestate) $ruleno
		    }
		} else {
		    lappend states(__all__) $ruleno
		}

		if {$code != "" && $code != "-"} {
		    set codes($ruleno) $code
		}

		if {$verbose > 1} {
		    puts $verbout "ylex: rule $ruleno `$orig_regex' expands to `$regex'"
		}
	    }

	    return $ruleno
	}

	#
	# ============================================================
	# Code handling
	# ============================================================
	#

	public method code {type thecode} {
	    switch -- $type {
		public -
		private -
		protected {
		    lappend usercode $type $thecode
		}
		constructor {
		    set userconstrcode $thecode
		}
		destructor {
		    set userdestrcode $thecode
		}
		error {
		    set usererrorcode $thecode
		}
		reset {
		    set userresetcode $thecode
		}
	    }
	}

	#
	# ============================================================
	# Dump generated Scanner
	# ============================================================
	#

	public method dump {} {
	    #
	    # Create scanner code
	    #

	    append data "itcl::class $name {\n"
	    append data "    public variable case $case\n"
	    append data "    public variable verbose 0\n"
	    append data "    public variable verbout stderr\n"
	    append data "    private variable yyistcl83 -1\n"
	    append data "\n"
	    append data "    public variable yydata \"\"\n"
	    append data "    public variable yyindex 0\n"
	    append data "    private variable yymatches\n"
	    append data "\n"
	    append data "    public variable yystate \"$start\"\n"
	    append data "    public variable yytext\n"
	    append data "    public variable yystart\n"
	    append data "    public variable yyend\n"
	    append data "\n"
	    append data "    private common yyregexs\n"
	    append data "    private common yyigncase\n"
	    append data "    private common yystates\n"
	    append data "\n"

	    #
	    # yyregexs:   map rule# -> regular expression
	    #

	    append data "    array set yyregexs {\n"

	    foreach ruleno [lsort -integer [array names regexs]] {
		append data "        $ruleno {$regexs($ruleno)}\n"
	    }

	    append data "    }\n"
	    append data "\n"

	    #
	    # yyigncase:  map rule# -> 1 if case should be ignored
	    #

	    append data "    array set yyigncase {\n"

	    foreach ruleno [lsort -integer [array names regexs]] {
		if {[info exists igncase($ruleno)]} {
		    append data "        $ruleno $igncase($ruleno)\n"
		} else {
		    append data "        $ruleno 0\n"
		}
	    }

	    append data "    }\n"
	    append data "\n"

	    #
	    # yystates: map name -> list of active rules
	    #

	    append data "    array set yystates {\n"

	    set hadall 0
	    foreach statename [lsort [array names states]] {
		append data "        $statename {\n"
		foreach ruleno $states($statename) {
		    append data "            $ruleno\n"
		}
		append data "        }\n"
		if {$statename == "__all__"} {
		    set hadall 1
		}
	    }

	    if {!$hadall} {
		append data "        __all__ {\n"
		append data "        }\n"
	    }

	    append data "    }\n"
	    append data "\n"

	    #
	    # user code
	    #

	    if {[info exists usercode]} {
		foreach {type thecode} $usercode {
		    append data "    $type {\n"
		    append data $thecode "\n"
		    append data "    }\n"
		    append data "\n"
		}
	    }

	    #
	    # constructor
	    #

	    if {[info exists userconstrcode]} {
		append data "    constructor " $userconstrcode "\n"
	    } else {
		append data "    constructor {args} {\n"
		append data "        eval \$this configure \$args\n"
		append data "    }\n"
		append data "    \n"
	    }

	    #
	    # destructor
	    #

	    if {[info exists userdestrcode]} {
		append data "    destructor " $userdestrcode "\n"
	    }

	    #
	    # reset
	    #

	    append data "    public method reset {} {\n"
	    append data "        if {\$verbose} {\n"
	    append data "            puts \$verbout \"$name: reset, entering state INITIAL\"\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yyindex 0\n"
	    append data "        set yystate \"$start\"\n"
	    append data "        catch {unset yymatches}\n"

	    if {[info exists userresetcode]} {
		append data "\n" $userresetcode "\n"
	    }

	    append data "    }\n"
	    append data "    \n"

	    #
	    # start
	    #

	    append data "    public method start {yynewstr} {\n"
	    append data "        reset\n"
	    append data "        set yydata \$yynewstr\n"
	    append data "    }\n"
	    append data "    \n"

	    #
	    # yyerror: overloadable error handling
	    #

	    append data "    protected method yyerror {yyerrmsg} {\n"

	    if {[info exists usererrorcode]} {
		append data $usererrorcode "\n"
	    } else {
		append data "        puts \$verbout \"$name: \$yyerrmsg\"\n"
	    }

	    append data "    }\n"
	    append data "    \n"

	    #
	    # yyupdate: check all regexps for the next match
	    #           returns rule for next best match
	    #

	    append data "    private method yyupdate {} {\n"
	    append data "        if {\$yyistcl83 == -1} {\n"
	    append data "            if {\[package vcompare \[info tclversion\] 8.3\] >= 0} {\n"
	    append data "                set yyistcl83 1\n"
	    append data "            } else {\n"
	    append data "                set yyistcl83 0\n"
	    append data "            }\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yybestmatch -1\n"
	    append data "        set yybestbegin \[string length \$yydata\]\n"
	    append data "        set yybestend   \$yybestbegin\n"
	    append data "        \n"
	    append data "        if {\$verbose >= 2} {\n"
	    append data "            set yycurdata \[string range \$yydata \$yyindex \[expr {\$yyindex + 16}\]\]\n"
	    append data "            set yycurout \[string map {\\r \\\\r \\n \\\\n} \$yycurdata\]\n"
	    append data "            if {\$yyindex + 16 < \[string length \$yydata\]} {\n"
	    append data "                append yycurout \"...\"\n"
	    append data "            }\n"
	    append data "            puts \$verbout \"$name: looking for match at position \$yyindex: `\$yycurout'\"\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        if {\[info exists yystates(\$yystate)\]} {\n"
	    append data "            set yyruleset \[concat \$yystates(\$yystate) \$yystates(__all__)\]\n"
	    append data "        } else {\n"
	    append data "            set yyruleset \$yystates(__all__)\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        if {\[llength \$yyruleset\] == 0} {\n"
	    append data "            if {\$verbose} {\n"
	    append data "                puts \$verbout \"$name: no active rules in state \$yystate\"\n"
	    append data "            }\n"
	    append data "        }\n"
	    set updatecode {

        foreach yyruleno $yyruleset {
            #
            # if the last match is in the past, rerun regexp
            #

            if {![info exists yymatches($yyruleno)] || \
                    [lindex [lindex $yymatches($yyruleno) 0] 0] < $yyindex} {
                if {$yyistcl83} {
                    if {!$case || $yyigncase($yyruleno)} {
                        set yyfound [regexp -nocase -start $yyindex \
                                -inline -indices -- \
                                $yyregexs($yyruleno) $yydata]
                    } else {
                        set yyfound [regexp -start $yyindex \
                                -inline -indices -- \
                                $yyregexs($yyruleno) $yydata]
                    }
                } else {
                    if {!$case || $yyigncase($yyruleno)} {
                        set yyres [regexp -nocase -start $yyindex \
                                -indices -- $yyregexs($yyruleno) \
                                $yydata yyfound]
                    } else {
                        set yyres [regexp -start $yyindex \
                                -indices -- $yyregexs($yyruleno) \
                                $yydata yyfound]
                    }

                    if {!$yyres} {
                        set yyfound [list]
                    } else {
                        set yyfound [list $yyfound]
                    }
                }

                if {[llength $yyfound] > 0} {
                    set yymatches($yyruleno) $yyfound
                } else {
                    set yymatches($yyruleno) [list \
                        [string length $yydata] \
                        [string length $yydata]]
                }

                if {$verbose >= 3 && [llength $yymatches($yyruleno)] > 0} {
                    set yymatchbegin [lindex [lindex $yymatches($yyruleno) 0] 0]
                    set yymatchend [lindex [lindex $yymatches($yyruleno) 0] 1]
                    if {$yymatchbegin != [string length $yydata]} {
                        set yymatchdata [string range $yydata $yymatchbegin $yymatchend]
			set yymatchout [string map {\r "\\r" \n "\\n"} $yymatchdata]
			if {[string length $yymatchout] > 20} {
			    set yymatchout [string range $yymatchout 0 16]
			    append yymatchout "..."
			}
                        puts $verbout "%name%: next match for rule $yyruleno is $yymatchbegin-$yymatchend: `$yymatchout'"
                    } else {
                        puts $verbout "%name%: rule $yyruleno does not match anwhere in remaining text"
		    }
                }
            }

            #
            # see if the match is better than the one we already have
            #

            set yymatchbegin [lindex [lindex $yymatches($yyruleno) 0] 0]
            set yymatchend [lindex [lindex $yymatches($yyruleno) 0] 1]

            if {($yymatchbegin < $yybestbegin) || \
                    ($yymatchbegin == $yybestbegin && $yymatchend > $yybestend)} {
                set yybestmatch $yyruleno
                set yybestbegin $yymatchbegin
                set yybestend   $yymatchend

                if {$verbose >= 2} {
                    set yybestdata [string range $yydata $yybestbegin $yybestend]
		    set yymatchout [string map {\r "\\r" \n "\\n"} $yybestdata]
		    if {[string length $yymatchout] > 20} {
			set yymatchout [string range $yymatchout 0 16]
			append yymatchout "..."
		    }
                    puts $verbout "%name%: new best match rule $yyruleno, $yybestbegin-$yybestend: `$yymatchout'"
                }
            }
        }
            }

	    append data [string map [list %name% $name] $updatecode]

	    append data "        \n"
	    append data "        return \$yybestmatch\n"
	    append data "    }\n"
	    append data "    \n"

	    #
	    # step
	    #

	    append data "    public method step {} {\n"
	    append data "        if {\$yyindex >= \[string length \$yydata\]} {\n"
	    append data "            if {\$verbose} {\n"
	    append data "                puts \$verbout \"$name: scanner at EOF\"\n"
	    append data "            }\n"
	    append data "            return \[list -1 1 \"\"\]\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yyruleno \[yyupdate\]\n"
	    append data "        \n"
	    append data "        if {\$yyruleno == -1} {\n"
	    append data "            if {\$verbose} {\n"
	    append data "                puts \$verbout \"$name: no further match until EOF\"\n"
	    append data "            }\n"
	    append data "            set yyindex \[string length \$yydata\]\n"
	    append data "            return \[list -1 1 \"\"\]\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yymatch \$yymatches(\$yyruleno)\n"
	    append data "        set yyindices \[lindex \$yymatch 0\]\n"
	    append data "        set yystart \[lindex \$yyindices 0\]\n"
	    append data "        set yyend \[lindex \$yyindices 1\]\n"
	    append data "        set yytext \[string range \$yydata \$yystart \$yyend\]\n"
	    append data "        \n"
	    append data "        if {\$verbose} {\n"
	    append data "            set yymatchout \[string map {\\r \\\\r \\n \\\\n} \$yytext\]\n"
	    append data "            if {\[string length \$yymatchout] > 20} {\n"
	    append data "                set yymatchout \[string range \$yymatchout 0 16\]\n"
	    append data "                append yymatchout \"...\"\n"
	    append data "            }\n"
	    append data "            puts \$verbout \"$name: best match at \$yyindex using rule \$yyruleno, \$yystart-\$yyend: `\$yymatchout'\"\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        set yyindex \[expr {\$yyend + 1}\]\n"
	    append data "        \n"

	    #
	    # Set $1, $2 ... to the submatches. We start at index
	    # zero, because the first list element is the complete
	    # match.
	    #

	    append data "        for {set yyi 0} {\$yyi < \[llength \$yymatch\]} {incr yyi} {\n"
	    append data "            set yysubidxs  \[lindex \$yymatch \$yyi\]\n"
	    append data "            set yysubbegin \[lindex \$yysubidxs 0\]\n"
	    append data "            set yysubend   \[lindex \$yysubidxs 1\]\n"
	    append data "            set \$yyi \[string range \$yydata \$yysubbegin \$yysubend\]\n"
	    append data "        }\n"
	    append data "        \n"

	    #
	    # exec user code
	    #

	    append data "        set yyoldstate \$yystate\n"
	    append data "        set yyretcode \[catch {\n"
	    append data "            switch -- \$yyruleno {\n"
	    foreach ruleno [lsort -integer [array names codes]] {
		append data "                $ruleno {\n"
		append data $codes($ruleno) "\n"
		append data "                }\n"
	    }
	    append data "            }\n"
	    append data "        } yyretdata\]\n"
	    append data "        \n"

	    #
	    # enter new state
	    #

	    append data "        if {\$verbose} {\n"
	    append data "            if {!\[string match \$yyoldstate \$yystate\]} {\n"
	    append data "                puts \$verbout \"$name: leaving state \$yyoldstate, entering \$yystate\"\n"
	    append data "            }\n"
	    append data "        }\n"
	    append data "        \n"

	    #
	    # did the user code throw an error?
	    #

	    append data "        if {\$yyretcode == 1} {\n"
	    append data "            global errorInfo\n"
	    append data "            set yyerrmsg \"script for rule # \$yyruleno failed: \$yyretdata\"\n"
	    append data "            yyerror \$yyerrmsg\n"
	    append data "            append errorInfo \"\\n    while executing script for rule # \$yyruleno\"\n"
	    append data "            error \$yyerrmsg \$errorInfo\n"
	    append data "        }\n"
	    append data "        \n"

	    #
	    # did the user code execute a return?
	    #

	    append data "        if {\$yyretcode == 2} {\n"
	    append data "            return \[list \$yyruleno 1 \$yyretdata\]\n"
	    append data "        }\n"
	    append data "        \n"
	    append data "        return \[list \$yyruleno 0 \"\"\]\n"
	    append data "    }\n"
	    append data "    \n"

	    #
	    # next
	    #

	    append data "    public method next {} {\n"
	    append data "        while {42} {\n"
	    append data "            set yysd \[step\]\n"
	    append data "            if {\[lindex \$yysd 1\] == 1} {\n"
	    append data "                return \[lindex \$yysd 2\]\n"
	    append data "            }\n"
	    append data "        }\n"
	    append data "    }\n"
	    append data "    \n"

	    #
	    # run
	    #

	    append data "    public method run {} {\n"
	    append data "        set yyresult \[list\]\n"
	    append data "        set yysd \[next\]\n"
	    append data "        while {\$yysd != \"\"} {\n"
	    append data "            lappend yyresult \$yysd\n"
	    append data "            set yysd \[next\]\n"
	    append data "        }\n"
	    append data "        return \$yyresult\n"
	    append data "    }\n"

	    #
	    # end of class
	    #

	    append data "}\n"
	    append data "\n"
	}
    }
}