make EvtStreams carry a single value

5 files changed, 126 insertions, 24 deletions

diff --git a/alv/result/evt.moon b/alv/result/evt.moon
index ad4c102..a89aa74 100644
--- a/alv/result/evt.moon
+++ b/alv/result/evt.moon
@@ -16,15 +16,16 @@ class EvtStream extends Result
 
   --- get the sequence of current events (if any).
   --
-  -- Returns `events` if `dirty`, or an empty table otherwise.
+  -- Returns `value` if `dirty`, or `nil` otherwise.
   -- Asserts `@type == type` if `type` is given.
   --
   -- @tparam[opt] type.Type type the type to check for
   -- @tparam[optchain] string msg message to throw if type don't match
-  -- @treturn {any,...} `events`
+  -- @treturn ?any `value`
   unwrap: (type, msg) =>
     assert type == @type, msg or "#{@} is not a #{type}" if type
-    if @dirty! then @events else {}
+    @value
+    if @dirty! then @value
 
   --- create a mutable copy of this stream.
   --
@@ -37,8 +38,7 @@ class EvtStream extends Result
   __call: (...) => @unwrap ...
 
   __tostring: =>
-    events = table.concat [@type\pp e for e in *@events], ' '
-    "<#{@type}#{@metatype} #{events}>"
+    "<#{@type}#{@metatype} #{if @dirty then @type\pp @value else 'nil'}>"
 
   --- the type of this Result's value.
   -- @tfield type.Type type
@@ -65,15 +65,13 @@ class EvtStream extends Result
   --- push an event value into the stream.
   --
   -- Marks this stream as dirty for the remainder of the current tick.
-  add: (event) =>
-    if not @dirty!
-      @events = {}
-
+  set: (event) =>
+    assert not @dirty!, "#{@} is already dirty!"
     @updated = COPILOT.T
-    table.insert @events, event
+    @value = event
 
   --- the wrapped Lua value.
-  -- @tfield {any,...} events
+  -- @tfield any value
 
 --- static functions
 -- @section static
@@ -84,7 +82,6 @@ class EvtStream extends Result
   -- @tparam type.Type type the type
   new: (type) =>
     super type
-    @events = {}
 
 {
   :EvtStream
diff --git a/spec/input_spec.moon b/spec/input_spec.moon
index 8dbd726..3a8eff9 100644
--- a/spec/input_spec.moon
+++ b/spec/input_spec.moon
@@ -13,8 +13,8 @@ basic_tests = (result, input) ->
     assert.is.equal result, input.result
 
   it 'forwards :unwrap', ->
-    assert.is.same result\unwrap!, input\unwrap!
-    assert.is.same result\unwrap!, input!
+    assert.is.equal result\unwrap!, input\unwrap!, nil
+    assert.is.equal result\unwrap!, input!, nil
 
   it 'gives access to the type string', ->
     assert.is.equal result.type, input\type!
@@ -96,7 +96,7 @@ describe 'Input.hot', ->
       input\finish_setup!
 
       COPILOT\next_tick!
-      result\add 1
+      result\set 1
 
       assert.is.true input\dirty!
       assert.is.true result\dirty!
diff --git a/spec/result/evt_spec.moon b/spec/result/evt_spec.moon
new file mode 100644
index 0000000..93c09e0
--- /dev/null
+++ b/spec/result/evt_spec.moon
@@ -0,0 +1,111 @@
+import do_setup from require 'spec.test_setup'
+import EvtStream, RTNode, Scope, SimpleRegistry, T from require 'alv'
+import Op, Builtin from require 'alv.base'
+
+setup do_setup
+
+describe 'EvtStream', ->
+  describe ':unwrap', ->
+    it 'returns the set value', ->
+      stream = EvtStream T.num
+      assert.is.nil stream\unwrap!
+
+      stream\set 3.14
+      assert.is.equal 3.14, stream\unwrap!
+
+    it 'returns nil if not dirty', ->
+      stream = EvtStream T.num
+      assert.is.nil stream\unwrap!
+
+      stream\set 3.14
+      COPILOT\next_tick!
+      assert.is.nil stream\unwrap!
+
+    test 'can assert the type', ->
+      assert.is.nil (EvtStream T.num)\unwrap T.num
+      assert.is.nil (EvtStream T.str)\unwrap T.str
+      assert.is.nil (EvtStream T.sym)\unwrap T.sym
+      assert.has_error -> (EvtStream T.num)\unwrap T.sym
+      assert.has_error -> (EvtStream T.str)\unwrap T.num
+      assert.has_error -> (EvtStream T.sym)\unwrap T.str
+
+    test 'has __call shorthand', ->
+      stream = EvtStream T.num
+      assert.is.nil stream!
+
+      stream\set 3.14
+      assert.is.equal 3.14, stream!
+
+  describe ':set', ->
+    it 'sets the value', ->
+      stream = EvtStream T.num
+      assert.is.false stream\dirty!
+
+      stream\set 4
+      assert.is.equal 4, stream\unwrap!
+      assert.is.true stream\dirty!
+
+      COPILOT\next_tick!
+
+      assert.is.false stream\dirty!
+      stream\set 3
+      assert.is.equal 3, stream\unwrap!
+      assert.is.true stream\dirty!
+
+    it 'errors when set twice', ->
+      stream = EvtStream T.num
+      stream\set 1
+      assert.has.error -> stream\set 2
+      assert.is.equal 1, stream\unwrap!
+
+    it 'resets on the next tick', ->
+      stream = EvtStream T.num
+      stream\set 1
+
+      COPILOT\next_tick!
+
+      assert.is.false stream\dirty!
+      stream\set 2
+      assert.is.equal 2, stream\unwrap!
+      assert.is.true stream\dirty!
+
+  describe ':fork', ->
+    it 'is clean', ->
+      a = EvtStream T.num
+      b = EvtStream T.str
+      b\set 'asdf'
+
+      aa, bb = a\fork!, b\fork!
+      assert.is.nil aa!
+      assert.is.nil bb!
+      assert.is.false aa\dirty!
+      assert.is.false bb\dirty!
+
+    it 'leaves the original', ->
+      a = EvtStream T.num
+      b = EvtStream T.str
+      b\set 'asdf'
+
+      aa, bb = a\fork!, b\fork!
+      assert.is.nil a!
+      assert.is.equal 'asdf', b!
+      assert.is.false a\dirty!
+      assert.is.true b\dirty!
+
+    it 'isolates the original from the fork', ->
+      a = EvtStream T.num
+      b = EvtStream T.str
+
+      aa, bb = a\fork!, b\fork!
+      a\set 1
+      bb\set 2
+
+      assert.is.equal 1, a!
+      assert.is.true a\dirty!
+      assert.is.nil aa!
+      assert.is.false aa\dirty!
+
+      assert.is.equal 2, bb!
+      assert.is.true bb\dirty!
+      assert.is.nil b!
+      assert.is.false b\dirty!
diff --git a/spec/result/sig_spec.moon b/spec/result/sig_spec.moon
index 6e9a11c..1a92bdc 100644
--- a/spec/result/sig_spec.moon
+++ b/spec/result/sig_spec.moon
@@ -2,12 +2,6 @@ import do_setup from require 'spec.test_setup'
 import SigStream, Constant, RTNode, Scope, SimpleRegistry, T from require 'alv'
 import Op, Builtin from require 'alv.base'
 
-class TestOp extends Op
-  new: (...) => super ...
-
-class TestBuiltin extends Builtin
-  new: (...) =>
-
 setup do_setup
 
 describe 'SigStream', ->
diff --git a/spec/rtnode_spec.moon b/spec/rtnode_spec.moon
index 5dfebf7..9c62350 100644
--- a/spec/rtnode_spec.moon
+++ b/spec/rtnode_spec.moon
@@ -115,7 +115,7 @@ describe 'RTNode', ->
       b_child = node_with_sideinput b_value, b_input
 
     it 'updates children when a side_input is dirty', ->
-      a_value\add 1
+      a_value\set 1
       assert.is.true a_input\dirty!
       assert.is.false b_input\dirty!
 
@@ -142,7 +142,7 @@ describe 'RTNode', ->
       assert.spy(b).was_not_called!
 
     it 'updates op when any op-inputs are dirty', ->
-      a_value\add 1
+      a_value\set 1
       assert.is.true a_input\dirty!
       assert.is.false b_input\dirty!
 
@@ -155,7 +155,7 @@ describe 'RTNode', ->
       assert.spy(s).was_called_with match.ref op
 
     it 'early-outs when no op-inputs are dirty', ->
-      a_value\add 1
+      a_value\set 1
       assert.is.true a_input\dirty!
       assert.is.false b_input\dirty!