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Diffstat (limited to 'ext/ply/test/yacc_misplaced.py')
-rw-r--r-- | ext/ply/test/yacc_misplaced.py | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/ext/ply/test/yacc_misplaced.py b/ext/ply/test/yacc_misplaced.py new file mode 100644 index 000000000..9159b0109 --- /dev/null +++ b/ext/ply/test/yacc_misplaced.py @@ -0,0 +1,68 @@ +# ----------------------------------------------------------------------------- +# yacc_misplaced.py +# +# A misplaced | in grammar rules +# ----------------------------------------------------------------------------- +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_expr(t): + 'statement : expression' + print(t[1]) + +def p_expression_binop(t): + ''' | 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() + + + + |