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.\" ========================================================================
.\"
.IX Title "TREEREG 1"
.TH TREEREG 1 "2017-06-14" "perl v5.34.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
treereg \- Compiler for Tree Regular Expressions
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 6
\&  treereg [\-m packagename] [[no]syntax] [[no]numbers] [\-severity 0|1|2|3] \e
\&          [\-p treeprefix] [\-o outputfile] [\-lib /path/to/library/] \-i filename[.trg] 
\&  treereg [\-m packagename] [[no]syntax] [[no]numbers] [\-severity 0|1|2|3] \e
\&          [\-p treeprefix] [\-lib /path/to/library/] [\-o outputfile] filename[.trg] 
\&  treereg \-v 
\&  treereg \-h
.Ve
.SH "OPTIONS"
.IX Header "OPTIONS"
Options can be used both with one dash and double dash.
It is not necessary to write the full name of the option.
A disambiguation prefix suffices.
.IP "\(bu" 4
\&\f(CW\*(C`\-i[n] filename\*(C'\fR
.Sp
Input file. Extension \f(CW\*(C`.trg\*(C'\fR is assumed if no extension is provided.
.IP "\(bu" 4
\&\f(CW\*(C`\-o[ut] filename\*(C'\fR
.Sp
Output file. By default is the name of the input file (concatenated with .pm)
.IP "\(bu" 4
\&\f(CW\*(C`\-m[od] packagename\*(C'\fR
.Sp
Name of the package containing the generated subroutines. 
By default is the longest prefix of the input file name that
conforms to the classic definition of integer \f(CW\*(C`[a\-z_A\-Z]\ew*\*(C'\fR.
.IP "\(bu" 4
\&\f(CW\*(C`\-l[ib] /path/to/library/\*(C'\fR
.Sp
Specifies that \f(CW\*(C`/path/to/library/\*(C'\fR will be included in \f(CW@INC\fR.
Useful when the \f(CW\*(C`syntax\*(C'\fR option is on. Can be inserted as many times as necessary.
.IP "\(bu" 4
\&\f(CW\*(C`\-p[refix] treeprefix\*(C'\fR
.Sp
Tree nodes automatically generated using \f(CW\*(C`Parse::Eyapp\*(C'\fR are objects blessed 
into the name of the production. To avoid crashes the programmer may prefix 
the class names with a given prefix when calling the parser; for example:
.Sp
.Vb 1
\&  $self\->YYParse( yylex => \e&_Lexer, yyerror => \e&_Error, yyprefix => _\|_PACKAGE_\|_."::")
.Ve
.Sp
The \f(CW\*(C`\-prefix treeprefix\*(C'\fR option simplifies the process of writing the tree 
grammar so that instead of writing with the full names
.Sp
.Vb 1
\& CLASS::TIMES(CLASS::NUM, $x) and { $NUM\->{VAL} == 0) => { $NUM }
.Ve
.Sp
it can be written:
.Sp
.Vb 1
\& TIMES(NUM, $x) and { $NUM\->{VAL} == 0) => { $NUM }
.Ve
.IP "\(bu" 4
\&\f(CW\*(C`\-n[umbers]\*(C'\fR
.Sp
Produces \f(CW\*(C`#line\*(C'\fR directives.
.IP "\(bu" 4
\&\f(CW\*(C`\-non[umbers]\*(C'\fR
.Sp
Disable source file line numbering embedded in your parser
.IP "\(bu" 4
\&\f(CW\*(C`\-sy[ntax]\*(C'\fR
.Sp
Checks that Perl code is syntactically correct.
.IP "\(bu" 4
\&\f(CW\*(C`\-nosy[ntax]\*(C'\fR
.Sp
Does not check the syntax of Perl code
.IP "\(bu" 4
\&\f(CW\*(C`\-se[verity] number\*(C'\fR
.RS 4
.IP "\- 0 = Don't  check arity (default). Matching does not check the arity. The actual node being visited may have more children." 2
.IX Item "- 0 = Don't check arity (default). Matching does not check the arity. The actual node being visited may have more children."
.PD 0
.IP "\- 1 = Check arity. Matching requires the equality of the number of children and the actual node and the pattern." 2
.IX Item "- 1 = Check arity. Matching requires the equality of the number of children and the actual node and the pattern."
.IP "\- 2 = Check arity and give a warning" 2
.IX Item "- 2 = Check arity and give a warning"
.IP "\- 3 = Check arity, give a warning and exit" 2
.IX Item "- 3 = Check arity, give a warning and exit"
.RE
.RS 4
.RE
.IP "\(bu" 4
.PD
\&\f(CW\*(C`\-v[ersion]\*(C'\fR
.Sp
Gives the version
.IP "\(bu" 4
\&\f(CW\*(C`\-u[sage]\*(C'\fR
.Sp
Prints the usage info
.IP "\(bu" 4
\&\f(CW\*(C`\-h[elp]\*(C'\fR
.Sp
Print this help
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\f(CW\*(C`Treereg\*(C'\fR translates a tree grammar specification
file (default extension \f(CW\*(C`.trg\*(C'\fR describing 
a set of tree patterns
and the actions to modify them 
using tree-terms like:
.PP
.Vb 1
\&  TIMES(NUM, $x) and { $NUM\->{VAL} == 0) => { $NUM }
.Ve
.PP
which says that wherever an abstract syntax tree representing
the product of a numeric expression with value 0 times
any other kind of expression, the \f(CW\*(C`TIMES\*(C'\fR tree can be substituted by
its left child.
.PP
The compiler produces a Perl module containing the subroutines
implementing those sets of pattern-actions.
.SH "EXAMPLE"
.IX Header "EXAMPLE"
Consider the following \f(CW\*(C`eyapp\*(C'\fR grammar (see the \f(CW\*(C`Parse::Eyapp\*(C'\fR documentation
to know more about \f(CW\*(C`Parse::Eyapp\*(C'\fR grammars):
.PP
.Vb 10
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&  nereida:~/LEyapp/examples> cat Rule6.yp
\&  %{
\&  use Data::Dumper;
\&  %}
\&  %right  \*(Aq=\*(Aq
\&  %left   \*(Aq\-\*(Aq \*(Aq+\*(Aq
\&  %left   \*(Aq*\*(Aq \*(Aq/\*(Aq
\&  %left   NEG
\&  %tree
\&
\&  %%
\&  line: exp  { $_[1] }
\&  ;
\&
\&  exp:      %name NUM
\&              NUM
\&          | %name VAR
\&            VAR
\&          | %name ASSIGN
\&            VAR \*(Aq=\*(Aq exp
\&          | %name PLUS
\&            exp \*(Aq+\*(Aq exp
\&          | %name MINUS
\&            exp \*(Aq\-\*(Aq exp
\&          | %name TIMES
\&            exp \*(Aq*\*(Aq exp
\&          | %name DIV
\&            exp \*(Aq/\*(Aq exp
\&          | %name UMINUS
\&            \*(Aq\-\*(Aq exp %prec NEG
\&          |   \*(Aq(\*(Aq exp \*(Aq)\*(Aq  { $_[2] } /* Let us simplify a bit the tree */
\&  ;
\&
\&  %%
\&
\&  sub _Error {
\&      die  "Syntax error.\en";
\&  }
\&
\&  sub _Lexer {
\&      my($parser)=shift;
\&
\&          $parser\->YYData\->{INPUT}
\&      or  $parser\->YYData\->{INPUT} = <STDIN>
\&      or  return(\*(Aq\*(Aq,undef);
\&
\&      $parser\->YYData\->{INPUT}=~s/^\es+//;
\&
\&      for ($parser\->YYData\->{INPUT}) {
\&          s/^([0\-9]+(?:\e.[0\-9]+)?)// and return(\*(AqNUM\*(Aq,$1);
\&          s/^([A\-Za\-z][A\-Za\-z0\-9_]*)// and return(\*(AqVAR\*(Aq,$1);
\&          s/^(.)//s and return($1,$1);
\&      }
\&  }
\&
\&  sub Run {
\&      my($self)=shift;
\&      $self\->YYParse( yylex => \e&_Lexer, yyerror => \e&_Error );
\&  }
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.Ve
.PP
Compile it using \f(CW\*(C`eyapp\*(C'\fR:
.PP
.Vb 5
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&  nereida:~/LEyapp/examples> eyapp Rule6.yp
\&  nereida:~/LEyapp/examples> ls \-ltr | tail \-1
\&  \-rw\-rw\-\-\-\-  1 pl users  4976 2006\-09\-15 19:56 Rule6.pm
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.Ve
.PP
Now consider this tree grammar:
.PP
.Vb 5
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&  nereida:~/LEyapp/examples> cat Transform2.trg
\&  %{
\&  my %Op = (PLUS=>\*(Aq+\*(Aq, MINUS => \*(Aq\-\*(Aq, TIMES=>\*(Aq*\*(Aq, DIV => \*(Aq/\*(Aq);
\&  %}
\&
\&  fold: \*(AqTIMES|PLUS|DIV|MINUS\*(Aq:bin(NUM($n), NUM($m))
\&    => {
\&      my $op = $Op{ref($bin)};
\&      $n\->{attr} = eval  "$n\->{attr} $op $m\->{attr}";
\&      $_[0] = $NUM[0];
\&    }
\&  zero_times_whatever: TIMES(NUM($x), .) and { $x\->{attr} == 0 } => { $_[0] = $NUM }
\&  whatever_times_zero: TIMES(., NUM($x)) and { $x\->{attr} == 0 } => { $_[0] = $NUM }
\&
\&  /* rules related with times */
\&  times_zero = zero_times_whatever whatever_times_zero;
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.Ve
.PP
Compile it with \f(CW\*(C`treereg\*(C'\fR:
.PP
.Vb 5
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&  nereida:~/LEyapp/examples> treereg Transform2.trg
\&  nereida:~/LEyapp/examples> ls \-ltr | tail \-1
\&  \-rw\-rw\-\-\-\-  1 pl users  1948 2006\-09\-15 19:57 Transform2.pm
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.Ve
.PP
The following program makes use of both modules \f(CW\*(C`Rule6.pm\*(C'\fR
and \f(CW\*(C`Transform2.pm\*(C'\fR:
.PP
.Vb 8
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&  nereida:~/LEyapp/examples> cat foldand0rule6_3.pl
\&  #!/usr/bin/perl \-w
\&  use strict;
\&  use Rule6;
\&  use Parse::Eyapp::YATW;
\&  use Data::Dumper;
\&  use Transform2;
\&
\&  $Data::Dumper::Indent = 1;
\&  my $parser = new Rule6();
\&  my $t = $parser\->Run;
\&  print "\en***** Before ******\en";
\&  print Dumper($t);
\&  $t\->s(@Transform2::all);
\&  print "\en***** After ******\en";
\&  print Dumper($t);
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.Ve
.PP
When the program runs with input \f(CW\*(C`b*(2\-2)\*(C'\fR produces the following output:
.PP
.Vb 3
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&  nereida:~/LEyapp/examples> foldand0rule6_3.pl
\&  b*(2\-2)
\&
\&  ***** Before ******
\&  $VAR1 = bless( {
\&    \*(Aqchildren\*(Aq => [
\&      bless( {
\&        \*(Aqchildren\*(Aq => [
\&          bless( { \*(Aqchildren\*(Aq => [], \*(Aqattr\*(Aq => \*(Aqb\*(Aq, \*(Aqtoken\*(Aq => \*(AqVAR\*(Aq }, \*(AqTERMINAL\*(Aq )
\&        ]
\&      }, \*(AqVAR\*(Aq ),
\&      bless( {
\&        \*(Aqchildren\*(Aq => [
\&          bless( { \*(Aqchildren\*(Aq => [
\&              bless( { \*(Aqchildren\*(Aq => [], \*(Aqattr\*(Aq => \*(Aq2\*(Aq, \*(Aqtoken\*(Aq => \*(AqNUM\*(Aq }, \*(AqTERMINAL\*(Aq )
\&            ]
\&          }, \*(AqNUM\*(Aq ),
\&          bless( {
\&            \*(Aqchildren\*(Aq => [
\&              bless( { \*(Aqchildren\*(Aq => [], \*(Aqattr\*(Aq => \*(Aq2\*(Aq, \*(Aqtoken\*(Aq => \*(AqNUM\*(Aq }, \*(AqTERMINAL\*(Aq )
\&            ]
\&          }, \*(AqNUM\*(Aq )
\&        ]
\&      }, \*(AqMINUS\*(Aq )
\&    ]
\&  }, \*(AqTIMES\*(Aq );
\&
\&  ***** After ******
\&  $VAR1 = bless( {
\&    \*(Aqchildren\*(Aq => [
\&      bless( { \*(Aqchildren\*(Aq => [], \*(Aqattr\*(Aq => 0, \*(Aqtoken\*(Aq => \*(AqNUM\*(Aq }, \*(AqTERMINAL\*(Aq )
\&    ]
\&  }, \*(AqNUM\*(Aq );
\&  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.Ve
.PP
See also the section \*(L"Compiling: More Options\*(R" in Parse::Eyapp  for a more
contrived example.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
.IP "\(bu" 4
Parse::Eyapp,
.IP "\(bu" 4
eyapptut
.IP "\(bu" 4
The pdf file in <http://nereida.deioc.ull.es/~pl/perlexamples/Eyapp.pdf>
.IP "\(bu" 4
<http://nereida.deioc.ull.es/~pl/perlexamples/section_eyappts.html> (Spanish),
.IP "\(bu" 4
eyapp,
.IP "\(bu" 4
treereg,
.IP "\(bu" 4
Parse::yapp,
.IP "\(bu" 4
\&\fByacc\fR\|(1),
.IP "\(bu" 4
\&\fBbison\fR\|(1),
.IP "\(bu" 4
the classic book \*(L"Compilers: Principles, Techniques, and Tools\*(R" by Alfred V. Aho, Ravi Sethi and
.IP "\(bu" 4
Jeffrey D. Ullman (Addison-Wesley 1986)
.IP "\(bu" 4
Parse::RecDescent.
.SH "AUTHOR"
.IX Header "AUTHOR"
Casiano Rodriguez-Leon
.SH "LICENSE AND COPYRIGHT"
.IX Header "LICENSE AND COPYRIGHT"
Copyright © 2006, 2007, 2008, 2009, 2010, 2011, 2012 Casiano Rodriguez-Leon.
Copyright © 2017 William N. Braswell, Jr.
All Rights Reserved.
.PP
Parse::Yapp is Copyright © 1998, 1999, 2000, 2001, Francois Desarmenien.
Parse::Yapp is Copyright © 2017 William N. Braswell, Jr.
All Rights Reserved.
.PP
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.8.8 or,
at your option, any later version of Perl 5 you may have available.
.SH "POD ERRORS"
.IX Header "POD ERRORS"
Hey! \fBThe above document had some coding errors, which are explained below:\fR
.IP "Around line 416:" 4
.IX Item "Around line 416:"
Non-ASCII character seen before =encoding in '©'. Assuming \s-1UTF\-8\s0