From Jason Turner

[format.parse.ctx]

C++23 → Trunk 5.3 KB 87 lines
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Archived: C++23
Markdown: C++23 | Trunk
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  1. tmp/tmpco55a0ic/{from.md → to.md} +67 -14
tmp/tmpco55a0ic/{from.md → to.md} RENAMED
@@ -4,11 +4,11 @@
4
  namespace std {
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  template<class charT>
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  class basic_format_parse_context {
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  public:
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  using char_type = charT;
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- using const_iterator = typename basic_string_view<charT>::const_iterator;
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  using iterator = const_iterator;
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  private:
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  iterator begin_; // exposition only
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  iterator end_; // exposition only
@@ -16,37 +16,49 @@ namespace std {
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  indexing indexing_; // exposition only
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  size_t next_arg_id_; // exposition only
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  size_t num_args_; // exposition only
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  public:
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- constexpr explicit basic_format_parse_context(basic_string_view<charT> fmt,
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- size_t num_args = 0) noexcept;
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  basic_format_parse_context(const basic_format_parse_context&) = delete;
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  basic_format_parse_context& operator=(const basic_format_parse_context&) = delete;
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  constexpr const_iterator begin() const noexcept;
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  constexpr const_iterator end() const noexcept;
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  constexpr void advance_to(const_iterator it);
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  constexpr size_t next_arg_id();
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  constexpr void check_arg_id(size_t id);
 
 
 
 
 
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  };
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  }
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  ```
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  An instance of `basic_format_parse_context` holds the format string
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- parsing state consisting of the format string range being parsed and the
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- argument counter for automatic indexing.
 
 
 
 
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  ``` cpp
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- constexpr explicit basic_format_parse_context(basic_string_view<charT> fmt,
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- size_t num_args = 0) noexcept;
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  ```
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  *Effects:* Initializes `begin_` with `fmt.begin()`, `end_` with
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  `fmt.end()`, `indexing_` with `unknown`, `next_arg_id_` with `0`, and
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- `num_args_` with `num_args`.
 
 
 
 
 
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  ``` cpp
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  constexpr const_iterator begin() const noexcept;
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  ```
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@@ -76,12 +88,14 @@ constexpr size_t next_arg_id();
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  if (indexing_ == unknown)
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  indexing_ = automatic;
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  return next_arg_id_++;
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  ```
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- *Throws:* `format_error` if `indexing_ == manual` is `true` which
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- indicates mixing of automatic and manual argument indexing.
 
 
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  *Remarks:* Let *`cur-arg-id`* be the value of `next_arg_id_` prior to
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  this call. Call expressions where *`cur-arg-id`*` >= num_args_` is
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  `true` are not core constant expressions [[expr.const]].
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@@ -94,11 +108,50 @@ constexpr void check_arg_id(size_t id);
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  ``` cpp
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  if (indexing_ == unknown)
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  indexing_ = manual;
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  ```
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- *Throws:* `format_error` if `indexing_ == automatic` is `true` which
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- indicates mixing of automatic and manual argument indexing.
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- *Remarks:* Call expressions where `id >= num_args_` is `true` are not
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- core constant expressions [[expr.const]].
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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  namespace std {
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  template<class charT>
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  class basic_format_parse_context {
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  public:
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  using char_type = charT;
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+ using const_iterator = basic_string_view<charT>::const_iterator;
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  using iterator = const_iterator;
11
 
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  private:
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  iterator begin_; // exposition only
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  iterator end_; // exposition only
 
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  indexing indexing_; // exposition only
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  size_t next_arg_id_; // exposition only
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  size_t num_args_; // exposition only
19
 
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  public:
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+ constexpr explicit basic_format_parse_context(basic_string_view<charT> fmt) noexcept;
 
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  basic_format_parse_context(const basic_format_parse_context&) = delete;
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  basic_format_parse_context& operator=(const basic_format_parse_context&) = delete;
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  constexpr const_iterator begin() const noexcept;
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  constexpr const_iterator end() const noexcept;
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  constexpr void advance_to(const_iterator it);
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  constexpr size_t next_arg_id();
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  constexpr void check_arg_id(size_t id);
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+
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+ template<class... Ts>
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+ constexpr void check_dynamic_spec(size_t id) noexcept;
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+ constexpr void check_dynamic_spec_integral(size_t id) noexcept;
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+ constexpr void check_dynamic_spec_string(size_t id) noexcept;
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  };
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  }
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  ```
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  An instance of `basic_format_parse_context` holds the format string
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+ parsing state, consisting of the format string range being parsed and
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+ the argument counter for automatic indexing.
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+
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+ If a program declares an explicit or partial specialization of
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+ `basic_format_parse_context`, the program is ill-formed, no diagnostic
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+ required.
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  ``` cpp
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+ constexpr explicit basic_format_parse_context(basic_string_view<charT> fmt) noexcept;
 
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  ```
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  *Effects:* Initializes `begin_` with `fmt.begin()`, `end_` with
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  `fmt.end()`, `indexing_` with `unknown`, `next_arg_id_` with `0`, and
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+ `num_args_` with `0`.
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+
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+ [*Note 1*: Any call to `next_arg_id`, `check_arg_id`, or
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+ `check_dynamic_spec` on an instance of `basic_format_parse_context`
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+ initialized using this constructor is not a core constant
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+ expression. — *end note*]
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  ``` cpp
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  constexpr const_iterator begin() const noexcept;
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  ```
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  if (indexing_ == unknown)
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  indexing_ = automatic;
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  return next_arg_id_++;
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  ```
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93
+ *Throws:* `format_error` if `indexing_ == manual` is `true`.
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+
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+ [*Note 2*: This indicates mixing of automatic and manual argument
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+ indexing. — *end note*]
97
 
98
  *Remarks:* Let *`cur-arg-id`* be the value of `next_arg_id_` prior to
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  this call. Call expressions where *`cur-arg-id`*` >= num_args_` is
100
  `true` are not core constant expressions [[expr.const]].
101
 
 
108
  ``` cpp
109
  if (indexing_ == unknown)
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  indexing_ = manual;
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  ```
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+ *Throws:* `format_error` if `indexing_ == automatic` is `true`.
 
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+ [*Note 3*: This indicates mixing of automatic and manual argument
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+ indexing. — *end note*]
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+
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+ *Remarks:* A call to this function is a core constant
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+ expression [[expr.const]] only if `id < num_args_` is `true`.
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+
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+ ``` cpp
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+ template<class... Ts>
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+ constexpr void check_dynamic_spec(size_t id) noexcept;
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+ ```
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+
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+ *Mandates:* `sizeof...(Ts)` ≥ 1. The types in `Ts...` are unique. Each
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+ type in `Ts...` is one of `bool`, `char_type`, `int`, `unsigned int`,
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+ `long long int`, `unsigned long long int`, `float`, `double`,
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+ `long double`, `const char_type*`, `basic_string_view<char_type>`, or
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+ `const void*`.
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+
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+ *Remarks:* A call to this function is a core constant expression only if
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+
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+ - `id < num_args_` is `true` and
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+ - the type of the corresponding format argument (after conversion to
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+ `basic_format_arg<Context>`) is one of the types in `Ts...`.
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+
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+ ``` cpp
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+ constexpr void check_dynamic_spec_integral(size_t id) noexcept;
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ check_dynamic_spec<int, unsigned int, long long int, unsigned long long int>(id);
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+ ```
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+
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+ ``` cpp
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+ constexpr void check_dynamic_spec_string(size_t id) noexcept;
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ check_dynamic_spec<const char_type*, basic_string_view<char_type>>(id);
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+ ```
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