diff options
Diffstat (limited to 'test/pkg_test6/parsing/expression.py')
-rw-r--r-- | test/pkg_test6/parsing/expression.py | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/test/pkg_test6/parsing/expression.py b/test/pkg_test6/parsing/expression.py new file mode 100644 index 0000000..028f662 --- /dev/null +++ b/test/pkg_test6/parsing/expression.py @@ -0,0 +1,31 @@ +# This file contains definitions of expression grammar + +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 |