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python-ply-3.4
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example
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BASIC
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# An implementation of Dartmouth BASIC (1964) # import sys sys.path.insert(0,"../..") if sys.version_info[0] >= 3: raw_input = input import logging logging.basicConfig( level = logging.INFO, filename = "parselog.txt", filemode = "w" ) log = logging.getLogger() import basiclex import basparse import basinterp # If a filename has been specified, we try to run it. # If a runtime error occurs, we bail out and enter # interactive mode below if len(sys.argv) == 2: data = open(sys.argv[1]).read() prog = basparse.parse(data,debug=log) if not prog: raise SystemExit b = basinterp.BasicInterpreter(prog) try: b.run() raise SystemExit except RuntimeError: pass else: b = basinterp.BasicInterpreter({}) # Interactive mode. This incrementally adds/deletes statements # from the program stored in the BasicInterpreter object. In # addition, special commands 'NEW','LIST',and 'RUN' are added. # Specifying a line number with no code deletes that line from # the program. while 1: try: line = raw_input("[BASIC] ") except EOFError: raise SystemExit if not line: continue line += "\n" prog = basparse.parse(line,debug=log) if not prog: continue keys = list(prog) if keys[0] > 0: b.add_statements(prog) else: stat = prog[keys[0]] if stat[0] == 'RUN': try: b.run() except RuntimeError: pass elif stat[0] == 'LIST': b.list() elif stat[0] == 'BLANK': b.del_line(stat[1]) elif stat[0] == 'NEW': b.new()