134 lines
4.3 KiB
Factor
134 lines
4.3 KiB
Factor
! :folding=indent:collapseFolds=1:
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! $Id$
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!
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! Copyright (C) 2004 Slava Pestov.
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!
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! Redistribution and use in source and binary forms, with or without
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! modification, are permitted provided that the following conditions are met:
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!
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! 1. Redistributions of source code must retain the above copyright notice,
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! this list of conditions and the following disclaimer.
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!
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! 2. Redistributions in binary form must reproduce the above copyright notice,
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! this list of conditions and the following disclaimer in the documentation
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! and/or other materials provided with the distribution.
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!
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! THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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! INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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! FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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! DEVELOPERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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! SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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! PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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! OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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! WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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! OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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! ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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IN: generic
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USE: errors
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USE: hashtables
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USE: kernel
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USE: lists
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USE: namespaces
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USE: parser
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USE: strings
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USE: words
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USE: vectors
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! A simple prototype-based generic word system.
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! Hashtable slot holding a selector->method map.
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SYMBOL: traits
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! Hashtable slot holding an optional delegate. Any undefined
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! methods are called on the delegate. The object can also
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! manually pass any methods on to the delegate.
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SYMBOL: delegate
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: traits-map ( type -- hash )
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#! The method map word property maps selector words to
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#! definitions.
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"traits-map" word-property ;
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: object-map ( obj -- hash )
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#! Get the method map for an object.
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#! We will use hashtable? here when its a first-class type.
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dup vector? [ traits swap hash ] [ drop f ] ifte ;
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: init-traits-map ( word -- )
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<namespace> "traits-map" set-word-property ;
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: undefined-method
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"No applicable method." throw ;
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: method ( selector traits -- traits quot )
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#! Look up the method with the traits object on the stack.
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#! Returns the traits to call the method on; either the
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#! original object, or one of the delegates.
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2dup object-map hash* dup [
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rot drop cdr ( method is defined )
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] [
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drop delegate swap hash* dup [
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cdr method ( check delegate )
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] [
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drop [ undefined-method ] ( no delegate )
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] ifte
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] ifte ;
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: predicate-word ( word -- word )
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word-name "?" cat2 "in" get create ;
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: define-predicate ( word -- )
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#! foo? where foo is a traits type tests if the top of stack
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#! is of this type.
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dup predicate-word swap
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[ object-map ] swap traits-map [ eq? ] cons append
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define-compound ;
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: TRAITS:
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#! TRAITS: foo creates a new traits type. Instances can be
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#! created with <foo>, and tested with foo?.
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CREATE
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dup define-symbol
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dup init-traits-map
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define-predicate ; parsing
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: GENERIC:
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#! GENERIC: bar creates a generic word bar that calls the
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#! bar method on the traits object, with the traits object
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#! on the stack.
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CREATE
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dup unit [ car swap method call ] cons
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define-compound ; parsing
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: constructor-word ( word -- word )
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word-name "<" swap ">" cat3 "in" get create ;
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: define-constructor ( word -- )
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[ constructor-word [ <namespace> ] ] keep
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traits-map [ traits pick set-hash ] cons append
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define-compound ;
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: C: ( -- word [ ] )
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#! C: foo ... begins definition for <foo> where foo is a
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#! traits type. We have to reverse the list at the end,
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#! since the parser conses onto the list, and it will be
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#! reversed again by ;C.
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scan-word [ constructor-word [ <namespace> ] ] keep
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traits-map [ traits pick set-hash ] cons append reverse ;
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parsing
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: ;C ( word [ ] -- )
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POSTPONE: ; ; parsing
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: M: ( -- type generic [ ] )
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#! M: foo bar begins a definition of the bar generic word
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#! specialized to the foo type.
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scan-word scan-word f ; parsing
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: ;M ( type generic def -- )
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#! ;M ends a method definition.
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rot traits-map [ reverse put ] bind ; parsing
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