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