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Docs: LazUtils/lazutf8. Updates UTF8CodepointCount content for changes in 27063a7d.

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(cherry picked from commit 44c78718af)
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dsiders 2024-08-30 21:40:50 +01:00
parent 4df9861768
commit 22eb8c0f62
1 changed files with 39 additions and 21 deletions
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docs/xml/lazutils/lazutf8.xml
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@ -634,42 +634,59 @@ Even faster UTF-8 character counting
<element name="UTF8CodepointCount">
<short>
Gets the number of UTF-8-encoded codepoints in the specified value.
Gets the number of valid UTF-8 codepoints in the specified value.
</short>
<descr>
<p>
<var>UTF8CodepointCount</var> is an overloaded <var>PtrInt</var> function used
to determine the number of UTF-8 codepoints found in the specified value. The
overloaded variants allow the value to be specified using either the String or
the PChar type.
<var>UTF8CodepointCount</var> is an overloaded <var>SizeInt</var> function used
to determine the number of UTF-8 codepoints found in the specified value. It is
similar to the UTF8Length routine, but excludes any invalid codepoints found in
the input value from the count in the return value. The overloaded variants
allow the input value to be specified using either the String or the PChar type.
</p>
<p>
UTF8CodepointCount iterates over the byte values in the s or p arguments, and
increments the return value when a valid UTF-8 codepoint is found. Valid
codepoints include those represented by combining character combinations.
UTF8CodepointLen (in system.pp) is called to the get the size for each
of the UTF-8 codepoints. The process is repeated until all of the bytes in the
input value have been examined, or a codepoint with a length of zero (0) is encountered.
increments the return value when a valid UTF-8 codepoint is found.
UTF8CodepointLen (in system.pp) is called to the get the size for each of the
UTF-8 codepoints. Valid codepoints include those represented using combining
characters. The process is repeated until all of the bytes in the input value
have been examined, or until a codepoint with a length of zero (0) is
encountered.
</p>
<p>
The return value is zero (0) if the s or p arguments are empty, or when the
ByteCount argument is zero (0).
</p>
<p>
For example:
</p>
<code>
// var
// Utf8Str, InvalidUtf8Str: String;
// Cnt, Len: Integer;
{A macron (decomposed)}
Utf8Str := 'A' + #$CC#$84;
{invalid single byte UTF-8}
InvalidUtf8Str := #$C0#$C1#$F5#$F6#$F7#$F8#$F9#$FA#$FB#$FC#$FD#$FE#$FF;
Cnt := UTF8CodePointCount(Utf8Str); // Cnt = 2
Len := UTF8Length(Utf8Str); // Len = 2
Cnt := UTF8CodePointCount(InvalidUtf8Str); // Cnt = 0
Len := UTF8Length(InvalidUtf8Str); // Len = 13
Cnt := UTF8CodePointCount(InvalidUtf8Str + Utf8Str); // Cnt = 2
Len := UTF8Length(InvalidUtf8Str + Utf8Str); // Len = 15
</code>
</descr>
<version>
Added in LazUtils version 4.0. (c8a1f93a)
Added in LazUtils version 4.0.
</version>
<notes>
<note>
I wrote a test application to compare the results for UTF8Length and
UTF8CodepointCount. They return exactly the same values for the UTF-8 strings I
cribbed from the Unicode web site.
So basically, why is this routine needed?
</note>
</notes>
<seealso>
<link id="UTF8CodepointSize"/>
<link id="UTF8Length"/>
<link id="UTF8CodepointSize"/>
<link id="UTF8LengthFast"/>
<link id="UTF8CharacterLength"/>
<link id="#rtl.system.UTF8CodepointLen">UTF8CodepointLen</link>
@ -677,7 +694,8 @@ So basically, why is this routine needed?
</element>
<element name="UTF8CodepointCount.Result">
<short>
Pointer to the Integer value with the number of codepoints including combining characters.
Integer value with the number of valid codepoints including combining
characters.
</short>
</element>
<element name="UTF8CodepointCount.s">