TrimLeftUtf8String

Short summary

This function removes whitespace from the left side (start) of a utf-8 string. It returns the string length in bytes.

Example:

myString :String(10) := ' Test' ;
newLength :UDINT;
------------------
TrimLeftUtf8String(
	stringAddress := ADR(myString),
	newStringLength => newLength
);

• Return type: UDINT

Parameters

Name	Type	Comment	Kind
stringAddress	POINTER TO BYTE	pointer to the utf-8 string	input
newStringLength	UDINT	new length of the string in bytes	output

Code

Declaration

FUNCTION TrimLeftUtf8String :UDINT
VAR_INPUT
	(*pointer to the utf-8 string*)
	stringAddress	:POINTER TO BYTE;
END_VAR
VAR_OUTPUT
	(* new length of the string in bytes *)
	newStringLength :UDINT := 0;
END_VAR
VAR
	stringLength :UDINT;
	codepoints :POINTER TO UnicodeCodePoint;
	codepointCount :UDINT;
END_VAR

Implementation

stringLength := GetUtf8StringLength(stringAddress);
TrimLeftUtf8String := stringLength;
RETURN (stringLength = 0);
codepoints := __NEW(UnicodeCodepoint, stringLength);
RETURN(codepoints = 0);

GetCodepointsFromUtf8String(
	utf8StringAddress := stringAddress,
	utf8StringByteCount := stringLength,
	codePointBuffer := codepoints,
	bufferSize := stringLength*SIZEOF(UnicodeCodepoint),
	codePointsCount => codepointCount
);

TrimLeftCodepoints(
	codepoints := codepoints,
	codepointCount := codepointCount,
	newCodepointCount => codepointCount
);

Tc2_System.MEMSET(stringAddress, 0, stringLength);

GetUtf8StringFromCodepoints(
	addressOfCodePoints := codepoints,
	codePointCount := codepointCount,
	utf8StringBuffer := stringAddress,
	bufferSize := stringLength + 1, // stringlength + NULL terminator
	utf8StringByteCount => newStringLength
);

__DELETE(codepoints);
TrimLeftUtf8String := newStringLength;