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Task/Stack/Phix/stack-3.phix

@@ -0,0 +1,43 @@
+sequence stacks = {}
+integer freelist = 0
+
+function new_stack()
+integer res = freelist
+    if res!=0 then
+        freelist = stacks[freelist]
+        stacks[res] = {}
+    else
+        stacks = append(stacks,{})
+        res = length(stacks)
+    end if
+    return res
+end function
+
+procedure free_stack(integer sid)
+    stacks[sid] = freelist
+    freelist = sid
+end procedure
+
+procedure push(integer sid, object what)
+    stacks[sid] = append(stacks[sid],what)
+end procedure
+
+function pop(integer sid)
+    object res = stacks[sid][$]
+    stacks[sid] = stacks[sid][1..$-1]
+    return res
+end function
+
+function empty(integer sid)
+    return length(stacks[sid])=0
+end function
+
+integer sid = new_stack()
+?empty(sid)                 -- 1
+push(sid,5)
+?empty(sid)                 -- 0
+push(sid,6)
+?pop(sid)                   -- 6
+?pop(sid)                   -- 5
+?empty(sid)                 -- 1
+free_stack(sid)