• 1993, Stepanov presents the main ideas at the November WG21 meeting • 1994, Stepanov and Lee create proposal for WG21 that was accepted later that year • 1994-1998, much additional work; adding the containers are implemented using a variety of basic data structures • Each STL container represents a sequence of elements • Containers have an internal structure and ordering • We can observe this ordering 20CppCon 2021 – Back to Basics: Classic STL Copyright © 2021 Bob Steagall Containers Overview • Sequence containers • vector • deque • list • array (C++11) • forward_list (C++11) • Associative containers

the customers table CREATE TABLE customers( id INTEGER NOT NULL PRIMARY KEY, name TEXT NOT NULL ); Customers id INTEGER PRIMARY KEY name TEXTCreate the orders table CREATE TABLE orders( id INTEGER ftsd::prepared_statement< // R"( CREATE TABLE customers( id INTEGER NOT NULL PRIMARY KEY, name TEXT NOT NULL );)" // >{sqldb} .execute();Create Orders ftsd::prepared_statement< // R"( CREATE TABLE orders( id false, std::make_index_sequence>::type; using parameters_type = typename meta_struct_from_type_specs< query_string, ts.params, true, std::make_index_sequence>::type;

something beautiful?A word about beauty and elegance • Situation: we want to apply a function f in sequence to each argument of a function • Note that this is not from me, but it made its way from twitter ((f(std::forward(args)), 0)...); } 68 … and we pass it a sequence of zeros, but after applying f to each argument in sequence. A fold expression over operator,()…A word about beauty and elegance with a value-based language class Integral { int value_ = create_value(); public: static int create_value() { std::cout << "in create_value\n"; return {}; } int value() const { return value_;

// Same as: int x = 42; typename[:^char:] c = '*'; // Same as: char c = '*';Early Observation •We create identifiers from strings • Plus ability to concatenate “m_”, “get_”, “set_” with parameter •Identifiers typename[:^char:] c = '*'; // Same as: char c = '*';Comparison of Splicing Models •The Spec API: function calls create a “spec” of a type that is spliced • Complex; problematic; death of a thousand cuts •The CodeReckons '*';Quoting & Splicing a Token Sequence Status: prototype implementation •Escapes inside a token sequence: • \( expr ) evaluates expr eagerly during creation of the token sequence • \id( e1, e2, ... ) concatenates

desired types const auto invoker = // helper lambda [&](std::index_sequence) { /// we need to unpack the parameter types and the indices together func(std::any_cast(params[Index])...); }; return invoker(std::make_index_sequence()); } ); } https://godbolt.org/z/Y74jse1WvCopyright Jason Turner @le�icus return [&](std::index_sequence) { return func(std::any_cast(params[Index])...); }(std::make_index_sequence()); /// IILE },

browser: text -> JSON parser -> JS object parse(text or tokens) -> value or errorParser Combinators Create a parser by combining existing parsers. parse_string_or_int(text, pos) -> parse_string(text, parse_int(text, pos) parse_string_or_int -> parse_string | parse_int Simplified syntax:Parser Generators Create a parser from a grammar. Popular parsing algorithms used in generators are LL, LL(k), LR, LR(k) ranges::to< vector >();Example – Runtime Parsers std::vector cats = { /*...*/ }; auto parser = create_parser(); auto func = parser("SELECT id, name WHERE age > 42"); std::vector result = func(cats);Example

Embedded processors • TI, Atmel, Intel, Freescale, FPGAs, etc. • Simply impractical (impossible?) to create a separate language and set of tools for every computing platform CppCon 2020 - The Abstract Machine state of the execution environment. (my emphasis) […] • [expr.pre](7.1) […] An expression is a sequence of operators and operands that specifies a computation. An expression can result in a value and match one of them • Expressions with non-observable side effects may be ignored • Expression - a sequence of operators and operands that specifies a computation • Side effects - changes in the program’s

remembering the sequence of operations it was made from 2 template class shaper { 3 // Types 4 public: 5 using type = shaper ; 6 using index_sequence = std:: index_sequence_for sequence of operations it was made from 2 template class shaper { 3 // ... 4 // Operators const noexcept { 24 return to_array( index_sequence (), x...); 25 } 26 template constexpr auto to_array(std :: index_sequence , X... x) const noexcept { 27 return

allowed (!) • Concepts identified by the source location, • When using negation or parens, you create a new expression • this means a new concept (breaks subsumption) 28x is Type 29x is Type 304 Ts> auto type_find_if() { [&](std::index_sequence){ std::cout << sizeof...(Is) << std::endl; }(std::index_sequence_for()); } int main() { type_find_if(); typename F> auto type_find_if(F fun) { [&](std::index_sequence){ fun(sizeof...(Is)); }(std::index_sequence_for()); } int main() { type_find_if([](auto

2023-10-03 22Parser generates a sequence of events { object_begin, Jonathan Müller — @foonathan Express your expectations CppCon 2023-10-03 23Parser generates a sequence of events { "id": object_begin generates a sequence of events { "id": 42, object_begin, key("id"), number(42), Jonathan Müller — @foonathan Express your expectations CppCon 2023-10-03 23Parser generates a sequence of events { Jonathan Müller — @foonathan Express your expectations CppCon 2023-10-03 23Parser generates a sequence of events { "id": 42, "name": "Jonathan Müller", "speaker": true, object_begin, key("id")