SQL::Statement::Function - abstract base class for all function executing terms



NAME

SQL::Statement::Function - abstract base class for all function executing terms


SYNOPSIS

  # this class doesn't have a common constructor, because all derived classes
  # have their special requirements


DESCRIPTION

SQL::Statement::Function is an abstract base class providing the interface for all function executing terms.


INHERITANCE

  SQL::Statement::Function
  ISA SQL::Statement::Term


METHODS

DESTROY

Destroys the term and undefines the weak reference to the owner as well as the reference to the parameter list.


NAME

SQL::Statement::Function::UserFunc - implements executing a perl subroutine


SYNOPSIS

  # create an user function term with an SQL::Statement object as owner,
  # specifying the function name, the subroutine name (full qualified)
  # and the parameters to the subroutine
  my $term = SQL::Statement::Function::UserFunc->new( $owner, $name, $sub, \@params );
  # access the result of that operation
  $term->value( $eval );


DESCRIPTION

SQL::Statement::Function::UserFunc implements a term which returns the result of the specified subroutine.


INHERITANCE

  SQL::Statement::Function
  ISA SQL::Statement::Term


METHODS

new

Instantiates a new SQL::Statement::Function::UserFunc instance.

value

Invokes the given subroutine with the values of the params and return it's result:

    my @params = map { $_->value($eval); } @{ $self->{PARAMS} };
    return $subpkg->$subname( $self->{OWNER}, @params );


NAME

SQL::Statement::Function::NumericEval - implements numeric evaluation of a term


SYNOPSIS

  # create an user function term with an SQL::Statement object as owner,
  # specifying the expression to evaluate and the parameters to the subroutine
  my $term = SQL::Statement::NumericEval->new( $owner, $expr, \@params );
  # access the result of that operation
  $term->value( $eval );


DESCRIPTION

SQL::Statement::Function::NumericEval implements the numeric evaluation of a term. All parameters are expected to be numeric.


INHERITANCE

  SQL::Statement::Function::NumericEval
  ISA SQL::Statement::Function
    ISA SQL::Statement::Term


METHODS

new

Instantiates a new SQL::Statement::Function::NumericEval instance. Takes $owner, $expr and \@params as arguments (in specified order).

value

Returns the result of the evaluated expression.


NAME

SQL::Statement::Function::Trim - implements the built-in trim function support


SYNOPSIS

  # create an trim function term with an SQL::Statement object as owner,
  # specifying the spec, char and the parameters to the subroutine
  my $term = SQL::Statement::Trim->new( $owner, $spec, $char, \@params );
  # access the result of that operation
  $term->value( $eval );


DESCRIPTION

SQL::Statement::Function::Trim implements string trimming.


INHERITANCE

  SQL::Statement::Function::Trim
  ISA SQL::Statement::Function
    ISA SQL::Statement::Term


METHODS

new

Instantiates a new SQL::Statement::Function::Trim instance. Takes $owner, $spec, $char and \@params as arguments (in specified order).

Meaning of the parameters:

$spec
Can be on of 'LEADING', 'TRAILING' 'BOTH'. Trims the leading chars, trailing chars or at both ends, respectively.

Defaults to 'BOTH'.

$char
The character to trim - defaults to ' '

\@params
Expected to be an array with exact 1 element (more aren't evaluated).

value

Returns the trimmed value of first parameter argument.


NAME

SQL::Statement::Function::SubString - implements the built-in sub-string function support


SYNOPSIS

  # create an substr function term with an SQL::Statement object as owner,
  # specifying the start and length of the sub string to extract from the
  # first element of \@params
  my $term = SQL::Statement::SubString->new( $owner, $start, $length, \@params );
  # access the result of that operation
  $term->value( $eval );


DESCRIPTION

SQL::Statement::Function::SubString implements a sub-string extraction term.


INHERITANCE

  SQL::Statement::Function::SubString
  ISA SQL::Statement::Function
    ISA SQL::Statement::Term


METHODS

new

Instantiates a new SQL::Statement::Function::SubString instance. Takes $owner, $start, $length and \@params as arguments (in specified order).

Meaning of the parameters:

$start
Specifies the start position to extract the sub-string. This is expected to be a the SQL::Statement::Term manpage instance. The first character in a string has the position 1.

$length
Specifies the length of the extracted sub-string. This is expected to be a the SQL::Statement::Term manpage instance.

If omitted, everything to the end of the string is returned.

\@params
Expected to be an array with exact 1 element (more aren't evaluated).

value

Returns the extracted sub-string value from first parameter argument.


NAME

SQL::Statement::Function::StrConcat - implements the built-in string concatenation


SYNOPSIS

  # create an substr function term with an SQL::Statement object as owner
  # and \@params to concatenate
  my $term = SQL::Statement::StrConcat->new( $owner, \@params );
  # access the result of that operation
  $term->value( $eval );


DESCRIPTION

SQL::Statement::Function::StrConcat implements a string concatenation term.


INHERITANCE

  SQL::Statement::Function::StrConcat
  ISA SQL::Statement::Function
    ISA SQL::Statement::Term


METHODS

new

Instantiates a new SQL::Statement::Function::StrConcat instance.

value

Returns the concatenated string composed of the parameter values.


AUTHOR AND COPYRIGHT

Copyright (c) 2009,2010 by Jens Rehsack: rehsackATcpan.org

All rights reserved.

You may distribute this module under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file.

 SQL::Statement::Function - abstract base class for all function executing terms