From 64de4d1bfe1a2d67b8aa3e846d8d86760682b395 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 17 Feb 2014 18:44:15 -0500
Subject: Move time module inside the signal module.

* 2d/signal.scm (make-boxed-signal, %signal-ref, %signal-set!): Don't
  export.
  (signal-sample, signal-delay, signal-throttle): New procedures.
* 2d/time.scm: Delete file.
---
 2d/signal.scm | 40 ++++++++++++++++++++++++++++++++++++----
 2d/time.scm   | 54 ------------------------------------------------------
 2 files changed, 36 insertions(+), 58 deletions(-)
 delete mode 100644 2d/time.scm

diff --git a/2d/signal.scm b/2d/signal.scm
index 272cbfb..53f676a 100644
--- a/2d/signal.scm
+++ b/2d/signal.scm
@@ -25,15 +25,13 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
   #:use-module (srfi srfi-26)
+  #:use-module (2d agenda)
   #:export (signal?
             signal-box?
             make-signal
-            make-boxed-signal
             define-signal
-            %signal-ref
             signal-ref
             signal-ref-maybe
-            %signal-set!
             signal-set!
             signal-proc
             signal-merge
@@ -44,7 +42,10 @@
             signal-reject
             signal-constant
             signal-count
-            signal-do))
+            signal-do
+            signal-sample
+            signal-delay
+            signal-throttle))
 
 ;;;
 ;;; Signals
@@ -227,3 +228,34 @@ from SIGNAL.  The value of the new signal will always be the value of
 SIGNAL.  This signal is a convenient way to sneak a procedure that has
 a side-effect into a signal chain."
   (signal-map (lambda (x) (proc x) x) signal))
+
+(define (signal-sample agenda delay signal)
+  "Create a new signal that emits the value contained within SIGNAL
+every DELAY ticks of AGENDA."
+  (let ((sampler (%make-signal (signal-ref signal) #f '())))
+    (define (tick)
+      (%signal-set! sampler (signal-ref signal)))
+    (schedule-interval agenda tick delay)
+    (make-signal-box sampler)))
+
+(define (signal-delay agenda delay signal)
+  "Create a new signal that delays propagation of SIGNAL by DELAY
+ticks of AGENDA."
+  (make-boxed-signal (signal-ref signal)
+                     (lambda (self value)
+                       (schedule agenda
+                                 (lambda ()
+                                   (%signal-set! self value))
+                                 delay))
+                     (list signal)))
+
+(define (signal-throttle agenda delay signal)
+  "Return a new signal that propagates SIGNAL at most once every DELAY
+ticks of AGENDA."
+  (make-boxed-signal (signal-ref signal)
+                     (let ((last-time (agenda-time agenda)))
+                       (lambda (self value)
+                         (when (>= (- (agenda-time agenda) last-time) delay)
+                           (%signal-set! self value)
+                           (set! last-time (agenda-time agenda)))))
+                     (list signal)))
diff --git a/2d/time.scm b/2d/time.scm
deleted file mode 100644
index e17be49..0000000
--- a/2d/time.scm
+++ /dev/null
@@ -1,54 +0,0 @@
-;;; guile-2d
-;;; Copyright (C) 2013 David Thompson <dthompson2@worcester.edu>
-;;;
-;;; Guile-2d is free software: you can redistribute it and/or modify it
-;;; under the terms of the GNU Lesser General Public License as
-;;; published by the Free Software Foundation, either version 3 of the
-;;; License, or (at your option) any later version.
-;;;
-;;; Guile-2d is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-;;; Lesser General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU Lesser General Public
-;;; License along with this program.  If not, see
-;;; <http://www.gnu.org/licenses/>.
-
-;;; Commentary:
-;;
-;; Time-based signals.
-;;
-;;; Code:
-
-(define-module (2d time)
-  #:use-module (2d agenda)
-  #:use-module (2d coroutine)
-  #:use-module (2d signals)
-  #:export (time-every
-            time-each
-            time-delay))
-
-(define (time-every agenda delay value)
-  "Create a new signal that emits VALUE every DELAY ticks of AGENDA.
-VALUE may be a signal, in which case the stored value of the signal
-will be emitted."
-  (let ((ticker (make-root-signal (signal-ref-maybe value))))
-    (define (tick)
-      (signal-set! ticker (signal-ref-maybe value)))
-    (schedule-interval agenda tick delay)
-    ticker))
-
-(define (time-each agenda value)
-  "Create a new signal that emits VALUE every agenda update."
-  (time-every agenda 1 value))
-
-(define (time-delay agenda delay signal)
-  "Create a new signal that delays propagation of values received from
-SIGNAL by DELAY ticks of AGENDA."
-  (make-signal (signal-ref signal)
-               (colambda (self from)
-                 (let ((value (signal-ref from)))
-                   (wait agenda delay)
-                   (signal-set! self value)))
-               (list signal)))
-- 
cgit v1.2.3