move lib to alv-lib module

1 files changed, 112 insertions, 0 deletions

diff --git a/alv-lib/util.moon b/alv-lib/util.moon
new file mode 100644
index 0000000..dc133e4
--- /dev/null
+++ b/alv-lib/util.moon
@@ -0,0 +1,112 @@
+import Op, ValueStream, EventStream, Input, val, evt from require 'alv.base'
+
+all_same = (list) ->
+  for v in *list[2,]
+    if v != list[1]
+      return false
+
+  list[1]
+
+switch_ = ValueStream.meta
+  meta:
+    name: 'switch'
+    summary: "Switch between multiple inputs."
+    examples: { '(switch i v0 [v1 v2…])' }
+    description: "
+- when `i` is `true`, the first value is reproduced.
+- when `i` is `false`, the second value is reproduced.
+- when `i` is a `num`, it is [math/floor][]ed and the matching argument
+  (indexed starting from 0) is reproduced."
+
+  value: class extends Op
+    val_or_evt = (val! / evt!)!
+    pattern = (val.num / val.bool) + val_or_evt*0
+    setup: (inputs) =>
+      { i, values } = pattern\match inputs
+
+      @state = values[1].value.__class == ValueStream
+
+      @out = if @state
+        ValueStream values[1]\type!
+      else
+        EventStream values[1]\type!
+
+      super
+        i: Input.hot i
+        values: [Input.hot v for v in *values]
+
+    tick: =>
+      { :i, :values } = @inputs
+      active = switch i!
+        when true
+          values[1]
+        when false
+          values[2]
+        else
+          i = 1 + (math.floor i!) % #values
+          values[i]
+      if @state
+        @out\set active and active!
+      else
+        if active and active\dirty!
+          for event in *active!
+            @out\add event
+
+edge = ValueStream.meta
+  meta:
+    name: 'edge'
+    summary: "Convert rising edges to bangs."
+    examples: { '(edge bool)' }
+
+  value: class extends Op
+    setup: (inputs) =>
+      @out or= EventStream 'bang'
+      value = val.bool\match inputs
+      super value: Input.hot value
+
+    tick: =>
+      now = @inputs.value!
+      if now and not @state.last
+        @out\set true
+        @state.last = now
+
+change = ValueStream.meta
+  meta:
+    name: 'change'
+    summary: "Convert value changes to events."
+    examples: { '(change val)' }
+
+  value: class extends Op
+    setup: (inputs) =>
+      value = val!\match inputs
+      @out or= EventStream value\type!
+      super value: Input.hot value
+
+    tick: =>
+      now = @inputs.value!
+      if now != @state
+        @out\add @inputs.value!
+        @state = now
+
+hold = ValueStream.meta
+  meta:
+    name: 'hold'
+    summary: "Convert events to value changes."
+    examples: { '(hold evt)' }
+
+  value: class extends Op
+    setup: (inputs) =>
+      event = evt!\match inputs
+      @out or= ValueStream event\type!
+      super event: Input.hot event
+
+    tick: =>
+      for val in *@inputs.event!
+        @out\set val
+
+{
+  'switch': switch_
+  :edge
+  :change
+  :hold
+}