75 lines
1.1 KiB
Python
75 lines
1.1 KiB
Python
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# An implementation of Dartmouth BASIC (1964)
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from ply import *
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keywords = (
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'LET','READ','DATA','PRINT','GOTO','IF','THEN','FOR','NEXT','TO','STEP',
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'END','STOP','DEF','GOSUB','DIM','REM','RETURN','RUN','LIST','NEW',
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)
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tokens = keywords + (
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'EQUALS','PLUS','MINUS','TIMES','DIVIDE','POWER',
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'LPAREN','RPAREN','LT','LE','GT','GE','NE',
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'COMMA','SEMI', 'INTEGER','FLOAT', 'STRING',
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'ID','NEWLINE'
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)
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t_ignore = ' \t'
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def t_REM(t):
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r'REM .*'
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return t
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def t_ID(t):
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r'[A-Z][A-Z0-9]*'
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if t.value in keywords:
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t.type = t.value
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return t
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t_EQUALS = r'='
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t_PLUS = r'\+'
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t_MINUS = r'-'
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t_TIMES = r'\*'
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t_POWER = r'\^'
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t_DIVIDE = r'/'
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t_LPAREN = r'\('
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t_RPAREN = r'\)'
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t_LT = r'<'
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t_LE = r'<='
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t_GT = r'>'
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t_GE = r'>='
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t_NE = r'<>'
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t_COMMA = r'\,'
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t_SEMI = r';'
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t_INTEGER = r'\d+'
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t_FLOAT = r'((\d*\.\d+)(E[\+-]?\d+)?|([1-9]\d*E[\+-]?\d+))'
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t_STRING = r'\".*?\"'
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def t_NEWLINE(t):
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r'\n'
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t.lexer.lineno += 1
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return t
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def t_error(t):
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print "Illegal character", t.value[0]
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t.lexer.skip(1)
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lex.lex()
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