; -*- scheme -*-
;
; Suggestions for policy mechanisms in the FFIGEN back-end for Chez Scheme.
; These are currently *not* implemented, and are only intended as examples.
;
; Mechanism falls into three categories: exclusion, overriding, and
; adaptation.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; Exclusion:
; At the outset, everything in the .ffi file is marked as referenced.
; The mechanisms for excluding stuff are based on an item's name.

; exclude-file takes a file name or list of file names and excludes every 
; item defined in that file and files included by it.

(exclude-file '())

; exclude-structure takes a structure name (i.e. either "struct FOO"
; or "union FOO" or "FOO") or list of names and inhibits generation of
; constructors, destructors, accessors, and mutators for it and all 
; typedefs derived from it.  If the name is a typedef name and the 
; structure named has a compiler-generated tag, then the structure 
; named by this typedef is  also excluded.

(exclude-structure "FILE")

; exclude-function excludes the named function(s).

(exclude-function "select")

; exclude-global excludes the named global variable.

(exclude-global "__iob")


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;
; Overriding

; Override-prototype gives the named function a new prototype.

(override-prototype "fgets" 
  `(function (,(primitive-type 'string)
	      ,(primitive-type 'int)
	      ,(pointer-type (struct-type "FILE")))
	     ,(pointer-type (primitive-type 'char))))


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;
; Adaptation

; Short-policy says something about how to handle shorts.  Three values are
; possible: warning, use-integer, and use-proxy.  If use-integer is the
; value, then an integer-32 FFI argument will be used on the assumption that
; this is meaningful in the native API.  If use-proxy is the value then a
; proxy function is generated which takes an integer argument and calls
; the real function with the argument cast to short.

(short-policy 'use-integer)

; Struct-param-policy says something about how to handle structure parameters.
; Values are: warning and use-proxy.  If use-proxy is the value, then
; an FF will be generated which takes structure pointers and which names a
; proxy function (this is transparent to Scheme code), and the real function
; will be called by the proxy.

(struct-param-policy 'warning)

; Struct-return-policy says something about how to handle structure return
; values. Values are: warning, alloc-new, and pass-placeholder.  If alloc-new
; is the value, then a proxy function will be generated which receives
; the return value, allocates an object on the heap for it, copies the value
; into the allocated memory, and returns a pointer to the memory. 
; If pass-placeholder is the value, then a FF and proxy will be generated
; that take an extra argument (the first); that argument must be a pointer
; to a structure in which to place the value.

(struct-return-policy 'warning)

; Variadic-policy says something about how to handle variadic procedures.
; Values are: warning and exclude.  If the value is exclude, a warning will
; be given and no FFI code will be generated; if the value is warning, then
; invalid FFI code will be generated.

(variadic-policy 'warning)

; eof