376 lines
9.2 KiB
Smalltalk
376 lines
9.2 KiB
Smalltalk
|
|
|
|
##
|
|
## TODO: is it better to inherit from Object???
|
|
## or treat Exception specially like UndefinedObject or Class???
|
|
##
|
|
#class Exception(Apex)
|
|
{
|
|
#dcl signalContext handlerContext messageText.
|
|
|
|
#method(#class) signal
|
|
{
|
|
^self new signal
|
|
}
|
|
|
|
#method(#class) signal: text
|
|
{
|
|
^self new signal: text
|
|
}
|
|
|
|
#method handlerContext: context
|
|
{
|
|
self.handlerContext := context.
|
|
}
|
|
|
|
#method messageText
|
|
{
|
|
^self.messageText
|
|
}
|
|
|
|
#method __signal
|
|
{
|
|
self.signalContext := thisContext.
|
|
((thisContext sender) findExceptionContext) handleException: self.
|
|
}
|
|
|
|
#method signal
|
|
{
|
|
| excctx excblk retval actpos |
|
|
|
|
self.signalContext := thisContext.
|
|
excctx := (thisContext sender) findExceptionContext.
|
|
[excctx notNil] whileTrue: [
|
|
excblk := excctx findExceptionHandlerFor: (self class).
|
|
(excblk notNil and:
|
|
[actpos := excctx basicSize - 1. excctx basicAt: actpos]) ifTrue: [
|
|
self.handlerContext := excctx.
|
|
excctx basicAt: actpos put: false.
|
|
[ retval := excblk value: self ] ensure: [
|
|
excctx basicAt: actpos put: true
|
|
].
|
|
|
|
thisContext unwindTo: (excctx sender) return: nil.
|
|
Processor return: retval to: (excctx sender).
|
|
].
|
|
excctx := (excctx sender) findExceptionContext.
|
|
].
|
|
|
|
## -----------------------------------------------------------------
|
|
## FATAL ERROR - no exception handler.
|
|
## -----------------------------------------------------------------
|
|
##thisContext unwindTo: nil return: nil.
|
|
##thisContext unwindTo: (Processor activeProcess initialContext) return: nil.
|
|
thisContext unwindTo: (thisProcess initialContext) return: nil.
|
|
('### EXCEPTION NOT HANDLED #### ', self class name, ' - ', self messageText) dump.
|
|
## TODO: debug the current process???? "
|
|
|
|
##Processor activeProcess terminate.
|
|
thisProcess terminate.
|
|
}
|
|
|
|
#method signal: text
|
|
{
|
|
self.messageText := text.
|
|
^self signal.
|
|
}
|
|
|
|
#method pass
|
|
{
|
|
## pass the exception to the outer context
|
|
((self.handlerContext sender) findExceptionContext) handleException: self.
|
|
}
|
|
|
|
#method return: value
|
|
{
|
|
(self.handlerContext notNil) ifTrue: [
|
|
Processor return: value to: self.handlerContext.
|
|
].
|
|
}
|
|
|
|
#method retry
|
|
{
|
|
## TODO: verify if return:to: causes unnecessary stack growth.
|
|
(self.handlerContext notNil) ifTrue: [
|
|
self.handlerContext pc: 0.
|
|
Processor return: self to: self.handlerContext.
|
|
].
|
|
}
|
|
|
|
#method resume: value
|
|
{
|
|
## TODO: verify if return:to: causes unnecessary stack growth.
|
|
## is this correct???
|
|
(self.signalContext notNil and: [self.handlerContext notNil]) ifTrue: [
|
|
| ctx |
|
|
ctx := self.signalContext sender.
|
|
self.signalContext := nil.
|
|
self.handlerContext := nil.
|
|
Processor return: value to: ctx.
|
|
].
|
|
}
|
|
|
|
#method resume
|
|
{
|
|
^self resume: nil.
|
|
}
|
|
}
|
|
|
|
##============================================================================
|
|
#extend Context
|
|
{
|
|
#method isExceptionContext
|
|
{
|
|
^false
|
|
}
|
|
|
|
#method isEnsureContext
|
|
{
|
|
^false
|
|
}
|
|
|
|
#method ensureBlock
|
|
{
|
|
^nil
|
|
}
|
|
|
|
#method findExceptionContext
|
|
{
|
|
| ctx |
|
|
ctx := self.
|
|
[ ctx notNil ] whileTrue: [
|
|
(ctx isExceptionContext) ifTrue: [^ctx].
|
|
ctx := ctx sender.
|
|
].
|
|
^nil
|
|
}
|
|
|
|
#method unwindTo: context return: retval
|
|
{
|
|
## -------------------------------------------------------------------
|
|
## <<private>>
|
|
## private: called by VM upon unwinding
|
|
## -------------------------------------------------------------------
|
|
|
|
| ctx stop |
|
|
|
|
ctx := self.
|
|
stop := false.
|
|
[stop] whileFalse: [
|
|
| eb |
|
|
eb := ctx ensureBlock.
|
|
(eb notNil) ifTrue: [
|
|
| donepos |
|
|
donepos := ctx basicSize - 1.
|
|
(ctx basicAt: donepos) ifFalse: [
|
|
ctx basicAt: donepos put: true.
|
|
eb value.
|
|
].
|
|
].
|
|
stop := (ctx == context).
|
|
ctx := ctx sender.
|
|
|
|
## stop ifFalse: [ stop := ctx isNil ].
|
|
].
|
|
|
|
^retval
|
|
}
|
|
}
|
|
|
|
##============================================================================
|
|
#extend MethodContext
|
|
{
|
|
#method isExceptionContext
|
|
{
|
|
## 10 - STIX_METHOD_PREAMBLE_EXCEPTION in VM.
|
|
^self.method preambleCode == 10.
|
|
}
|
|
|
|
#method isEnsureContext
|
|
{
|
|
## 10 - STIX_METHOD_PREAMBLE_ENSURE in VM.
|
|
^self.method preambleCode == 11
|
|
}
|
|
|
|
#method ensureBlock
|
|
{
|
|
## TODO: change 8 to a constant when stix is enhanced to support constant definition
|
|
(self.method preambleCode == 11) ifFalse: [^nil].
|
|
^self basicAt: 8.
|
|
}
|
|
|
|
|
|
#method findExceptionHandlerFor: exception_class
|
|
{
|
|
## find an exception handler block for a given exception class.
|
|
##
|
|
## for this to work, self must be an exception handler context.
|
|
## For a single on:do: call,
|
|
## self class specNumInstVars must return 8.
|
|
## basicAt: 8 must be the on: argument.
|
|
## basicAt: 9 must be the do: argument
|
|
|
|
(self isExceptionContext) ifTrue: [
|
|
| bound exc |
|
|
## NOTE: if on:do: has a temporary varible, bound must be adjusted to reflect it.
|
|
bound := self basicSize - 1.
|
|
## TODO: change 8 to a constant when stix is enhanced to support constant definition
|
|
## or calcuate the minimum size using the class information.
|
|
8 to: bound by: 2 do: [ :i |
|
|
exc := self basicAt: i.
|
|
((exception_class == exc) or: [exception_class inheritsFrom: exc]) ifTrue: [^self basicAt: (i + 1)].
|
|
]
|
|
].
|
|
^nil.
|
|
}
|
|
|
|
#method handleException: exception
|
|
{
|
|
## -------------------------------------------------------------------
|
|
## <<private>>
|
|
## called by Exception>>signal.
|
|
## this method only exists in the MethodContext and UndefinedObject.
|
|
## the caller must make sure that the receiver object is
|
|
## a method context or nil. Exception>>signal invokes this method
|
|
## only for an exception context which is a method context. it
|
|
## invokes it for nil when no exception context is found.
|
|
## -------------------------------------------------------------------
|
|
|
|
| excblk retval actpos |
|
|
|
|
## position of the temporary variable 'active' in MethodContext>>on:do.
|
|
## for this code to work, it must be the last temporary variable in the method.
|
|
actpos := (self basicSize) - 1.
|
|
|
|
excblk := self findExceptionHandlerFor: (exception class).
|
|
(excblk isNil or: [(self basicAt: actpos) not]) ifTrue: [
|
|
## self is an exception context but doesn't have a matching
|
|
## exception handler or the exception context is already
|
|
## in the middle of evaluation.
|
|
^(self.sender findExceptionContext) handleException: exception.
|
|
].
|
|
|
|
exception handlerContext: self.
|
|
|
|
## -------------------------------------------------------------------
|
|
## if an exception occurs within an exception handler block,
|
|
## the search will reach this context again as the exception block
|
|
## is evaluated before actual unwinding. set the temporary variable
|
|
## in the exception context to mask out this context from the search
|
|
## list.
|
|
## -------------------------------------------------------------------
|
|
self basicAt: actpos put: false.
|
|
[ retval := excblk value: exception ] ensure: [
|
|
self basicAt: actpos put: true
|
|
].
|
|
|
|
##(self.sender isNil) ifTrue: [ "TODO: CANNOT RETURN" ].
|
|
|
|
## -------------------------------------------------------------------
|
|
## return to self.sender which is a caller of the exception context (on:do:)
|
|
## pass the first ensure context between thisContext and self.sender.
|
|
##
|
|
## [ [Exception signal: 'xxx'] ensure: [20] ] on: Exception do: [:ex | ...]
|
|
##
|
|
## -------------------------------------------------------------------
|
|
thisContext unwindTo: self.sender return: nil.
|
|
Processor return: retval to: self.sender.
|
|
}
|
|
}
|
|
|
|
##============================================================================
|
|
#extend BlockContext
|
|
{
|
|
#method on: anException do: anExceptionBlock
|
|
{
|
|
| exception_active |
|
|
<exception>
|
|
|
|
"thisContext isExceptionContext dump.
|
|
(thisContext basicSize) dump.
|
|
(thisContext basicAt: 8) dump. ## this should be anException
|
|
(thisContext basicAt: 9) dump. ## this should be anExceptionBlock
|
|
(thisContext basicAt: 10) dump. ## this should be handlerActive
|
|
'on:do: ABOUT TO EVALUE THE RECEIVER BLOCK' dump."
|
|
|
|
exception_active := true.
|
|
^self value.
|
|
}
|
|
|
|
#method on: exc1 do: blk1 on: exc2 do: blk2
|
|
{
|
|
| exception_active |
|
|
<exception>
|
|
exception_active := true.
|
|
^self value.
|
|
}
|
|
|
|
#method ensure: aBlock
|
|
{
|
|
| retval done |
|
|
<ensure>
|
|
|
|
done := false.
|
|
retval := self value.
|
|
|
|
## the temporary variable 'done' may get changed
|
|
## during evaluation for exception handling.
|
|
done ifFalse: [
|
|
done := true.
|
|
aBlock value.
|
|
].
|
|
^retval
|
|
}
|
|
|
|
#method ifCurtailed: aBlock
|
|
{
|
|
| v ok |
|
|
|
|
ok := false.
|
|
[ v := self value. ok := true. ] ensure: [ ok ifFalse: [aBlock value] ].
|
|
^v.
|
|
}
|
|
}
|
|
|
|
|
|
##============================================================================
|
|
#class NoSuchMessageException(Exception)
|
|
{
|
|
}
|
|
|
|
#class PrimitiveFailureException(Exception)
|
|
{
|
|
}
|
|
|
|
#extend Apex
|
|
{
|
|
#method(#class) primitiveFailed
|
|
{
|
|
## TODO: implement this
|
|
## experimental backtrace...
|
|
| ctx |
|
|
ctx := thisContext.
|
|
[ctx notNil] whileTrue: [
|
|
(ctx class == MethodContext)
|
|
ifTrue: [ (ctx method owner name, '>>', ctx method name) dump ].
|
|
## TODO: include blockcontext???
|
|
ctx := ctx sender.
|
|
].
|
|
'------ END OF BACKTRACE -----------' dump.
|
|
PrimitiveFailureException signal: 'PRIMITIVE FAILED'.
|
|
}
|
|
|
|
#method(#class) cannotInstantiate
|
|
{
|
|
Exception signal: 'Cannot instantiate'.
|
|
}
|
|
|
|
#method(#class) doesNotUnderstand: messageSymbol
|
|
{
|
|
## TODO: implement this properly
|
|
NoSuchMessageException signal: (messageSymbol, ' not understood by ', (self name)).
|
|
}
|
|
}
|
|
|
|
|