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std.array.Appender/appender - multiple declarations

Function appender

Convenience function that returns an Appender instance, optionally initialized with array.

Appender!A appender(A)()
if (isDynamicArray!A);

Appender!(E[]) appender(A, E) (
  auto ref A array
);

Example

auto w = appender!string;
// pre-allocate space for at least 10 elements (this avoids costly reallocations)
w.reserve(10);
assert(w.capacity >= 10);

w.put('a'); // single elements
w.put("bc"); // multiple elements

// use the append syntax
w ~= 'd';
w ~= "ef";

writeln(w.data); // "abcdef"

Function appender

Convenience function that returns a RefAppender instance initialized with arrayPtr. Don't use null for the array pointer, use the other version of appender instead.

RefAppender!(E[]) appender(P, E) (
  P arrayPtr
);

Example

int[] a = [1, 2];
auto app2 = appender(&a);
writeln(app2.data); // [1, 2]
writeln(a); // [1, 2]
app2 ~= 3;
app2 ~= [4, 5, 6];
writeln(app2.data); // [1, 2, 3, 4, 5, 6]
writeln(a); // [1, 2, 3, 4, 5, 6]

app2.reserve(5);
assert(app2.capacity >= 5);

Struct Appender

Implements an output range that appends data to an array. This is recommended over array ~= data when appending many elements because it is more efficient. Appender maintains its own array metadata locally, so it can avoid global locking for each append where capacity is non-zero.

struct Appender(A)
  
if (isDynamicArray!A);

Constructors

NameDescription
this Constructs an Appender with a given array. Note that this does not copy the data. If the array has a larger capacity as determined by arr.capacity, it will be used by the appender. After initializing an appender on an array, appending to the original array will reallocate.

Properties

NameTypeDescription
capacity[get] size_t
data[get] inout(ElementEncodingType!A)[]

Methods

NameDescription
clear Clears the managed array. This allows the elements of the array to be reused for appending.
opOpAssign Appends rhs to the managed array.
put Appends item to the managed array. Performs encoding for char types if A is a differently typed char array.
put Appends an entire range to the managed array. Performs encoding for char elements if A is a differently typed char array.
reserve Reserve at least newCapacity elements for appending. Note that more elements may be reserved than requested. If newCapacity <= capacity, then nothing is done.
shrinkTo Shrinks the managed array to the given length.
toString Gives a string in the form of Appender!(A)(data).

Parameters

NameDescription
A the array type to simulate.

See Also

appender

Example

auto app = appender!string();
string b = "abcdefg";
foreach (char c; b)
    app.put(c);
writeln(app.data); // "abcdefg"

int[] a = [ 1, 2 ];
auto app2 = appender(a);
app2.put(3);
app2.put([ 4, 5, 6 ]);
writeln(app2.data); // [1, 2, 3, 4, 5, 6]

Authors

Andrei Alexandrescu and Jonathan M Davis

License

Boost License 1.0.