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Operator Specifications DSL

Overview

AKTIVE uses a Tcl-based domain-specific language to simplify the specification of image processing operators.

The implementation of the DSL translates the specifications into the

• Boilerplate C code embedding and linking the operator into AKTIVE's runtime framework.
• Operator documentation in Markdown, including examples (and underlying example Tcl code).

Implementation

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Files:

• support/dsl.tcl
• support/reader.tcl
• support/writer.tcl

Main commands

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Command	Description
def	Define a sharable text block. Global or local to an operator
import	Import definitions from the specified file, fail for a mising file
import?	See above. However, ignore a missing file
nyi	Disable the command it is a prefix of
operator	Define a (set of) operators
type	Define a type for use in parameter and results
vector	Declare for which types we need vector/slice support

def

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Syntax
def NAME TEXT [(KEY VALUE)...]

This command creates a named sharable block of text, at either global level or local to an operator specification. The created block is usable wherever templating is performed.

The command further creates a Tcl variable of the same name in the calling scope also containing the text.

Note that this command applies templating to the text before it is saved. In other words, the definition of a block can reference blocks defined before it. Furthermore the optional set of key and value arguments serves as map of ultra-local placeholders to handle.

import, import?

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Syntax
import PATH
import? PATH

Both commands read the referenced file and execute the commands in the context of the import. This can be global or within an operator specification.

The import? variant ignores a missing PATH, whereas import will throw an error in that case.

nyi

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Syntax
nyi [WORD...]

nyi is a prefix command whose use disables the command it is made a prefix of.

The name stands for not yet implemented.

operator

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Syntax
operator NAME SPEC
operator NAMELIST SPEC
operator VARLIST OPLIST SPEC

This command names and specifies one or more (related) image processing operators, using a suite of subordinate commands within its spec.

Given the complexity it has its own page containing the full details.

type

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Syntax
type ID CRITCL C CONVERTER

The command declares a type the DSL can use for operator parameter and results. Note that types have to be declared before their use.

The core types needed by AKTIVE's runtime framework itself are declared in

• etc/runtime.tcl

Arguments:

Name	Description
ID	Name the type is identified by when used in vector and operator commands
CRITCL	The associated Critcl type. - defaults to the ID
C	The associated C type. - defaults to the CRITCL name
CONVERTER	C code fragment to convert a C value of the type into a Tcl_Obj

Converter notes:

• The fragment has to return a Tcl_Obj* value.
• The fragment expects to have access to a C variable value holding a pointer to the C value to convert

vector

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Syntax
vector [ID...]

The command declares that we need vector/slice support for the types named in its arguments.

In other words, it arranges for the generator to emit C code that provides the types and functions for the management of dynamic arrays for values of this type.