gnu-smalltalk-common 3.2.5-1build2 / usr / share / gnu-smalltalk / kernel / ObjDumper.st

"======================================================================
|
|   ObjectDumper Method Definitions
|
|
 ======================================================================"

"======================================================================
|
| Copyright 1999, 2000, 2001, 2002, 2003, 2006, 2008, 2009
| Free Software Foundation, Inc.
| Written by Paolo Bonzini.
|
| This file is part of the GNU Smalltalk class library.
|
| The GNU Smalltalk class library is free software; you can redistribute it
| and/or modify it under the terms of the GNU Lesser General Public License
| as published by the Free Software Foundation; either version 2.1, or (at
| your option) any later version.
| 
| The GNU Smalltalk class library 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.  See the GNU Lesser
| General Public License for more details.
| 
| You should have received a copy of the GNU Lesser General Public License
| along with the GNU Smalltalk class library; see the file COPYING.LIB.
| If not, write to the Free Software Foundation, 59 Temple Place - Suite
| 330, Boston, MA 02110-1301, USA.  
|
 ======================================================================"



Stream subclass: ObjectDumper [
    | toObjects fromObjects stream |
    
    <category: 'Streams-Files'>
    <comment: 'I''m not part of a normal Smalltalk system, but most
Smalltalks provide a similar feature: that is, support for storing objects
in a binary format; there are many advantages in using me instead of #storeOn:
and the Smalltalk compiler.

The data is stored in a very compact format, which has the side effect of
making loading much faster when compared with compiling the Smalltalk code
prepared by #storeOn:.  In addition, my instances support circular references
between objects, while #storeOn: supports it only if you know of such
references at design time and you override #storeOn: to deal with them'>

    SpecialCaseDump := nil.
    SpecialCaseLoad := nil.
    Proxies := nil.

    ObjectDumper class >> example [
	"This is a real torture test: it outputs recursive objects,
	 identical objects multiple times, classes, metaclasses,
	 integers, characters and proxies (which is also a test of more
	 complex objects)!"

	<category: 'testing'>
	| file test dumper method |
	Transcript
	    nextPutAll: 'Must print true without errors.';
	    nl.
	file := FileStream open: 'dumptest' mode: FileStream write.
	test := Array new: 1.
	test at: 1 put: test.
	method := thisContext method.
	(ObjectDumper on: file)
	    dump: 'asdf';
	    dump: #('asdf' 1 2 $a);
	    dump: Array;
	    dump: 'asdf';
	    dump: Array class;
	    dump: test;
	    dump: Processor;
	    dump: Processor;
	    dump: method;
	    dump: method.	"String"	"Array"	"Class"	"String (must be identical to the first)"	"Metaclass"	"Circular reference"	"SingletonProxy"	"SingletonProxy"	"PluggableProxy"	"PluggableProxy"
	file close.
	file := FileStream open: 'dumptest' mode: FileStream read.
	dumper := ObjectDumper on: file.
	((test := dumper load) = 'asdf') printNl.
	(dumper load = #('asdf' 1 2 $a)) printNl.
	(dumper load == Array) printNl.
	(dumper load == test) printNl.
	(dumper load == Array class) printNl.
	test := dumper load.
	(test == (test at: 1)) printNl.
	(dumper load == Processor) printNl.
	(dumper load == Processor) printNl.
	(dumper load == method) printNl.
	(dumper load == method) printNl.
	file close
    ]

    ObjectDumper class >> hasProxyFor: aClass [
	"Answer whether a proxy class has been registered for instances
	 of aClass."

	<category: 'establishing proxy classes'>
	Proxies keysDo: 
		[:any | 
		(aClass inheritsFrom: any) ifTrue: [^true].
		aClass == any ifTrue: [^true]].
	^false
    ]

    ObjectDumper class >> disableProxyFor: aClass [
	"Disable proxies for instances of aClass and its descendants"

	<category: 'establishing proxy classes'>
	self registerProxyClass: NullProxy for: aClass
    ]

    ObjectDumper class >> registerProxyClass: aProxyClass for: aClass [
	"Register the proxy class aProxyClass - descendent of DumperProxy -
	 to be used for instances of aClass and its descendants"

	<category: 'establishing proxy classes'>
	(aProxyClass acceptUsageForClass: aClass) 
	    ifFalse: [self error: 'registration request denied'].
	Proxies at: aClass put: aProxyClass
    ]

    ObjectDumper class >> proxyFor: anObject [
	"Answer a valid proxy for an object, or the object itself if none could
	 be found"

	<category: 'establishing proxy classes'>
	Proxies 
	    keysAndValuesDo: [:key :value | (anObject isKindOf: key) ifTrue: [^value on: anObject]].
	^anObject
    ]

    ObjectDumper class >> proxyClassFor: anObject [
	"Answer the class of a valid proxy for an object, or nil if none could
	 be found"

	<category: 'establishing proxy classes'>
	Proxies 
	    keysAndValuesDo: [:key :value | (anObject isKindOf: key) ifTrue: [^value]].
	^nil
    ]

    ObjectDumper class >> specialCaseIf: aBlock dump: dumpBlock load: loadBlock [
	"Private - This method establishes a condition on which a particular
	 method must be used to save an object.
	 An application should not use this method, since it might cause
	 failure to load file that set the special-case blocks differently;
	 instead, you should use ObjectDumper's higher level proxy feature,
	 i.e. its #registerProxyClass:for: method - which builds on the
	 low-level feature enabled by this method but without its inherent
	 problems."

	<category: 'private - initialization'>
	SpecialCaseDump addLast: aBlock -> dumpBlock.
	SpecialCaseLoad addLast: loadBlock
    ]

    ObjectDumper class >> initialize [
	"Initialize the ObjectDumper class"

	<category: 'private - initialization'>
	Proxies := IdentityDictionary new.
	SpecialCaseDump := OrderedCollection new.
	SpecialCaseLoad := OrderedCollection new.

	"We can only use #isNil, #==, #class here"
	self
	    specialCaseIf: [:object | object == nil]
		dump: [:client :object | ]
		load: [:client | nil];
	    specialCaseIf: [:object | object == true]
		dump: [:client :object | ]
		load: [:client | true];
	    specialCaseIf: [:object | object == false]
		dump: [:client :object | ]
		load: [:client | false];
	    specialCaseIf: [:object | object class == SmallInteger]
		dump: [:client :object | client nextPutLong: object]
		load: [:client | client nextLong];
	    specialCaseIf: [:object | object class == Character]
		dump: [:client :object | client stream nextPut: object]
		load: [:client | client stream next];
	    specialCaseIf: [:object | object class class == Metaclass]
		dump: [:client :object | client storeGlobal: object]
		load: [:client | client loadGlobal];
	    specialCaseIf: [:object | object class == Metaclass]
		dump: [:client :object | client storeGlobal: object asClass]
		load: [:client | client loadGlobal class];
	    specialCaseIf: [:object | object == Smalltalk]
		dump: [:client :object | ]
		load: [:client | Smalltalk];
	    specialCaseIf: [:object | object class == Namespace]
		dump: [:client :object | client storeGlobal: object]
		load: [:client | client loadGlobal];
	    specialCaseIf: [:object | object class == RootNamespace]
		dump: [:client :object | client storeGlobal: object]
		load: [:client | client loadGlobal];
	    specialCaseIf: [:object | object class == Symbol]
		dump: 
		    [:client :object | 
		    client stream nextPutAll: object.
		    client nextPutByte: 0]
		load: [:client | client nextAsciiz asSymbol];
	    specialCaseIf: [:object | self hasProxyFor: object class]
		dump: 
		    [:client :object | 
		    | class |
		    (client lookup: object) 
			ifFalse: 
			    [client storeGlobal: (class := self proxyClassFor: object).
			    (class on: object) dumpTo: client.
			    client register: object]]
		load: 
		    [:client | 
		    "Special-case metaclasses and other objects"

		    | index |
		    index := client nextLong.
		    index = 0 
			ifTrue: [client register: (client loadGlobal loadFrom: client)]
			ifFalse: [client lookupIndex: index]];
	    specialCaseIf: [:object | object class == UnicodeCharacter]
		dump: [:client :object | client nextPutLong: object codePoint]
		load: [:client | client nextLong asCharacter]
    ]

    ObjectDumper class >> on: aFileStream [
	"Answer an ObjectDumper working on aFileStream."

	<category: 'instance creation'>
	^self basicNew initializeStream: aFileStream
    ]

    ObjectDumper class >> new [
	<category: 'instance creation'>
	self shouldNotImplement
    ]

    ObjectDumper class >> dump: anObject to: aFileStream [
	"Dump anObject to aFileStream. Answer anObject"

	<category: 'shortcuts'>
	^(self on: aFileStream) dump: anObject
    ]

    ObjectDumper class >> loadFrom: aFileStream [
	"Load an object from aFileStream and answer it"

	<category: 'shortcuts'>
	^(self on: aFileStream) load
    ]

    atEnd [
	"Answer whether the underlying stream is at EOF"

	<category: 'stream interface'>
	^stream atEnd
    ]

    next [
	"Load an object from the underlying stream"

	<category: 'stream interface'>
	^self load
    ]

    nextPut: anObject [
	"Store an object on the underlying stream"

	<category: 'stream interface'>
	self dump: anObject
    ]

    dump: anObject [
	"Dump anObject on the stream associated with the receiver. Answer
	 anObject"

	<category: 'loading/dumping objects'>
	(self lookup: anObject) ifTrue: [^anObject].
	(self specialCaseDump: anObject) 
	    ifFalse: 
		[anObject preStore.
		[self primDump: anObject] ensure: [anObject postStore]]
    ]

    load [
	"Load an object from the stream associated with the receiver and answer
	 it"

	<category: 'loading/dumping objects'>
	"Special-case metaclasses and other objects"

	| index class |
	stream atEnd ifTrue: [^self pastEnd].
	index := self nextLong.
	index < 0 ifTrue: [^self specialCaseLoad: index].
	index > 0 ifTrue: [^self lookupIndex: index].
	class := self loadClass.
	^self primLoad: class
    ]

    flush [
	"`Forget' any information on previously stored objects."

	<category: 'accessing'>
	toObjects := OrderedCollection new.
	fromObjects := IdentityDictionary new
    ]

    stream [
	"Answer the ByteStream to which the ObjectDumper will write
	 and from which it will read."

	<category: 'accessing'>
	^stream
    ]

    stream: aByteStream [
	"Set the ByteStream to which the ObjectDumper will write
	 and from which it will read."

	<category: 'accessing'>
	stream := aByteStream
    ]

    lookup: anObject [
	<category: 'private - handling maps'>
	| index |
	index := fromObjects at: anObject ifAbsent: [0].
	self nextPutLong: index.
	^index > 0
    ]

    lookupIndex: index [
	"Private - If index is a valid index into the toObjects map, evaluate
	 return the object associated to it.  Else, fail."

	<category: 'private - handling maps'>
	^toObjects at: index
    ]

    register: anObject [
	"Private - Register the anObject in the fromObjects and toObjects maps.
	 Assumes that anObject is absent in these maps. Answer anObject"

	"(fromObject includesKey: anObject) ifTrue: [
	 ^self error: 'Huh?!? Assertion failed' ]."

	<category: 'private - handling maps'>
	toObjects addLast: anObject.
	fromObjects at: anObject put: toObjects size.
	^anObject
    ]

    dumpContentsOf: anObject [
	"Dump anObject on the stream associated with the receiver. Answer
	 anObject"

	<category: 'private'>
	| index |
	(self lookup: anObject) ifTrue: [^anObject].
	anObject preStore.
	[self primDump: anObject] ensure: [anObject postStore].
	^self register: anObject
    ]

    initializeStream: aStream [
	"Private - Initialize the receiver's instance variables"

	<category: 'private'>
	stream := aStream.
	self flush.
	^self
    ]

    isClass: loadedClass [
	"Private - Answer whether loadedClass is really a class; only use
	 optimized selectors to avoid mess with objects that do not inherit
	 from Object."

	<category: 'private'>
	^loadedClass class class == Metaclass
    ]

    loadClass [
	"Private - Load the next object's class from stream"

	<category: 'private'>
	| isMeta loadedClass |
	isMeta := self nextByte = 0.
	loadedClass := self loadGlobal.
	(self isClass: loadedClass) ifFalse: [^self error: 'Bad class'].
	^isMeta ifTrue: [loadedClass class] ifFalse: [loadedClass]
    ]

    loadGlobal [
	"Private - Load a global object from the stream"

	<category: 'private'>
	| object space index |
	index := self nextLong.
	index > 0 ifTrue: [^self lookupIndex: index].
	space := self load.
	space isNil ifTrue: [space := Smalltalk].
	object := space at: self nextAsciiz asGlobalKey
		    ifAbsent: [^self error: 'Unknown global referenced'].
	^self register: object
    ]

    load: anObject through: aBlock [
	"Private - Fill anObject's indexed instance variables from the stream.
	 To get a variable, evaluate aBlock. Answer anObject"

	<category: 'private'>
	1 to: anObject basicSize do: [:i | anObject basicAt: i put: aBlock value].
	^anObject
	    postLoad;
	    yourself
    ]

    loadFixedPart: class [
	"Private - Load the fixed instance variables of a new instance of class"

	<category: 'private'>
	| object |
	object := class isVariable 
		    ifTrue: [class basicNew: self nextLong]
		    ifFalse: [class basicNew].
	self register: object.
	1 to: class instSize do: [:i | object instVarAt: i put: self load].
	^object
    ]

    nextAsciiz [
	"Private - Get a Null-terminated string from stream and answer it"

	<category: 'private'>
	| ch answer |
	answer := WriteStream on: (String new: 30).	"Hopefully large enough"
	
	[ch := stream next.
	ch asciiValue = 0] whileFalse: [answer nextPut: ch].
	^answer contents
    ]

    primDump: anObject [
	"Private - Basic code to dump anObject on the stream associated with the
	 receiver, without using proxies and the like."

	<category: 'private'>
	| class shape |
	self storeClass: (class := anObject class).
	self register: anObject.
	class isVariable ifTrue: [self nextPutLong: anObject basicSize].
	1 to: class instSize do: [:i | self dump: (anObject instVarAt: i)].
	class isVariable ifFalse: [^self].
	class isPointers 
	    ifTrue: [^self store: anObject through: [:obj | self dump: obj]].
	shape := class shape.
	shape == #character 
	    ifTrue: [^self store: anObject through: [:char | stream nextPut: char]].
	(shape == #byte or: [shape == #int8]) 
	    ifTrue: [^self store: anObject through: [:byte | self nextPutByte: byte]].
	(shape == #short or: [shape == #ushort]) 
	    ifTrue: [^self store: anObject through: [:short | self nextPutShort: short]].
	(shape == #int or: [shape == #int]) 
	    ifTrue: [^self store: anObject through: [:int | self nextPutLong: int]].
	(shape == #int64 or: [shape == #uint64]) 
	    ifTrue: [^self store: anObject through: [:int64 | self nextPutInt64: int64]].
	shape == #utf32 
	    ifTrue: 
		[^self store: anObject through: [:char | self nextPutLong: char codePoint]].
	shape == #float 
	    ifTrue: [^self store: anObject through: [:float | self nextPutFloat: float]].
	shape == #double 
	    ifTrue: 
		[^self store: anObject through: [:double | self nextPutFloat: double]].
	self notYetImplemented
    ]

    loadFromVersion: version fixedSize: instSize index: index [
	"Private - Basic code to load an object from a stream associated with
	 the receiver, calling the class'
	 #convertFromVersion:withFixedVariables:instanceVariables:for: method.
	 version will be the first parameter to that method, while instSize
	 will be the size of the second parameter.  The object returned by
	 that method is registered and returned."

	<category: 'private'>
	| object class realSize size fixed indexed placeholder shape |
	index > 0 ifTrue: [^self lookupIndex: index].
	class := self loadClass.
        version == class binaryRepresentationVersion ifTrue: [ ^ self primLoad: class ].
	self register: (placeholder := Object new).
	class isVariable ifTrue: [size := self nextUlong].
	realSize := instSize isNil 
		    ifTrue: [class nonVersionedInstSize]
		    ifFalse: [instSize].
	fixed := (1 to: realSize) collect: [:i | self load].
	class isVariable 
	    ifTrue: 
		[class isPointers 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self load]].
		shape := class shape.
		shape == #character 
		    ifTrue: [indexed := (1 to: size) collect: [:i | Character value: self nextByte]].
		(shape == #byte and: [indexed isNil]) 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextByte]].
		shape == #int8 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextSignByte]].
		shape == #short 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextShort]].
		shape == #ushort 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextUshort]].
		shape == #int 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextLong]].
		shape == #uint 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextUlong]].
		shape == #int64 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextInt64]].
		shape == #uint64 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextUint64]].
		shape == #utf32 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextLong asCharacter]].
		shape == #float 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextFloat]].
		shape == #double 
		    ifTrue: [indexed := (1 to: size) collect: [:i | self nextDouble]].
		indexed isNil ifTrue: [self shouldNotImplement]].
	placeholder become: (class 
		    convertFromVersion: version
		    withFixedVariables: fixed
		    indexedVariables: indexed
		    for: self).
	^placeholder
    ]

    primLoad: class [
	"Private - Basic code to load an object from the stream associated with the
	 receiver, assuming it doesn't use proxies and the like.  The class of the
	 loaded object is in index"

	<category: 'private'>
	| object shape |
	class isMetaclass ifTrue: [^class instanceClass].
	object := self loadFixedPart: class.
	class isVariable ifFalse: [^object postLoad; yourself].
	class isPointers ifTrue: [^self load: object through: [self load]].
	shape := class shape.
	shape == #character ifTrue: [^self load: object through: [Character value: self nextByte]].
	shape == #byte ifTrue: [^self load: object through: [self nextByte]].
	shape == #int8 ifTrue: [^self load: object through: [self nextSignByte]].
	shape == #short ifTrue: [^self load: object through: [self nextShort]].
	shape == #ushort ifTrue: [^self load: object through: [self nextUshort]].
	shape == #int ifTrue: [^self load: object through: [self nextLong]].
	shape == #uint ifTrue: [^self load: object through: [self nextUlong]].
	shape == #int64 ifTrue: [^self load: object through: [self nextInt64]].
	shape == #uint64 ifTrue: [^self load: object through: [self nextUint64]].
	shape == #utf32 
	    ifTrue: [^self load: object through: [self nextLong asCharacter]].
	shape == #float ifTrue: [^self load: object through: [self nextFloat]].
	shape == #double ifTrue: [^self load: object through: [self nextDouble]].
	self shouldNotImplement
    ]

    specialCaseDump: anObject [
	"Private - Store special-cased objects. These include booleans, integers,
	 nils, characters, classes and Processor. Answer true if object belongs
	 to one of these categories, else do nothing and answer false"

	<category: 'private'>
	SpecialCaseDump keysAndValuesDo: 
		[:index :each | 
		(each key value: anObject) 
		    ifTrue: 
			[stream skip: -4.
			self nextPutLong: index negated.
			each value value: self value: anObject.
			self register: anObject.
			^true]].
	^false
    ]

    specialCaseLoad: index [
	"Private - The first 4 bytes in the file were less than 0.
	 Load the remaining info about the object and answer it."

	<category: 'private'>
	| object |
	index > SpecialCaseLoad size ifTrue: [^self error: 'error in file'].
	object := (SpecialCaseLoad at: index negated) value: self.
	^self register: object
    ]

    storeClass: aClass [
	"Private - Store the aClass class in stream. The format is:
	 - for a metaclass, a 0 followed by the asciiz name of its instance
	 - for a class, a 1 followed by its asciiz name"

	"We don't register metaclasses; instead we register their instance
	 (the class) and use a byte to distinguish between the two cases."

	<category: 'private'>
	aClass isMetaclass 
	    ifTrue: [self nextPutByte: 0]
	    ifFalse: [self nextPutByte: 1].
	self storeGlobal: aClass asClass
    ]

    storeGlobal: anObject [
	<category: 'private'>
	| namespace |
	(self lookup: anObject) ifTrue: [^anObject].
	(anObject respondsTo: #environment) 
	    ifTrue: [namespace := anObject environment]
	    ifFalse: 
		[(anObject respondsTo: #superspace) 
		    ifTrue: [namespace := anObject superspace]
		    ifFalse: [namespace := nil	"read as `Smalltalk' upon load."]].
	self
	    dump: namespace;
	    register: anObject.
	stream nextPutAll: anObject name.
	self nextPutByte: 0
    ]

    store: anObject through: aBlock [
	"Private - Store anObject's indexed instance variables into the stream.
	 To store a variable, pass its value to aBlock."

	<category: 'private'>
	1 to: anObject basicSize do: [:i | aBlock value: (anObject basicAt: i)].
	^anObject
    ]

    nextByte [
	"Return the next byte in the byte array"

	<category: 'private - binary I/O'>
	^stream next asInteger
    ]

    nextByteArray: numBytes [
	"Return the next numBytes bytes in the byte array"

	<category: 'private - binary I/O'>
	^(stream next: numBytes) asByteArray
    ]

    nextSignedByte [
	"Return the next byte in the byte array, interpreted as a 8 bit signed number"

	<category: 'private - binary I/O'>
	^self nextBytes: 1 signed: true
    ]

    nextDouble [
	"Return the next 64-bit float in the byte array"

	<category: 'private - binary I/O'>
	^(FloatD new: 8)
	    at: 1 put: self nextByte;
	    at: 2 put: self nextByte;
	    at: 3 put: self nextByte;
	    at: 4 put: self nextByte;
	    at: 5 put: self nextByte;
	    at: 6 put: self nextByte;
	    at: 7 put: self nextByte;
	    at: 8 put: self nextByte
    ]

    nextFloat [
	"Return the next 32-bit float in the byte array"

	<category: 'private - binary I/O'>
	^(FloatE new: 4)
	    at: 1 put: self nextByte;
	    at: 2 put: self nextByte;
	    at: 3 put: self nextByte;
	    at: 4 put: self nextByte
    ]

    nextUint64 [
	"Return the next 8 bytes in the byte array, interpreted as a 64 bit unsigned int"

	<category: 'private - binary I/O'>
	^self nextBytes: 8 signed: false
    ]

    nextLongLong [
	"Return the next 8 bytes in the byte array, interpreted as a 64 bit signed int"

	<category: 'private - binary I/O'>
	^self nextBytes: 8 signed: true
    ]

    nextUlong [
	"Return the next 4 bytes in the byte array, interpreted as a 32 bit unsigned int"

	<category: 'private - binary I/O'>
	^self nextBytes: 4 signed: false
    ]

    nextLong [
	"Return the next 4 bytes in the byte array, interpreted as a 32 bit signed int"

	<category: 'private - binary I/O'>
	^self nextBytes: 4 signed: true
    ]

    nextUshort [
	"Return the next 2 bytes in the byte array, interpreted as a 16 bit unsigned int"

	<category: 'private - binary I/O'>
	^self nextBytes: 2 signed: false
    ]

    nextShort [
	"Return the next 2 bytes in the byte array, interpreted as a 16 bit signed int"

	<category: 'private - binary I/O'>
	^self nextBytes: 2 signed: true
    ]

    nextPutDouble: aDouble [
	"Store aDouble as a 64-bit float in the byte array"

	<category: 'private - binary I/O'>
	| d |
	d := aDouble asFloatD.
	self nextPutByte: (d at: 1).
	self nextPutByte: (d at: 2).
	self nextPutByte: (d at: 3).
	self nextPutByte: (d at: 4).
	self nextPutByte: (d at: 5).
	self nextPutByte: (d at: 6).
	self nextPutByte: (d at: 7).
	self nextPutByte: (d at: 8)
    ]

    nextPutFloat: aFloat [
	"Return the next 32-bit float in the byte array"

	<category: 'private - binary I/O'>
	| f |
	f := aFloat asFloatE.
	self nextPutByte: (f at: 1).
	self nextPutByte: (f at: 2).
	self nextPutByte: (f at: 3).
	self nextPutByte: (f at: 4)
    ]

    nextPutByte: anInteger [
	"Store anInteger (range: -128..255) on the byte array"

	<category: 'private - binary I/O'>
	| int |
	int := anInteger < 0 
		    ifTrue: [256 + anInteger]
		    ifFalse: [anInteger].
	^stream nextPut: (Character value: int)
    ]

    nextPutByteArray: aByteArray [
	"Store aByteArray on the byte array"

	<category: 'private - binary I/O'>
	^self nextPutAll: aByteArray
    ]

    nextPutInt64: anInteger [
	"Store anInteger (range: -2^63..2^64-1) on the byte array as 4 bytes"

	<category: 'private - binary I/O'>
	self nextPutBytes: 8 of: anInteger
    ]

    nextPutLong: anInteger [
	"Store anInteger (range: -2^31..2^32-1) on the byte array as 4 bytes"

	<category: 'private - binary I/O'>
	self nextPutBytes: 4 of: anInteger
    ]

    nextPutShort: anInteger [
	"Store anInteger (range: -32768..65535) on the byte array as 2 bytes"

	<category: 'private - binary I/O'>
	self nextPutBytes: 2 of: anInteger
    ]

    nextBytes: n signed: signed [
	"Private - Get an integer out of the next anInteger bytes in the stream"

	<category: 'private'>
	| int msb |
	int := 0.
	0 to: n * 8 - 16
	    by: 8
	    do: [:i | int := int + (self nextByte bitShift: i)].
	msb := self nextByte.
	(signed and: [msb > 127]) ifTrue: [msb := msb - 256].
	^int + (msb bitShift: n * 8 - 8)
    ]

    nextPutBytes: n of: anInteger [
	"Private - Store the n least significant bytes of int in little-endian format"

	<category: 'private'>
	| int |
	int := anInteger.
	n timesRepeat: 
		[self nextPutByte: (int bitAnd: 255).
		int := int bitShift: -8.
		(int = 0 and: [anInteger < 0]) ifTrue: [int := 255]]
    ]

]



Object subclass: DumperProxy [
    
    <category: 'Streams-Files'>
    <comment: 'I am an helper class for ObjectDumper. When an
object cannot be saved in the standard way, you can register a subclass of me
to provide special means to save that object.'>

    DumperProxy class >> loadFrom: anObjectDumper [
	"Reload a proxy stored in anObjectDumper and reconstruct the object"

	<category: 'accessing'>
	^anObjectDumper load object
    ]

    DumperProxy class >> acceptUsageForClass: aClass [
	"The receiver was asked to be used as a proxy for the class aClass.
	 Answer whether the registration is fine.  By default, answer true"

	<category: 'accessing'>
	^true
    ]

    DumperProxy class >> on: anObject [
	"Answer a proxy to be used to save anObject. This method
	 MUST be overridden and anObject must NOT be stored in the
	 object's instance variables unless you override #dumpTo:,
	 because that would result in an infinite loop!"

	<category: 'instance creation'>
	self subclassResponsibility
    ]

    dumpTo: anObjectDumper [
	"Dump the proxy to anObjectDumper -- the #loadFrom: class method
	 will reconstruct the original object."

	<category: 'saving and restoring'>
	anObjectDumper dump: self
    ]

    object [
	"Reconstruct the object stored in the proxy and answer it"

	<category: 'saving and restoring'>
	self subclassResponsibility
    ]
]



DumperProxy subclass: AlternativeObjectProxy [
    | object |
    
    <category: 'Streams-Files'>
    <comment: 'I am a proxy that uses the same ObjectDumper
to store an object which is not the object to be dumped, but from which the
dumped object can be reconstructed.  I am an abstract class, using me would
result in infinite loops because by default I try to store the same object
again and again.  See the method comments for more information'>

    AlternativeObjectProxy class >> acceptUsageForClass: aClass [
	"The receiver was asked to be used as a proxy for the class aClass.
	 Answer whether the registration is fine.  By default, answer true
	 except if AlternativeObjectProxy itself is being used."

	<category: 'instance creation'>
	^self ~~ AlternativeObjectProxy
    ]

    AlternativeObjectProxy class >> on: anObject [
	"Answer a proxy to be used to save anObject. IMPORTANT: this method
	 MUST be overridden so that the overridden version sends #on: to super
	 passing an object that is NOT the same as anObject (alternatively,
	 you can override #dumpTo:, which is what NullProxy does), because that
	 would result in an infinite loop!  This also means that
	 AlternativeObjectProxy must never be used directly -- only as
	 a superclass."

	<category: 'instance creation'>
	^self new object: anObject
    ]

    object [
	"Reconstruct the object stored in the proxy and answer it.  A
	 subclass will usually override this"

	<category: 'accessing'>
	^object
    ]

    primObject [
	"Reconstruct the object stored in the proxy and answer it.  This
	 method must not be overridden"

	<category: 'accessing'>
	^object
    ]

    object: theObject [
	"Set the object to be dumped to theObject.  This should not be
	 overridden."

	<category: 'accessing'>
	object := theObject
    ]
]



AlternativeObjectProxy subclass: NullProxy [
    
    <category: 'Streams-Files'>
    <comment: 'I am a proxy that does no special processing on the object
to be saved. I can be used to disable proxies for particular subclasses.  My
subclasses add to the stored information, but share the fact that the format
is about the same as that of #dump: without a proxy.'>

    NullProxy class >> loadFrom: anObjectDumper [
	"Reload the object stored in anObjectDumper"

	<category: 'instance creation'>
	^anObjectDumper load
    ]

    dumpTo: anObjectDumper [
	"Dump the object stored in the proxy to anObjectDumper"

	<category: 'accessing'>
	anObjectDumper dumpContentsOf: self object
    ]
]



AlternativeObjectProxy subclass: PluggableProxy [
    
    <category: 'Streams-Files'>
    <comment: 'I am a proxy that stores a different object
and, upon load, sends #reconstructOriginalObject to that object (which
can be a DirectedMessage, in which case the message is sent).  The
object to be stored is retrieved by sending #binaryRepresentationObject to
the object.'>

    PluggableProxy class >> on: anObject [
	"Answer a proxy to be used to save anObject.  The proxy
	 stores a different object obtained by sending to anObject
	 the #binaryRepresentationObject message (embedded
	 between #preStore and #postStore as usual)."

	<category: 'accessing'>
	anObject preStore.
	^[super on: anObject binaryRepresentationObject] 
	    ensure: [anObject postStore]
    ]

    object [
	"Reconstruct the object stored in the proxy and answer it;
	 the binaryRepresentationObject is sent the
	 #reconstructOriginalObject message, and the resulting
	 object is sent the #postLoad message."

	<category: 'saving and restoring'>
	^(super object reconstructOriginalObject)
	    postLoad;
	    yourself
    ]
]



NullProxy subclass: VersionableObjectProxy [
    
    <category: 'Streams-Files'>
    <comment: 'I am a proxy that stores additional
information to allow different versions of an object''s representations
to be handled by the program.  VersionableObjectProxies are backwards
compatible, that is you can support versioning even if you did not use
a VersionableObjectProxy for that class when the object was originarily
dumped.  VersionableObjectProxy does not support classes that changed
shape across different versions.  See the method comments for more
information.'>

    VersionableObjectProxy class >> loadFrom: anObjectDumper [
	"Retrieve the object.  If the version number doesn't match the
	 #binaryRepresentationVersion answered by the class, call the class'
	 #convertFromVersion:withFixedVariables:instanceVariables:for: method.
	 The stored version number will be the first parameter to that method
	 (or nil if the stored object did not employ a VersionableObjectProxy),
	 the remaining parameters will be respectively the fixed instance
	 variables, the indexed instance variables (or nil if the class is
	 fixed), and the ObjectDumper itself.
	 If no VersionableObjectProxy, the class is sent #nonVersionedInstSize
	 to retrieve the number of fixed instance variables stored for the
	 non-versioned object."

	<category: 'saving and restoring'>
	| version object instSize index |
	version := anObjectDumper nextLong.
	version := version >= 0 
		    ifTrue: 
			["The version was actually an object index."
			instSize := nil.
			index := version.
			nil]
		    ifFalse: 
			[instSize := anObjectDumper nextUlong.
			index := anObjectDumper nextLong.
			-1 - version].
	^anObjectDumper loadFromVersion: version fixedSize: instSize index: index
    ]

    dumpTo: anObjectDumper [
	"Save the object with extra versioning information."

	<category: 'saving and restoring'>
	anObjectDumper
	    nextPutLong: -1 - self object class binaryRepresentationVersion;
	    nextPutLong: self object class instSize.
	super dumpTo: anObjectDumper
    ]
]



AlternativeObjectProxy subclass: SingletonProxy [
    
    <category: 'Streams-Files'>
    <comment: 'I am a proxy that stores the class of an
object rather than the object itself, and pretends that a registered
instance (which most likely is a singleton instance of the stored class)
was stored instead.'>

    SingletonProxy class [
	| singletons |
	
    ]

    SingletonProxy class >> singletons [
	<category: 'private'>
	^singletons isNil 
	    ifTrue: [singletons := IdentityDictionary new]
	    ifFalse: [singletons]
    ]

    SingletonProxy class >> acceptUsageForClass: aClass [
	"The receiver was asked to be used as a proxy for the class aClass.
	 The registration is fine if the class is actually a singleton."

	<category: 'accessing'>
	| singleton |
	singleton := aClass someInstance.
	singleton nextInstance isNil ifFalse: [^false].
	self singletons at: aClass put: singleton.
	^true
    ]

    SingletonProxy class >> on: anObject [
	"Answer a proxy to be used to save anObject.  The proxy
	 stores the class and restores the object by looking into
	 a dictionary of class -> singleton objects."

	<category: 'instance creation'>
	(self singletons includesKey: anObject class) 
	    ifTrue: [^super on: anObject class].
	self error: 'class not registered within SingletonProxy'
    ]

    object [
	"Reconstruct the object stored in the proxy and answer it;
	 the binaryRepresentationObject is sent the
	 #reconstructOriginalObject message, and the resulting
	 object is sent the #postLoad message."

	<category: 'saving and restoring'>
	^self class singletons at: super object
	    ifAbsent: [self error: 'class not registered within SingletonProxy']
    ]
]



Eval [
    ObjectDumper
	initialize;
	registerProxyClass: PluggableProxy for: CompiledMethod;
	registerProxyClass: PluggableProxy for: CompiledBlock;
	registerProxyClass: SingletonProxy for: Processor class
]