valid pragma syntax

On Sun, 10 Jan 2016, Nicolai Hess wrote:

pharo fogbugz issue: 17359 MessageNotUnderstood: receiver of "keywords" is nil


is this valid pragma syntax:

    <apicall: bool 'SetCursorPos' (long long) module: 'user32.dll'>

This is not a pragma, but the special syntax used by FFI. AFAIK it predates pragmas.

our (pharo) parser can not parse this (does not recognizes the
"selector parts" (apicall:module:) right)

Any recommendations how to fix this
- fix RBParser or
- change this pragma, for example, like this
  <apicall: #(bool SetCursorPos (long long)) module: 'user32.dll'>

There's nothing to fix here. Either you change your parser, compiler and decompiler to support this syntax, but knowing how things work in Pharo, this is not an option

, or change the methods with these callouts, introducing another incompatibility between Pharo and the rest, to use pragmas and create a custom parser, compiler and decompiler to be able to compile FFI callouts into methods when such pragmas are present.

Levente

nicolai

pharo fogbugz issue: 17359 MessageNotUnderstood: receiver of "keywords" is nil

is this valid pragma syntax:

    <apicall: bool 'SetCursorPos' (long long) module: 'user32.dll'>

our (pharo) parser can not parse this (does not recognizes the

"selector parts" (apicall:module:) right)

Any recommendations how to fix this

- fix RBParser or

- change this pragma, for example, like this
  <apicall: #(bool SetCursorPos (long long)) module: 'user32.dll'>

nicolai

 

Hi Nicolai,

On Sun, Jan 10, 2016 at 3:16 AM, Nicolai Hess <[hidden email]> wrote:

pharo fogbugz issue: 17359 MessageNotUnderstood: receiver of "keywords" is nil

is this valid pragma syntax:

    <apicall: bool 'SetCursorPos' (long long) module: 'user32.dll'>

As others have said this is not a valid pragma.  A valid pragma is a message expression (a message with no receiver) that has only literal arguments.  There is one exception, to accept a variable name for the error code in a primitive invocation.

And as Levente has said it is a goal of the new FFI to get rid of the old syntax you show above.

And as Igor Stasenko discovered /any/ C signature can be written as a literal Array, providing we allow underscores in Symbols (which is a preference).  So for example, the heapsort declaration from the standard C library:

int

     heapsort(void *base, size_t nel, size_t width,

         int (*compar)(const void *, const void *)) 

could be written as a pragma via e.g.

    <ffiCCall: #(int heapsort(void *base, size_t nel, size_t width, int (*compar)(const void *, const void *)))>

in which case it is equal to

   <ffiCCall: #(#int #heapsort #( #void #* #base #, #size_t #nel #, #size_t #width #, #int #( #* #compar ) #( #const #void #*, #const #void #*)))>

which, while a massive hack, is pretty neat.  The only difficulty in parsing the above s that void *, is #void #*, not #void #* #,.

So for me, the natural pragma syntax for the new FFI should be a single keyword starting with ffi that includes the language with which to parse the pragma's argument, followed by a literal Array containing the signature (rather than e.g. a String).  I'd also provide a special-purpose pretty-printer for literal arrays that would be used to pretty-print the above, e.g. when decompiling.

This would easily allow extensions such as

     <ffiCcall: #(wchar_t * wcschr(const wchar_t *s, wchar_t c)) arg1is: #UnicodeString arg2is: Character>

to guide a marshalling engine in providing automatic checks and conversions.

[Slightly OT]

Note that I'm already using this syntax in Alien callbacks because one thing it does is to normalize the signature, eliminating the significance of most whitespace (the #*, above being one example where it fails).  So a Callback for heapsort above looks like

voidstarvoidstarRetint: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *)) abi: #IA32>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien unsignedLongAt: 1))

value: (Alien forPointer: (spAlien unsignedLongAt: 5)))

or

voidstarvoidstarRetintARM32: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *)) abi: #ARM32>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien registerAt: 1))

value: (Alien forPointer: (spAlien registerAt: 2)))

Hmmm, if Callback had subclasses for each ABI then the above would become

IA32Callback methods for signature

voidstarvoidstarRetint: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *))>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien unsignedLongAt: 1))

value: (Alien forPointer: (spAlien unsignedLongAt: 5)))

ARM32Callback methods for signatures

voidstarvoidstarRetint: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *))>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien registerAt: 1))

value: (Alien forPointer: (spAlien registerAt: 2)))

Much nicer.  I shall make it so.

our (pharo) parser can not parse this (does not recognizes the

"selector parts" (apicall:module:) right)

Any recommendations how to fix this

- fix RBParser or

- change this pragma, for example, like this
  <apicall: #(bool SetCursorPos (long long)) module: 'user32.dll'>

nicolai

_,,,^..^,,,_

best, Eliot

 

well… UnifiedFFI, UFFI or whatever it will be called already does that… as you know.

Currently we are using “older” NB way: as a method call, then solving it in first call. This is nice because is compatible and easies some stuff. 

But final objective is to provide a pragma and solve it in compilation time. 

Then we can 100% deprecate the invalid pragma old FFI uses today. 

At least, that’s what we have talk :)

Esteban

On 12 Jan 2016, at 20:06, Nicolai Hess <[hidden email]> wrote:

2016-01-10 16:57 GMT+01:00 Eliot Miranda <[hidden email]>:

 

Hi Nicolai,

On Sun, Jan 10, 2016 at 3:16 AM, Nicolai Hess <[hidden email]> wrote:

pharo fogbugz issue: 17359 MessageNotUnderstood: receiver of "keywords" is nil

is this valid pragma syntax:

    <apicall: bool 'SetCursorPos' (long long) module: 'user32.dll'>

As others have said this is not a valid pragma.  A valid pragma is a message expression (a message with no receiver) that has only literal arguments.  There is one exception, to accept a variable name for the error code in a primitive invocation.

And as Levente has said it is a goal of the new FFI to get rid of the old syntax you show above.

Thanks Eliot.

I think I will wait what Esteban will say to this, he put those classes in the image, maybe he had a plan for the new ffi/apicall syntax

And as Igor Stasenko discovered /any/ C signature can be written as a literal Array, providing we allow underscores in Symbols (which is a preference).  So for example, the heapsort declaration from the standard C library:

int

     heapsort(void *base, size_t nel, size_t width,

         int (*compar)(const void *, const void *)) 

could be written as a pragma via e.g.

    <ffiCCall: #(int heapsort(void *base, size_t nel, size_t width, int (*compar)(const void *, const void *)))>

in which case it is equal to

   <ffiCCall: #(#int #heapsort #( #void #* #base #, #size_t #nel #, #size_t #width #, #int #( #* #compar ) #( #const #void #*, #const #void #*)))>

which, while a massive hack, is pretty neat.  The only difficulty in parsing the above s that void *, is #void #*, not #void #* #,.

So for me, the natural pragma syntax for the new FFI should be a single keyword starting with ffi that includes the language with which to parse the pragma's argument, followed by a literal Array containing the signature (rather than e.g. a String).  I'd also provide a special-purpose pretty-printer for literal arrays that would be used to pretty-print the above, e.g. when decompiling.

This would easily allow extensions such as

     <ffiCcall: #(wchar_t * wcschr(const wchar_t *s, wchar_t c)) arg1is: #UnicodeString arg2is: Character>

to guide a marshalling engine in providing automatic checks and conversions.

[Slightly OT]

Note that I'm already using this syntax in Alien callbacks because one thing it does is to normalize the signature, eliminating the significance of most whitespace (the #*, above being one example where it fails).  So a Callback for heapsort above looks like

voidstarvoidstarRetint: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *)) abi: #IA32>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien unsignedLongAt: 1))

value: (Alien forPointer: (spAlien unsignedLongAt: 5)))

or

voidstarvoidstarRetintARM32: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *)) abi: #ARM32>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien registerAt: 1))

value: (Alien forPointer: (spAlien registerAt: 2)))

Hmmm, if Callback had subclasses for each ABI then the above would become

IA32Callback methods for signature

voidstarvoidstarRetint: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *))>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien unsignedLongAt: 1))

value: (Alien forPointer: (spAlien unsignedLongAt: 5)))

ARM32Callback methods for signatures

voidstarvoidstarRetint: callbackContext sp: spAlien

<signature: #(int (*)(const void *, const void *))>

^callbackContext wordResult:

(block

value: (Alien forPointer: (spAlien registerAt: 1))

value: (Alien forPointer: (spAlien registerAt: 2)))

Much nicer.  I shall make it so.

our (pharo) parser can not parse this (does not recognizes the

"selector parts" (apicall:module:) right)

Any recommendations how to fix this

- fix RBParser or

- change this pragma, for example, like this
  <apicall: #(bool SetCursorPos (long long)) module: 'user32.dll'>

nicolai

_,,,^..^,,,_

best, Eliot