void push( const value_type& value ); | ||
void push( value_type&& value ); | (since C++11) |
Pushes the given element value
to the top of the stack.
c.push_back(value)
c.push_back(std::move(value))
value | - | the value of the element to push |
(none).
Equal to the complexity of Container::push_back
.
This program implements the BrainHack DSL, when the use of std::stack
is an idiomatic way to process paired brackets.
#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; unsigned program_pos_{0}; std::array<std::uint8_t, 32768> data_; int data_pos_{0}; void collect_brackets_positions(const std::string_view program) { std::stack<unsigned> brackets_stack; for (auto pos{0U}; pos != program.length(); ++pos) { const char c{program[pos]}; if ('[' == 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 pos >= static_cast<int>(data_.size())) throw std::out_of_range{"data pointer out of bound"}; } public: BrainHackInterpreter(const std::string_view program) { collect_brackets_positions(program); data_.fill(0); for (; program_pos_ < program.length(); ++program_pos_) { switch (program[program_pos_]) { case '<': check_data_pos(--data_pos_); break; case '>': check_data_pos(++data_pos_); break; case '-': --data_[data_pos_]; break; case '+': ++data_[data_pos_]; break; case '.': std::cout << data_[data_pos_]; break; case ',': std::cin >> data_[data_pos_]; break; case '[': if (data_[data_pos_] == 0) program_pos_ = open_brackets[program_pos_]; break; case ']': if (data_[data_pos_] != 0) program_pos_ = close_brackets[program_pos_]; break; } } } }; int main() { BrainHackInterpreter { "++++++++[>++>>++>++++>++++<<<<<-]>[<+++>>+++<-]>[<+" "+>>>+<<-]<[>+>+<<-]>>>--------.<<+++++++++.<<----.>" ">>>>.<<<------.>..++.<++.+.-.>.<.>----.<--.++.>>>+." }; }
Output:
Hi, cppreference!
(C++11) | constructs element in-place at the top (public member function) |
removes the top element (public member function) |
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