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1 # An implementation of Dartmouth BASIC (1964)
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2 #
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3
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4 import sys
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5 sys.path.insert(0,"../..")
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6
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7 if sys.version_info[0] >= 3:
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8 raw_input = input
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9
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10 import basiclex
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11 import basparse
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12 import basinterp
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13
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14 # If a filename has been specified, we try to run it.
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15 # If a runtime error occurs, we bail out and enter
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16 # interactive mode below
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17 if len(sys.argv) == 2:
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18 data = open(sys.argv[1]).read()
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19 prog = basparse.parse(data)
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20 if not prog: raise SystemExit
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21 b = basinterp.BasicInterpreter(prog)
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22 try:
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23 b.run()
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24 raise SystemExit
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25 except RuntimeError:
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26 pass
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27
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28 else:
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29 b = basinterp.BasicInterpreter({})
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30
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31 # Interactive mode. This incrementally adds/deletes statements
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32 # from the program stored in the BasicInterpreter object. In
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33 # addition, special commands 'NEW','LIST',and 'RUN' are added.
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34 # Specifying a line number with no code deletes that line from
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35 # the program.
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36
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37 while 1:
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38 try:
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39 line = raw_input("[BASIC] ")
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40 except EOFError:
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41 raise SystemExit
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42 if not line: continue
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43 line += "\n"
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44 prog = basparse.parse(line)
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45 if not prog: continue
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46
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47 keys = list(prog)
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48 if keys[0] > 0:
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49 b.add_statements(prog)
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50 else:
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51 stat = prog[keys[0]]
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52 if stat[0] == 'RUN':
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53 try:
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54 b.run()
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55 except RuntimeError:
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56 pass
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57 elif stat[0] == 'LIST':
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58 b.list()
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59 elif stat[0] == 'BLANK':
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60 b.del_line(stat[1])
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61 elif stat[0] == 'NEW':
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62 b.new()
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63
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64
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65
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66
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67
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68
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69
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70
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71
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