std::stack<T,Container>::push
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std::stack void push( const value_type& value );
(1)
void push( value_type&& value );
(2)
(since C++11)
Pushes the given element value to the top of the stack.
1) Equivalent to: c.push_back(value).
2) Equivalent to: c.push_back(std::move(value)).
[edit] Parameters
value
-
the value of the element to push
[edit] Return value
(none)
[edit] Complexity
Equal to the complexity of Container::push_back.
[edit] Example
This program implements the BrainHack DSL, when the use of std::stack is an idiomatic way to process paired brackets.
Run this code
#include <array> #include <cstdint> #include <iostream> #include <map> #include <stack> #include <stdexcept> #include <string_view> class BrainHackInterpreter { std::map <unsigned, unsigned> open_brackets, close_brackets; std::array <std::uint8_t, 32768> data_{0}; unsigned program_{0}; int pos_{0}; void collect_brackets(const std::string_view program) { std::stack <unsigned> brackets_stack; for (auto pos{0U}; pos != program.length(); ++pos) { if (const char c{program[pos]}; '[' == c) brackets_stack.push(pos); else if (']' == c) { if (brackets_stack.empty()) throw std::runtime_error ("Brackets [] do not match!"); else { open_brackets[brackets_stack.top()] = pos; close_brackets[pos] = brackets_stack.top(); brackets_stack.pop(); } } } if (!brackets_stack.empty()) throw std::runtime_error ("Brackets [] do not match!"); } void check_data_pos(int pos) { if (pos < 0 or static_cast<int>(data_.size()) <= pos) throw std::out_of_range {"Data pointer out of bound!"}; } public: BrainHackInterpreter(const std::string_view program) { for (collect_brackets(program); program_ < program.length(); ++program_) switch (program[program_]) { case '<': check_data_pos(--pos_); break; case '>': check_data_pos(++pos_); break; case '-': --data_[pos_]; break; case '+': ++data_[pos_]; break; case '.': std::cout << data_[pos_]; break; case ',': std::cin >> data_[pos_]; break; case '[': if (data_[pos_] == 0) program_ = open_brackets[program_]; break; case ']': if (data_[pos_] != 0) program_ = close_brackets[program_]; break; } } }; int main() { BrainHackInterpreter { "++++++++[>++>>++>++++>++++<<<<<-]>[<+++>>+++<-]>[<+" "+>>>+<<-]<[>+>+<<-]>>>--------.<<+++++++++.<<----.>" ">>>>.<<<------.>..++.<++.+.-.>.<.>----.<--.++.>>>+." }; std::cout << '\n'; }
Output:
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