;; Author: Nicolas Petton <nicolas@petton.fr>
;; Keywords: stream, laziness, sequences
-;; Version: 2.0.1
+;; Version: 2.1.0
;; Package-Requires: ((emacs "25"))
;; Package: stream
(defmacro stream-make (&rest body)
"Return a stream built from BODY.
-BODY must return nil or a cons cell, which cdr is itself a
+BODY must return nil or a cons cell whose cdr is itself a
stream."
(declare (debug t))
`(list ',stream--identifier (thunk-delay ,@body)))
(cl-defmethod stream ((buffer buffer) &optional pos)
"Return a stream of the characters of the buffer BUFFER.
-BUFFER-OR-NAME may be a buffer or a string (buffer name).
+BUFFER may be a buffer or a string (buffer name).
The sequence starts at POS if non-nil, 1 otherwise."
(with-current-buffer buffer
(unless pos (setq pos (point-min)))
(char-after (point)))))
(stream buffer (1+ pos)))))
+(declare-function iter-next "generator")
+
+(defun stream-from-iterator (iterator)
+ "Return a stream generating new elements through ITERATOR.
+ITERATOR is an iterator object in terms of the \"generator\"
+package."
+ (stream-make
+ (condition-case nil
+ (cons (iter-next iterator) (stream-from-iterator iterator))
+ (iter-end-of-sequence nil))))
+
+(defun stream-regexp (buffer regexp)
+ (stream-make
+ (let (match)
+ (with-current-buffer buffer
+ (setq match (re-search-forward regexp nil t)))
+ (when match
+ (cons (match-data) (stream-regexp buffer regexp))))))
+
(defun stream-range (&optional start end step)
"Return a stream of the integers from START to END, stepping by STEP.
If START is nil, it defaults to 0. If STEP is nil, it defaults to
"Return a stream of all but the first element of STREAM."
(or (cdr (thunk-force (cadr stream)))
(stream-empty)))
+
+(defun stream-append (&rest streams)
+ "Concatenate the STREAMS.
+Requesting elements from the resulting stream will request the
+elements in the STREAMS in order."
+ (if (null streams)
+ (stream-empty)
+ (stream-make
+ (let ((first (pop streams)))
+ (while (and (stream-empty-p first) streams)
+ (setq first (pop streams)))
+ (if (stream-empty-p first)
+ nil
+ (cons (stream-first first)
+ (if streams (apply #'stream-append (stream-rest first) streams)
+ (stream-rest first))))))))
+
+(defmacro stream-pop (stream)
+ "Return the first element of STREAM and set the value of STREAM to its rest."
+ (unless (symbolp stream)
+ (error "STREAM must be a symbol"))
+ `(prog1
+ (stream-first ,stream)
+ (setq ,stream (stream-rest ,stream))))
\f
;;; cl-generic support for streams
-(defvar stream--generalizer
- (cl-generic-make-generalizer
- 11
- (lambda (name)
- `(when (streamp ,name)
- 'stream))
- (lambda (tag)
- (when (eq tag 'stream)
- '(stream)))))
+(cl-generic-define-generalizer stream--generalizer
+ 11
+ (lambda (name)
+ `(when (streamp ,name)
+ 'stream))
+ (lambda (tag)
+ (when (eq tag 'stream)
+ '(stream))))
(cl-defmethod cl-generic-generalizers ((_specializer (eql stream)))
"Support for `stream' specializers."
;;; Implementation of seq.el generic functions
-(cl-defmethod seq-p ((_stream stream))
+(cl-defmethod seqp ((_stream stream))
t)
(cl-defmethod seq-elt ((stream stream) n)
(seq-take (seq-drop stream start) (- end start)))
(cl-defmethod seq-into-sequence ((stream stream))
- "Convert STREAM into a sequence"
+ "Convert STREAM into a sequence."
(let ((list))
(seq-doseq (elt stream)
(push elt list))
(stream-rest stream)))))
(cl-defmethod seq-map (function (stream stream))
- "Return a stream.
-The elements of the produced sequence consist of the application
-of FUNCTION to each element of STREAM."
- (if (stream-empty-p stream)
- stream
- (stream-cons
- (funcall function (stream-first stream))
- (seq-map function (stream-rest stream)))))
+ "Return a stream representing the mapping of FUNCTION over STREAM.
+The elements of the produced stream are the results of the
+applications of FUNCTION on each element of STREAM in succession."
+ (stream-make
+ (when (not (stream-empty-p stream))
+ (cons (funcall function (stream-first stream))
+ (seq-map function (stream-rest stream))))))
(cl-defmethod seq-do (function (stream stream))
"Evaluate FUNCTION for each element of STREAM eagerly, and return nil.
-`seq-do' should never be used on infinite streams."
+`seq-do' should never be used on infinite streams without some
+kind of nonlocal exit."
(while (not (stream-empty-p stream))
(funcall function (stream-first stream))
(setq stream (stream-rest stream))))