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1 # -----------------------------------------------------------------------------
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2 # calclex.py
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3 # -----------------------------------------------------------------------------
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4 import sys
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5
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6 if ".." not in sys.path: sys.path.insert(0,"..")
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7 import ply.lex as lex
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8
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9 tokens = (
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10 'NAME','NUMBER',
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11 'PLUS','MINUS','TIMES','DIVIDE','EQUALS',
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12 'LPAREN','RPAREN',
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13 )
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14
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15 # Tokens
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16
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17 t_PLUS = r'\+'
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18 t_MINUS = r'-'
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19 t_TIMES = r'\*'
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20 t_DIVIDE = r'/'
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21 t_EQUALS = r'='
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22 t_LPAREN = r'\('
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23 t_RPAREN = r'\)'
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24 t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*'
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25
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26 def t_NUMBER(t):
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27 r'\d+'
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28 try:
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29 t.value = int(t.value)
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30 except ValueError:
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31 print("Integer value too large %s" % t.value)
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32 t.value = 0
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33 return t
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34
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35 t_ignore = " \t"
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36
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37 def t_newline(t):
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38 r'\n+'
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39 t.lexer.lineno += t.value.count("\n")
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40
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41 def t_error(t):
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42 print("Illegal character '%s'" % t.value[0])
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43 t.lexer.skip(1)
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44
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45 # Build the lexer
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46 lexer = lex.lex()
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47
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48
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49
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