Minor crafting improvements

README.md

@@ -125,3 +125,8 @@ Custom crafting recipes must be specified in JSON files within the `config/recip
     }
 ]
 ```
+
+Recipe inputs are consumed by default. Set `consumed` to `false` for a
+reusable component. It is placed in the machine for crafting, then returned
+to network storage after all outputs have been collected, before the machine
+can start another recipe.

inv/Item.lua

@@ -40,6 +40,11 @@ function Item:init(spec)
     if spec.count ~= nil then
         self.count = spec.count
     end
+
+    -- bool: Whether this item is consumed by the recipe. This is meaningful
+    -- for recipe inputs; inputs are consumed by default for compatibility
+    -- with existing recipes.
+    self.consumed = spec.consumed ~= false
 end
 
 -- Returns true if the other item satisfies the criteria specified by this Item.

inv/device/Machine.lua

@@ -63,8 +63,8 @@ end
 -- Empties an output slot of the machine and counts any crafted items.
 function Machine:handleOutputSlot(item, virtSlot, realSlot)
     if item then
-        n = self.server.invManager:pullItemsFrom(item, self, realSlot)
         if self.recipe.output[virtSlot]:matches(item) then
+            local n = self.server.invManager:pullItemsFrom(item, self, realSlot)
             self.remaining[virtSlot] = self.remaining[virtSlot] - n
             if self.dest then
                 local outItem = self.recipe.output[virtSlot]:copy()
@@ -77,9 +77,33 @@ function Machine:handleOutputSlot(item, virtSlot, realSlot)
     end
 end
 
+-- Removes all input items which the recipe did not consume from the machine.
+-- These are returned to network storage just like normal machine output.
+function Machine:pullNonConsumedInputs()
+    if not self.recipe then
+        return true
+    end
+    for virtSlot, input in pairs(self.recipe.input) do
+        if not input.consumed then
+            local realSlot = self:mapSlot(virtSlot)
+            local item = self:getItemDetail(realSlot)
+            if item then
+                local moved = self.server.invManager:pullItemsFrom(item, self, realSlot)
+                if moved < item.count then
+                    return false
+                end
+            end
+        end
+    end
+    return true
+end
+
 -- Empties all output slots of this machine, counting the crafted items
 -- and updating the machine state as necessary.
 function Machine:pullOutput()
+    if not self.recipe then
+        return
+    end
     for virtSlot, rem in pairs(self.remaining) do
         local realSlot = self:mapSlot(virtSlot)
         local item = self:getItemDetail(realSlot)
@@ -90,6 +114,14 @@ function Machine:pullOutput()
             return
         end
     end
+
+    -- A non-consumed input remains in the machine after crafting. Empty it
+    -- before making the machine available for another recipe. If storage is
+    -- temporarily unable to accept it, leave the machine busy and retry on
+    -- the next task update.
+    if not self:pullNonConsumedInputs() then
+        return
+    end
     self.recipe = nil
 end