Item2247: query optimisation (constant folding) reduces size of query…

… expressions.

git-svn-id: http://svn.foswiki.org/trunk@7131 0b4bb1d4-4e5a-0410-9cc4-b2b747904278

core/lib/Foswiki/Contrib/core/MANIFEST

@@ -688,6 +688,7 @@ lib/Foswiki/Prefs/Web.pm 0444
 lib/Foswiki/Query/BinaryOP.pm 0444
 lib/Foswiki/Query/HoistREs.pm 0444
 lib/Foswiki/Query/Node.pm 0444
+lib/Foswiki/Query/OP.pm 0444
 lib/Foswiki/Query/OP_and.pm 0444
 lib/Foswiki/Query/OP_d2n.pm 0444
 lib/Foswiki/Query/OP_dot.pm 0444

core/lib/Foswiki/Func.pm

@@ -24,7 +24,7 @@ API version $Date$ (revision $Rev$)
 *Since* _date_ indicates where functions or parameters have been added since
 the baseline of the API (Foswiki 1.0.0). The _date_ indicates the
 earliest date of a Foswiki release that will support that function or
-parameter.
+parameter. See Foswiki:Download.ReleaseDates for version release dates.
 
 *Deprecated* _date_ indicates where a function or parameters has been
 [[http://en.wikipedia.org/wiki/Deprecation][deprecated]]. Deprecated
@@ -3279,6 +3279,7 @@ Module of Foswiki - The Free and Open Source Wiki, http://foswiki.org/, http://F
 Copyright (C) 2008-2010 Foswiki Contributors. Foswiki Contributors
 are listed in the AUTHORS file in the root of this distribution.
 NOTE: Please extend that file, not this notice.
+
 Additional copyrights apply to some or all of the code in this
 file as follows:
 

core/lib/Foswiki/Query/BinaryOP.pm

@@ -57,4 +57,32 @@ sub evalTest {
     }
 }
 
+sub evaluatesToConstant {
+    my $this = shift;
+    my $node = shift;
+    return 0 unless $node->{params}[0]->evaluatesToConstant(@_);
+    return $node->{params}[1]->evaluatesToConstant(@_);
+}
+
 1;
+__END__
+
+Module of Foswiki - The Free and Open Source Wiki, http://foswiki.org/, http://Foswiki.org/
+
+Copyright (C) 2009 Foswiki Contributors. All Rights Reserved.
+Foswiki Contributors are listed in the AUTHORS file in the root
+of this distribution. NOTE: Please extend that file, not this notice.
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version. For
+more details read LICENSE in the root of this distribution.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+As per the GPL, removal of this notice is prohibited.
+
+Author: Crawford Currie http://c-dot.co.uk

core/lib/Foswiki/Query/Node.pm

@@ -127,22 +127,77 @@ sub evaluate {
     return $result;
 }
 
+=begin TML
+
+---++ evaluatesToConstant(%opts)
+
+Determine if this node evaluates to a constant or not. "Constant" is defined
+as "anything that doesn't involve actually looking in searched topics".
+This function takes the same parameters (%domain) as evaluate(). Note that
+no reference to the tom or data web or topic will be made, so you can
+simply pass an arbitrary Foswiki::Meta.
+
+=cut
+
+sub evaluatesToConstant {
+    my $this = shift;
+    if (!ref($this->{op})
+          && ($this->{op} == $Foswiki::Infix::Node::NUMBER
+                || $this->{op} == $Foswiki::Infix::Node::STRING)) {
+        return 1;
+    }
+    elsif (ref($this->{op})) {
+        return $this->{op}->evaluatesToConstant($this, @_);
+    }
+    return 0;
+}
+
+=begin TML
+
+---++ simplify(%opts)
+
+Simplify the query by spotting constant expressions and evaluating them,
+replacing the constant expression with an atomic value in the expression tree.
+This function takes the same parameters (%domain) as evaluate(). Note that
+no reference to the tom or data web or topic will be made, so you can
+simply pass an arbitrary Foswiki::Meta.
+
+=cut
+
+sub simplify {
+    my $this = shift;
+
+    if ($this->evaluatesToConstant(@_)) {
+        my $c = $this->evaluate(@_) || 0;
+        if ($c =~ /^[+-]?(\d+\.\d+|\d+\.|\.\d+|\d+)([eE][+-]?\d+)?$/) {
+            $this->{op} = $Foswiki::Infix::Node::NUMBER;
+        } else {
+            $this->{op} = $Foswiki::Infix::Node::STRING;
+        }
+        @{$this->{params}} = ( $c );
+    } else {
+        for my $f (@{$this->{params}}) {
+            if (UNIVERSAL::can($f, 'simplify')) {
+                $f->simplify(@_);
+            }
+        }
+    }
+}
+
 1;
 __DATA__
 
 Module of Foswiki - The Free and Open Source Wiki, http://foswiki.org/, http://Foswiki.org/
 
-# Copyright (C) 2008-2009 Foswiki Contributors. All Rights Reserved.
-# Foswiki Contributors are listed in the AUTHORS file in the root
-# of this distribution. NOTE: Please extend that file, not this notice.
-#
-# Additional copyrights apply to some or all of the code in this
-# file as follows:
-#
-# Copyright (C) 2005-2007 TWiki Contributors. All Rights Reserved.
-# TWiki Contributors are listed in the AUTHORS file in the root
-# of this distribution. NOTE: Please extend that file, not this notice.
-#
+Copyright (C) 2008-2010 Foswiki Contributors. All Rights Reserved.
+Foswiki Contributors are listed in the AUTHORS file in the root
+of this distribution. NOTE: Please extend that file, not this notice.
+
+Additional copyrights apply to some or all of the code in this
+file as follows:
+
+Copyright (C) 2005-2007 TWiki Contributors. All Rights Reserved.
+
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2

core/lib/Foswiki/Query/OP.pm

@@ -8,6 +8,12 @@ sub new {
     return bless(\%opts, $class);
 }
 
+# Does this operator evaluate to a constant?
+# See Foswiki::Query::Node::evaluatesToConstant
+sub evaluatesToConstant {
+    return 0;
+}
+
 1;
 __END__
 

core/lib/Foswiki/Query/OP_and.pm

@@ -27,6 +27,17 @@ sub evaluate {
     return $b->evaluate(@_) ? 1 : 0;
 }
 
+sub evaluatesToConstant {
+    my $this = shift;
+    my $node = shift;
+    my $ac = $node->{params}[0]->evaluatesToConstant(@_);
+    my $bc = $node->{params}[1]->evaluatesToConstant(@_);
+    return 1 if ($ac && $bc);
+    return 1 if $ac && ! $node->{params}[0]->evaluate(@_);
+    return 1 if $bc && ! $node->{params}[1]->evaluate(@_);
+    return 0;
+}
+
 1;
 
 __DATA__

core/lib/Foswiki/Query/OP_or.pm

@@ -27,6 +27,17 @@ sub evaluate {
     return $b->evaluate(@_) ? 1 : 0;
 }
 
+sub evaluatesToConstant {
+    my $this = shift;
+    my $node = shift;
+    my $ac = $node->{params}[0]->evaluatesToConstant(@_);
+    my $bc = $node->{params}[1]->evaluatesToConstant(@_);
+    return 1 if ($ac && $bc);
+    return 1 if $ac && $node->{params}[0]->evaluate(@_);
+    return 1 if $bc && $node->{params}[1]->evaluate(@_);
+    return 0;
+}
+
 1;
 
 __DATA__

core/lib/Foswiki/Query/OP_ref.pm

@@ -65,23 +65,30 @@ sub evaluate {
     return \@result;
 }
 
+sub evaluatesToConstant {
+    my $this = shift;
+    my $node = shift;
+    return 1 if $node->{params}[0]->evaluatesToConstant(@_);
+    # param[1] may contain non-constant terms, but that's OK because
+    # they are evaluated relative to the (constant) param[0]
+    return 0;
+}
+
 1;
 
 __DATA__
 
 Module of Foswiki - The Free and Open Source Wiki, http://foswiki.org/, http://Foswiki.org/
 
-# Copyright (C) 2008-2009 Foswiki Contributors. All Rights Reserved.
-# Foswiki Contributors are listed in the AUTHORS file in the root
-# of this distribution. NOTE: Please extend that file, not this notice.
-#
-# Additional copyrights apply to some or all of the code in this
-# file as follows:
-#
-# Copyright (C) 2005-2007 TWiki Contributors. All Rights Reserved.
-# TWiki Contributors are listed in the AUTHORS file in the root
-# of this distribution. NOTE: Please extend that file, not this notice.
-#
+Copyright (C) 2008-2009 Foswiki Contributors. All Rights Reserved.
+Foswiki Contributors are listed in the AUTHORS file in the root
+of this distribution. NOTE: Please extend that file, not this notice.
+
+Additional copyrights apply to some or all of the code in this
+file as follows:
+
+Copyright (C) 2005-2007 TWiki Contributors. All Rights Reserved.
+
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2

core/lib/Foswiki/Query/UnaryOP.pm

@@ -26,6 +26,12 @@ sub evalUnary {
     }
 }
 
+sub evaluatesToConstant {
+    my $this = shift;
+    my $node = shift;
+    return $node->{params}[0]->evaluatesToConstant(@_);
+}
+
 1;
 __END__
 

core/lib/Foswiki/Store/QueryAlgorithms/BruteForce.pm

@@ -37,6 +37,10 @@ sub query {
     #    return new Foswiki::Search::InfoCache($session, '');
     #}
 
+    # Eliminate static expressions
+    my $context = Foswiki::Meta->new( $session, $session->{webName} );
+    $query->simplify(tom => $context, data => $context );
+
     my $webNames = $options->{web}       || '';
     my $recurse = $options->{'recurse'} || '';
     my $isAdmin = $session->{users}->isAdmin( $session->{user} );