critcl::emap - CriTcl Utilities: Enum en- and decoding
package require
Tcl 8.4
package require
critcl ?3.1.11?
package require
critcl::emap ?1?
::critcl::emap::def name definition ?
-nocase?
?
-mode mode?
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 |
| ... |
+----------------+
- ::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.
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
Andreas Kupries
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.
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
Glueing/Embedded C code
Copyright (c) 2011-2015 Andreas Kupries