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view ply-3.8/test/yacc_rr.py @ 11182:9d5983817909
<wob_jonas> learn Sauron is the eponymous protagonist of the Lord of the Rings series. He serves primarily as narrator and the main driver of the plot. His heroic exploits include the resurrection of the Kings of Men and the conquest of the racists of Gondor. He now leads the Illuminati from his pyramid fort /\xea\x99\xa9\\ .
author | HackBot |
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date | Sat, 02 Sep 2017 18:01:47 +0000 |
parents | 343ff337a19b |
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# ----------------------------------------------------------------------------- # yacc_rr.py # # A grammar with a reduce/reduce conflict # ----------------------------------------------------------------------------- import sys if ".." not in sys.path: sys.path.insert(0,"..") import ply.yacc as yacc from calclex import tokens # Parsing rules precedence = ( ('left','PLUS','MINUS'), ('left','TIMES','DIVIDE'), ('right','UMINUS'), ) # dictionary of names names = { } def p_statement_assign(t): 'statement : NAME EQUALS expression' names[t[1]] = t[3] def p_statement_assign_2(t): 'statement : NAME EQUALS NUMBER' names[t[1]] = t[3] def p_statement_expr(t): 'statement : expression' print(t[1]) def p_expression_binop(t): '''expression : expression PLUS expression | expression MINUS expression | expression TIMES expression | expression DIVIDE expression''' if t[2] == '+' : t[0] = t[1] + t[3] elif t[2] == '-': t[0] = t[1] - t[3] elif t[2] == '*': t[0] = t[1] * t[3] elif t[2] == '/': t[0] = t[1] / t[3] def p_expression_uminus(t): 'expression : MINUS expression %prec UMINUS' t[0] = -t[2] def p_expression_group(t): 'expression : LPAREN expression RPAREN' t[0] = t[2] def p_expression_number(t): 'expression : NUMBER' t[0] = t[1] def p_expression_name(t): 'expression : NAME' try: t[0] = names[t[1]] except LookupError: print("Undefined name '%s'" % t[1]) t[0] = 0 def p_error(t): print("Syntax error at '%s'" % t.value) yacc.yacc()