Documentation: Core / IPP (Pass 1)
- Using Wildcards
- Special `Use' Variant
- Special `Depends' Variant
- Input Line Synchronization
- Include Variables
- Implicit IPP Variables
- End-Of-File Stopping
- End-Of-Line Continuation
ipp - Include Pre-Processor
ipp [-D name=value] [-S includedir] [-I includedir] [-s includefile] [-i includefile] [-M options] [-P path] [-m mapfile] [-N nosynclines] [-o outputfile] [-v] inputfile ...
The ipp program reads all inputfiles and recursively expands all
directives by substituting the directive with the contents of the file. The output is send to stdout or to outputfile. The files are searched according to the following scheme:
- #include 'file'
The file is searched in the current working directory only. Use this to force the loading of a local file.
- #include ``file''
The file is searched in all directories given by the -I option in the right-to-left order they are specified on the command line. Note that a -I . implicit option is automatically appended to command-line options, then files are first searched in current directory.
- #include <file>
First the file is searched in the system wide
ippinclude directory specified with the -S option. Second if it was not not found there it is searched for in all directories given by the -I option.
And it provides eight additional features:
These characters have a special meaning in filenames:
*Matches any string, including the null string.
?Matches any single character.
[...]Like bracketed expressions in regexps, matches any of the enclosed characters.
If you want to include all your templates, you may write
With the following parameters you can control the order and the number of included files using the #include 'pattern' directive:
IPP_SORT=schemeSpecify a sort criterion to include files. There are actually 3 different criteria : date (files are sorted according to their last modification time), name (this is the default) and numeric (filenames are sorted numerically).
IPP_REVERSE=schemeAs above, but resulting list of filenames is sorted in reverse order.
IPP_MAX=nmaxOnly nmax files are included.
If you want to include the 5 newest include files of the news directory
with file names like
20000131.inc, you may write:
In the files included with the
#include 'pattern'directive, the following variables are set and can be read using
IPP_THISthe full name of the included source file including path and extension
IPP_PREVthe full name of the previous included file, unset in the first file
IPP_NEXTthe full name of the next included file, unset in the last file
Keep in mind that a directive without wildcards does not set these variables.
In analogon to Perl's
use statement, ipp provides a special variant of
This internally is equivalent to the directive
plus the special semantic that the include file is included (=used) only once, i.e. multiple inclusion is automatically avoided. In other words
results in three inclusions of 'file'. Two from the
#include's and only once from the
You can easily write fragments of Makefiles with the -M flag (see below) to keep tracks of which files the output file depends on, When
ippis invoked as a piece of
WML, the final output file may depend on other files. You can tell
ippabout these hidden dependencies by using the
#dependsvariant , e.g.
The contents of the file is not inserted, only informations about dependencies are updated.
All include commands insert some special stuff to help
WMLkeeping track of input line numbers. This feature may be disabled by appending the string
#include(or its variants) command. See also the
You can addname[=value]
pairs at the end of
#use) directives to let
=valueis missing) in this include file and all its recursively included files.
There are the following forms of the
$(name)syntax, similar to the functionality any Bourne Shell provides:
`Use Only Value': The standard interpolation.
if (exists(name)) expandto(valueof(name)) else expandto("")
`Assign Value': Set a variable.
name := string
`Use Default String': The standard interpolation with a default value.
if (exists(name)) expandto(valueof(name)) else expandto(string)
`Use Default String and Assign': The standard interpolation with a default value and additional assignment for later use.
if (exists(name)) expandto(valueof(name)) else expandto(string) name := string
`Use Alternate String'. The replacement interpolation.
if (exists(name)) expandto(string) else expandto("")
`Use Negative Alternate String'. The replacement interpolation with negated logic.
if (exists(name)) expandto("") else expandto(string)
`Indicate Error If Unset'. The error message interpolation. This can also be used in conjunction with the above variants.
if (exists(name)) expandto(valueof(name)) else Error(string)
Previous constructs may be nested when variable expansion contains no parenthesis. You may for instance need these forms:
`Set a variable if unset'.
`Redefine a variable if it is already set.'
Notice that nested expressions are not handled as shells do. In shells
expressions are treated from left to right, whereas
ipp treat inner
expressions first. With this example below
Bourne shells will show
ipp will print
It is also possible to undefine a variable. To do so, assign an empty value to this variable, e.g.
Notice the possibility to do simple If-Then-Else constructs:
This is equivalent to the following pseudo-code:
if (exists(foo)) expandto(string_when_set) else expandto(string_when_not_set)
__LINE__ are always substituted by the
currently processed include file and the current line number.
IPP provides support for up-to-end-of-line comments.
This type of comment is like the one found in Bourne-Shell or Perl, i.e. any
line which starts with a sharp symbol (`
#') is entirely (i.e. including the
newline at the end) removed from the input. Additionally these lines can have
whitespaces in front of the sharp symbol. When you really need a sharp symbol
at the start of a line you can use
\#, i.e. prefix it with an escaping
It stops processing the current include file when a line containing just
occurs. Use this to append POD documents to include files for documentation
purposes as in Perl. You can use
__END__ in constructs like
$(SHORTENING:+__END__), so that the processing is only stopped
when the variable SHORTENING is set.
It removes all occurences of the pattern
Use this to let one or more lines to be concatenated.
- -D name=value
Defines a variable the for the initial inputfile the same way you define ones with the #include for include files. The variable can be interpolated via
$(name)in all files.
- -S includedir
Adds a system wide include directory. You can use this option more than once. The files are searched in right-to-left order.
- -I includedir
This adds an entry to the include path where include files are searched for. You can use this option more than once. The files are searched in right-to-left order. The current working directory is always appended as the last directory to this list, and so is searched first.
- -s includefile
Pre-load a particular include file, i.e. virtually adds a
in front of inputfile. Use this to automatically load default system include files. You can also use the syntax
type::category::filewhich leads to a virtually added
- -i includefile
Pre-loads a particular include file, i.e. virtually adds a
in front of inputfile. Use this to automatically load default user include files. You can also use the syntax
type::category::filewhich leads to a virtually added
- -M options
Output a rule suitable for `make' describing the dependencies of each output file, as `gcc' does. It has only sense when the -o option is used.
The D flag option writes the rule to a dependency file. The name of this file is obtained by replacing the suffix of the output file by ``.d''.
The M flag option deletes the system files from the list of dependencies.
- -P path
This sets up one or more prolog program path which are applied to each single input file just before real processing starts. Use this to pre-process the data. Each program receives the data to act on as STDIN and has to produce the filtered data on STDOUT.
- -m mapfile
This adds an entry to the list of mapfiles where a mapping between obsolete include file names and current ones can be found. You can use this option more than once. The mapfiles can contain the following lines:
<blank line> <oldname>[,<oldname>] <newname> \[S|W|E: <text>\]
<std/headfoot.wml>,wml::std::headfoot wml::OBSOLETE::std::headfoot [S]
- -N nosynclines
By default, WML inserts some instructions to synchronize line numbers, which are then interpreted in passes 2 and 3. This option disables this feature.
- -o outputfile
This redirects the output to outputfile. Usually the output will be send to
stdoutif no such option is specified or outputfile is ``
This sets verbose mode where some processing information will be given on the console.
Ralf S. Engelschall firstname.lastname@example.org www.engelschall.com
Denis Barbier email@example.com