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* lisp/emacs-lisp/bindat.el (bindat-spec): New macro.

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It's basically an alias for `quote`, but it offers the advantage of
providing Edebug support and opens the possibility of compiling
the bindat spec to ELisp code.

* doc/lispref/processes.texi (Bindat Spec): Document `bindat-spec`.
(Bindat Functions): Tweak a few things to adjust to the state of the code.

* test/lisp/emacs-lisp/bindat-tests.el: Use it.

* test/lisp/emacs-lisp/edebug-tests.el (edebug-tests--read): New function.
(edebug-tests--&rest-behavior): New test.
This commit is contained in:
Stefan Monnier 2021-02-15 21:25:15 -05:00
parent 2106b12fa7
commit 83d9fbe3bb
5 changed files with 91 additions and 24 deletions
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59
lisp/emacs-lisp/bindat.el
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@ -65,13 +65,15 @@
;; The corresponding Lisp bindat specification looks like this:
;;
;; (setq header-bindat-spec
;; '((dest-ip ip)
;; (bindat-spec
;; (dest-ip ip)
;; (src-ip ip)
;; (dest-port u16)
;; (src-port u16)))
;;
;; (setq data-bindat-spec
;; '((type u8)
;; (bindat-spec
;; (type u8)
;; (opcode u8)
;; (length u16r) ;; little endian order
;; (id strz 8)
@ -79,7 +81,8 @@
;; (align 4)))
;;
;; (setq packet-bindat-spec
;; '((header struct header-bindat-spec)
;; (bindat-spec
;; (header struct header-bindat-spec)
;; (items u8)
;; (fill 3)
;; (item repeat (items)
@ -179,7 +182,7 @@
;; is interpreted by evalling TAG_VAL and then comparing that to
;; each TAG using equal; if a match is found, the corresponding SPEC
;; is used.
;; If TAG is a form (eval EXPR), EXPR is evalled with `tag' bound to the
;; If TAG is a form (eval EXPR), EXPR is eval'ed with `tag' bound to the
;; value of TAG_VAL; the corresponding SPEC is used if the result is non-nil.
;; Finally, if TAG is t, the corresponding SPEC is used unconditionally.
;;
@ -368,8 +371,7 @@ e.g. corresponding to STRUCT.FIELD1[INDEX2].FIELD3..."
(setq field (cdr field)))
struct)
;; Calculate bindat-raw length of structured data
;;;; Calculate bindat-raw length of structured data
(defvar bindat--fixed-length-alist
'((u8 . 1) (byte . 1)
@ -452,13 +454,13 @@ e.g. corresponding to STRUCT.FIELD1[INDEX2].FIELD3..."
(setq bindat-idx (+ bindat-idx len))))))))
(defun bindat-length (spec struct)
"Calculate bindat-raw length for STRUCT according to bindat SPEC."
"Calculate `bindat-raw' length for STRUCT according to bindat SPEC."
(let ((bindat-idx 0))
(bindat--length-group struct spec)
bindat-idx))
;; Pack structured data into bindat-raw
;;;; Pack structured data into bindat-raw
(defun bindat--pack-u8 (v)
(aset bindat-raw bindat-idx (logand v 255))
@ -623,8 +625,47 @@ Optional fourth arg IDX is the starting offset into RAW."
(bindat--pack-group struct spec)
(if raw nil bindat-raw)))
;;;; Debugging support
;; Misc. format conversions
(def-edebug-elem-spec 'bindat-spec '(&rest bindat-item))
(def-edebug-elem-spec 'bindat-item
'(([&optional bindat-field]
&or ["eval" form]
["fill" bindat-len]
["align" bindat-len]
["struct" form] ;A reference to another bindat-spec.
["union" bindat-tag-val &rest (bindat-tag bindat-spec)]
["repeat" integerp bindat-spec]
bindat-type)))
(def-edebug-elem-spec 'bindat-type
'(&or ("eval" form)
["str" bindat-len]
["strz" bindat-len]
["vec" bindat-len &optional bindat-type]
["bits" bindat-len]
symbolp))
(def-edebug-elem-spec 'bindat-field
'(&or ("eval" form) symbolp))
(def-edebug-elem-spec 'bindat-len '(&or [] "nil" bindat-arg))
(def-edebug-elem-spec 'bindat-tag-val '(bindat-arg))
(def-edebug-elem-spec 'bindat-tag '(&or ("eval" form) atom))
(def-edebug-elem-spec 'bindat-arg
'(&or ("eval" form) integerp (&rest symbolp integerp)))
(defmacro bindat-spec (&rest fields)
"Build the bindat spec described by FIELDS."
(declare (indent 0) (debug (bindat-spec)))
;; FIXME: We should really "compile" this to a triplet of functions!
`',fields)
;;;; Misc. format conversions
(defun bindat-format-vector (vect fmt sep &optional len)
"Format vector VECT using element format FMT and separator SEP.