diff mbox

[libstdc++] Add specific error message into exceptions

Message ID CAG4ZjN=j0B3njx13d1hDk+aRgW6HijvFs_saED8xAHMQ7foCPQ@mail.gmail.com
State New
Headers show

Commit Message

Tim Shen Sept. 12, 2015, 2:04 a.m. UTC 
On Mon, Sep 7, 2015 at 4:06 AM, Jonathan Wakely <jwakely@redhat.com> wrote:
> On 28/08/15 11:23 -0700, Tim Shen wrote:
>>
>> On Fri, Aug 28, 2015 at 8:59 AM, Jonathan Wakely <jwakely@redhat.com>
>> wrote:
>>>
>>> There seems to be no need to construct a std::string here, just pass a
>>> const char* (see below).
>>
>>
>> To be honest, I wasn't considering performance for a bit, since
>> exceptions are already considered slow by me :P. But yes, we can do
>> less allocations.
>>
>>> I wonder if we want to make this more efficient by adding a private
>>> member to regex_error that would allow information to be appended to
>>> the string, rather then creating a new regex_error with a new string.
>
>
> In case it wasn't clear, I was suggesting to add a private member
> *function* not data member.
>
>> I can add a helper function to _Scanner to construct the exception
>> object for only once. For functions that can't access this helper, use
>> return value for error handling.
>>
>>> I suggest adding another overload that takes a const char* rather than
>>> std::string. The reason is that when using the new ABI this function
>>> will take a std::__cxx11::string, so calling it will allocate memory
>>> for the string data, then that string is passed to the regex_error
>>> constructor which has to convert it internally to an old std::string,
>>> which has to allocate a second time.
>>
>>
>> First, to make it clear: due to _M_get_location_string(), we need
>> dynamic allocation.
>>
>> So is it good to have an owned raw pointer stored in runtime_error,
>> pointing to a heap allocated char chunk, which will be deallocated in
>> regex_error's dtor?
>
>
> No, adding that pointer is an ABI change.
>
> If you can't do it without an ABI change then you will have to lose
> the _M_get_location_string() functionality. It seems non-essential
> anyway.

Ok then, let's not append dynamic location information, but use a
string literal pointer only.
diff mbox

Patch

diff --git a/libstdc++-v3/include/bits/regex_automaton.h b/libstdc++-v3/include/bits/regex_automaton.h
index b6ab307..1f672ee 100644
--- a/libstdc++-v3/include/bits/regex_automaton.h
+++ b/libstdc++-v3/include/bits/regex_automaton.h
@@ -327,7 +327,11 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
 	this->push_back(std::move(__s));
 	if (this->size() > _GLIBCXX_REGEX_STATE_LIMIT)
-	  __throw_regex_error(regex_constants::error_space);
+	  __throw_regex_error(
+	    regex_constants::error_space,
+	    "Number of NFA states exceeds limit. Please use shorter regex "
+	    "string, or use smaller brace expression, or make "
+	    "_GLIBCXX_REGEX_STATE_LIMIT larger.");
 	return this->size()-1;
       }
 
diff --git a/libstdc++-v3/include/bits/regex_automaton.tcc b/libstdc++-v3/include/bits/regex_automaton.tcc
index f6f63a1..9bb1164 100644
--- a/libstdc++-v3/include/bits/regex_automaton.tcc
+++ b/libstdc++-v3/include/bits/regex_automaton.tcc
@@ -149,7 +149,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _NFA<_TraitsT>::_M_insert_backref(size_t __index)
     {
       if (this->_M_flags & regex_constants::__polynomial)
-	__throw_regex_error(regex_constants::error_complexity);
+	__throw_regex_error(regex_constants::error_complexity,
+			    "Unexpected back-reference in polynomial mode.");
       // To figure out whether a backref is valid, a stack is used to store
       // unfinished sub-expressions. For example, when parsing
       // "(a(b)(c\\1(d)))" at '\\1', _M_subexpr_count is 3, indicating that 3
@@ -158,10 +159,14 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // _M_paren_stack is {1, 3}, for incomplete "(a.." and "(c..". At this
       // time, "\\2" is valid, but "\\1" and "\\3" are not.
       if (__index >= _M_subexpr_count)
-	__throw_regex_error(regex_constants::error_backref);
+	__throw_regex_error(
+	  regex_constants::error_backref,
+	  "Back-reference index exceeds current sub-expression count.");
       for (auto __it : this->_M_paren_stack)
 	if (__index == __it)
-	  __throw_regex_error(regex_constants::error_backref);
+	  __throw_regex_error(
+	    regex_constants::error_backref,
+	    "Back-reference referred to an opened sub-expression.");
       this->_M_has_backref = true;
       _StateT __tmp(_S_opcode_backref);
       __tmp._M_backref_index = __index;
diff --git a/libstdc++-v3/include/bits/regex_compiler.h b/libstdc++-v3/include/bits/regex_compiler.h
index 07a9ed3..1f6348a 100644
--- a/libstdc++-v3/include/bits/regex_compiler.h
+++ b/libstdc++-v3/include/bits/regex_compiler.h
@@ -392,7 +392,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	auto __st = _M_traits.lookup_collatename(__s.data(),
 						 __s.data() + __s.size());
 	if (__st.empty())
-	  __throw_regex_error(regex_constants::error_collate);
+	  __throw_regex_error(regex_constants::error_collate,
+			      "Invalid collate element.");
 	_M_char_set.push_back(_M_translator._M_translate(__st[0]));
 	_GLIBCXX_DEBUG_ONLY(_M_is_ready = false);
 	return __st;
@@ -404,7 +405,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	auto __st = _M_traits.lookup_collatename(__s.data(),
 						 __s.data() + __s.size());
 	if (__st.empty())
-	  __throw_regex_error(regex_constants::error_collate);
+	  __throw_regex_error(regex_constants::error_collate,
+			      "Invalid equivalence class.");
 	__st = _M_traits.transform_primary(__st.data(),
 					   __st.data() + __st.size());
 	_M_equiv_set.push_back(__st);
@@ -419,7 +421,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 						 __s.data() + __s.size(),
 						 __icase);
 	if (__mask == 0)
-	  __throw_regex_error(regex_constants::error_ctype);
+	  __throw_regex_error(regex_constants::error_collate,
+			      "Invalid character class.");
 	if (!__neg)
 	  _M_class_set |= __mask;
 	else
@@ -431,7 +434,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _M_make_range(_CharT __l, _CharT __r)
       {
 	if (__l > __r)
-	  __throw_regex_error(regex_constants::error_range);
+	  __throw_regex_error(regex_constants::error_range,
+			      "Invalid range in bracket expression.");
 	_M_range_set.push_back(make_pair(_M_translator._M_transform(__l),
 					 _M_translator._M_transform(__r)));
 	_GLIBCXX_DEBUG_ONLY(_M_is_ready = false);
diff --git a/libstdc++-v3/include/bits/regex_compiler.tcc b/libstdc++-v3/include/bits/regex_compiler.tcc
index 336a2e8..f7d52fc 100644
--- a/libstdc++-v3/include/bits/regex_compiler.tcc
+++ b/libstdc++-v3/include/bits/regex_compiler.tcc
@@ -162,7 +162,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  auto __neg = _M_value[0] == 'n';
 	  this->_M_disjunction();
 	  if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
-	    __throw_regex_error(regex_constants::error_paren);
+	    __throw_regex_error(regex_constants::error_paren,
+				"Parenthesis is not closed.");
 	  auto __tmp = _M_pop();
 	  __tmp._M_append(_M_nfa->_M_insert_accept());
 	  _M_stack.push(
@@ -184,7 +185,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       auto __init = [this, &__neg]()
 	{
 	  if (_M_stack.empty())
-	    __throw_regex_error(regex_constants::error_badrepeat);
+	    __throw_regex_error(regex_constants::error_badrepeat,
+				"Nothing to repeat before a quantifier.");
 	  __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);
 	};
       if (_M_match_token(_ScannerT::_S_token_closure0))
@@ -220,9 +222,11 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       else if (_M_match_token(_ScannerT::_S_token_interval_begin))
 	{
 	  if (_M_stack.empty())
-	    __throw_regex_error(regex_constants::error_badrepeat);
+	    __throw_regex_error(regex_constants::error_badrepeat,
+				"Nothing to repeat before a quantifier.");
 	  if (!_M_match_token(_ScannerT::_S_token_dup_count))
-	    __throw_regex_error(regex_constants::error_badbrace);
+	    __throw_regex_error(regex_constants::error_badbrace,
+				"Unexpected token in brace expression.");
 	  _StateSeqT __r(_M_pop());
 	  _StateSeqT __e(*_M_nfa, _M_nfa->_M_insert_dummy());
 	  long __min_rep = _M_cur_int_value(10);
@@ -238,7 +242,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  else
 	    __n = 0;
 	  if (!_M_match_token(_ScannerT::_S_token_interval_end))
-	    __throw_regex_error(regex_constants::error_brace);
+	    __throw_regex_error(regex_constants::error_brace,
+				"Unexpected end of brace expression.");
 
 	  __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);
 
@@ -257,7 +262,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  else
 	    {
 	      if (__n < 0)
-		__throw_regex_error(regex_constants::error_badbrace);
+		__throw_regex_error(regex_constants::error_badbrace,
+				    "Invalid range in brace expression.");
 	      auto __end = _M_nfa->_M_insert_dummy();
 	      // _M_alt is the "match more" branch, and _M_next is the
 	      // "match less" one. Switch _M_alt and _M_next of all created
@@ -324,7 +330,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  _StateSeqT __r(*_M_nfa, _M_nfa->_M_insert_dummy());
 	  this->_M_disjunction();
 	  if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
-	    __throw_regex_error(regex_constants::error_paren);
+	    __throw_regex_error(regex_constants::error_paren,
+				"Parenthesis is not closed.");
 	  __r._M_append(_M_pop());
 	  _M_stack.push(__r);
 	}
@@ -333,7 +340,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  _StateSeqT __r(*_M_nfa, _M_nfa->_M_insert_subexpr_begin());
 	  this->_M_disjunction();
 	  if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
-	    __throw_regex_error(regex_constants::error_paren);
+	    __throw_regex_error(regex_constants::error_paren,
+				"Parenthesis is not closed.");
 	  __r._M_append(_M_pop());
 	  __r._M_append(_M_nfa->_M_insert_subexpr_end());
 	  _M_stack.push(__r);
@@ -474,7 +482,11 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		{
 		  if (_M_match_token(_ScannerT::_S_token_bracket_end))
 		    return false;
-		  __throw_regex_error(regex_constants::error_range);
+		  __throw_regex_error(
+		    regex_constants::error_range,
+		    "Unexpected dash in bracket expression. For POSIX syntax, "
+		    "a dash is not treated literally only when it is at "
+		    "beginning or end.");
 		}
 	      __last_char.first = true;
 	      __last_char.second = _M_value[0];
@@ -492,7 +504,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		    {
 		      if (_M_scanner._M_get_token()
 			  != _ScannerT::_S_token_bracket_end)
-			__throw_regex_error(regex_constants::error_range);
+			__throw_regex_error(
+			  regex_constants::error_range,
+			  "Unexpected end of bracket expression.");
 		      __matcher._M_add_char(_M_value[0]);
 		    }
 		}
@@ -508,7 +522,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 					 _M_ctype.is(_CtypeT::upper,
 						     _M_value[0]));
       else
-	__throw_regex_error(regex_constants::error_brack);
+	__throw_regex_error(regex_constants::error_brack,
+			    "Unexpected character in bracket expression.");
 
       return true;
     }
diff --git a/libstdc++-v3/include/bits/regex_error.h b/libstdc++-v3/include/bits/regex_error.h
index 778edd5..be19fc1 100644
--- a/libstdc++-v3/include/bits/regex_error.h
+++ b/libstdc++-v3/include/bits/regex_error.h
@@ -155,6 +155,13 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     regex_constants::error_type
     code() const
     { return _M_code; }
+
+  private:
+    regex_error(regex_constants::error_type __ecode, const char* __what)
+    : std::runtime_error(__what), _M_code(__ecode)
+    { }
+
+    friend void __throw_regex_error(regex_constants::error_type, const char*);
   };
 
   //@} // group regex
@@ -162,5 +169,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
   void
   __throw_regex_error(regex_constants::error_type __ecode);
 
+  inline void
+  __throw_regex_error(regex_constants::error_type __ecode, const char* __what)
+  { _GLIBCXX_THROW_OR_ABORT(regex_error(__ecode, __what)); }
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
diff --git a/libstdc++-v3/include/bits/regex_scanner.tcc b/libstdc++-v3/include/bits/regex_scanner.tcc
index c158c65..7d24e06 100644
--- a/libstdc++-v3/include/bits/regex_scanner.tcc
+++ b/libstdc++-v3/include/bits/regex_scanner.tcc
@@ -108,7 +108,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       if (__c == '\\')
 	{
 	  if (_M_current == _M_end)
-	    __throw_regex_error(regex_constants::error_escape);
+	    __throw_regex_error(
+	      regex_constants::error_escape,
+	      "Unexpected end of regex when escaping.");
 
 	  if (!_M_is_basic()
 	      || (*_M_current != '('
@@ -125,7 +127,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  if (_M_is_ecma() && *_M_current == '?')
 	    {
 	      if (++_M_current == _M_end)
-		__throw_regex_error(regex_constants::error_paren);
+		__throw_regex_error(
+		  regex_constants::error_paren,
+		  "Unexpected end of regex when in an open parenthesis.");
 
 	      if (*_M_current == ':')
 		{
@@ -145,7 +149,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		  _M_value.assign(1, 'n');
 		}
 	      else
-		__throw_regex_error(regex_constants::error_paren);
+		__throw_regex_error(
+		  regex_constants::error_paren,
+		  "Invalid special open parenthesis.");
 	    }
 	  else if (_M_flags & regex_constants::nosubs)
 	    _M_token = _S_token_subexpr_no_group_begin;
@@ -204,14 +210,17 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_scan_in_bracket()
     {
       if (_M_current == _M_end)
-	__throw_regex_error(regex_constants::error_brack);
+	__throw_regex_error(
+	  regex_constants::error_brack,
+	  "Unexpected end of regex when in bracket expression.");
 
       auto __c = *_M_current++;
 
       if (__c == '[')
 	{
 	  if (_M_current == _M_end)
-	    __throw_regex_error(regex_constants::error_brack);
+	    __throw_regex_error(regex_constants::error_brack,
+				"Unexpected character class open bracket.");
 
 	  if (*_M_current == '.')
 	    {
@@ -261,7 +270,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_scan_in_brace()
     {
       if (_M_current == _M_end)
-	__throw_regex_error(regex_constants::error_brace);
+	__throw_regex_error(
+	  regex_constants::error_brace,
+	  "Unexpected end of regex when in brace expression.");
 
       auto __c = *_M_current++;
 
@@ -285,7 +296,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	      ++_M_current;
 	    }
 	  else
-	    __throw_regex_error(regex_constants::error_badbrace);
+	    __throw_regex_error(regex_constants::error_badbrace,
+				"Unexpected character in brace expression.");
 	}
       else if (__c == '}')
 	{
@@ -293,7 +305,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  _M_token = _S_token_interval_end;
 	}
       else
-	__throw_regex_error(regex_constants::error_badbrace);
+	__throw_regex_error(regex_constants::error_badbrace,
+			    "Unexpected character in brace expression.");
     }
 
   template<typename _CharT>
@@ -302,7 +315,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_eat_escape_ecma()
     {
       if (_M_current == _M_end)
-	__throw_regex_error(regex_constants::error_escape);
+	__throw_regex_error(regex_constants::error_escape,
+			    "Unexpected end of regex when escaping.");
 
       auto __c = *_M_current++;
       auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));
@@ -336,7 +350,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       else if (__c == 'c')
 	{
 	  if (_M_current == _M_end)
-	    __throw_regex_error(regex_constants::error_escape);
+	    __throw_regex_error(
+	      regex_constants::error_escape,
+	      "Unexpected end of regex when reading control code.");
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, *_M_current++);
 	}
@@ -347,7 +363,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    {
 	      if (_M_current == _M_end
 		  || !_M_ctype.is(_CtypeT::xdigit, *_M_current))
-		__throw_regex_error(regex_constants::error_escape);
+		__throw_regex_error(
+		  regex_constants::error_escape,
+		  "Unexpected end of regex when ascii character.");
 	      _M_value += *_M_current++;
 	    }
 	  _M_token = _S_token_hex_num;
@@ -376,7 +394,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_eat_escape_posix()
     {
       if (_M_current == _M_end)
-	__throw_regex_error(regex_constants::error_escape);
+	__throw_regex_error(regex_constants::error_escape,
+			    "Unexpected end of regex when escaping.");
 
       auto __c = *_M_current;
       auto __pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0'));
@@ -401,7 +420,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	{
 #ifdef __STRICT_ANSI__
 	  // POSIX says it is undefined to escape ordinary characters
-	  __throw_regex_error(regex_constants::error_escape);
+	  __throw_regex_error(regex_constants::error_escape,
+			      "Unexpected escape character.");
 #else
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, __c);
@@ -441,7 +461,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  return;
 	}
       else
-	__throw_regex_error(regex_constants::error_escape);
+	__throw_regex_error(regex_constants::error_escape,
+			    "Unexpected escape character.");
     }
 
   // Eats a character class or throws an exception.
@@ -460,9 +481,11 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  || *_M_current++ != ']') // skip ']'
 	{
 	  if (__ch == ':')
-	    __throw_regex_error(regex_constants::error_ctype);
+	    __throw_regex_error(regex_constants::error_ctype,
+				"Unexpected end of character class.");
 	  else
-	    __throw_regex_error(regex_constants::error_collate);
+	    __throw_regex_error(regex_constants::error_collate,
+				"Unexpected end of character class.");
 	}
     }