Chopper allows for building of strings with variable values. With choppers use of templates strings can be rendered efficiently.

To use Chopper, a template of type Chop_Template_typ will need to be declared. Optionally a function block of type Chopper can be used instead of functions.

Declare a variable template of type Chop_Template_typ and a variable Chop of type Chopper. Before using Chop, set pSource, pTemplate, pDest, and destSize. template is not required to be compiled before using Chop.

variable.text:= 'Chopper FUB';
source:= 'This is a {{var.text}} example!';

Chop.pSource:= 		ADR(source);
Chop.pTemplate:= 	ADR(template);
Chop.pDest:= 		ADR(destination);
Chop.destSize:= 	SIZEOF(destination);

Each time Chop is called it will compile pTemplate if not already compiled or recompile is true, and render to pDest. Chop will render in a single call and can be called multiple times per a cycle. A single fub can be used to compile/render multiple templates.

Chop();
// destination = 'This is a Chopper Fub example!'

• pTemplate - pointer to Chop_Template_typ. Where compiled data is stored.
• pDest - pointer to destination where rendered string is written to.
• destSize - size of destination.
• pSource - pointer to Source to be compiled. Only required when a compile is needed.
• recompile - force a compile.

• renderLength - length of last render.
• Status - status of last fub call. Refer to Status below.

ChopCompile does a compile from pSource into pTemplate. Returns function status as DINT. Refer to status for more information. Variables in source should be surrounded by double curly braces "{{", "}}", and should be specified in format TaskName:VarName for local variables and VarName for global variables. Only variables declared in .var files can be used by name.

Chopper Compiles can take an some time for larger sources. It is recommended to use caution when compiling in a fast cyclic.

variable.text:= 'Chopper';
source:= 'This is a {{var.text}} example!';
ChopCompile(ADR(template), ADR(source));

ChopRender does render from pTemplate into pDest. If renderLength is larger than destSize then a the pDest will end with '...', followed by a null character. If pRenderLength is not 0 then it will be filled with renderLength.

Chopper Renders are quick when using a precompiled template and are okay to use in fast cyclics.

variable.text:= 'Chopper';
source:= 'This is a {{var.text}} example!';
ChopCompile(ADR(template), ADR(source));
ChopRender(ADR(destination), ADR(template), SIZEOF(destination), ADR(length));
// destination = 'This is a Chopper example!'
// length = 26

NOTE: Any variable that can not be found is replaced with "undefined" when rendered.

ChopRepalceVar replaces all pTag in pTemplate with variable specified by name in pVarName. Variable name is in format TaskName:VarName for local variables and VarName for global variables.

firstVar:= 1;
secondVar:= 2;

ChopCompile(ADR(template), ADR('My variable value is {{firstVar}}'));
ChopRender(ADR(dest), ADR(template), SIZEOF(template), ADR(renderLength)); 
//dest= 'My variable value is 1'

ChopReplaceVar(ADR(template),ADR('firstVar'),ADR('secondVar'));
ChopRender(ADR(dest), ADR(template), SIZEOF(template), ADR(renderLength));
//dest= 'My variable value is 2'

ChopRepalce replaces all pTag in pTemplate with a new variable. Specified by address and type. Types are specified as VAR_TYPE_enum, refer to VarTools documentation for more information.

firstVar:= 1;
secondVar:= 2;

ChopCompile(ADR(template), ADR('My variable value is {{firstVar}}'));
ChopRender(ADR(dest), ADR(template), SIZEOF(template), ADR(renderLength)); 
//dest= 'My variable value is 1'

ChopReplace(ADR(template),ADR('firstVar'),ADR(secondVar),VAR_TYPE_USINT);
ChopRender(ADR(dest), ADR(template), SIZEOF(template), ADR(renderLength));
//dest= 'My variable value is 2'

ChopGetErrorMsg retrieves text for given errorID and copies it to pDest. pDest is required to be a string of length at least 29. Less could result in memory overflow. ChopGetErrorMsg returns a status.

ChopGetErrorMsg(ADR(msg), 50000);
// msg = Input to function is invalid  

0 - OK

50000 - CHOP_ERR_INVALID_INPUT - Input to function is invalid.

50001 - CHOP_ERR_SOURCE_LENGTH - Provided source is too long. Check source for missing null char. If source is greater than CHOP_TEMPLATE_STRLEN_SOURCE contact ARG.

50002 - CHOP_ERR_TEMPLATE_FULL - Template full of items. Contact ARG.

50003 - CHOP_ERR_NO_END_OF_VAR - No end of variable detected during compile. Check source!

50004 - CHOP_ERR_NOT_COMPILED - Attempted to render but template is not compiled. First compile template.

50005 - CHOP_ERR_DEST_LENGTH - Destination buffer too small.

50006 - CHOP_ERR_INTERNAL - Internal Error.