Make front and popFront for arrays public

This commit adds tanya.range.array module which contains functions to make
the arrays act as ranges. These functions don't do any auto-decoding for
strings.
This commit is contained in:
Eugen Wissner 2017-08-21 06:49:02 +02:00
parent beb5d6963b
commit ce90b4865b
3 changed files with 239 additions and 24 deletions

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@ -30,31 +30,11 @@ import core.exception;
import std.algorithm.comparison; import std.algorithm.comparison;
import std.algorithm.mutation; import std.algorithm.mutation;
import std.algorithm.searching; import std.algorithm.searching;
import std.range; import std.range : isInfinite, isInputRange, ElementEncodingType, hasLength,
popFrontN, empty;
import std.traits; import std.traits;
import tanya.memory; import tanya.memory;
import tanya.range.array;
private ref const(wchar) front(const wchar[] str)
pure nothrow @safe @nogc
in
{
assert(str.length > 0);
}
body
{
return str[0];
}
private void popFront(ref const(wchar)[] str, const size_t s = 1)
pure nothrow @safe @nogc
in
{
assert(str.length >= s);
}
body
{
str = str[s .. $];
}
/** /**
* Thrown on encoding errors. * Thrown on encoding errors.
@ -790,7 +770,7 @@ struct String
} }
dchar d = (range[0] - 0xd800) | ((range[1] - 0xdc00) >> 10); dchar d = (range[0] - 0xd800) | ((range[1] - 0xdc00) >> 10);
range.popFront(2); range.popFrontN(2);
} }
else else
{ {

220
source/tanya/range/array.d Normal file
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@ -0,0 +1,220 @@
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* $(D_PSYMBOL tanya.range.array) implements range primitives for built-in arrays.
*
* This module is a submodule of
* $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/range/package.d, tanya.range).
*
* After importing of
* $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/range/array.d, tanya/range/array.d)
* built-in arrays can act as bidirectional ranges. For that to work the module
* defines a set of functions that accept a built-in array of any type as their
* first argument, so thanks to UFCS (Uniform Function Call Syntax) they can be
* called as if they were array member functions. For example the arrays the
* `.length`-property, but no `.empty` property. So here can be find the
* $(D_PSYMBOL empty) function. Since $(D_INLINECODE empty(array)) and
* $(D_INLINECODE array.empty) are equal for the arrays, arrays get a faked
* property `empty`.
*
* The functions in this module don't change array elements or its underlying
* storage, but some functions alter the slice. Each array maintains a pointer
* to its data and the length and there can be several pointers which point to
* the same data. Array pointer can be advanced and the length can be reduced
* without changing the underlying storage. So slices offer the possibility to
* have multiple views into the same array, point to different positions inside
* it.
*
* Strings ($(D_INLINECODE char[]), (D_INLINECODE wchar[]) and
* (D_INLINECODE dchar[])) are treated as any other normal array, they aren't
* auto-decoded.
*
* Copyright: Eugene Wissner 2017.
* License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
* Mozilla Public License, v. 2.0).
* Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
* Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/range/array.d,
* tanya/range/array.d)
*/
module tanya.range.array;
/**
* Returns the first element of the $(D_PARAM array).
*
* The element is returned by reference, so $(D_PSYMBOL front) can be also used
* to change the first element of $(D_PARAM array) if it is mutable.
*
* Params:
* T = Element type of $(D_PARAM array).
* array = Built-in array.
*
* Returns: First element.
*
* Precondition: $(D_INLINECODE array.length > 0).
*/
@property ref T front(T)(T[] array)
in
{
assert(array.length > 0);
}
body
{
return array[0];
}
///
pure nothrow @safe @nogc unittest
{
string s = "Wenn die Wunde nicht mehr wehtut, schmerzt die Narbe";
static assert(is(typeof(s.front) == immutable char));
assert(s.front == 'W');
wstring w = "Волны несутся, гремя и сверкая";
static assert(is(typeof(w.front) == immutable wchar));
assert(w.front == 'В');
dstring d = "Для писателя память - это почти все";
static assert(is(typeof(d.front) == immutable dchar));
assert(d.front == 'Д');
}
/**
* Returns the last element of the $(D_PARAM array).
*
* The element is returned by reference, so $(D_PSYMBOL back) can be also used
* to change the last element of $(D_PARAM array) if it is mutable.
*
* Params:
* T = Element type of $(D_PARAM array).
* array = Built-in array.
*
* Returns: Last element.
*
* Precondition: $(D_INLINECODE array.length > 0).
*/
@property ref T back(T)(T[] array)
in
{
assert(array.length > 0);
}
body
{
return array[$ - 1];
}
///
pure nothrow @safe @nogc unittest
{
string s = "Brecht";
static assert(is(typeof(s.back) == immutable char));
assert(s.back == 't');
wstring w = "Тютчев";
static assert(is(typeof(w.back) == immutable wchar));
assert(w.back == 'в');
dstring d = "Паустовский";
static assert(is(typeof(d.back) == immutable dchar));
assert(d.back == 'й');
}
/**
* $(D_PSYMBOL popFront) and $(D_PSYMBOL popBack) advance the $(D_PARAM array)
* and remove one element from its back, respectively.
*
* $(D_PSYMBOL popFront) and $(D_PSYMBOL popBack) don't alter the array
* storage, they only narrow the view into the array.
*
* Params:
* T = Element type of $(D_PARAM array).
* array = Built-in array.
*
* Precondition: $(D_INLINECODE array.length > 0).
*/
void popFront(T)(ref T[] array)
in
{
assert(array.length > 0);
}
body
{
array = array[1 .. $];
}
/// Ditto.
void popBack(T)(ref T[] array)
in
{
assert(array.length > 0);
}
body
{
array = array[0 .. $ - 1];
}
///
pure nothrow @safe @nogc unittest
{
wstring array = "Der finstere Ozean der Metaphysik. Nietzsche";
array.popFront();
assert(array.length == 43);
assert(array.front == 'e');
array.popBack();
assert(array.length == 42);
assert(array.back == 'h');
}
/**
* Tests whether $(D_PARAM array) is empty.
*
* Params:
* T = Element type of $(D_PARAM array).
* array = Built-in array.
*
* Returns: $(D_KEYWORD true) if $(D_PARAM array) has no elements,
* $(D_KEYWORD false) otherwise.
*/
@property bool empty(T)(const T[] array)
{
return array.length == 0;
}
///
pure nothrow @safe @nogc unittest
{
int[1] array;
assert(!array.empty);
assert(array[1 .. 1].empty);
}
/**
* Returns a copy of the slice $(D_PARAM array).
*
* $(D_PSYMBOL save) doesn't copy the array itself, but only the data pointer
* and the length.
*
* Params:
* T = Element type of $(D_PARAM array).
* array = Built-in array.
*
* Returns: A copy of the slice $(D_PARAM array).
*/
@property T[] save(T)(T[] array)
{
return array;
}
///
pure nothrow @safe @nogc unittest
{
ubyte[8] array;
auto slice = array.save;
assert(slice.length == array.length);
slice.popFront();
assert(slice.length < array.length);
}

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@ -0,0 +1,15 @@
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Copyright: Eugene Wissner 2017.
* License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
* Mozilla Public License, v. 2.0).
* Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
* Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/range/package.d,
* tanya/range/package.d)
*/
module tanya.range;
public import tanya.range.array;