OpenFst is a library for constructing, combining, optimizing, and searching
weighted finite-state transducers (FSTs).
REQUIREMENTS:
This version is known to work under Linux using g++ (>= 4.9) and OS X using
XCode (>= 5). It is expected to work wherever adequate POSIX (dlopen,
ssize_t, basename), C99 (snprintf, strtoll, <stdint.h>), and C++17
(constexpr-if, <forward_list>, <string_view>, <unordered_map>,
<unordered_set>) support is available.
INSTALLATION:
Follow the generic GNU build system instructions in ./INSTALL. We
recommend configuring with --enable-static=no for faster compiles.
Optional features:
--enable-bin Enable fst::script and executables (def: yes)
--enable-compact-fsts Enable CompactFst extensions (def: no)
--enable-compress Enable compression extension (def: no)
--enable-const-fsts Enable ConstFst extensions (def: no)
--enable-far Enable FAR extensions (def: no)
--enable-fsts Enable all FST SO extensions (def: no)
--enable-grm Enable all dependencies of OpenGrm (def: no)
--enable-linear-fsts Enable LinearTagger/ClassifierFst extensions
(def: no)
--enable-lookahead-fsts Enable LookAheadFst extensions (def: no)
--enable-mpdt Enable MPDT extensions (def: no)
--enable-ngram-fsts Enable NGramFst extensions (def: no)
--enable-pdt Enable PDT extensions (def: no)
--enable-python Enable Python extension (def: no)
--enable-special Enable special-matcher extensions (def: no)
Configuring with --enable-bin=no gives very fast compiles, but excludes the
command line utilities.
Configuring with --enable-python will attempt to install the Python module to
whichever site-packages (or dist-packages, on Debian or Ubuntu) is found
during configuration. If `import pywrapfst` fails from a PYthon 3.6 or better
interpreter after installation, relocate pywrapfst.so to a directory in your
interpreter's `sys.path` or $PYTHONPATH.
The flag --with-libfstdir specifies where FST extensions should be installed;
it defaults to ${libdir}/fst.
Compiling with -Wall -Wno-sign-compare under g++ should give no warnings from
this library.
If you encounter an error about loading shared objects when attempting to use
the library immediately after installation, (e.g, `...cannot open shared
object file...`) you may need to refresh your system's shared object cache.
On Linux, this is accomplished by invoking ldconfig; the corresponding
command on OS X is called update_dyld_shared_cache. Both of these require
superuser privileges and so should be executed with `sudo`.
The Python wrapper is difficult to install because the autoconf macros do
not have a detailed understanding of Python packaging. One alternative is to
install the `pynini` extension from PyPI.org via `pip`; this includes a
copy of `pywrapfst` as well:
pip install pynini
On Linux x86_64, this will install precompiled binaries; on other platforms,
it will attempt to built the package from source. If building from source,
first build and install OpenFst while issuing `--enable-grm` during the
configuration phase.
If instead using `--enable-python`, the Python wrapper is ordinarily
installed to the local `site-packages`. This may cause issues on
Debian-based Linux distributions as these use a non-standard `dist-packages`
directory and do not include `site-packages` in their Python module path. To
correct this, move, copy, or link `pywrapfst.so` into `dist-packages`, or
modify your module load path (e.g., environmental variable `$PYTHONPATH`) to
include the local `site-packages` directory.
USAGE:
Assuming you've installed under the default /usr/local, the FST binaries are
found on /usr/local/bin.
To use in your own program, include <fst/fstlib.h> and compile with
-I/usr/local/include. The compiler must support C++11 (for g++ add the flag
-std=c++17). Link against /usr/local/lib/libfst.so and -ldl. Set your
LD_LIBRARY_PATH (or equivalent) to contain /usr/local/lib. The linking is,
by default, dynamic so that the Fst and Arc type DSO extensions can be used
correctly if desired. Any extensions will be found under /usr/local/lib/fst
or /usr/local/include/fst/extensions.
BUILDING WITH BAZEL:
Release 1.7.2 provides the ability to build the core library and binaries as
well as several extensions with Bazel and to depend on OpenFst as an
external dependency in other projects compiled with Bazel. Please refer to
https://bazel.build for information on using Bazel. OpenFst can be compiled
from anywhere in the source tree, as follows:
$ bazel build //:all
Tests can be run in a similar fashion:
$ bazel test //:all
The Bazel build-file is provided as-is.
DOCUMENTATION:
See www.openfst.org for general documentation.
See ./NEWS for updates since the last release.