From 4007ea18f294aefb6128cbe82c5446cd8cb72c50 Mon Sep 17 00:00:00 2001 From: Louis Burda Date: Thu, 14 Mar 2024 21:30:16 +0100 Subject: Add solution --- chall/ply-2.2/test/yacc_sr.py | 64 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 chall/ply-2.2/test/yacc_sr.py (limited to 'chall/ply-2.2/test/yacc_sr.py') diff --git a/chall/ply-2.2/test/yacc_sr.py b/chall/ply-2.2/test/yacc_sr.py new file mode 100644 index 0000000..e2f03ec --- /dev/null +++ b/chall/ply-2.2/test/yacc_sr.py @@ -0,0 +1,64 @@ +# ----------------------------------------------------------------------------- +# yacc_sr.py +# +# A grammar with shift-reduce conflicts +# ----------------------------------------------------------------------------- +import sys +sys.tracebacklimit = 0 + +sys.path.insert(0,"..") +import ply.yacc as yacc + +from calclex import tokens + +# Parsing rules + +# dictionary of names +names = { } + +def p_statement_assign(t): + 'statement : NAME EQUALS expression' + 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[3] == '/': t[0] = t[1] / t[3] + +def p_expression_uminus(t): + 'expression : MINUS expression' + 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() + + + + -- cgit v1.2.3-71-gd317