Data commit

Task/Universal-Turing-machine/Python/universal-turing-machine.py

@@ -0,0 +1,87 @@
+from __future__ import print_function
+
+def run_utm(
+        state = None,
+        blank = None,
+        rules = [],
+        tape = [],
+        halt = None,
+        pos = 0):
+    st = state
+    if not tape: tape = [blank]
+    if pos < 0: pos += len(tape)
+    if pos >= len(tape) or pos < 0: raise Error( "bad init position")
+    rules = dict(((s0, v0), (v1, dr, s1)) for (s0, v0, v1, dr, s1) in rules)
+
+    while True:
+        print(st, '\t', end=" ")
+        for i, v in enumerate(tape):
+            if i == pos: print("[%s]" % (v,), end=" ")
+            else: print(v, end=" ")
+        print()
+
+        if st == halt: break
+        if (st, tape[pos]) not in rules: break
+
+        (v1, dr, s1) = rules[(st, tape[pos])]
+        tape[pos] = v1
+        if dr == 'left':
+            if pos > 0: pos -= 1
+            else: tape.insert(0, blank)
+        if dr == 'right':
+            pos += 1
+            if pos >= len(tape): tape.append(blank)
+        st = s1
+
+
+# EXAMPLES
+
+print("incr machine\n")
+run_utm(
+    halt = 'qf',
+	state = 'q0',
+	tape = list("111"),
+	blank = 'B',
+	rules = map(tuple,
+               ["q0 1 1 right q0".split(),
+		        "q0 B 1 stay  qf".split()]
+        )
+    )
+
+print("\nbusy beaver\n")
+run_utm(
+    halt = 'halt',
+	state = 'a',
+	blank = '0',
+	rules = map(tuple,
+        ["a 0 1 right b".split(),
+         "a 1 1 left  c".split(),
+         "b 0 1 left  a".split(),
+         "b 1 1 right b".split(),
+         "c 0 1 left  b".split(),
+         "c 1 1 stay  halt".split()]
+        )
+    )
+
+print("\nsorting test\n")
+run_utm(halt = 'STOP',
+	state = 'A',
+	blank = '0',
+	tape = "2 2 2 1 2 2 1 2 1 2 1 2 1 2".split(),
+	rules = map(tuple,
+       ["A 1 1 right A".split(),
+		"A 2 3 right B".split(),
+		"A 0 0 left  E".split(),
+		"B 1 1 right B".split(),
+		"B 2 2 right B".split(),
+		"B 0 0 left  C".split(),
+		"C 1 2 left  D".split(),
+		"C 2 2 left  C".split(),
+		"C 3 2 left  E".split(),
+		"D 1 1 left  D".split(),
+		"D 2 2 left  D".split(),
+		"D 3 1 right A".split(),
+		"E 1 1 left  E".split(),
+		"E 0 0 right STOP".split()]
+        )
+    )