SQL::Statement::Function(3) 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 SQL::Statement::Term 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 SQL::Statement::Term 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) 2009-2016 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.

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