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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 %s" % t.value[0])
t.lexer.skip(1)
lex.lex(debug=0)
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