Merge pull request 'Feature: stateful timeline function for jumping between timelines' (#1669) from alternative-timeline into main

Reviewed-on: https://codeberg.org/uzu/strudel/pulls/1669

packages/core/impure.mjs

@@ -0,0 +1,90 @@
+/*
+stateful.mjs - File of shame for stateful, impure and otherwise illegal pattern methods
+Copyright (C) 2025 Strudel contributors - see <https://codeberg.org/uzu/strudel/src/branch/main/packages/core/index.mjs>
+This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program 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 Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { register, reify, Pattern } from './pattern.mjs';
+
+let timelines = {};
+
+export const reset_state = function () {
+  reset_timelines();
+};
+
+export const reset_timelines = function () {
+  timelines = {};
+};
+
+/***
+ * Allows you to switch a pattern between different 'timelines'. This is particularly useful when
+ * live coding, for example when you want to cue a pattern up to play from its start.
+ *
+ * Timelines are specified by number, so that if you had a pattern like
+ * `n("<0 1 2 3>").s("num").timeline(1)` playing, then changed the '1'
+ * to '2', it would always align '0' to the nearest cycle. You will likely want to trigger
+ * an evaluation a little bit before the cycle starts, to avoid missing events.
+ *
+ * After the first use, a timeline will continue with the same 'offset'. That is, if you change
+ * a pattern without changing its timeline number, it will stay on that timeline without resetting.
+ *
+ * Rather than incrementing a timeline to reset it, it's easier to negate it, e.g. by switching between `-2`
+ * and `2`. This is because when you negate a timeline it will always reset.
+ *
+ * You can also pattern the timeline if you want, to create strange resetting patterns.
+ * @param {number | Pattern} timeline The timeline that the pattern should play on.
+ * @example
+ * n("<0 1 2 3>(3,8)")
+ *   .sound("num")
+ *   // resets the timeline every two cycles, by negating the timeline.
+ *   // in a lot of cases this will be edited by a human live coder
+ *   // rather than patterned!
+ *   .timeline("<2 -2>".slow(2))
+ */
+
+export const timeline = register(
+  'timeline',
+  function (tpat, pat) {
+    tpat = reify(tpat);
+    const f = function (state) {
+      // Is this called from the scheduler? (rather than from e.g. the visualiser)
+      const scheduler = !!state.controls.cyclist;
+      const timehaps = tpat.query(state);
+      const result = [];
+      for (const timehap of timehaps) {
+        const tlid = timehap.value;
+        let offset;
+        if (tlid === 0) {
+          offset = 0;
+        } else if (tlid in timelines) {
+          offset = timelines[tlid];
+        } else {
+          const timearc = timehap.wholeOrPart();
+          if (!scheduler || state.span.begin.lt(timearc.midpoint())) {
+            offset = timearc.begin;
+          } else {
+            // Sync to end of timearc if we first see it over halfway into its
+            // timespan. Allows 'cuing up' next timeline when live coding.
+            offset = timearc.end;
+          }
+        }
+        if (scheduler) {
+          // update state
+          timelines[tlid] = offset;
+          if (tlid !== 0) {
+            delete timelines[-tlid];
+          }
+        }
+
+        const pathaps = pat
+          .late(offset)
+          .query(state.setSpan(timehap.part))
+          .map((h) => h.setContext(h.combineContext(timehap)));
+        result.push(...pathaps);
+      }
+      return result;
+    };
+    return new Pattern(f, pat._steps);
+  },
+  false,
+);

packages/core/index.mjs

@@ -1,6 +1,6 @@
 /*
 index.mjs - <short description TODO>
-Copyright (C) 2022 Strudel contributors - see <https://codeberg.org/uzu/strudel/src/branch/main/packages/core/index.mjs>
+Copyright (C) 2025 Strudel contributors - see <https://codeberg.org/uzu/strudel/src/branch/main/packages/core/index.mjs>
 This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program 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 Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
@@ -11,20 +11,21 @@ import createClock from './zyklus.mjs';
 import { logger } from './logger.mjs';
 export { Fraction, controls, createClock };
 export * from './controls.mjs';
-export * from './hap.mjs';
-export * from './pattern.mjs';
-export * from './signal.mjs';
-export * from './pick.mjs';
-export * from './state.mjs';
-export * from './timespan.mjs';
-export * from './util.mjs';
-export * from './speak.mjs';
-export * from './evaluate.mjs';
-export * from './repl.mjs';
 export * from './cyclist.mjs';
+export * from './evaluate.mjs';
+export * from './hap.mjs';
+export * from './impure.mjs';
 export * from './logger.mjs';
+export * from './pattern.mjs';
+export * from './pick.mjs';
+export * from './repl.mjs';
+export * from './signal.mjs';
+export * from './speak.mjs';
+export * from './state.mjs';
 export * from './time.mjs';
+export * from './timespan.mjs';
 export * from './ui.mjs';
+export * from './util.mjs';
 export { default as drawLine } from './drawLine.mjs';
 // below won't work with runtime.mjs (json import fails)
 /* import * as p from './package.json';

packages/core/repl.mjs

@@ -5,6 +5,7 @@ import { errorLogger, logger } from './logger.mjs';
 import { setTime } from './time.mjs';
 import { evalScope } from './evaluate.mjs';
 import { register, Pattern, isPattern, silence, stack } from './pattern.mjs';
+import { reset_state } from './impure.mjs';
 
 export function repl({
   defaultOutput,
@@ -52,6 +53,9 @@ export function repl({
     onToggle: (started) => {
       updateState({ started });
       onToggle?.(started);
+      if (!started) {
+        reset_state();
+      }
     },
     setInterval,
     clearInterval,