Merge branch 'master' of git://factorcode.org/git/factor

basis/bootstrap/image/image.factor

@@ -52,6 +52,9 @@ GENERIC: (eql?) ( obj1 obj2 -- ? )
 
 M: integer (eql?) = ;
 
+M: float (eql?)
+    over float? [ fp-bitwise= ] [ 2drop f ] if ;
+
 M: sequence (eql?)
     over sequence? [
         2dup [ length ] bi@ =

basis/dlists/dlists-docs.factor

@@ -15,6 +15,7 @@ $nl
 "Iterating over elements:"
 { $subsection dlist-each }
 { $subsection dlist-find }
+{ $subsection dlist-filter }
 { $subsection dlist-any? }
 "Deleting a node matching a predicate:"
 { $subsection delete-node-if* }
@@ -40,6 +41,11 @@ HELP: dlist-find
     "This operation is O(n)."
 } ;
 
+HELP: dlist-filter
+{ $values { "dlist" { $link dlist } } { "quot" quotation } { "dlist" { $link dlist } } }
+{ $description "Applies the quotation to each element of the " { $link dlist } " in turn, removing the corresponding nodes if the quotation returns " { $link f } "." }
+{ $side-effects { "dlist" } } ;
+
 HELP: dlist-any?
 { $values { "dlist" { $link dlist } } { "quot" quotation } { "?" "a boolean" } }
 { $description "Just like " { $link dlist-find } " except it doesn't return the object." }

basis/dlists/dlists-tests.factor

@@ -79,3 +79,8 @@ IN: dlists.tests
 [ V{ f 3 1 f } ] [ <dlist> 1 over push-front 3 over push-front f over push-front f over push-back dlist>seq ] unit-test
 
 [ V{ } ] [ <dlist> dlist>seq ] unit-test
+
+[ V{ 0 2 4 } ] [ <dlist> { 0 1 2 3 4 } over push-all-back [ even? ] dlist-filter dlist>seq ] unit-test
+[ V{ 2 4 } ] [ <dlist> { 1 2 3 4 } over push-all-back [ even? ] dlist-filter dlist>seq ] unit-test
+[ V{ 2 4 } ] [ <dlist> { 1 2 3 4 5 } over push-all-back [ even? ] dlist-filter dlist>seq ] unit-test
+[ V{ 0 2 4 } ] [ <dlist> { 0 1 2 3 4 5 } over push-all-back [ even? ] dlist-filter dlist>seq ] unit-test

basis/dlists/dlists.factor

@@ -95,7 +95,7 @@ M: dlist pop-front* ( dlist -- )
     [
         [
             [ empty-dlist ] unless*
-            [ f ] change-next drop
+            next>>
             f over set-prev-when
         ] change-front drop
     ] keep
@@ -108,7 +108,7 @@ M: dlist pop-back* ( dlist -- )
     [
         [
             [ empty-dlist ] unless*
-            [ f ] change-prev drop
+            prev>>
             f over set-next-when
         ] change-back drop
     ] keep
@@ -157,6 +157,9 @@ M: dlist clear-deque ( dlist -- )
 
 : 1dlist ( obj -- dlist ) <dlist> [ push-front ] keep ;
 
+: dlist-filter ( dlist quot -- dlist )
+    over [ '[ dup obj>> @ [ drop ] [ _ delete-node ] if ] dlist-each-node ] keep ; inline
+
 M: dlist clone
     <dlist> [ '[ _ push-back ] dlist-each ] keep ;
 

basis/math/polynomials/polynomials-docs.factor

@@ -93,7 +93,13 @@ HELP: pdiff
 { $description "Finds the derivative of " { $snippet "p" } "." } ;
 
 HELP: polyval
-{ $values { "p" "a polynomial" } { "x" number } { "p[x]" number } }
+{ $values { "x" number } { "p" "a polynomial" } { "p[x]" number } }
 { $description "Evaluate " { $snippet "p" } " with the input " { $snippet "x" } "." }
-{ $examples { $example "USING: math.polynomials prettyprint ;" "{ 1 0 1 } 2 polyval ." "5" } } ;
+{ $examples { $example "USING: math.polynomials prettyprint ;" "2 { 1 0 1 } polyval ." "5" } } ;
 
+HELP: polyval*
+{ $values { "p" "a literal polynomial" } }
+{ $description "Macro version of " { $link polyval } ". Evaluates the literal polynomial " { $snippet "p" } " at the value off the top of the stack." }
+{ $examples { $example "USING: math.polynomials prettyprint ;" "2 { 1 0 1 } polyval* ." "5" } } ;
+
+{ polyval polyval* } related-words

basis/math/polynomials/polynomials.factor

@@ -1,7 +1,7 @@
 ! Copyright (C) 2008 Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: arrays kernel make math math.order math.vectors sequences
-    splitting vectors ;
+    splitting vectors macros combinators ;
 IN: math.polynomials
 
 <PRIVATE
@@ -80,6 +80,12 @@ PRIVATE>
 : pdiff ( p -- p' )
     dup length v* { 0 } ?head drop ;
 
-: polyval ( p x -- p[x] )
+: polyval ( x p -- p[x] )
-    [ dup length ] dip powers v. ;
+    [ length swap powers ] [ nip ] 2bi v. ;
+
+MACRO: polyval* ( p -- )
+    reverse
+    [ 1 tail [ \ * swap \ + [ ] 3sequence ] map ]
+    [ first \ drop swap [ ] 2sequence ] bi
+    prefix \ cleave [ ] 2sequence ;
 

basis/math/rectangles/prettyprint/authors.txt

@@ -0,0 +1 @@
+Slava Pestov

basis/math/rectangles/prettyprint/prettyprint.factor

@@ -0,0 +1,7 @@
+! Copyright (C) 2009 Slava Pestov.
+! See http://factorcode.org/license.txt for BSD license.
+USING: accessors math.rectangles kernel prettyprint.custom prettyprint.backend ;
+IN: math.rectangles.prettyprint
+
+M: rect pprint*
+    \ RECT: [ [ loc>> ] [ dim>> ] bi [ pprint* ] bi@ ] pprint-prefix ;

basis/math/rectangles/rectangles.factor

@@ -1,7 +1,7 @@
 ! Copyright (C) 2008, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel arrays sequences math math.vectors accessors
-parser prettyprint.custom prettyprint.backend ;
+parser ;
 IN: math.rectangles
 
 TUPLE: rect { loc initial: { 0 0 } } { dim initial: { 0 0 } } ;
@@ -10,9 +10,6 @@ TUPLE: rect { loc initial: { 0 0 } } { dim initial: { 0 0 } } ;
 
 SYNTAX: RECT: scan-object scan-object <rect> parsed ;
 
-M: rect pprint*
-    \ RECT: [ [ loc>> ] [ dim>> ] bi [ pprint* ] bi@ ] pprint-prefix ;
-
 : <zero-rect> ( -- rect ) rect new ; inline
 
 : point>rect ( loc -- rect ) { 0 0 } <rect> ; inline
@@ -64,3 +61,7 @@ M: rect contains-point?
     [ [ loc>> ] dip (>>loc) ]
     [ [ dim>> ] dip (>>dim) ]
     2bi ; inline
+
+USING: vocabs vocabs.loader ;
+
+"prettyprint" vocab [ "math.rectangles.prettyprint" require ] when

basis/math/vectors/vectors.factor

@@ -41,6 +41,13 @@ IN: math.vectors
 : set-axis ( u v axis -- w )
     [ [ zero? 2over ? ] dip swap nth ] map-index 2nip ;
 
+: 2tetra@ ( p q r s t u v w quot -- )
+    dup [ [ 2bi@ ] curry 4dip ] dip 2bi@ ; inline
+
+: trilerp ( aaa baa aba bba aab bab abb bbb {t,u,v} -- a_tuv )
+    [ first lerp ] [ second lerp ] [ third lerp ] tri-curry
+    [ 2tetra@ ] [ 2bi@ ] [ call ] tri* ;
+
 : bilerp ( aa ba ab bb {t,u} -- a_tu )
     [ first lerp ] [ second lerp ] bi-curry
     [ 2bi@ ] [ call ] bi* ;
@@ -72,3 +79,6 @@ HINTS: v. { array array } ;
 
 HINTS: vlerp { array array array } ;
 HINTS: vnlerp { array array object } ;
+
+HINTS: bilerp { object object object object array } ;
+HINTS: trilerp { object object object object object object object object array } ;

basis/ui/gadgets/gadgets.factor

@@ -3,8 +3,7 @@
 USING: accessors arrays hashtables kernel models math namespaces
 make sequences quotations math.vectors combinators sorting
 binary-search vectors dlists deques models threads
-concurrency.flags math.order math.rectangles fry locals
+concurrency.flags math.order math.rectangles fry locals ;
-prettyprint.backend prettyprint.custom ;
 IN: ui.gadgets
 
 ! Values for orientation slot
@@ -28,9 +27,6 @@ interior
 boundary
 model ;
 
-! Don't print gadgets with RECT: syntax
-M: gadget pprint* pprint-tuple ;
-
 M: gadget equal? 2drop f ;
 
 M: gadget hashcode* nip [ [ \ gadget counter ] unless* ] change-id id>> ;
@@ -397,3 +393,7 @@ M: f request-focus-on 2drop ;
 
 : focus-path ( gadget -- seq )
     [ focus>> ] follow ;
+
+USING: vocabs vocabs.loader ;
+
+"prettyprint" vocab [ "ui.gadgets.prettyprint" require ] when

basis/ui/gadgets/prettyprint/authors.txt

@@ -0,0 +1 @@
+Slava Pestov

basis/ui/gadgets/prettyprint/prettyprint.factor

@@ -0,0 +1,7 @@
+! Copyright (C) 2009 Slava Pestov.
+! See http://factorcode.org/license.txt for BSD license.
+USING: ui.gadgets prettyprint.backend prettyprint.custom ;
+IN: ui.gadgets.prettyprint
+
+! Don't print gadgets with RECT: syntax
+M: gadget pprint* pprint-tuple ;

core/generic/single/single.factor

@@ -163,7 +163,7 @@ M: hi-tag-dispatch-engine compile-engine
 
 : build-fast-hash ( methods -- buckets )
     >alist V{ } clone [ hashcode 1array ] distribute-buckets
-    [ compile-engines* >alist >array ] map ;
+    [ compile-engines* >alist { } join ] map ;
 
 M: echelon-dispatch-engine compile-engine
     dup n>> 0 = [

core/math/math-docs.factor

@@ -274,7 +274,7 @@ HELP: fp-nan-payload
 { $description "If " { $snippet "x" } " is an IEEE Not-a-Number value, returns the payload encoded in the value. Returns " { $link f } " if " { $snippet "x" } " is not a " { $link float } "." } ;
 
 HELP: <fp-nan>
-{ $values { "payload" integer } { "float" float } }
+{ $values { "payload" integer } { "nan" float } }
 { $description "Constructs an IEEE Not-a-Number value with a payload of " { $snippet "payload" } "." }
 { $notes "A " { $snippet "payload" } " of " { $snippet "0" } " will construct an Infinity value." } ;
 

core/math/math.factor

@@ -81,6 +81,8 @@ TUPLE: complex { real real read-only } { imaginary real read-only } ;
 
 UNION: number real complex ;
 
+: fp-bitwise= ( x y -- ? ) [ double>bits ] bi@ = ; inline
+
 GENERIC: fp-special? ( x -- ? )
 GENERIC: fp-nan? ( x -- ? )
 GENERIC: fp-qnan? ( x -- ? )

extra/game-worlds/game-worlds.factor

@@ -0,0 +1,25 @@
+USING: accessors game-input game-loop kernel math ui.gadgets
+ui.gadgets.worlds ui.gestures ;
+IN: game-worlds
+
+TUPLE: game-world < world
+    game-loop
+    { tick-slice float initial: 0.0 } ;
+
+GENERIC: tick-length ( world -- millis )
+
+M: game-world draw*
+    swap >>tick-slice draw-world ;
+
+M: game-world begin-world
+    dup [ tick-length ] [ ] bi <game-loop> [ >>game-loop ] keep start-loop
+    drop
+    open-game-input ;
+
+M: game-world end-world
+    close-game-input
+    [ [ stop-loop ] when* f ] change-game-loop
+    drop ;
+
+M: game-world focusable-child* drop t ;
+

extra/math/affine-transforms/affine-transforms.factor

@@ -17,6 +17,8 @@ CONSTANT: identity-transform T{ affine-transform f { 1.0 0.0 } { 0.0 1.0 } { 0.0
     [ drop origin>> ] 2tri
     v+ v+ ;
 
+: <identity> ( -- a )
+    { 1.0 0.0 } { 0.0 1.0 } { 0.0 0.0 } <affine-transform> ;
 : <translation> ( origin -- a )
     [ { 1.0 0.0 } { 0.0 1.0 } ] dip <affine-transform> ;
 : <rotation> ( theta -- transform )

extra/noise/noise.factor

@@ -1,61 +1,60 @@
 USING: byte-arrays combinators fry images kernel locals math
 math.affine-transforms math.functions math.order
 math.polynomials math.vectors random random.mersenne-twister
-sequences sequences.product ;
+sequences sequences.product hints arrays sequences.private
+combinators.short-circuit math.private ;
 IN: noise
 
 : <perlin-noise-table> ( -- table )
-    256 iota >byte-array randomize dup append ;
+    256 iota >byte-array randomize dup append ; inline
 
 : with-seed ( seed quot -- )
     [ <mersenne-twister> ] dip with-random ; inline
 
 <PRIVATE
 
-: fade ( point -- point' )
+: (fade) ( x y z -- x' y' z' )
-    { 0.0 0.0 0.0 10.0 -15.0 6.0 } swap [ polyval ] with map ;
+    [ { 0.0 0.0 0.0 10.0 -15.0 6.0 } polyval* ] tri@ ;
 
-:: grad ( hash gradients -- gradient )
+HINTS: (fade) { float float float } ;
-    hash 8  bitand zero? [ gradients first ] [ gradients second ] if
+
+: fade ( point -- point' )
+    first3 (fade) 3array ; inline
+
+:: grad ( hash x y z -- gradient )
+    hash 8  bitand zero? [ x ] [ y ] if
         :> u
     hash 12 bitand zero?
-    [ gradients second ]
+    [ y ] [ hash 13 bitand 12 = [ x ] [ z ] if ] if
-    [ hash 13 bitand 12 = [ gradients first ] [ gradients third ] if ] if
         :> v
 
     hash 1 bitand zero? [ u ] [ u neg ] if
     hash 2 bitand zero? [ v ] [ v neg ] if + ;
 
+HINTS: grad { fixnum float float float } ;
+
 : unit-cube ( point -- cube )
-    [ floor >fixnum 256 mod ] map ;
+    [ floor >fixnum 256 rem ] map ;
 
-:: hashes ( table cube -- aaa baa aba bba aab bab abb bbb )
+:: hashes ( table x y z -- aaa baa aba bba aab bab abb bbb )
-    cube first  :> x
+    x               table nth-unsafe y fixnum+fast :> a
-    cube second :> y
+    x 1 fixnum+fast table nth-unsafe y fixnum+fast :> b
-    cube third  :> z
-    x     table nth y + :> a
-    x 1 + table nth y + :> b
 
-    a     table nth z + :> aa
+    a               table nth-unsafe z fixnum+fast :> aa
-    b     table nth z + :> ba
+    b               table nth-unsafe z fixnum+fast :> ba
-    a 1 + table nth z + :> ab
+    a 1 fixnum+fast table nth-unsafe z fixnum+fast :> ab
-    b 1 + table nth z + :> bb
+    b 1 fixnum+fast table nth-unsafe z fixnum+fast :> bb
 
-    aa     table nth 
+    aa               table nth-unsafe 
-    ba     table nth 
+    ba               table nth-unsafe 
-    ab     table nth 
+    ab               table nth-unsafe 
-    bb     table nth 
+    bb               table nth-unsafe 
-    aa 1 + table nth 
+    aa 1 fixnum+fast table nth-unsafe 
-    ba 1 + table nth 
+    ba 1 fixnum+fast table nth-unsafe 
-    ab 1 + table nth 
+    ab 1 fixnum+fast table nth-unsafe 
-    bb 1 + table nth ;
+    bb 1 fixnum+fast table nth-unsafe ; inline
 
-:: 2tetra@ ( p q r s t u v w quot -- )
+HINTS: hashes { byte-array fixnum fixnum fixnum } ;
-    p q quot call
-    r s quot call
-    t u quot call
-    v w quot call
-    ; inline
 
 : >byte-map ( floats -- bytes )
     [ 255.0 * >fixnum ] B{ } map-as ;
@@ -63,26 +62,33 @@ IN: noise
 : >image ( bytes dim -- image )
     swap [ L f ] dip image boa ;
 
-PRIVATE>
+:: perlin-noise-unsafe ( table point -- value )
-
-:: perlin-noise ( table point -- value )
     point unit-cube :> cube
     point dup vfloor v- :> gradients
     gradients fade :> faded
 
-    table cube hashes {
+    table cube first3 hashes {
-        [ gradients                       grad ]
+        [ gradients first3                                    grad ]
-        [ gradients { -1.0  0.0  0.0 } v+ grad ]
+        [ gradients first3 [ 1.0 - ] [       ] [       ] tri* grad ]
-        [ gradients {  0.0 -1.0  0.0 } v+ grad ]
+        [ gradients first3 [       ] [ 1.0 - ] [       ] tri* grad ]
-        [ gradients { -1.0 -1.0  0.0 } v+ grad ]
+        [ gradients first3 [ 1.0 - ] [ 1.0 - ] [       ] tri* grad ]
-        [ gradients {  0.0  0.0 -1.0 } v+ grad ]
+        [ gradients first3 [       ] [       ] [ 1.0 - ] tri* grad ]
-        [ gradients { -1.0  0.0 -1.0 } v+ grad ]
+        [ gradients first3 [ 1.0 - ] [       ] [ 1.0 - ] tri* grad ]
-        [ gradients {  0.0 -1.0 -1.0 } v+ grad ]
+        [ gradients first3 [       ] [ 1.0 - ] [ 1.0 - ] tri* grad ]
-        [ gradients { -1.0 -1.0 -1.0 } v+ grad ]
+        [ gradients first3 [ 1.0 - ] [ 1.0 - ] [ 1.0 - ] tri* grad ]
     } spread
-    [ faded first lerp ] 2tetra@
+    faded trilerp ;
-    [ faded second lerp ] 2bi@
+
-    faded third lerp ;
+ERROR: invalid-perlin-noise-table table ;
+
+: validate-table ( table -- table )
+    dup { [ byte-array? ] [ length 512 >= ] } 1&&
+    [ invalid-perlin-noise-table ] unless ;
+
+PRIVATE>
+
+: perlin-noise ( table point -- value )
+    [ validate-table ] dip perlin-noise-unsafe ; inline
 
 : normalize-0-1 ( sequence -- sequence' )
     [ supremum ] [ infimum [ - ] keep ] [ ] tri
@@ -92,7 +98,8 @@ PRIVATE>
     [ 0.0 max 1.0 min ] map ;
 
 : perlin-noise-map ( table transform dim -- map ) 
-    [ iota ] map [ a.v 0.0 suffix perlin-noise ] with with product-map ;
+    [ validate-table ] 2dip
+    [ iota ] map [ a.v 0.0 suffix perlin-noise-unsafe ] with with product-map ;
 
 : perlin-noise-byte-map ( table transform dim -- map )
     perlin-noise-map normalize-0-1 >byte-map ;

extra/terrain/terrain.factor

@@ -1,11 +1,11 @@
-USING: accessors arrays combinators game-input
+USING: accessors arrays combinators game-input game-loop
-game-input.scancodes game-loop grouping kernel literals locals
+game-input.scancodes grouping kernel literals locals
 math math.constants math.functions math.matrices math.order
 math.vectors opengl opengl.capabilities opengl.gl
 opengl.shaders opengl.textures opengl.textures.private
 sequences sequences.product specialized-arrays.float
 terrain.generation terrain.shaders ui ui.gadgets
-ui.gadgets.worlds ui.pixel-formats ;
+ui.gadgets.worlds ui.pixel-formats game-worlds method-chains ;
 IN: terrain
 
 CONSTANT: FOV $[ 2.0 sqrt 1+ ]
@@ -15,7 +15,6 @@ CONSTANT: PLAYER-START-LOCATION { 0.5 0.51 0.5 }
 CONSTANT: PLAYER-HEIGHT $[ 3.0 1024.0 / ]
 CONSTANT: GRAVITY $[ 1.0 4096.0 / ]
 CONSTANT: JUMP $[ 1.0 1024.0 / ]
-CONSTANT: TICK-LENGTH $[ 1000 30 /i ]
 CONSTANT: MOUSE-SCALE $[ 1.0 10.0 / ]
 CONSTANT: MOVEMENT-SPEED $[ 1.0 16384.0 / ]
 CONSTANT: FRICTION 0.95
@@ -28,11 +27,13 @@ CONSTANT: terrain-vertex-row-length $[ 512 1 + 2 * ]
 TUPLE: player
     location yaw pitch velocity ;
 
-TUPLE: terrain-world < world
+TUPLE: terrain-world < game-world
     player
     terrain terrain-segment terrain-texture terrain-program
-    terrain-vertex-buffer
+    terrain-vertex-buffer ;
-    game-loop ;
+
+M: terrain-world tick-length
+    drop 1000 30 /i ;
 
 : frustum ( dim -- -x x -y y near far )
     dup first2 min v/n
@@ -137,8 +138,11 @@ TUPLE: terrain-world < world
 : apply-gravity ( velocity -- velocity' )
     1 over [ GRAVITY - ] change-nth ;
 
+: clamp-coords ( coords dim -- coords' )
+    [ { 0 0 } vmax ] dip { 2 2 } v- vmin ;
+
 :: pixel-indices ( coords dim -- indices )
-    coords vfloor [ >integer ] map :> floor-coords
+    coords vfloor [ >integer ] map dim clamp-coords :> floor-coords
     floor-coords first2 dim first * + :> base-index
     base-index dim first + :> next-row-index
 
@@ -171,9 +175,6 @@ M: terrain-world tick*
     [ dup focused?>> [ handle-input ] [ drop ] if ]
     [ dup player>> tick-player ] bi ;
 
-M: terrain-world draw*
-    nip draw-world ;
-
 : set-heightmap-texture-parameters ( texture -- )
     GL_TEXTURE_2D GL_TEXTURE0 bind-texture-unit
     GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER GL_LINEAR glTexParameteri
@@ -181,7 +182,7 @@ M: terrain-world draw*
     GL_TEXTURE_2D GL_TEXTURE_WRAP_S GL_CLAMP_TO_EDGE glTexParameteri
     GL_TEXTURE_2D GL_TEXTURE_WRAP_T GL_CLAMP_TO_EDGE glTexParameteri ;
 
-M: terrain-world begin-world
+BEFORE: terrain-world begin-world
     "2.0" { "GL_ARB_vertex_buffer_object" "GL_ARB_shader_objects" }
     require-gl-version-or-extensions
     GL_DEPTH_TEST glEnable
@@ -195,14 +196,10 @@ M: terrain-world begin-world
     terrain-vertex-shader terrain-pixel-shader <simple-gl-program>
     >>terrain-program
     vertex-array >vertex-buffer >>terrain-vertex-buffer
-    TICK-LENGTH over <game-loop> [ >>game-loop ] keep start-loop
-    open-game-input
     drop ;
 
-M: terrain-world end-world
+AFTER: terrain-world end-world
-    close-game-input
     {
-        [ game-loop>> stop-loop ]
         [ terrain-vertex-buffer>> delete-gl-buffer ]
         [ terrain-program>> delete-gl-program ]
         [ terrain-texture>> delete-texture ]
@@ -224,7 +221,6 @@ M: terrain-world draw-world*
     ] with-gl-program ]
     tri gl-error ;
 
-M: terrain-world focusable-child* drop t ;
 M: terrain-world pref-dim* drop { 640 480 } ;
 
 : terrain-window ( -- )

vm/dispatch.cpp

@@ -8,15 +8,14 @@ cell megamorphic_cache_misses;
 
 static cell search_lookup_alist(cell table, cell klass)
 {
-	array *pairs = untag<array>(table);
+	array *elements = untag<array>(table);
-	fixnum index = array_capacity(pairs) - 1;
+	fixnum index = array_capacity(elements) - 2;
 	while(index >= 0)
 	{
-		array *pair = untag<array>(array_nth(pairs,index));
+		if(array_nth(elements,index) == klass)
-		if(array_nth(pair,0) == klass)
+			return array_nth(elements,index + 1);
-			return array_nth(pair,1);
 		else
-			index--;
+			index -= 2;
 	}
 
 	return F;