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version 2.089.0

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Alias std.utf.byUTF

Iterate an input range of characters by char type C by encoding the elements of the range.

alias byUTF(C, Flag!("useReplacementDchar") useReplacementDchar = Yes.useReplacementDchar) = byUTF!(Unqual!C);

UTF sequences that cannot be converted to the specified encoding are either replaced by U+FFFD per "5.22 Best Practice for U+FFFD Substitution" of the Unicode Standard 6.2 or result in a thrown UTFException. Hence byUTF is not symmetric. This algorithm is lazy, and does not allocate memory. @nogc, pure-ity, nothrow, and @safe-ty are inferred from the r parameter.

Parameters

NameDescription
C char, wchar, or dchar
useReplacementDchar UseReplacementDchar.yes means replace invalid UTF with replacementDchar, UseReplacementDchar.no means throw UTFException for invalid UTF

Throws

UTFException if invalid UTF sequence and useReplacementDchar is set to UseReplacementDchar.yes

GC

Does not use GC if useReplacementDchar is set to UseReplacementDchar.no

Returns

A forward range if R is a range and not auto-decodable, as defined by isAutodecodableString, and if the base range is also a forward range.

Or, if R is a range and it is auto-decodable and is(ElementEncodingType!typeof(r) == C), then the range is passed to byCodeUnit.

Otherwise, an input range of characters.

Example

import std.algorithm.comparison : equal;

// hellö as a range of `char`s, which are UTF-8
"hell\u00F6".byUTF!char().equal(['h', 'e', 'l', 'l', 0xC3, 0xB6]);

// `wchar`s are able to hold the ö in a single element (UTF-16 code unit)
"hell\u00F6".byUTF!wchar().equal(['h', 'e', 'l', 'l', 'ö']);

// 𐐷 is four code units in UTF-8, two in UTF-16, and one in UTF-32
"𐐷".byUTF!char().equal([0xF0, 0x90, 0x90, 0xB7]);
"𐐷".byUTF!wchar().equal([0xD801, 0xDC37]);
"𐐷".byUTF!dchar().equal([0x00010437]);

Example

import std.algorithm.comparison : equal;
import std.exception : assertThrown;

assert("hello\xF0betty".byChar.byUTF!(dchar, UseReplacementDchar.yes).equal("hello\uFFFDetty"));
assertThrown!UTFException("hello\xF0betty".byChar.byUTF!(dchar, UseReplacementDchar.no).equal("hello betty"));

Authors

Walter Bright and Jonathan M Davis

License

Boost License 1.0.