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builtin_accessor.md

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Built-In Accessor

Built-in accessor for common types.

String Type（papilio::utf::basic_string_container<CharT>）

Indexing by Integer

Forward index starts from 0 , returns null character when exceeding maximum index.
Backward (Reverse) index starts from -1 (similar to Python), also returns null character when exceeding maximum index.
Example: Given string "hello world!", then

  • [0]: Returns 'h'.
  • [100]: Returns null character.
  • [-1]: Returns '!'.
  • [-100]: Returns null character.

Indexing by Range

The left-closed, right-opened range [begin, end) consists of index pair begin, end. Default values are 0 and .length, respectively.

Example: Given string "hello world!"

  • [:]: Returns "hello world!"
  • [:-1]: Returns "hello world"
  • [6:-1]: Returns "world"
  • [-6:]: Returns "world!"

Attributes

  • size：The number of elements in the string. That is, the string is regarded as a container whose value type is char (or other character type), and the result is its number of elements.
  • length：The number of characters in the string.
    For string containing non-ASCII characters, these two values may not be equal.
    For example, the size of string "ü" is 2, but its length is 1. For string L"ü" (wchar_t string), its size and length are both 1.

Tuples (tuple and pair)

Indexing by Integer

Forward index starts from 0 and returns null when exceeding maximum index
Backward (Reverse) index starts from -1 and returns null when exceeding maximum index
Note: Outputting null value will cause an exception.

Attributes

  • size: Number of elements in tuple (i.e. std::tuple_size_v).

The type pair has two additional attributes:

  • first: The first element of pair.
  • second: The second element of pair.

Contiguous Ranges (e.g. std::vector, std::array and std::span)

Indexing by Integer

Forward index starts from 0 and returns null when exceeding maximum index.
Backward (reverse) index starts from -1 and returns null when exceeding maximum index.
Note: Outputting null value will cause an exception.

Attributes

  • size: Size of the container.

Associative Containers (std::map)

Indexing by Integer or String

Will return the corresponding value in the container, or null value if the key doesn't exist. This function is only enabled when key_type of the container is integer or string.

Attributes

  • size: Size of the container.

If the comparator of the container (i.e. the key_compare type) is specialization of std::less<T> or std::greater<T>, there are will be two additional attributes:

  • min: The minimum element of the container, or null value if the container is empty.
  • max: The maximum element of the container, or null value if the container is empty.