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|
"======================================================================
|
| DeferredVariableBinding Method Definitions
|
|
======================================================================"
"======================================================================
|
| Copyright 2007, 2008 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.
|
======================================================================"
LookupKey subclass: DeferredVariableBinding [
| class defaultDictionary association path |
<category: 'Language-Data types'>
<comment: 'I represent a binding to a variable that is not tied to a particular
dictionary until the first access. Then, lookup rules for global variables
in the scope of a given class are used.'>
DeferredVariableBinding class >> path: anArray class: aClass defaultDictionary: aDictionary [
"As with #key:class:defaultDictionary:, but accepting an array
of symbols, representing a namespace path, instead."
<category: 'basic'>
^(self key: anArray first)
class: aClass;
defaultDictionary: aDictionary;
path: anArray allButFirst;
yourself
]
DeferredVariableBinding class >> key: aSymbol class: aClass defaultDictionary: aDictionary [
"Answer a binding that will look up aSymbol as a variable in
aClass's environment at first access. See #resolveBinding's
comment for aDictionary's meaning."
<category: 'basic'>
^(self key: aSymbol)
class: aClass;
defaultDictionary: aDictionary;
yourself
]
value [
"Answer a new instance of the receiver with the given key and value"
<category: 'basic'>
association isNil
ifTrue: [association := self resolvePathFrom: self resolveBinding].
^association value
]
value: anObject [
"Answer a new instance of the receiver with the given key and value"
<category: 'basic'>
association isNil
ifTrue: [association := self resolvePathFrom: self resolveBinding].
association value: anObject
]
path [
"Answer the path followed after resolving the first key."
<category: 'basic'>
^path
]
class: aClass [
<category: 'private'>
class := aClass
]
defaultDictionary: aDictionary [
<category: 'private'>
defaultDictionary := aDictionary
]
path: anArray [
<category: 'private'>
path := anArray isEmpty ifTrue: [nil] ifFalse: [anArray]
]
resolvePathFrom: assoc [
"Given the resolution of the first key, resolve the rest of the path.
The final element might be put in Undeclared, the ones in the middle
instead must exist."
<category: 'private'>
| pathAssoc |
path isNil ifTrue: [^assoc].
pathAssoc := assoc.
1 to: path size - 1
do: [:each | pathAssoc := pathAssoc value associationAt: (path at: each)].
^pathAssoc value associationAt: path last
ifAbsent:
[Undeclared
at: path last put: nil;
associationAt: path last]
]
resolveBinding [
"Look for a pool dictionary of class that includes the key. If not found,
add the variable to the defaultDictionary. If already bound, reuse the
bound that was found on the previous lookup."
<category: 'private'>
"See if a previous access has created the binding."
| assoc |
assoc := defaultDictionary associationAt: self key ifAbsent: [nil].
assoc isNil ifFalse: [^assoc].
"Look for the binding in the class environment."
class allSharedPoolDictionariesDo:
[:env |
assoc := env hereAssociationAt: self key ifAbsent: [nil].
assoc isNil ifFalse: [^assoc]].
"Create it as a temporary."
defaultDictionary at: self key ifAbsentPut: [nil].
^defaultDictionary associationAt: self key
]
printOn: aStream [
"Put on aStream some Smalltalk code compiling to the receiver"
<category: 'storing'>
aStream nextPut: ${.
aStream nextPutAll: self key.
self path isNil
ifFalse:
[self path do:
[:each |
aStream
nextPut: $.;
nextPutAll: each]].
aStream nextPut: $}
]
storeOn: aStream [
"Put on aStream some Smalltalk code compiling to the receiver"
<category: 'storing'>
aStream nextPut: $#.
self printOn: aStream
]
]
|
