Currently this module understands the following types. h2xs may only know
a subset. The sizes of the numeric types are chosen by the "Configure"
script at compile time.
- C_stringify NAME
-
A function which returns a 7 bit ASCII correctly \ escaped version of the
string passed suitable for C's "" or ''. It will die if passed Unicode
characters.
- perl_stringify NAME
-
A function which returns a 7 bit ASCII correctly \ escaped version of the
string passed suitable for a perl "" string.
- constant_types
-
A function returning a single scalar with "#define" definitions for the
constants used internally between the generated C and XS functions.
- memEQ_clause NAME, CHECKED_AT, INDENT
-
A function to return a suitable C "if" statement to check whether NAME
is equal to the C variable "name". If CHECKED_AT is defined, then it
is used to avoid "memEQ" for short names, or to generate a comment to
highlight the position of the character in the "switch" statement.
If CHECKED_AT is a reference to a scalar, then instead it gives
the characters pre-checked at the beginning, (and the number of chars by
which the C variable name has been advanced. These need to be chopped from
the front of NAME).
- assign INDENT, TYPE, PRE, POST, VALUE...
-
A function to return a suitable assignment clause. If TYPE is aggregate
(eg PVN expects both pointer and length) then there should be multiple
VALUEs for the components. PRE and POST if defined give snippets
of C code to proceed and follow the assignment. PRE will be at the start
of a block, so variables may be defined in it.
- return_clause
-
return_clause ITEM, INDENT
A function to return a suitable "#ifdef" clause. ITEM is a hashref
(as passed to "C_constant" and "match_clause". INDENT is the number
of spaces to indent, defaulting to 6.
XXX document me
- switch_clause INDENT, NAMELEN, ITEMHASH, ITEM...
-
An internal function to generate a suitable "switch" clause, called by
"C_constant" ITEMs are in the hash ref format as given in the description
of "C_constant", and must all have the names of the same length, given by
NAMELEN (This is not checked). ITEMHASH is a reference to a hash,
keyed by name, values being the hashrefs in the ITEM list.
(No parameters are modified, and there can be keys in the ITEMHASH that
are not in the list of ITEMs without causing problems).
- params WHAT
-
An internal function. WHAT should be a hashref of types the constant
function will return. params returns a hashref keyed IV NV PV SV to show
which combination of pointers will be needed in the C argument list.
- dump_names
-
dump_names DEFAULT_TYPE, TYPES, INDENT, OPTIONS, ITEM...
An internal function to generate the embedded perl code that will regenerate
the constant subroutines. DEFAULT_TYPE, TYPES and ITEMs are the
same as for C_constant. INDENT is treated as number of spaces to indent
by. OPTIONS is a hashref of options. Currently only "declare_types" is
recognised. If the value is true a $types is always declared in the perl
code generated, if defined and false never declared, and if undefined $types
is only declared if the values in TYPES as passed in cannot be inferred from
DEFAULT_TYPES and the ITEMs.
- dogfood
-
dogfood PACKAGE, SUBNAME, DEFAULT_TYPE, TYPES, INDENT, BREAKOUT, ITEM...
An internal function to generate the embedded perl code that will regenerate
the constant subroutines. Parameters are the same as for C_constant.
- C_constant
-
C_constant PACKAGE, SUBNAME, DEFAULT_TYPE, TYPES, INDENT, BREAKOUT, ITEM...
A function that returns a list of C subroutine definitions that return
the value and type of constants when passed the name by the XS wrapper.
ITEM... gives a list of constant names. Each can either be a string,
which is taken as a C macro name, or a reference to a hash with the following
keys
-
- name
-
The name of the constant, as seen by the perl code.
- type
-
The type of the constant (IV, NV etc)
- value
-
A C expression for the value of the constant, or a list of C expressions if
the type is aggregate. This defaults to the name if not given.
- macro
-
The C pre-processor macro to use in the "#ifdef". This defaults to the
name, and is mainly used if value is an "enum". If a reference an
array is passed then the first element is used in place of the "#ifdef"
line, and the second element in place of the "#endif". This allows
pre-processor constructions such as
#if defined (foo)
#if !defined (bar)
...
#endif
#endif
to be used to determine if a constant is to be defined.
A ``macro'' 1 signals that the constant is always defined, so the "#if"/"#endif"
test is omitted.
- default
-
Default value to use (instead of "croak"ing with ``your vendor has not
defined...'') to return if the macro isn't defined. Specify a reference to
an array with type followed by value(s).
- pre
-
C code to use before the assignment of the value of the constant. This allows
you to use temporary variables to extract a value from part of a "struct"
and return this as value. This C code is places at the start of a block,
so you can declare variables in it.
- post
-
C code to place between the assignment of value (to a temporary) and the
return from the function. This allows you to clear up anything in pre.
Rarely needed.
- def_pre =item def_post
-
Equivalents of pre and post for the default value.
- utf8
-
Generated internally. Is zero or undefined if name is 7 bit ASCII,
``no'' if the name is 8 bit (and so should only match if SvUTF8() is false),
``yes'' if the name is utf8 encoded.
The internals automatically clone any name with characters 128-255 but none
256+ (ie one that could be either in bytes or utf8) into a second entry
which is utf8 encoded.
-
PACKAGE is the name of the package, and is only used in comments inside the
generated C code.
The next 5 arguments can safely be given as "undef", and are mainly used
for recursion. SUBNAME defaults to "constant" if undefined.
DEFAULT_TYPE is the type returned by "ITEM"s that don't specify their
type. In turn it defaults to IV. TYPES should be given either as a comma
separated list of types that the C subroutine "constant" will generate or as
a reference to a hash. DEFAULT_TYPE will be added to the list if not
present, as will any types given in the list of ITEMs. The resultant list
should be the same list of types that "XS_constant" is given. [Otherwise
"XS_constant" and "C_constant" may differ in the number of parameters to the
constant function. INDENT is currently unused and ignored. In future it may
be used to pass in information used to change the C indentation style used.]
The best way to maintain consistency is to pass in a hash reference and let
this function update it.
BREAKOUT governs when child functions of SUBNAME are generated. If there
are BREAKOUT or more ITEMs with the same length of name, then the code
to switch between them is placed into a function named SUBNAME_LEN, for
example "constant_5" for names 5 characters long. The default BREAKOUT is
3. A single "ITEM" is always inlined.
- XS_constant PACKAGE, TYPES, SUBNAME, C_SUBNAME
-
A function to generate the XS code to implement the perl subroutine
PACKAGE::constant used by PACKAGE::AUTOLOAD to load constants.
This XS code is a wrapper around a C subroutine usually generated by
"C_constant", and usually named "constant".
TYPES should be given either as a comma separated list of types that the
C subroutine "constant" will generate or as a reference to a hash. It should
be the same list of types as "C_constant" was given.
[Otherwise "XS_constant" and "C_constant" may have different ideas about
the number of parameters passed to the C function "constant"]
You can call the perl visible subroutine something other than "constant" if
you give the parameter SUBNAME. The C subroutine it calls defaults to
the name of the perl visible subroutine, unless you give the parameter
C_SUBNAME.
- autoload PACKAGE, VERSION, AUTOLOADER
-
A function to generate the AUTOLOAD subroutine for the module PACKAGE
VERSION is the perl version the code should be backwards compatible with.
It defaults to the version of perl running the subroutine. If AUTOLOADER
is true, the AUTOLOAD subroutine falls back on AutoLoader::AUTOLOAD for all
names that the constant() routine doesn't recognise.
- WriteMakefileSnippet
-
WriteMakefileSnippet ATTRIBUTE => VALUE [, ...]
A function to generate perl code for Makefile.PL that will regenerate
the constant subroutines. Parameters are named as passed to "WriteConstants",
with the addition of "INDENT" to specify the number of leading spaces
(default 2).
Currently only "INDENT", "NAME", "DEFAULT_TYPE", "NAMES", "C_FILE" and
"XS_FILE" are recognised.
- WriteConstants ATTRIBUTE => VALUE [, ...]
-
Writes a file of C code and a file of XS code which you should "#include"
and "INCLUDE" in the C and XS sections respectively of your module's XS
code. You probably want to do this in your "Makefile.PL", so that you can
easily edit the list of constants without touching the rest of your module.
The attributes supported are
-
- NAME
-
Name of the module. This must be specified
- DEFAULT_TYPE
-
The default type for the constants. If not specified "IV" is assumed.
- BREAKOUT_AT
-
The names of the constants are grouped by length. Generate child subroutines
for each group with this number or more names in.
- NAMES
-
An array of constants' names, either scalars containing names, or hashrefs
as detailed in ``C_constant''.
- C_FILE
-
The name of the file to write containing the C code. The default is
"const-c.inc". The "-" in the name ensures that the file can't be
mistaken for anything related to a legitimate perl package name, and
not naming the file ".c" avoids having to override Makefile.PL's
".xs" to ".c" rules.
- XS_FILE
-
The name of the file to write containing the XS code. The default is
"const-xs.inc".
- SUBNAME
-
The perl visible name of the XS subroutine generated which will return the
constants. The default is "constant".
- C_SUBNAME
-
The name of the C subroutine generated which will return the constants.
The default is SUBNAME. Child subroutines have "_" and the name
length appended, so constants with 10 character names would be in
"constant_10" with the default XS_SUBNAME.
-