forked from mirrors/gecko-dev
a470038314
--HG-- rename : config/Preprocessor.py => python/mozbuild/mozbuild/preprocessor.py rename : config/tests/unit-Expression.py => python/mozbuild/mozbuild/test/test_expression.py rename : config/tests/unit-LineEndings.py => python/mozbuild/mozbuild/test/test_line_endings.py rename : config/tests/unit-Preprocessor.py => python/mozbuild/mozbuild/test/test_preprocessor.py
244 lines
5.2 KiB
ReStructuredText
244 lines
5.2 KiB
ReStructuredText
.. _preprocessor:
|
|
|
|
=================
|
|
Text Preprocessor
|
|
=================
|
|
|
|
The build system contains a text preprocessor similar to the C preprocessor,
|
|
meant for processing files which have no built-in preprocessor such as XUL
|
|
and JavaScript documents. It is implemented at ``python/mozbuild/mozbuild/preprocessor.py`` and
|
|
is typically invoked via :ref:`jar_manifests`.
|
|
|
|
While used to preprocess CSS files, the directives are changed to begin with
|
|
``%`` instead of ``#`` to avoid conflict of the id selectors.
|
|
|
|
Directives
|
|
==========
|
|
|
|
Variable Definition
|
|
-------------------
|
|
|
|
define
|
|
^^^^^^
|
|
|
|
::
|
|
|
|
#define variable
|
|
#define variable value
|
|
|
|
Defines a preprocessor variable.
|
|
|
|
Note that, unlike the C preprocessor, instances of this variable later in the
|
|
source are not automatically replaced (see #filter). If value is not supplied,
|
|
it defaults to ``1``.
|
|
|
|
Note that whitespace is significant, so ``"#define foo one"`` and
|
|
``"#define foo one "`` is different (in the second case, ``foo`` is defined to
|
|
be a four-character string).
|
|
|
|
undef
|
|
^^^^^
|
|
|
|
::
|
|
|
|
#undef variable
|
|
|
|
Undefines a preprocessor variable.
|
|
|
|
Conditionals
|
|
------------
|
|
|
|
if
|
|
^^
|
|
|
|
::
|
|
|
|
#if variable
|
|
#if !variable
|
|
#if variable==string
|
|
#if variable!=string
|
|
|
|
Disables output if the conditional is false. This can be nested to arbitrary
|
|
depths. Note that in the equality checks, the variable must come first, and
|
|
the comparison operator must not be surrounded by any whitespace.
|
|
|
|
else
|
|
^^^^
|
|
|
|
::
|
|
|
|
#else
|
|
|
|
Reverses the state of the previous conditional block; for example, if the
|
|
last ``#if`` was true (output was enabled), an ``#else`` makes it off
|
|
(output gets disabled).
|
|
|
|
.. warning:: An ``#else`` is relative to the last conditional block only,
|
|
unlike the C preprocessor.
|
|
|
|
It does not matter whether any blocks before it were true. This behavior
|
|
changed on trunk (Gecko 1.9) on 2006-12-07; see Bug 277122 for details.
|
|
|
|
::
|
|
|
|
#if 1
|
|
always included
|
|
#elif 1
|
|
never included
|
|
#else
|
|
always included
|
|
#endif
|
|
|
|
endif
|
|
^^^^^
|
|
|
|
::
|
|
|
|
#endif
|
|
|
|
Ends the conditional block.
|
|
|
|
ifdef / ifndef
|
|
^^^^^^^^^^^^^^
|
|
|
|
::
|
|
|
|
#ifdef variable
|
|
#ifndef variable
|
|
|
|
An ``#if`` conditional that is true only if the preprocessor variable
|
|
variable is defined (in the case of ``ifdef``) or not defined (``ifndef``).
|
|
|
|
elif / elifdef / elifndef
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
::
|
|
|
|
#elif variable
|
|
#elif !variable
|
|
#elif variable == string
|
|
#elif variable != string
|
|
#elifdef variable
|
|
#elifndef variable
|
|
|
|
A shorthand to mean an ``#else`` combined with the relevant conditional.
|
|
The following two blocks are equivalent::
|
|
|
|
#ifdef foo
|
|
block 1
|
|
#elifdef bar
|
|
block 2
|
|
#endif
|
|
|
|
::
|
|
|
|
#ifdef foo
|
|
block 1
|
|
#else
|
|
#ifdef bar
|
|
block 2
|
|
#endif
|
|
#endif
|
|
|
|
.. warning:: An ``#elif``, ``#elifdef``, or ``#elifndef`` is relative to
|
|
the last conditional block only (as well as the condition it implies),
|
|
unlike the C preprocessor. It does not matter whether any blocks before
|
|
it were true. This behavior changed on trunk (Gecko 1.9) on 2006-12-07.
|
|
See Bug 277122 for details.
|
|
|
|
File Inclusion
|
|
--------------
|
|
|
|
include
|
|
^^^^^^^
|
|
|
|
::
|
|
|
|
#include filename
|
|
|
|
The file specified by filename is processed as if the contents was placed
|
|
at this position. This also means that preprocessor conditionals can even
|
|
be started in one file and ended in another (but is highly discouraged).
|
|
There is no limit on depth of inclusion, or repeated inclusion of the same
|
|
file, or self inclusion; thus, care should be taken to avoid infinite loops.
|
|
|
|
includesubst
|
|
^^^^^^^^^^^^
|
|
|
|
::
|
|
|
|
#includesubst @variable@filename
|
|
|
|
Same as a ``#include`` except that all instances of variable in the included
|
|
file is also expanded as in ``#filter`` substitution
|
|
|
|
expand
|
|
^^^^^^
|
|
|
|
::
|
|
|
|
#expand string
|
|
|
|
All variables wrapped in ``__`` are replaced with their value, for this line
|
|
only. If the variable is not defined, it expands to an empty string. For
|
|
example, if ``foo`` has the value ``bar``, and ``baz`` is not defined, then::
|
|
|
|
#expand This <__foo__> <__baz__> gets expanded
|
|
|
|
Is expanded to::
|
|
|
|
This <bar> <> gets expanded
|
|
|
|
filter / unfilter
|
|
^^^^^^^^^^^^^^^^^
|
|
|
|
::
|
|
|
|
#filter filter1 filter2 ... filterN
|
|
#unfilter filter1 filter2 ... filterN
|
|
|
|
``#filter`` turns on the given filter.
|
|
|
|
Filters are run in alphabetical order on a per-line basis.
|
|
|
|
``#unfilter`` turns off the given filter. Available filters are:
|
|
|
|
emptyLines
|
|
strips blank lines from the output
|
|
slashslash
|
|
strips everything from the first two consecutive slash (``/``)
|
|
characters until the end of the line
|
|
spaces
|
|
collapses consecutive sequences of spaces into a single space,
|
|
and strips leading and trailing spaces
|
|
substitution
|
|
all variables wrapped in @ are replaced with their value. If the
|
|
variable is not defined, it is a fatal error. Similar to ``#expand``
|
|
and ``#filter``
|
|
attemptSubstitution
|
|
all variables wrapped in ``@`` are replaced with their value, or an
|
|
empty string if the variable is not defined. Similar to ``#expand``.
|
|
|
|
literal
|
|
^^^^^^^
|
|
|
|
::
|
|
|
|
#literal string
|
|
|
|
Output the string (i.e. the rest of the line) literally, with no other fixups.
|
|
This is useful to output lines starting with ``#``, or to temporarily
|
|
disable filters.
|
|
|
|
Other
|
|
-----
|
|
|
|
#error
|
|
^^^^^^
|
|
|
|
::
|
|
|
|
#error string
|
|
|
|
Cause a fatal error at this point, with the error message being the
|
|
given string.
|