Provided by: critcl_3.1.17+dfsg-1_all 
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? ?-mode mode?
_________________________________________________________________________________________________
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? ?-mode mode?
This command defines 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 (if not fully constant), 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.
If the option -mode is specified its contents will interpreted as a list of access
modes to support. The two allowed modes are c and tcl. Both modes can be used
together. The default mode is tcl.
The package generates multiple things (declarations and definitions) with names
derived from name, which has to be a proper C identifier. Some of the things are
generated conditional on the chosen modes.
name_encode
The tcl-mode 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_encode_cstr
The c-mode function for encoding a C string into the equivalent state code.
Its signature is
int name_encode_cstr (const char* state);
The return value of the function is the encoded state, or -1 if the argument is not
a vlaid state.
name_decode
The tcl-mode function for decoding a state code into the equivalent Tcl
string. Its signature is
Tcl_Obj* name_decode (Tcl_Interp* interp, int state);
name_decode_cstr
The c-mode function for decoding a state code into the equivalent C string.
Its signature is
const char* name_decode_cstr (int state);
The return value of the function is the C string for the state, or NULL if the
state argument does not contain a valid state value.
name.h A header file containing the declarations for the 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 For mode tcl the command registers a new argument-type for critcl::cproc
with critcl, encapsulating the encoder function.
name For mode tcl the command registers a new result-type for critcl::cproc with
critcl, encapsulating the decoder function.
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