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utf.d
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utf.d
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// Written in the D programming language.
/++
Encode and decode UTF-8, UTF-16 and UTF-32 strings.
UTF character support is restricted to
$(D '\u0000' <= character <= '\U0010FFFF').
See_Also:
$(LINK2 http://en.wikipedia.org/wiki/Unicode, Wikipedia)<br>
$(LINK http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8)<br>
$(LINK http://anubis.dkuug.dk/JTC1/SC2/WG2/docs/n1335)
Macros:
WIKI = Phobos/StdUtf
Copyright: Copyright Digital Mars 2000 - 2012.
License: $(WEB www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
Authors: $(WEB digitalmars.com, Walter Bright) and Jonathan M Davis
Source: $(PHOBOSSRC std/_utf.d)
+/
module std.utf;
import std.conv; // to, assumeUnique
import std.exception; // enforce, assumeUnique
import std.range; // walkLength
import std.traits; // isSomeChar, isSomeString
import std.typetuple; // TypeTuple
//debug=utf; // uncomment to turn on debugging printf's
debug (utf) import core.stdc.stdio : printf;
version(unittest)
{
import core.exception;
import std.string;
}
/++
Exception thrown on errors in std.utf functions.
+/
class UTFException : Exception
{
uint[4] sequence;
size_t len;
@safe pure nothrow
UTFException setSequence(uint[] data...)
{
import std.algorithm;
assert(data.length <= 4);
len = min(data.length, 4);
sequence[0 .. len] = data[0 .. len];
return this;
}
@safe pure nothrow
this(string msg, string file = __FILE__, size_t line = __LINE__, Throwable next = null)
{
super(msg, file, line, next);
}
@safe pure
this(string msg, size_t index, string file = __FILE__, size_t line = __LINE__, Throwable next = null)
{
import std.string;
super(msg ~ format(" (at index %s)", index), file, line, next);
}
override string toString()
{
import std.string;
if (len == 0)
return super.toString();
string result = "Invalid UTF sequence:";
foreach (i; sequence[0 .. len])
result ~= format(" %02x", i);
if (super.msg.length > 0)
{
result ~= " - ";
result ~= super.msg;
}
return result;
}
}
// Explicitly undocumented. It will be removed in November 2013.
deprecated("Please use std.utf.UTFException instead.") alias UtfException = UTFException;
/++
Returns whether $(D c) is a valid UTF-32 character.
$(D '\uFFFE') and $(D '\uFFFF') are considered valid by $(D isValidDchar),
as they are permitted for internal use by an application, but they are
not allowed for interchange by the Unicode standard.
+/
@safe
pure nothrow bool isValidDchar(dchar c)
{
/* Note: FFFE and FFFF are specifically permitted by the
* Unicode standard for application internal use, but are not
* allowed for interchange.
* (thanks to Arcane Jill)
*/
return c < 0xD800 ||
(c > 0xDFFF && c <= 0x10FFFF /*&& c != 0xFFFE && c != 0xFFFF*/);
}
unittest
{
debug(utf) printf("utf.isValidDchar.unittest\n");
assert( isValidDchar(cast(dchar)'a') == true);
assert( isValidDchar(cast(dchar)0x1FFFFF) == false);
assert(!isValidDchar(cast(dchar)0x00D800));
assert(!isValidDchar(cast(dchar)0x00DBFF));
assert(!isValidDchar(cast(dchar)0x00DC00));
assert(!isValidDchar(cast(dchar)0x00DFFF));
assert( isValidDchar(cast(dchar)0x00FFFE));
assert( isValidDchar(cast(dchar)0x00FFFF));
assert( isValidDchar(cast(dchar)0x01FFFF));
assert( isValidDchar(cast(dchar)0x10FFFF));
assert(!isValidDchar(cast(dchar)0x110000));
}
/++
$(D stride) returns the length of the UTF-8 sequence starting at $(D index)
in $(D str).
$(D stride) works with both UTF-8 strings and ranges of $(D char). If no
index is passed, then an input range will work, but if an index is passed,
then a random-access range is required.
$(D index) defaults to $(D 0) if none is passed.
Returns:
The number of bytes in the UTF-8 sequence.
Throws:
May throw a $(D UTFException) if $(D str[index]) is not the start of a
valid UTF-8 sequence.
Notes:
$(D stride) will only analize the first $(D str[index]) element. It
will not fully verify the validity of UTF-8 sequence, nor even verify
the presence of the sequence: it will not actually guarantee that
$(D index + stride(str, index) <= str.length).
+/
uint stride(S)(auto ref S str, size_t index)
if (is(S : const char[]) ||
(isRandomAccessRange!S && is(Unqual!(ElementType!S) == char)))
{
static if (is(typeof(str.length) : ulong))
assert(index < str.length, "Past the end of the UTF-8 sequence");
immutable c = str[index];
if (c < 0x80)
return 1;
else
return strideImpl(c, index);
}
/// Ditto
uint stride(S)(auto ref S str)
if (is(S : const char[]) ||
(isInputRange!S && is(Unqual!(ElementType!S) == char)))
{
static if (is(S : const char[]))
immutable c = str[0];
else
immutable c = str.front;
if (c < 0x80)
return 1;
else
return strideImpl(c, 0);
}
private uint strideImpl(char c, size_t index) @trusted pure
in { assert(c & 0x80); }
body
{
import core.bitop;
immutable msbs = 7 - bsr(~c);
if (msbs < 2 || msbs > 6)
throw new UTFException("Invalid UTF-8 sequence", index);
return msbs;
}
unittest
{
static void test(string s, dchar c, size_t i = 0, size_t line = __LINE__)
{
enforce(stride(s, i) == codeLength!char(c),
new AssertError(format("Unit test failure string: %s", s), __FILE__, line));
enforce(stride(RandomCU!char(s), i) == codeLength!char(c),
new AssertError(format("Unit test failure range: %s", s), __FILE__, line));
auto refRandom = new RefRandomCU!char(s);
immutable randLen = refRandom.length;
enforce(stride(refRandom, i) == codeLength!char(c),
new AssertError(format("Unit test failure rand ref range: %s", s), __FILE__, line));
enforce(refRandom.length == randLen,
new AssertError(format("Unit test failure rand ref range length: %s", s), __FILE__, line));
if (i == 0)
{
enforce(stride(s) == codeLength!char(c),
new AssertError(format("Unit test failure string 0: %s", s), __FILE__, line));
enforce(stride(InputCU!char(s)) == codeLength!char(c),
new AssertError(format("Unit test failure range 0: %s", s), __FILE__, line));
auto refBidir = new RefBidirCU!char(s);
immutable bidirLen = refBidir.length;
enforce(stride(refBidir) == codeLength!char(c),
new AssertError(format("Unit test failure bidir ref range code length: %s", s), __FILE__, line));
enforce(refBidir.length == bidirLen,
new AssertError(format("Unit test failure bidir ref range length: %s", s), __FILE__, line));
}
}
test("a", 'a');
test(" ", ' ');
test("\u2029", '\u2029'); //paraSep
test("\u0100", '\u0100');
test("\u0430", '\u0430');
test("\U00010143", '\U00010143');
test("abcdefcdef", 'a');
test("hello\U00010143\u0100\U00010143", 'h', 0);
test("hello\U00010143\u0100\U00010143", 'e', 1);
test("hello\U00010143\u0100\U00010143", 'l', 2);
test("hello\U00010143\u0100\U00010143", 'l', 3);
test("hello\U00010143\u0100\U00010143", 'o', 4);
test("hello\U00010143\u0100\U00010143", '\U00010143', 5);
test("hello\U00010143\u0100\U00010143", '\u0100', 9);
test("hello\U00010143\u0100\U00010143", '\U00010143', 11);
foreach (S; TypeTuple!(char[], const char[], string))
{
enum str = to!S("hello world");
static assert(isSafe!({ stride(str, 0); }));
static assert(isSafe!({ stride(str); }));
static assert((functionAttributes!({ stride(str, 0); }) & FunctionAttribute.pure_) != 0);
static assert((functionAttributes!({ stride(str); }) & FunctionAttribute.pure_) != 0);
}
}
/++
$(D strideBack) returns the length of the UTF-8 sequence ending one code
unit before $(D index) in $(D str).
$(D strideBack) works with both UTF-8 strings and bidirectional ranges of
$(D char). If no index is passed, then a bidirectional range will work, but
if an index is passed, then a random-access range is required.
$(D index) defaults to $(D str.length) if none is passed.
Returns:
The number of bytes in the UTF-8 sequence.
Throws:
May throw a $(D UTFException) if $(D str[index]) is not one past the
end of a valid UTF-8 sequence.
Notes:
$(D strideBack) will not fully verify the validity of the UTF-8
sequence. It will, however, guarantee that
$(D index - stride(str, index)) is a valid index.
+/
uint strideBack(S)(auto ref S str, size_t index)
if (is(S : const char[]) ||
(isRandomAccessRange!S && is(Unqual!(ElementType!S) == char)))
{
static if (is(typeof(str.length) : ulong))
assert(index <= str.length, "Past the end of the UTF-8 sequence");
assert(index > 0, "Not the end of the UTF-8 sequence");
if ((str[index-1] & 0b1100_0000) != 0b1000_0000)
return 1;
if (index >= 4) //single verification for most common case
{
foreach (i; TypeTuple!(2, 3, 4))
{
if ((str[index-i] & 0b1100_0000) != 0b1000_0000)
return i;
}
}
else
{
foreach (i; TypeTuple!(2, 3))
{
if (index >= i && (str[index-i] & 0b1100_0000) != 0b1000_0000)
return i;
}
}
throw new UTFException("Not the end of the UTF sequence", index);
}
/// Ditto
uint strideBack(S)(auto ref S str)
if (is(S : const char[]) ||
(isRandomAccessRange!S && hasLength!S && is(Unqual!(ElementType!S) == char)))
{
return strideBack(str, str.length);
}
uint strideBack(S)(auto ref S str)
if (isBidirectionalRange!S && is(Unqual!(ElementType!S) == char) && !isRandomAccessRange!S)
{
assert(!str.empty, "Past the end of the UTF-8 sequence");
auto temp = str.save;
foreach (i; TypeTuple!(1, 2, 3, 4))
{
if ((temp.back & 0b1100_0000) != 0b1000_0000)
return i;
temp.popBack();
if (temp.empty)
break;
}
throw new UTFException("The last code unit is not the end of the UTF-8 sequence");
}
unittest
{
static void test(string s, dchar c, size_t i = size_t.max, size_t line = __LINE__)
{
enforce(strideBack(s, i == size_t.max ? s.length : i) == codeLength!char(c),
new AssertError(format("Unit test failure string: %s", s), __FILE__, line));
enforce(strideBack(RandomCU!char(s), i == size_t.max ? s.length : i) == codeLength!char(c),
new AssertError(format("Unit test failure range: %s", s), __FILE__, line));
auto refRandom = new RefRandomCU!char(s);
immutable randLen = refRandom.length;
enforce(strideBack(refRandom, i == size_t.max ? s.length : i) == codeLength!char(c),
new AssertError(format("Unit test failure rand ref range: %s", s), __FILE__, line));
enforce(refRandom.length == randLen,
new AssertError(format("Unit test failure rand ref range length: %s", s), __FILE__, line));
if (i == size_t.max)
{
enforce(strideBack(s) == codeLength!char(c),
new AssertError(format("Unit test failure string code length: %s", s), __FILE__, line));
enforce(strideBack(BidirCU!char(s)) == codeLength!char(c),
new AssertError(format("Unit test failure range code length: %s", s), __FILE__, line));
auto refBidir = new RefBidirCU!char(s);
immutable bidirLen = refBidir.length;
enforce(strideBack(refBidir) == codeLength!char(c),
new AssertError(format("Unit test failure bidir ref range code length: %s", s), __FILE__, line));
enforce(refBidir.length == bidirLen,
new AssertError(format("Unit test failure bidir ref range length: %s", s), __FILE__, line));
}
}
test("a", 'a');
test(" ", ' ');
test("\u2029", '\u2029'); //paraSep
test("\u0100", '\u0100');
test("\u0430", '\u0430');
test("\U00010143", '\U00010143');
test("abcdefcdef", 'f');
test("\U00010143\u0100\U00010143hello", 'o', 15);
test("\U00010143\u0100\U00010143hello", 'l', 14);
test("\U00010143\u0100\U00010143hello", 'l', 13);
test("\U00010143\u0100\U00010143hello", 'e', 12);
test("\U00010143\u0100\U00010143hello", 'h', 11);
test("\U00010143\u0100\U00010143hello", '\U00010143', 10);
test("\U00010143\u0100\U00010143hello", '\u0100', 6);
test("\U00010143\u0100\U00010143hello", '\U00010143', 4);
foreach (S; TypeTuple!(char[], const char[], string))
{
enum str = to!S("hello world");
static assert(isSafe!({ strideBack(str, 0); }));
static assert(isSafe!({ strideBack(str); }));
static assert((functionAttributes!({ strideBack(str, 0); }) & FunctionAttribute.pure_) != 0);
static assert((functionAttributes!({ strideBack(str); }) & FunctionAttribute.pure_) != 0);
}
}
/++
$(D stride) returns the length of the UTF-16 sequence starting at $(D index)
in $(D str).
$(D stride) works with both UTF-16 strings and ranges of $(D wchar). If no
index is passed, then an input range will work, but if an index is passed,
then a random-access range is required.
$(D index) defaults to $(D 0) if none is passed.
Returns:
The number of bytes in the UTF-16 sequence.
Throws:
May throw a $(D UTFException) if $(D str[index]) is not the start of a
valid UTF-16 sequence.
Notes:
$(D stride) will only analize the first $(D str[index]) element. It
will not fully verify the validity of UTF-16 sequence, nor even verify
the presence of the sequence: it will not actually guarantee that
$(D index + stride(str, index) <= str.length).
+/
uint stride(S)(auto ref S str, size_t index)
if (is(S : const wchar[]) ||
(isRandomAccessRange!S && is(Unqual!(ElementType!S) == wchar)))
{
static if (is(typeof(str.length) : ulong))
assert(index < str.length, "Past the end of the UTF-16 sequence");
immutable uint u = str[index];
return 1 + (u >= 0xD800 && u <= 0xDBFF);
}
/// Ditto
uint stride(S)(auto ref S str) @safe pure
if (is(S : const wchar[]))
{
return stride(str, 0);
}
uint stride(S)(auto ref S str)
if (isInputRange!S && is(Unqual!(ElementType!S) == wchar))
{
assert(!str.empty, "UTF-16 sequence is empty");
immutable uint u = str.front;
return 1 + (u >= 0xD800 && u <= 0xDBFF);
}
@trusted unittest
{
static void test(wstring s, dchar c, size_t i = 0, size_t line = __LINE__)
{
enforce(stride(s, i) == codeLength!wchar(c),
new AssertError(format("Unit test failure string: %s", s), __FILE__, line));
enforce(stride(RandomCU!wchar(s), i) == codeLength!wchar(c),
new AssertError(format("Unit test failure range: %s", s), __FILE__, line));
auto refRandom = new RefRandomCU!wchar(s);
immutable randLen = refRandom.length;
enforce(stride(refRandom, i) == codeLength!wchar(c),
new AssertError(format("Unit test failure rand ref range: %s", s), __FILE__, line));
enforce(refRandom.length == randLen,
new AssertError(format("Unit test failure rand ref range length: %s", s), __FILE__, line));
if (i == 0)
{
enforce(stride(s) == codeLength!wchar(c),
new AssertError(format("Unit test failure string 0: %s", s), __FILE__, line));
enforce(stride(InputCU!wchar(s)) == codeLength!wchar(c),
new AssertError(format("Unit test failure range 0: %s", s), __FILE__, line));
auto refBidir = new RefBidirCU!wchar(s);
immutable bidirLen = refBidir.length;
enforce(stride(refBidir) == codeLength!wchar(c),
new AssertError(format("Unit test failure bidir ref range code length: %s", s), __FILE__, line));
enforce(refBidir.length == bidirLen,
new AssertError(format("Unit test failure bidir ref range length: %s", s), __FILE__, line));
}
}
test("a", 'a');
test(" ", ' ');
test("\u2029", '\u2029'); //paraSep
test("\u0100", '\u0100');
test("\u0430", '\u0430');
test("\U00010143", '\U00010143');
test("abcdefcdef", 'a');
test("hello\U00010143\u0100\U00010143", 'h', 0);
test("hello\U00010143\u0100\U00010143", 'e', 1);
test("hello\U00010143\u0100\U00010143", 'l', 2);
test("hello\U00010143\u0100\U00010143", 'l', 3);
test("hello\U00010143\u0100\U00010143", 'o', 4);
test("hello\U00010143\u0100\U00010143", '\U00010143', 5);
test("hello\U00010143\u0100\U00010143", '\u0100', 7);
test("hello\U00010143\u0100\U00010143", '\U00010143', 8);
foreach (S; TypeTuple!(wchar[], const wchar[], wstring))
{
enum str = to!S("hello world");
static assert(isSafe!({ stride(str, 0); }));
static assert(isSafe!({ stride(str); }));
static assert((functionAttributes!({ stride(str, 0); }) & FunctionAttribute.pure_) != 0);
static assert((functionAttributes!({ stride(str); }) & FunctionAttribute.pure_) != 0);
}
}
/++
$(D strideBack) returns the length of the UTF-16 sequence ending one code
unit before $(D index) in $(D str).
$(D strideBack) works with both UTF-16 strings and ranges of $(D wchar). If
no index is passed, then a bidirectional range will work, but if an index is
passed, then a random-access range is required.
$(D index) defaults to $(D str.length) if none is passed.
Returns:
The number of bytes in the UTF-16 sequence.
Throws:
May throw a $(D UTFException) if $(D str[index]) is not one past the
end of a valid UTF-16 sequence.
Notes:
$(D stride) will only analize the element at $(D str[index - 1])
element. It will not fully verify the validity of UTF-16 sequence, nor
even verify the presence of the sequence: it will not actually
guarantee that $(D stride(str, index) <= index).
+/
//UTF-16 is self synchronizing: The length of strideBack can be found from
//the value of a single wchar
uint strideBack(S)(auto ref S str, size_t index)
if (is(S : const wchar[]) ||
(isRandomAccessRange!S && is(Unqual!(ElementType!S) == wchar)))
{
static if (is(typeof(str.length) : ulong))
assert(index <= str.length, "Past the end of the UTF-16 sequence");
assert(index > 0, "Not the end of a UTF-16 sequence");
immutable c2 = str[index-1];
return 1 + (0xDC00 <= c2 && c2 < 0xE000);
}
/// Ditto
uint strideBack(S)(auto ref S str)
if (is(S : const wchar[]) ||
(isBidirectionalRange!S && is(Unqual!(ElementType!S) == wchar)))
{
assert(!str.empty, "UTF-16 sequence is empty");
static if (is(S : const(wchar)[]))
immutable c2 = str[$ - 1];
else
immutable c2 = str.back;
return 1 + (0xDC00 <= c2 && c2 <= 0xE000);
}
unittest
{
static void test(wstring s, dchar c, size_t i = size_t.max, size_t line = __LINE__)
{
enforce(strideBack(s, i == size_t.max ? s.length : i) == codeLength!wchar(c),
new AssertError(format("Unit test failure string: %s", s), __FILE__, line));
enforce(strideBack(RandomCU!wchar(s), i == size_t.max ? s.length : i) == codeLength!wchar(c),
new AssertError(format("Unit test failure range: %s", s), __FILE__, line));
auto refRandom = new RefRandomCU!wchar(s);
immutable randLen = refRandom.length;
enforce(strideBack(refRandom, i == size_t.max ? s.length : i) == codeLength!wchar(c),
new AssertError(format("Unit test failure rand ref range: %s", s), __FILE__, line));
enforce(refRandom.length == randLen,
new AssertError(format("Unit test failure rand ref range length: %s", s), __FILE__, line));
if (i == size_t.max)
{
enforce(strideBack(s) == codeLength!wchar(c),
new AssertError(format("Unit test failure string code length: %s", s), __FILE__, line));
enforce(strideBack(BidirCU!wchar(s)) == codeLength!wchar(c),
new AssertError(format("Unit test failure range code length: %s", s), __FILE__, line));
auto refBidir = new RefBidirCU!wchar(s);
immutable bidirLen = refBidir.length;
enforce(strideBack(refBidir) == codeLength!wchar(c),
new AssertError(format("Unit test failure bidir ref range code length: %s", s), __FILE__, line));
enforce(refBidir.length == bidirLen,
new AssertError(format("Unit test failure bidir ref range length: %s", s), __FILE__, line));
}
}
test("a", 'a');
test(" ", ' ');
test("\u2029", '\u2029'); //paraSep
test("\u0100", '\u0100');
test("\u0430", '\u0430');
test("\U00010143", '\U00010143');
test("abcdefcdef", 'f');
test("\U00010143\u0100\U00010143hello", 'o', 10);
test("\U00010143\u0100\U00010143hello", 'l', 9);
test("\U00010143\u0100\U00010143hello", 'l', 8);
test("\U00010143\u0100\U00010143hello", 'e', 7);
test("\U00010143\u0100\U00010143hello", 'h', 6);
test("\U00010143\u0100\U00010143hello", '\U00010143', 5);
test("\U00010143\u0100\U00010143hello", '\u0100', 3);
test("\U00010143\u0100\U00010143hello", '\U00010143', 2);
foreach (S; TypeTuple!(wchar[], const wchar[], wstring))
{
enum str = to!S("hello world");
static assert(isSafe!({ strideBack(str, 0); }));
static assert(isSafe!({ strideBack(str); }));
static assert((functionAttributes!({ strideBack(str, 0); }) & FunctionAttribute.pure_) != 0);
static assert((functionAttributes!({ strideBack(str); }) & FunctionAttribute.pure_) != 0);
}
}
/++
$(D stride) returns the length of the UTF-32 sequence starting at $(D index)
in $(D str).
$(D stride) works with both UTF-32 strings and ranges of $(D dchar).
Returns:
The number of bytes in the UTF-32 sequence (always $(D 1)).
Throws:
Never.
+/
uint stride(S)(auto ref S str, size_t index = 0)
if (is(S : const dchar[]) ||
(isInputRange!S && is(Unqual!(ElementEncodingType!S) == dchar)))
{
static if (is(typeof(str.length) : ulong))
assert(index < str.length, "Past the end of the UTF-32 sequence");
else
assert(!str.empty, "UTF-32 sequence is empty.");
return 1;
}
unittest
{
static void test(dstring s, dchar c, size_t i = 0, size_t line = __LINE__)
{
enforce(stride(s, i) == codeLength!dchar(c),
new AssertError(format("Unit test failure string: %s", s), __FILE__, line));
enforce(stride(RandomCU!dchar(s), i) == codeLength!dchar(c),
new AssertError(format("Unit test failure range: %s", s), __FILE__, line));
auto refRandom = new RefRandomCU!dchar(s);
immutable randLen = refRandom.length;
enforce(stride(refRandom, i) == codeLength!dchar(c),
new AssertError(format("Unit test failure rand ref range: %s", s), __FILE__, line));
enforce(refRandom.length == randLen,
new AssertError(format("Unit test failure rand ref range length: %s", s), __FILE__, line));
if (i == 0)
{
enforce(stride(s) == codeLength!dchar(c),
new AssertError(format("Unit test failure string 0: %s", s), __FILE__, line));
enforce(stride(InputCU!dchar(s)) == codeLength!dchar(c),
new AssertError(format("Unit test failure range 0: %s", s), __FILE__, line));
auto refBidir = new RefBidirCU!dchar(s);
immutable bidirLen = refBidir.length;
enforce(stride(refBidir) == codeLength!dchar(c),
new AssertError(format("Unit test failure bidir ref range code length: %s", s), __FILE__, line));
enforce(refBidir.length == bidirLen,
new AssertError(format("Unit test failure bidir ref range length: %s", s), __FILE__, line));
}
}
test("a", 'a');
test(" ", ' ');
test("\u2029", '\u2029'); //paraSep
test("\u0100", '\u0100');
test("\u0430", '\u0430');
test("\U00010143", '\U00010143');
test("abcdefcdef", 'a');
test("hello\U00010143\u0100\U00010143", 'h', 0);
test("hello\U00010143\u0100\U00010143", 'e', 1);
test("hello\U00010143\u0100\U00010143", 'l', 2);
test("hello\U00010143\u0100\U00010143", 'l', 3);
test("hello\U00010143\u0100\U00010143", 'o', 4);
test("hello\U00010143\u0100\U00010143", '\U00010143', 5);
test("hello\U00010143\u0100\U00010143", '\u0100', 6);
test("hello\U00010143\u0100\U00010143", '\U00010143', 7);
foreach (S; TypeTuple!(dchar[], const dchar[], dstring))
{
enum str = to!S("hello world");
static assert(isSafe!({ stride(str, 0); }));
static assert(isSafe!({ stride(str); }));
static assert((functionAttributes!({ stride(str, 0); }) & FunctionAttribute.pure_) != 0);
static assert((functionAttributes!({ stride(str); }) & FunctionAttribute.pure_) != 0);
}
}
/++
$(D strideBack) returns the length of the UTF-32 sequence ending one code
unit before $(D index) in $(D str).
$(D strideBack) works with both UTF-32 strings and ranges of $(D dchar). If
no index is passed, then a bidirectional range will work, but if an index is
passed, then a random-access range is required.
$(D index) defaults to $(D str.length) if none is passed.
Returns:
The number of bytes in the UTF-32 sequence (always $(D 1)).
Throws:
Never.
+/
uint strideBack(S)(auto ref S str, size_t index)
if (isRandomAccessRange!S && is(Unqual!(ElementEncodingType!S) == dchar))
{
static if (is(typeof(str.length) : ulong))
assert(index <= str.length, "Past the end of the UTF-32 sequence");
assert(index > 0, "Not the end of the UTF-32 sequence");
return 1;
}
/// Ditto
uint strideBack(S)(auto ref S str)
if (isBidirectionalRange!S && is(Unqual!(ElementEncodingType!S) == dchar))
{
assert(!str.empty, "Empty UTF-32 sequence");
return 1;
}
unittest
{
static void test(dstring s, dchar c, size_t i = size_t.max, size_t line = __LINE__)
{
enforce(strideBack(s, i == size_t.max ? s.length : i) == codeLength!dchar(c),
new AssertError(format("Unit test failure string: %s", s), __FILE__, line));
enforce(strideBack(RandomCU!dchar(s), i == size_t.max ? s.length : i) == codeLength!dchar(c),
new AssertError(format("Unit test failure range: %s", s), __FILE__, line));
auto refRandom = new RefRandomCU!dchar(s);
immutable randLen = refRandom.length;
enforce(strideBack(refRandom, i == size_t.max ? s.length : i) == codeLength!dchar(c),
new AssertError(format("Unit test failure rand ref range: %s", s), __FILE__, line));
enforce(refRandom.length == randLen,
new AssertError(format("Unit test failure rand ref range length: %s", s), __FILE__, line));
if (i == size_t.max)
{
enforce(strideBack(s) == codeLength!dchar(c),
new AssertError(format("Unit test failure string code length: %s", s), __FILE__, line));
enforce(strideBack(BidirCU!dchar(s)) == codeLength!dchar(c),
new AssertError(format("Unit test failure range code length: %s", s), __FILE__, line));
auto refBidir = new RefBidirCU!dchar(s);
immutable bidirLen = refBidir.length;
enforce(strideBack(refBidir) == codeLength!dchar(c),
new AssertError(format("Unit test failure bidir ref range code length: %s", s), __FILE__, line));
enforce(refBidir.length == bidirLen,
new AssertError(format("Unit test failure bidir ref range length: %s", s), __FILE__, line));
}
}
test("a", 'a');
test(" ", ' ');
test("\u2029", '\u2029'); //paraSep
test("\u0100", '\u0100');
test("\u0430", '\u0430');
test("\U00010143", '\U00010143');
test("abcdefcdef", 'f');
test("\U00010143\u0100\U00010143hello", 'o', 8);
test("\U00010143\u0100\U00010143hello", 'l', 7);
test("\U00010143\u0100\U00010143hello", 'l', 6);
test("\U00010143\u0100\U00010143hello", 'e', 5);
test("\U00010143\u0100\U00010143hello", 'h', 4);
test("\U00010143\u0100\U00010143hello", '\U00010143', 3);
test("\U00010143\u0100\U00010143hello", '\u0100', 2);
test("\U00010143\u0100\U00010143hello", '\U00010143', 1);
foreach (S; TypeTuple!(dchar[], const dchar[], dstring))
{
enum str = to!S("hello world");
static assert(isSafe!({ strideBack(str, 0); }));
static assert(isSafe!({ strideBack(str); }));
static assert((functionAttributes!({ strideBack(str, 0); }) & FunctionAttribute.pure_) != 0);
static assert((functionAttributes!({ strideBack(str); }) & FunctionAttribute.pure_) != 0);
}
}
/++
Given $(D index) into $(D str) and assuming that $(D index) is at the start
of a UTF sequence, $(D toUCSindex) determines the number of UCS characters
up to $(D index). So, $(D index) is the index of a code unit at the
beginning of a code point, and the return value is how many code points into
the string that that code point is.
+/
size_t toUCSindex(C)(const(C)[] str, size_t index) @safe pure
if (isSomeChar!C)
{
static if (is(Unqual!C == dchar))
return index;
else
{
size_t n = 0;
size_t j = 0;
for (; j < index; ++n)
j += stride(str, j);
if (j > index)
{
static if (is(Unqual!C == char))
throw new UTFException("Invalid UTF-8 sequence", index);
else
throw new UTFException("Invalid UTF-16 sequence", index);
}
return n;
}
}
///
unittest
{
assert(toUCSindex(`hello world`, 7) == 7);
assert(toUCSindex(`hello world`w, 7) == 7);
assert(toUCSindex(`hello world`d, 7) == 7);
assert(toUCSindex(`Ma Chérie`, 7) == 6);
assert(toUCSindex(`Ma Chérie`w, 7) == 7);
assert(toUCSindex(`Ma Chérie`d, 7) == 7);
assert(toUCSindex(`さいごの果実 / ミツバチと科学者`, 9) == 3);
assert(toUCSindex(`さいごの果実 / ミツバチと科学者`w, 9) == 9);
assert(toUCSindex(`さいごの果実 / ミツバチと科学者`d, 9) == 9);
}
/++
Given a UCS index $(D n) into $(D str), returns the UTF index.
So, $(D n) is how many code points into the string the code point is, and
the array index of the code unit is returned.
+/
size_t toUTFindex(C)(const(C)[] str, size_t n) @safe pure
if (isSomeChar!C)
{
static if (is(Unqual!C == dchar))
{
return n;
}
else
{
size_t i;
while (n--)
{
i += stride(str, i);
}
return i;
}
}
///
unittest
{
assert(toUTFindex(`hello world`, 7) == 7);
assert(toUTFindex(`hello world`w, 7) == 7);
assert(toUTFindex(`hello world`d, 7) == 7);
assert(toUTFindex(`Ma Chérie`, 6) == 7);
assert(toUTFindex(`Ma Chérie`w, 7) == 7);
assert(toUTFindex(`Ma Chérie`d, 7) == 7);
assert(toUTFindex(`さいごの果実 / ミツバチと科学者`, 3) == 9);
assert(toUTFindex(`さいごの果実 / ミツバチと科学者`w, 9) == 9);
assert(toUTFindex(`さいごの果実 / ミツバチと科学者`d, 9) == 9);
}
/* =================== Decode ======================= */
/++
Decodes and returns the code point starting at $(D str[index]). $(D index)
is advanced to one past the decoded code point. If the code point is not
well-formed, then a $(D UTFException) is thrown and $(D index) remains
unchanged.
decode will only work with strings and random access ranges of code units
with length and slicing, whereas $(LREF decodeFront) will work with any
input range of code units.
Throws:
$(LREF UTFException) if $(D str[index]) is not the start of a valid UTF
sequence.
+/
dchar decode(S)(auto ref S str, ref size_t index)
if (!isSomeString!S &&
isRandomAccessRange!S && hasSlicing!S && hasLength!S && isSomeChar!(ElementType!S))
in
{
assert(index < str.length, "Attempted to decode past the end of a string");
}
out (result)
{
assert(isValidDchar(result));
}
body
{
if (str[index] < codeUnitLimit!S)
return str[index++];
return decodeImpl!true(str, index);
}
dchar decode(S)(auto ref S str, ref size_t index) @trusted pure
if (isSomeString!S)
in
{
assert(index < str.length, "Attempted to decode past the end of a string");
}
out (result)
{
assert(isValidDchar(result));
}
body
{
if (str[index] < codeUnitLimit!S)
return str[index++];
return decodeImpl!true(str, index);
}
/++
$(D decodeFront) is a variant of $(LREF decode) which specifically decodes
the first code point. Unlike $(LREF decode), $(D decodeFront) accepts any
input range of code units (rather than just a string or random access
range). It also takes the range by $(D ref) and pops off the elements as it
decodes them. If $(D numCodeUnits) is passed in, it gets set to the number
of code units which were in the code point which was decoded.
Throws:
$(LREF UTFException) if $(D str.front) is not the start of a valid UTF
sequence. If an exception is thrown, then there is no guarantee as to
the number of code units which were popped off, as it depends on the
type of range being used and how many code units had to be popped off
before the code point was determined to be invalid.
+/
dchar decodeFront(S)(ref S str, out size_t numCodeUnits)
if (!isSomeString!S && isInputRange!S && isSomeChar!(ElementType!S))
in
{
assert(!str.empty);
}
out (result)
{
assert(isValidDchar(result));
}
body
{
immutable fst = str.front;
if (fst < codeUnitLimit!S)
{
str.popFront();
numCodeUnits = 1;
return fst;
}
//@@@BUG@@@ 8521 forces canIndex to be done outside of decodeImpl, which
//is undesirable, since not all overloads of decodeImpl need it. So, it
//should be moved back into decodeImpl once bug# 8521 has been fixed.
enum canIndex = isRandomAccessRange!S && hasSlicing!S && hasLength!S;
immutable retval = decodeImpl!canIndex(str, numCodeUnits);
// The other range types were already popped by decodeImpl.
static if (isRandomAccessRange!S && hasSlicing!S && hasLength!S)
str = str[numCodeUnits .. str.length];
return retval;
}
dchar decodeFront(S)(ref S str, out size_t numCodeUnits) @trusted pure
if (isSomeString!S)
in
{
assert(!str.empty);
}
out (result)
{
assert(isValidDchar(result));
}
body