C++ Mathematical Expression Library (ExprTk) http://www.partow.net/programming/exprtk/index.html
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Arash Partow
parent
63c2644981
commit
a2af37c630
145
exprtk.hpp
145
exprtk.hpp
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@ -18792,20 +18792,42 @@ namespace exprtk
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e_usr_constant_type = 1
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};
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enum usr_mode
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{
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e_usrmode_default = 0,
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e_usrmode_extended = 1
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};
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usr_mode mode;
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unknown_symbol_resolver(const usr_mode m = e_usrmode_default)
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: mode(m)
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{}
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virtual ~unknown_symbol_resolver()
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{}
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virtual bool process(const std::string& /*unknown_symbol*/,
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usr_symbol_type& st,
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T& default_value,
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std::string& error_message)
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usr_symbol_type& st,
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T& default_value,
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std::string& error_message)
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{
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if (e_usrmode_default != mode)
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return false;
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st = e_usr_variable_type;
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default_value = T(0);
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error_message.clear();
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return true;
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}
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virtual bool process(const std::string& /* unknown_symbol */,
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symbol_table_t& /* symbol_table */,
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std::string& /* error_message */)
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{
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return false;
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}
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};
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enum collect_type
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@ -19948,6 +19970,11 @@ namespace exprtk
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unknown_symbol_resolver_ = &default_usr_;
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}
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inline void enable_unknown_symbol_resolver(unknown_symbol_resolver& usr)
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{
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enable_unknown_symbol_resolver(&usr);
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}
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inline void disable_unknown_symbol_resolver()
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{
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resolve_unknown_symbol_ = false;
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@ -24539,63 +24566,93 @@ namespace exprtk
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{
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if (!(settings_.rsrvd_sym_usr_disabled() && details::is_reserved_symbol(symbol)))
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{
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T default_value = T(0);
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symbol_table_t& symtab = symtab_store_.get_symbol_table();
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std::string error_message;
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typename unknown_symbol_resolver::usr_symbol_type usr_symbol_type;
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if (unknown_symbol_resolver_->process(symbol,usr_symbol_type,default_value,error_message))
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if (unknown_symbol_resolver::e_usrmode_default == unknown_symbol_resolver_->mode)
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{
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bool create_result = false;
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T default_value = T(0);
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typename unknown_symbol_resolver::usr_symbol_type usr_symbol_type;
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symbol_table_t& symtab = symtab_store_.get_symbol_table();
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switch (usr_symbol_type)
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if (unknown_symbol_resolver_->process(symbol, usr_symbol_type, default_value, error_message))
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{
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case unknown_symbol_resolver::e_usr_variable_type : create_result = symtab.create_variable(symbol,default_value);
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break;
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bool create_result = false;
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case unknown_symbol_resolver::e_usr_constant_type : create_result = symtab.add_constant(symbol,default_value);
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break;
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default : create_result = false;
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}
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if (create_result)
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{
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expression_node_ptr var = symtab_store_.get_variable(symbol);
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if (var)
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switch (usr_symbol_type)
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{
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if (symtab_store_.is_constant_node(symbol))
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case unknown_symbol_resolver::e_usr_variable_type : create_result = symtab.create_variable(symbol, default_value);
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break;
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case unknown_symbol_resolver::e_usr_constant_type : create_result = symtab.add_constant(symbol, default_value);
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break;
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default : create_result = false;
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}
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if (create_result)
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{
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expression_node_ptr var = symtab_store_.get_variable(symbol);
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if (var)
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{
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var = expression_generator_(var->value());
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if (symtab_store_.is_constant_node(symbol))
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{
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var = expression_generator_(var->value());
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}
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lodge_symbol(symbol,e_st_variable);
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if (!post_variable_process(symbol))
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return error_node();
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next_token();
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return var;
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}
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lodge_symbol(symbol,e_st_variable);
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if (!post_variable_process(symbol))
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return error_node();
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next_token();
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return var;
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}
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}
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set_error(
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make_error(parser_error::e_symtab,
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current_token(),
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"ERR183 - Failed to create variable: '" + symbol + "'"));
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"ERR183 - Failed to create variable: '" + symbol + "'" +
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(error_message.empty() ? "" : " - " + error_message)));
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return error_node();
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}
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else if (unknown_symbol_resolver::e_usrmode_extended == unknown_symbol_resolver_->mode)
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{
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if (unknown_symbol_resolver_->process(symbol, symtab, error_message))
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{
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static bool usr_extmode_active = false;
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if (!usr_extmode_active)
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{
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usr_extmode_active = true;
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expression_node_ptr result = parse_symtab_symbol();
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usr_extmode_active = false;
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if (result)
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{
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return result;
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}
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}
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}
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set_error(
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make_error(parser_error::e_symtab,
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current_token(),
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"ERR184 - Failed to resolve symbol: '" + symbol + "'" +
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(error_message.empty() ? "" : " - " + error_message)));
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}
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return error_node();
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}
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}
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set_error(
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make_error(parser_error::e_syntax,
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current_token(),
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"ERR184 - Undefined symbol: '" + symbol + "'"));
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"ERR185 - Undefined symbol: '" + symbol + "'"));
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return error_node();
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}
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@ -24701,7 +24758,7 @@ namespace exprtk
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set_error(
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make_error(parser_error::e_symtab,
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current_token(),
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"ERR185 - Variable or function detected, yet symbol-table is invalid, Symbol: " + current_token().value));
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"ERR186 - Variable or function detected, yet symbol-table is invalid, Symbol: " + current_token().value));
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return error_node();
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}
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@ -24726,7 +24783,7 @@ namespace exprtk
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set_error(
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make_error(parser_error::e_numeric,
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current_token(),
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"ERR186 - Failed to convert '" + current_token().value + "' to a number"));
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"ERR187 - Failed to convert '" + current_token().value + "' to a number"));
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return error_node();
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}
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@ -24752,7 +24809,7 @@ namespace exprtk
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set_error(
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make_error(parser_error::e_syntax,
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current_token(),
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"ERR187 - Expected ')' instead of: '" + current_token().value + "'"));
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"ERR188 - Expected ')' instead of: '" + current_token().value + "'"));
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free_node(node_allocator_,branch);
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@ -24776,7 +24833,7 @@ namespace exprtk
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set_error(
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make_error(parser_error::e_syntax,
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current_token(),
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"ERR188 - Expected ']' instead of: '" + current_token().value + "'"));
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"ERR189 - Expected ']' instead of: '" + current_token().value + "'"));
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free_node(node_allocator_,branch);
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@ -24800,7 +24857,7 @@ namespace exprtk
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set_error(
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make_error(parser_error::e_syntax,
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current_token(),
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"ERR189 - Expected '}' instead of: '" + current_token().value + "'"));
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"ERR190 - Expected '}' instead of: '" + current_token().value + "'"));
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free_node(node_allocator_,branch);
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@ -24839,7 +24896,7 @@ namespace exprtk
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set_error(
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make_error(parser_error::e_syntax,
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current_token(),
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"ERR190 - Premature end of expression[1]"));
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"ERR191 - Premature end of expression[1]"));
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return error_node();
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}
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@ -24848,7 +24905,7 @@ namespace exprtk
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set_error(
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make_error(parser_error::e_syntax,
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current_token(),
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"ERR191 - Premature end of expression[2]"));
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"ERR192 - Premature end of expression[2]"));
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return error_node();
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}
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75
readme.txt
75
readme.txt
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@ -2841,7 +2841,7 @@ simple user defined USR:
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T& default_value,
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std::string& error_message)
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{
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if (0 != unknown_symbol.find('var_'))
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if (0 != unknown_symbol.find("var_"))
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{
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error_message = "Invalid symbol: " + unknown_symbol;
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return false;
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@ -2884,6 +2884,77 @@ USR's process method will be invoked. The USR in the example will only
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variables, all other unknown symbols will result in a compilation
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error being raised.
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In the example above the callback of the USR that is invoked during
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the unknown symbol resolution process only allows for scalar variables
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to be defined and resolved - as that is the simplest and most common
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form.
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There is also an extended version of the callback that can be
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overridden that will allow for more control and choice over the type
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of symbol being resolved. The following is an example definition of
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said extended callback:
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template <typename T>
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struct my_usr : public parser_t::unknown_symbol_resolver
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{
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typedef typename parser_t::unknown_symbol_resolver usr_t;
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my_usr()
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: usr_t(usr_t::e_usrmode_extended)
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{}
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virtual bool process(const std::string& unknown_symbol,
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symbol_table_t& symbol_table,
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std::string& error_message)
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{
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bool result = false;
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if (0 == unknown_symbol.find("var_"))
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{
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// Default value of zero
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result = symbol_table.create_variable(unknown_symbol,0);
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if (!result)
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{
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error_message = "Failed to create variable...";
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}
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}
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else if (0 == unknown_symbol.find("str_"))
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{
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// Default value of empty string
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result = symbol_table.create_stringvar(unknown_symbol,"");
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if (!result)
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{
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error_message = "Failed to create string variable...";
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}
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}
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else
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error_message = "Indeterminable symbol type.";
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return result;
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}
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};
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In the example above, the USR callback when invoked will pass the
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primary symbol table associated with the expression being parsed. The
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symbol resolution business logic can then determine under what
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conditions a symbol will be resolved including its type (scalar,
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string, vector etc) and default value. When the callback successfully
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returns the symbol parsing and resolution process will again be
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executed by the parser. The idea here is that given the primary symbol
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table will now have the previously detected unknown symbol registered,
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it will be correctly resolved and the general parsing processing can
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then resume as per normal.
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Note: In order to have the USR's extended mode callback be invoked It
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is necessary to pass the e_usrmode_extended enum value during the
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constructor of the user defined USR.
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Note: The primary symbol table for an expression is the first symbol
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table to be registered with that instance of the expression.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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[SECTION 19 - ENABLING & DISABLING FEATURES]
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@ -4658,4 +4729,4 @@ ExprTk and their structural representations.
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| +--<--- [,] <-----+ |
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+-------------------------------------------------------------+
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+-------------------------------------------------------------+
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