| # 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) | |