script: a callback's one-item reply re-enters the multiplexer, and :else acts on its value

packages/script/README.md

@@ -256,7 +256,7 @@ they're interned values available everywhere:
 |--------|---------|
 | `:redo` | Re-enter the current multiplexer (after reading more data) |
 | `:skip` | Skip the current item, continue to next |
-| `:else` | Fallback key in multiplexers — fires when no other key matches |
+| `:else` | Fallback key in multiplexers — fires when no other key matches and no more output arrives within `fast` seconds; its value acts like any key's (`:redo` keeps listening, `null` moves on) |
 | `:this` | In a multiplexer value, return the matched text itself |
 | `:pure` | Raw mode — no line terminator appended to sends |
 

packages/script/script.rip

@@ -199,15 +199,16 @@ class Engine
     else if typeof val is 'function'
       back = invoke! val, back
       if Array.isArray(back)
-        if back.length > 0 and back[0] is :pure
+        reply = back
+        if reply.length > 0 and reply[0] is :pure
           savedLine = @line
           @line = ''
-          back = @chat!(null, ...back.slice(1)) unless back.length is 1
+          back = @chat!(null, ...reply.slice(1)) unless reply.length is 1
           @line = savedLine
-          back = :redo if back.length <= 2
+          back = :redo if reply.length <= 2
         else
-          back = @chat!(null, ...back) unless back.length is 0
-          back = :redo if back.length <= 1
+          back = @chat!(null, ...reply) unless reply.length is 0
+          back = :redo if reply.length <= 1
       back
     else if val instanceof Map or (typeof val is 'object' and val isnt null and not Array.isArray(val))
       @chat! val
@@ -330,10 +331,9 @@ class Engine
             matched = true
             talk = false
             back = null
-          else if fast and elseVal?
+          else if fast and hasElse
             matched = true
-            back = :else
-            @dispatchVal! elseVal, back
+            back = @dispatchVal! elseVal, :else
           else
             for [key, val] in entries
               continue if key is :else or key is 'else'

packages/script/test.rip

@@ -420,7 +420,44 @@ test! ":else fires when nothing matches within the fast window", ->
       }
     ]
     eq hit, 'else'
-    ok back is :else
+    eq back, true
+
+# The shell commands below spell their prompts through printf's %s, so
+# the PTY's echo of the command line never contains the prompt text.
+TWO_QUESTIONS = "printf 'Q%s? ' 1; read a; SLEEP printf 'Q%s? ' 2; read b; printf '[%s|%s]%s%s\\n' \"$a\" \"$b\" EN D"
+
+test! "a callback's one-item reply re-enters the multiplexer, whatever its length", ->
+  withChat! (chat) ->
+    back = chat! [
+      /\$\s*/, TWO_QUESTIONS.replace('SLEEP ', '')
+      {
+        'Q1? ':  -> ['abc']
+        'Q2? ':  -> [:pure, "xyz\n"]
+        ']END':  :this
+      }
+    ]
+    ok back.endsWith('[abc|xyz]END')
+
+test! ":else: :redo keeps the multiplexer listening through a pause", ->
+  withChat! (chat) ->
+    back = chat! [
+      /\$\s*/, TWO_QUESTIONS.replace('SLEEP', 'sleep 1;')
+      *{
+        'Q1? ':  ['abc']
+        'Q2? ':  ['xyz']
+        ']END':  :this
+        :else:   :redo
+      }
+    ]
+    ok back.endsWith('[abc|xyz]END')
+
+test! ":else: null leaves the multiplexer when nothing matches", ->
+  withChat! (chat) ->
+    back = chat! [
+      /\$\s*/, 'echo ZZZ'
+      *{ NOMATCH: 'x', :else: null }
+    ]
+    eq back, null
 
 test! ":this returns the matched text itself", ->
   withChat! (chat) ->