refactor multiversion

src/runtime/multiversion.js

@@ -19,25 +19,22 @@ function binarySearch(arr, el, compare_fn) {
 export class Multiversion {
   constructor(cxt, initial) {
     this.cxt = cxt
-    this.is_expanding_calltree_node = cxt.is_expanding_calltree_node
+    this.expand_calltree_node_number = cxt.expand_calltree_node_number
     this.latest = initial
     this.versions = [{version_number: cxt.version_counter, value: initial}]
   }
 
+  is_created_during_current_expand() {
+    return this.expand_calltree_node_number == this.cxt.expand_calltree_node_number
+  }
+
   get() {
     if(!this.cxt.is_expanding_calltree_node) {
       return this.latest
     } else {
-      if(this.is_expanding_calltree_node) {
-        // var was created during current expansion, use its latest value
+      if(this.is_created_during_current_expand()) {
         return this.latest
       } else {
-        if(this.latest_copy != null) {
-          // value was set during expand_calltree_node, use this value
-          return this.latest
-        }
-        // TODO on first read, set latest and latest_copy? Note that it will
-        // interfere with at_moment_in_time
         const version_number = this.cxt.version_counter
         return this.get_version(version_number)
       }
@@ -61,16 +58,11 @@ export class Multiversion {
   set(value) {
     const version_number = ++this.cxt.version_counter
     if(this.cxt.is_expanding_calltree_node) {
-      if(this.is_expanding_calltree_node) {
+      if(this.is_created_during_current_expand()) {
         this.latest = value
         this.set_version(version_number, value)
-        this.cxt.touched_multiversions.add(this)
       } else {
-        if(this.latest_copy == null) {
-          this.latest_copy = {value: this.latest}
-        }
-        this.cxt.touched_multiversions.add(this)
-        this.latest = value
+        // do nothing
       }
     } else {
       this.latest = value

src/runtime/runtime.js

@@ -194,7 +194,9 @@ export const set_record_call = cxt => {
 export const do_eval_expand_calltree_node = (cxt, node) => {
   cxt.is_recording_deferred_calls = false
   cxt.is_expanding_calltree_node = true
-  cxt.touched_multiversions = new Set()
+  cxt.expand_calltree_node_number = cxt.expand_calltree_node_number == null
+    ? 0
+    : cxt.expand_calltree_node_number + 1
 
   // Save call counter and set it to the value it had when executed 'fn' for
   // the first time
@@ -227,16 +229,6 @@ export const do_eval_expand_calltree_node = (cxt, node) => {
   // Restore version_counter
   cxt.version_counter = version_counter
 
-  // Recover multiversions affected by expand_calltree_node
-  for(let m of cxt.touched_multiversions) {
-    if(m.is_expanding_calltree_node) {
-      delete m.is_expanding_calltree_node
-    }
-    if(m.latest_copy != null) {
-      m.latest = m.latest_copy.value
-    }
-  }
-  delete cxt.touched_multiversions
 
   cxt.is_expanding_calltree_node = false
   cxt.is_recording_deferred_calls = true

test/test.js

@@ -4682,4 +4682,32 @@ const y = x()`
     const moved = COMMANDS.move_cursor(expanded, code.indexOf('return x'))
     assert_equal(moved.value_explorer.result.value, 2)
   }),
+
+  test('let_versions deferred calls get value', () => {
+    const code = `
+      let x = 0
+
+      function noop() {
+      }
+      
+      function set(value) {
+        x = value
+        noop()
+      }
+
+      set(1)
+      set(2)
+      set(3)
+
+      export const get = () => x
+    `
+
+    const {state: i} = test_deferred_calls_state(code)
+
+    const second_set_call = root_calltree_node(i).children[1]
+    assert_equal(second_set_call.has_more_children, true)
+
+    const exp = COMMANDS.calltree.click(i, second_set_call.id)
+    assert_equal(exp.modules[''].get(), 3)
+  }),
 ]