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Struct std.uni.Grapheme

A structure designed to effectively pack characters of a grapheme cluster.

struct Grapheme ;

Grapheme has value semantics so 2 copies of a Grapheme always refer to distinct objects. In most actual scenarios a Grapheme fits on the stack and avoids memory allocation overhead for all but quite long clusters.

Constructors

NameDescription
this Ctor

Properties

NameTypeDescription
length[get] ulongGrapheme cluster length in code points.
valid[get] boolTrue if this object contains valid extended grapheme cluster. Decoding primitives of this module always return a valid Grapheme.

Methods

NameDescription
opIndex Gets a code point at the given index in this cluster.
opIndexAssign Writes a code point ch at given index in this cluster.
opOpAssign Append character ch to this grapheme.
opOpAssign Append all characters from the input range inp to this Grapheme.
opSlice Random-access range over Grapheme's characters.

See Also

decodeGrapheme, graphemeStride

Example

import std.algorithm.comparison : equal;
import std.algorithm.iteration : filter;
import std.range : isRandomAccessRange;

string bold = "ku\u0308hn";

// note that decodeGrapheme takes parameter by ref
auto first = decodeGrapheme(bold);

writeln(first.length); // 1
writeln(first[0]); // 'k'

// the next grapheme is 2 characters long
auto wideOne = decodeGrapheme(bold);
// slicing a grapheme yields a random-access range of dchar
assert(wideOne[].equal("u\u0308"));
writeln(wideOne.length); // 2
static assert(isRandomAccessRange!(typeof(wideOne[])));

// all of the usual range manipulation is possible
assert(wideOne[].filter!isMark().equal("\u0308"));

auto g = Grapheme("A");
assert(g.valid);
g ~= '\u0301';
assert(g[].equal("A\u0301"));
assert(g.valid);
g ~= "B";
// not a valid grapheme cluster anymore
assert(!g.valid);
// still could be useful though
assert(g[].equal("A\u0301B"));

Authors

Dmitry Olshansky

License

Boost License 1.0.