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1 # -----------------------------------------------------------------------------
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2 # calclex.py
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3 # -----------------------------------------------------------------------------
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4
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5 import ply.lex as lex
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6
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7 tokens = (
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8 'NAME','NUMBER',
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9 'PLUS','MINUS','TIMES','DIVIDE','EQUALS',
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10 'LPAREN','RPAREN',
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11 )
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12
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13 # Tokens
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14
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15 t_PLUS = r'\+'
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16 t_MINUS = r'-'
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17 t_TIMES = r'\*'
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18 t_DIVIDE = r'/'
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19 t_EQUALS = r'='
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20 t_LPAREN = r'\('
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21 t_RPAREN = r'\)'
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22 t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*'
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23
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24 def t_NUMBER(t):
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25 r'\d+'
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26 try:
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27 t.value = int(t.value)
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28 except ValueError:
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29 print("Integer value too large %s" % t.value)
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30 t.value = 0
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31 return t
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32
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33 t_ignore = " \t"
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34
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35 def t_newline(t):
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36 r'\n+'
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37 t.lexer.lineno += t.value.count("\n")
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38
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39 def t_error(t):
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40 print("Illegal character '%s'" % t.value[0])
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41 t.lexer.skip(1)
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42
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43 # Build the lexer
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44 import os.path
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45 lexer = lex.lex(optimize=True, outputdir=os.path.dirname(__file__))
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46
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47
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48
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