From 1261c54df6548cf558405a118b2134805f63376d Mon Sep 17 00:00:00 2001 From: Alexei Sheplyakov Date: Sun, 14 Sep 2008 03:26:33 +0400 Subject: [PATCH] parser: add necessary checks to operator() to stop accepting nonsense. Since the parser is recursive parse_* methods (in particular, parse_binop_rhs()) does NOT check if the last unparsed token is valid. Thus parse_expression() stops if it encounters an unknown token. That's why parser::operator() needs to make sure nothing is left in the input stream. --- check/parser_bugs.cpp | 17 +++++++++++++++++ ginac/parser/parser.cpp | 7 +++++++ 2 files changed, 24 insertions(+) diff --git a/check/parser_bugs.cpp b/check/parser_bugs.cpp index a83f668a..af32c5ef 100644 --- a/check/parser_bugs.cpp +++ b/check/parser_bugs.cpp @@ -58,6 +58,22 @@ static int check3(std::ostream& err_str) return 0; } +/// parser happily accepted various junk like 'x^2()+1' +static int check4(std::ostream& err_str) +{ + const std::string junk("x^2()+1"); + parser reader; + ex e; + try { + e = reader(junk); + err_str << "parser accepts junk: \"" << junk << "\"" << std::endl; + return 1; + } catch (parse_error& err) { + // Ok, parser rejects the nonsense. + return 0; + } +} + int main(int argc, char** argv) { std::cout << "checking for parser bugs. " << std::flush; @@ -66,6 +82,7 @@ int main(int argc, char** argv) errors += check1(err_str); errors += check2(err_str); errors += check3(err_str); + errors += check4(err_str); if (errors) { std::cout << "Yes, unfortunately:" << std::endl; std::cout << err_str.str(); diff --git a/ginac/parser/parser.cpp b/ginac/parser/parser.cpp index 6cac523c..6411ba14 100644 --- a/ginac/parser/parser.cpp +++ b/ginac/parser/parser.cpp @@ -138,6 +138,13 @@ ex parser::operator()(std::istream& input) scanner->switch_input(&input); get_next_tok(); ex ret = parse_expression(); + // parse_expression() stops if it encounters an unknown token. + // This is not a bug: since the parser is recursive checking + // whether the next token is valid is responsibility of the caller. + // Hence make sure nothing is left in the stream: + if (token != lexer::token_type::eof) + Parse_error("expected EOF"); + return ret; } -- 2.44.0