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critcl::emap(n) C Runtime In Tcl (CriTcl) critcl::emap(n)
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NAME
critcl::emap - CriTcl Utilities: Enum en- and decoding
SYNOPSIS
package require Tcl 8.4
package require critcl ?3.1.11?
package require critcl::emap ?1?
::critcl::emap::def name definition ?-nocase?
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DESCRIPTION
Welcome to the C Runtime In Tcl, CriTcl for short, a system to build C
extension packages for Tcl on the fly, from C code embedded within Tcl
scripts, for all who wish to make their code go faster.
This document is the reference manpage for the critcl::emap package.
This package provides convenience commands for advanced functionality
built on top of both critcl core and package critcl::iassoc.
C level libraries often use enumerations or integer values to encode
information, like the state of a system. Tcl bindings to such libraries
now have the task of converting a Tcl representation, i.e. a string
into such state, and back. Note here that the C-level information has
to be something which already exists. The package does not create these
values. This is in contrast to the package critcl::enum which creates
an enumeration based on the specified symbolic names.
This package was written to make the declaration and management of such
enumerations and their associated conversions functions easy, hiding
all attendant complexity from the user.
Its intended audience are mainly developers wishing to write Tcl
packages with embedded C code.
This package resides in the Core Package Layer of CriTcl.
+----------------+
|Applications |
| critcl |
| critcl::app |
+----------------+
*================*
|Core Packages |
| critcl |
| critcl::util |
*================*
+----------------+
|Support Packages|
| stubs::* |
| md5, platform |
| ... |
+----------------+
API
::critcl::emap::def name definition ?-nocase?
This command defines two C functions for the conversion of the
named state code into a Tcl string, and vice versa. The
underlying mapping tables are automatically initialized on first
access, and finalized on interpreter destruction.
The definition dictionary provides the mapping from the Tcl-
level symbolic names of the state to their C expressions (often
the name of the macro specifying the actual value). Note here
that the C-level information has to be something which already
exists. The package does not create these values. This is in
contrast to the package critcl::enum which creates an
enumeration based on the specified symbolic names.
Further note that multiple strings can be mapped to the same C
expression. When converting to Tcl the first string for the
mapping is returned. An important thing to know: If all C
expressions are recognizable as integer numbers and their
covered range is not too large (at most 50) the package will
generate code using direct and fast mapping tables instead of
using a linear search.
If the option -nocase is specified then the encoder will match
strings case-insensitively, and the decoder will always return a
lower-case string, regardless of the string's case in the
definition.
The package generates multiple things (declarations and
definitions) with names derived from name, which has to be a
proper C identifier.
name_encode
The function for encoding a Tcl string into the
equivalent state code. Its signature is
int name_encode (Tcl_Interp* interp, Tcl_Obj* state, int* result);
The return value of the function is a Tcl error code, i.e.
TCL_OK, TCL_ERROR, etc.
name_decode
The function for decoding a state code into the
equivalent Tcl strings. Its signature is
Tcl_Obj* name_decode (Tcl_Interp* interp, int state);
name.h A header file containing the declarations for the two
conversion functions, for use by other parts of the
system, if necessary.
The generated file is stored in a place where it will not
interfere with the overall system outside of the package,
yet also be available for easy inclusion by package files
(csources).
name The name of a critcl argument type encapsulating the
encoder function for use by critcl::cproc.
name The name of a critcl result type encapsulating the
decoder function for use by critcl::cproc.
EXAMPLE
The example shown below is the specification for the possible modes of
entry (normal, no feedback, stars) used by the Tcl binding to the
linenoise library.
package require Tcl 8.5
package require critcl 3.1.11
critcl::buildrequirement {
package require critcl::emap
}
critcl::emap::def hiddenmode {
no 0 n 0 off 0 false 0 0 0
all 1 yes 1 y 1 on 1 true 1 1 1
stars 2
} -nocase
# Declarations: hiddenmode.h
# Encoder: int hiddenmode_encode (Tcl_Interp* interp, Tcl_Obj* state, int* result);
# Decoder: Tcl_Obj* hiddenmode_decode (Tcl_Interp* interp, int state);
# ResultType: hiddenmode
# ArgumentType: hiddenmode
AUTHORS
Andreas Kupries
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain
bugs and other problems. Please report such at
https://github.com/andreas-kupries/critcl. Please also report any
ideas for enhancements you may have for either package and/or
documentation.
KEYWORDS
C code, Embedded C Code, Tcl Interp Association, bitmask, bitset, code
generator, compile & run, compiler, dynamic code generation, dynamic
compilation, flags, generate package, linker, on demand compilation,
on-the-fly compilation, singleton
CATEGORY
Glueing/Embedded C code
COPYRIGHT
Copyright (c) 2011-2015 Andreas Kupries
doc 1 critcl::emap(n)