branch: elpa/llama
commit f4a59f215438243fbbdc103a6db11fb2e99cff99
Author: Jonas Bernoulli <jo...@bernoul.li>
Commit: Jonas Bernoulli <jo...@bernoul.li>
Support &optional arguments
---
README.md | 28 ++++++++++++-------
llama.el | 93 ++++++++++++++++++++++++++++++++++++++++++---------------------
2 files changed, 81 insertions(+), 40 deletions(-)
diff --git a/README.md b/README.md
index 30189c2e12..caa7d2daf2 100644
--- a/README.md
+++ b/README.md
@@ -9,31 +9,39 @@ to a `lambda` expressions, which wraps around its arguments.
This `lambda` expression calls the function FN with arguments
ARGS and returns its value. Its own arguments are derived from
-symbols found in ARGS. Each symbol from `%1` through `%9`, which
-appears in ARGS, is treated as a positional argument. Missing
-arguments are named `_%N`, which keeps the byte-compiler quiet.
-In place of `%1` the shorthand `%` can be used, but only one of
-these two can appear in ARGS. `%*` represents extra `&rest`
-arguments.
+symbols found in ARGS.
+
+Each symbol from `%1` through `%9`, which appears in ARGS,
+specifies an argument. Each symbol from `&1` through `&9`, which
+appears in ARGS, specifies an optional argument. All arguments
+following an optional argument have to be optional as well, thus
+their names have to begin with `&`. Symbol `&*` specifies extra
+(`&rest`) arguments.
+
+Instead of `%1`, the shorthand `%` can be used; but that should
+only be done if it is the only argument, and using both `%1` and
+`%` is not allowed. Likewise `&` can be substituted for `&1`.
+Finally, for backward compatibility, `%*` can be used in place
+of `&*`, but only if there are no optional arguments.
Instead of:
```elisp
-(lambda (a _ c &rest d)
+(lambda (a _ &optional c &rest d)
(foo a (bar c) d))
```
you can use this macro and write:
```elisp
-(##foo % (bar %3) %*)
+(##foo %1 (bar &3) &*)
```
which expands to:
```elisp
-(lambda (% _%2 %3 &rest %*)
- (foo % (bar %3) %*))
+(lambda (%1 _%2 &optional &3 &rest %*)
+ (foo %1 (bar &3) %*))
```
The name `##` was choosen because that allows (optionally)
diff --git a/llama.el b/llama.el
index 85ae9ed2e7..ca7ffbfa9d 100644
--- a/llama.el
+++ b/llama.el
@@ -36,26 +36,34 @@
;; This `lambda' expression calls the function FN with arguments
;; ARGS and returns its value. Its own arguments are derived from
-;; symbols found in ARGS. Each symbol from `%1' through `%9', which
-;; appears in ARGS, is treated as a positional argument. Missing
-;; arguments are named `_%N', which keeps the byte-compiler quiet.
-;; In place of `%1' the shorthand `%' can be used, but only one of
-;; these two can appear in ARGS. `%*' represents extra `&rest'
-;; arguments.
+;; symbols found in ARGS.
+
+;; Each symbol from `%1' through `%9', which appears in ARGS,
+;; specifies an argument. Each symbol from `&1' through `&9', which
+;; appears in ARGS, specifies an optional argument. All arguments
+;; following an optional argument have to be optional as well, thus
+;; their names have to begin with `&'. Symbol `&*' specifies extra
+;; (`&rest') arguments.
+
+;; Instead of `%1', the shorthand `%' can be used; but that should
+;; only be done if it is the only argument, and using both `%1' and
+;; `%' is not allowed. Likewise `&' can be substituted for `&1'.
+;; Finally, for backward compatibility, `%*' can be used in place
+;; of `&*', but only if there are no optional arguments.
;; Instead of:
;;
-;; (lambda (a _ c &rest d)
+;; (lambda (a _ &optional c &rest d)
;; (foo a (bar c) d))
;;
;; you can use this macro and write:
;;
-;; (##foo % (bar %3) %*)
+;; (##foo %1 (bar %3) %*)
;;
;; which expands to:
;;
-;; (lambda (% _%2 %3 &rest %*)
-;; (foo % (bar %3) %*))
+;; (lambda (%1 _%2 &optional %3 &rest %*)
+;; (foo %1 (bar %3) %*))
;; The name `##' was choosen because that allows (optionally)
;; omitting the whitespace between it and the following symbol.
@@ -71,26 +79,34 @@
This `lambda' expression calls the function FN with arguments
ARGS and returns its value. Its own arguments are derived from
-symbols found in ARGS. Each symbol from `%1' through `%9', which
-appears in ARGS, is treated as a positional argument. Missing
-arguments are named `_%N', which keeps the byte-compiler quiet.
-In place of `%1' the shorthand `%' can be used, but only one of
-these two can appear in ARGS. `%*' represents extra `&rest'
-arguments.
+symbols found in ARGS.
+
+Each symbol from `%1' through `%9', which appears in ARGS,
+specifies an argument. Each symbol from `&1' through `&9', which
+appears in ARGS, specifies an optional argument. All arguments
+following an optional argument have to be optional as well, thus
+their names have to begin with `&'. Symbol `&*' specifies extra
+(`&rest') arguments.
+
+Instead of `%1', the shorthand `%' can be used; but that should
+only be done if it is the only argument, and using both `%1' and
+`%' is not allowed. Likewise `&' can be substituted for `&1'.
+Finally, for backward compatibility, `%*' can be used in place
+of `&*', but only if there are no optional arguments.
Instead of:
- (lambda (a _ c &rest d)
+ (lambda (a _ &optional c &rest d)
(foo a (bar c) d))
you can use this macro and write:
- (##foo % (bar %3) %*)
+ (##foo %1 (bar &3) &*)
which expands to:
- (lambda (% _%2 %3 &rest %*)
- (foo % (bar %3) %*))
+ (lambda (%1 _%2 &optional &3 &rest %*)
+ (foo %1 (bar &3) %*))
The name `##' was choosen because that allows (optionally)
omitting the whitespace between it and the following symbol.
@@ -103,25 +119,42 @@ It also looks a bit like #\\='function."
(defun llama--arguments (data)
(let ((args (make-vector 10 nil)))
(llama--collect data args)
- `(,@(let ((n 0))
- (mapcar (lambda (symbol)
- (setq n (1+ n))
- (or symbol (intern (format "_%%%s" n))))
- (reverse (seq-drop-while
- 'null
- (reverse (seq-subseq args 1))))))
- ,@(and (aref args 0) '(&rest %*)))))
+ (let ((optional nil)
+ (pos 0))
+ (apply #'nconc
+ (mapcar
+ (lambda (symbol)
+ (setq pos (1+ pos))
+ (cond
+ ((not symbol)
+ (list (intern (format "_%s%s" (if optional "&" "%") pos))))
+ ((eq (aref (symbol-name symbol) 0) ?%)
+ (cond (optional
+ (error "%s cannot follow optional argument" symbol))
+ ((eq symbol '%*)
+ (list '&rest symbol))
+ ((list symbol))))
+ ((eq symbol '&*)
+ (list '&rest symbol))
+ (optional
+ (list symbol))
+ ((setq optional t)
+ (list '&optional symbol))))
+ (vconcat (reverse (seq-drop-while
+ #'null
+ (reverse (seq-subseq args 1))))
+ (and-let* ((rest (aref args 0))) (list rest))))))))
(defun llama--collect (data args)
(cond
((symbolp data)
(let ((name (symbol-name data)) pos)
(save-match-data
- (when (string-match "\\`%\\([1-9*]\\)?\\'" name)
+ (when (string-match "\\`[%&]\\([1-9*]\\)?\\'" name)
(setq pos (match-string 1 name))
(setq pos (cond ((equal pos "*") 0)
((not pos) 1)
- (t (string-to-number pos))))
+ ((string-to-number pos))))
(when (and (= pos 1)
(aref args 1)
(not (equal data (aref args 1))))
