1 files changed, 564 insertions, 0 deletions
diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..412a78c
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,564 @@
+License information for this artifact
+=====================================
+This artifact consists of a few parts. We choose to license most of
+our code under the 3-clause BSD license (SPDX: BSD-3-Clause), with an
+exception of the Nix test suite that we have adopted, which remains
+licensed under LGPL 2.1 (SPDX: LGPL-2.1-or-later).
+Specifically:
+- The following files in lib/nix/ are derived from nixformat [1] by
+  Denis Korzunov:
+    lexer.ml, nix.ml, parser.mly, printer.ml and types.ml
+  nixformat is licensed under ISC (SPDX: ISC). For consistency, we
+  choose to relicense these files under the 3-clause BSD license (as
+  it subsumes the ISC license). We also include a copy of the ISC
+  license as required.
+- The files in test/testdata/ come from Nix [2] and remain licensed
+  under version 2.1 of the LGPL license. We also include a copy of
+  this license below. The only exception here is the file
+    test/testdata/importdef.sexp
+  which was created by us (and is therefore licensed under the 3-clause BSD
+  license).
+- Any files not described by the preceding items is licensed under the
+  3-clause BSD license.
+[1]: https://github.com/d2km/nixformat
+[2]: https://github.com/NixOs/nix
+The 3-clause BSD license (BSD-3-Clause)
+---------------------------------------
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+    1. Redistributions of source code must retain the above copyright
+       notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above
+       copyright notice, this list of conditions and the following
+       disclaimer in the documentation and/or other materials provided
+       with the distribution.
+    3. Neither the name of the copyright holder nor the names of its
+       contributors may be used to endorse or promote products derived
+       from this software without specific prior written permission.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+The ISC license (ISC)
+---------------------
+Permission to use, copy, modify, and /or distribute this software for
+any purpose with or without fee is hereby granted, provided that the
+above copyright notice and this permission notice appear in all
+copies.
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.
+Version 2.1 of the LGPL license (LGPL-2.1-or-later)
+---------------------------------------------------
+Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+Everyone is permitted to copy and distribute verbatim copies of this
+license document, but changing it is not allowed.
+[This is the first released version of the Lesser GPL. It also counts
+as the successor of the GNU Library Public License, version 2, hence
+the version number 2.1.]
+Preamble
+The licenses for most software are designed to take away your freedom
+to share and change it. By contrast, the GNU General Public Licenses
+are intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.
+This license, the Lesser General Public License, applies to some
+specially designated software packages--typically libraries--of the
+Free Software Foundation and other authors who decide to use it. You
+can use it too, but we suggest you first think carefully about whether
+this license or the ordinary General Public License is the better
+strategy to use in any particular case, based on the explanations
+below.
+When we speak of free software, we are referring to freedom of use,
+not price. Our General Public Licenses are designed to make sure that
+you have the freedom to distribute copies of free software (and charge
+for this service if you wish); that you receive source code or can get
+it if you want it; that you can change the software and use pieces of
+it in new free programs; and that you are informed that you can do
+these things.
+To protect your rights, we need to make restrictions that forbid
+distributors to deny you these rights or to ask you to surrender these
+rights. These restrictions translate to certain responsibilities for
+you if you distribute copies of the library or if you modify it.
+For example, if you distribute copies of the library, whether gratis
+or for a fee, you must give the recipients all the rights that we gave
+you. You must make sure that they, too, receive or can get the source
+code. If you link other code with the library, you must provide
+complete object files to the recipients, so that they can relink them
+with the library after making changes to the library and recompiling
+it. And you must show them these terms so they know their rights.
+We protect your rights with a two-step method: (1) we copyright the
+library, and (2) we offer you this license, which gives you legal
+permission to copy, distribute and/or modify the library.
+To protect each distributor, we want to make it very clear that there
+is no warranty for the free library. Also, if the library is modified
+by someone else and passed on, the recipients should know that what
+they have is not the original version, so that the original author's
+reputation will not be affected by problems that might be introduced
+by others.
+Finally, software patents pose a constant threat to the existence of
+any free program. We wish to make sure that a company cannot
+effectively restrict the users of a free program by obtaining a
+restrictive license from a patent holder. Therefore, we insist that
+any patent license obtained for a version of the library must be
+consistent with the full freedom of use specified in this license.
+Most GNU software, including some libraries, is covered by the
+ordinary GNU General Public License. This license, the GNU Lesser
+General Public License, applies to certain designated libraries, and
+is quite different from the ordinary General Public License. We use
+this license for certain libraries in order to permit linking those
+libraries into non-free programs.
+When a program is linked with a library, whether statically or using a
+shared library, the combination of the two is legally speaking a
+combined work, a derivative of the original library. The ordinary
+General Public License therefore permits such linking only if the
+entire combination fits its criteria of freedom. The Lesser General
+Public License permits more lax criteria for linking other code with
+the library.
+We call this license the "Lesser" General Public License because it
+does Less to protect the user's freedom than the ordinary General
+Public License. It also provides other free software developers Less
+of an advantage over competing non-free programs. These disadvantages
+are the reason we use the ordinary General Public License for many
+libraries. However, the Lesser license provides advantages in certain
+special circumstances.
+For example, on rare occasions, there may be a special need to
+encourage the widest possible use of a certain library, so that it
+becomes a de-facto standard. To achieve this, non-free programs must
+be allowed to use the library. A more frequent case is that a free
+library does the same job as widely used non-free libraries. In this
+case, there is little to gain by limiting the free library to free
+software only, so we use the Lesser General Public License.
+In other cases, permission to use a particular library in non-free
+programs enables a greater number of people to use a large body of
+free software. For example, permission to use the GNU C Library in
+non-free programs enables many more people to use the whole GNU
+operating system, as well as its variant, the GNU/Linux operating
+system.
+Although the Lesser General Public License is Less protective of the
+users' freedom, it does ensure that the user of a program that is
+linked with the Library has the freedom and the wherewithal to run
+that program using a modified version of the Library.
+The precise terms and conditions for copying, distribution and
+modification follow. Pay close attention to the difference between a
+"work based on the library" and a "work that uses the library". The
+former contains code derived from the library, whereas the latter must
+be combined with the library in order to run.
+GNU LESSER GENERAL PUBLIC LICENSE
+TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+     0. This License Agreement applies to any software library or
+        other program which contains a notice placed by the copyright
+        holder or other authorized party saying it may be distributed
+        under the terms of this Lesser General Public License (also
+        called "this License"). Each licensee is addressed as "you".
+ 
+        A "library" means a collection of software functions and/or
+        data prepared so as to be conveniently linked with application
+        programs (which use some of those functions and data) to form
+        executables.
+ 
+        The "Library", below, refers to any such software library or
+        work which has been distributed under these terms. A "work
+        based on the Library" means either the Library or any
+        derivative work under copyright law: that is to say, a work
+        containing the Library or a portion of it, either verbatim or
+        with modifications and/or translated straightforwardly into
+        another language. (Hereinafter, translation is included
+        without limitation in the term "modification".)
+ 
+        "Source code" for a work means the preferred form of the work
+        for making modifications to it. For a library, complete source
+        code means all the source code for all modules it contains,
+        plus any associated interface definition files, plus the
+        scripts used to control compilation and installation of the
+        library.
+ 
+        Activities other than copying, distribution and modification
+        are not covered by this License; they are outside its scope.
+        The act of running a program using the Library is not
+        restricted, and output from such a program is covered only if
+        its contents constitute a work based on the Library
+        (independent of the use of the Library in a tool for writing
+        it). Whether that is true depends on what the Library does and
+        what the program that uses the Library does. 1. You may copy
+        and distribute verbatim copies of the Library's complete
+        source code as you receive it, in any medium, provided that
+        you conspicuously and appropriately publish on each copy an
+        appropriate copyright notice and disclaimer of warranty; keep
+        intact all the notices that refer to this License and to the
+        absence of any warranty; and distribute a copy of this License
+        along with the Library.
+ 
+        You may charge a fee for the physical act of transferring a
+        copy, and you may at your option offer warranty protection in
+        exchange for a fee.
+ 
+     2. You may modify your copy or copies of the Library or any
+        portion of it, thus forming a work based on the Library, and
+        copy and distribute such modifications or work under the terms
+        of Section 1 above, provided that you also meet all of these
+        conditions:
+ 
+         a) The modified work must itself be a software library.
+         b) You must cause the files modified to carry prominent
+            notices stating that you changed the files and the date of
+            any change.
+         c) You must cause the whole of the work to be licensed at no
+            charge to all third parties under the terms of this
+            License.
+         d) If a facility in the modified Library refers to a function
+            or a table of data to be supplied by an application
+            program that uses the facility, other than as an argument
+            passed when the facility is invoked, then you must make a
+            good faith effort to ensure that, in the event an
+            application does not supply such function or table, the
+            facility still operates, and performs whatever part of its
+            purpose remains meaningful.
+ 
+        (For example, a function in a library to compute square roots
+        has a purpose that is entirely well-defined independent of the
+        application. Therefore, Subsection 2d requires that any
+        application-supplied function or table used by this function
+        must be optional: if the application does not supply it, the
+        square root function must still compute square roots.)
+ 
+        These requirements apply to the modified work as a whole. If
+        identifiable sections of that work are not derived from the
+        Library, and can be reasonably considered independent and
+        separate works in themselves, then this License, and its
+        terms, do not apply to those sections when you distribute them
+        as separate works. But when you distribute the same sections
+        as part of a whole which is a work based on the Library, the
+        distribution of the whole must be on the terms of this
+        License, whose permissions for other licensees extend to the
+        entire whole, and thus to each and every part regardless of
+        who wrote it.
+ 
+        Thus, it is not the intent of this section to claim rights or
+        contest your rights to work written entirely by you; rather,
+        the intent is to exercise the right to control the
+        distribution of derivative or collective works based on the
+        Library.
+ 
+        In addition, mere aggregation of another work not based on the
+        Library with the Library (or with a work based on the Library)
+        on a volume of a storage or distribution medium does not bring
+        the other work under the scope of this License.
+ 
+     3. You may opt to apply the terms of the ordinary GNU General
+        Public License instead of this License to a given copy of the
+        Library. To do this, you must alter all the notices that refer
+        to this License, so that they refer to the ordinary GNU
+        General Public License, version 2, instead of to this License.
+        (If a newer version than version 2 of the ordinary GNU General
+        Public License has appeared, then you can specify that version
+        instead if you wish.) Do not make any other change in these
+        notices.
+ 
+        Once this change is made in a given copy, it is irreversible
+        for that copy, so the ordinary GNU General Public License
+        applies to all subsequent copies and derivative works made
+        from that copy.
+ 
+        This option is useful when you wish to copy part of the code
+        of the Library into a program that is not a library.
+ 
+     4. You may copy and distribute the Library (or a portion or
+        derivative of it, under Section 2) in object code or
+        executable form under the terms of Sections 1 and 2 above
+        provided that you accompany it with the complete corresponding
+        machine-readable source code, which must be distributed under
+        the terms of Sections 1 and 2 above on a medium customarily
+        used for software interchange.
+ 
+        If distribution of object code is made by offering access to
+        copy from a designated place, then offering equivalent access
+        to copy the source code from the same place satisfies the
+        requirement to distribute the source code, even though third
+        parties are not compelled to copy the source along with the
+        object code.
+ 
+     5. A program that contains no derivative of any portion of the
+        Library, but is designed to work with the Library by being
+        compiled or linked with it, is called a "work that uses the
+        Library". Such a work, in isolation, is not a derivative work
+        of the Library, and therefore falls outside the scope of this
+        License.
+ 
+        However, linking a "work that uses the Library" with the
+        Library creates an executable that is a derivative of the
+        Library (because it contains portions of the Library), rather
+        than a "work that uses the library". The executable is
+        therefore covered by this License. Section 6 states terms for
+        distribution of such executables.
+ 
+        When a "work that uses the Library" uses material from a
+        header file that is part of the Library, the object code for
+        the work may be a derivative work of the Library even though
+        the source code is not. Whether this is true is especially
+        significant if the work can be linked without the Library, or
+        if the work is itself a library. The threshold for this to be
+        true is not precisely defined by law.
+ 
+        If such an object file uses only numerical parameters, data
+        structure layouts and accessors, and small macros and small
+        inline functions (ten lines or less in length), then the use
+        of the object file is unrestricted, regardless of whether it
+        is legally a derivative work. (Executables containing this
+        object code plus portions of the Library will still fall under
+        Section 6.)
+ 
+        Otherwise, if the work is a derivative of the Library, you may
+        distribute the object code for the work under the terms of
+        Section 6. Any executables containing that work also fall
+        under Section 6, whether or not they are linked directly with
+        the Library itself.
+ 
+     6. As an exception to the Sections above, you may also combine or
+        link a "work that uses the Library" with the Library to
+        produce a work containing portions of the Library, and
+        distribute that work under terms of your choice, provided that
+        the terms permit modification of the work for the customer's
+        own use and reverse engineering for debugging such
+        modifications.
+ 
+        You must give prominent notice with each copy of the work that
+        the Library is used in it and that the Library and its use are
+        covered by this License. You must supply a copy of this
+        License. If the work during execution displays copyright
+        notices, you must include the copyright notice for the Library
+        among them, as well as a reference directing the user to the
+        copy of this License. Also, you must do one of these things:
+ 
+         a) Accompany the work with the complete corresponding
+            machine-readable source code for the Library including
+            whatever changes were used in the work (which must be
+            distributed under Sections 1 and 2 above); and, if the
+            work is an executable linked with the Library, with the
+            complete machine-readable "work that uses the Library", as
+            object code and/or source code, so that the user can
+            modify the Library and then relink to produce a modified
+            executable containing the modified Library. (It is
+            understood that the user who changes the contents of
+            definitions files in the Library will not necessarily be
+            able to recompile the application to use the modified
+            definitions.)
+         b) Use a suitable shared library mechanism for linking with
+            the Library. A suitable mechanism is one that (1) uses at
+            run time a copy of the library already present on the
+            user's computer system, rather than copying library
+            functions into the executable, and (2) will operate
+            properly with a modified version of the library, if the
+            user installs one, as long as the modified version is
+            interface-compatible with the version that the work was
+            made with.
+         c) Accompany the work with a written offer, valid for at
+            least three years, to give the same user the materials
+            specified in Subsection 6a, above, for a charge no more
+            than the cost of performing this distribution.
+         d) If distribution of the work is made by offering access to
+            copy from a designated place, offer equivalent access to
+            copy the above specified materials from the same place.
+         e) Verify that the user has already received a copy of these
+            materials or that you have already sent this user a copy.
+ 
+        For an executable, the required form of the "work that uses
+        the Library" must include any data and utility programs needed
+        for reproducing the executable from it. However, as a special
+        exception, the materials to be distributed need not include
+        anything that is normally distributed (in either source or
+        binary form) with the major components (compiler, kernel, and
+        so on) of the operating system on which the executable runs,
+        unless that component itself accompanies the executable.
+ 
+        It may happen that this requirement contradicts the license
+        restrictions of other proprietary libraries that do not
+        normally accompany the operating system. Such a contradiction
+        means you cannot use both them and the Library together in an
+        executable that you distribute.
+ 
+     7. You may place library facilities that are a work based on the
+        Library side-by-side in a single library together with other
+        library facilities not covered by this License, and distribute
+        such a combined library, provided that the separate
+        distribution of the work based on the Library and of the other
+        library facilities is otherwise permitted, and provided that
+        you do these two things:
+ 
+         a) Accompany the combined library with a copy of the same
+            work based on the Library, uncombined with any other
+            library facilities. This must be distributed under the
+            terms of the Sections above.
+         b) Give prominent notice with the combined library of the
+            fact that part of it is a work based on the Library, and
+            explaining where to find the accompanying uncombined form
+            of the same work.
+ 
+     8. You may not copy, modify, sublicense, link with, or distribute
+        the Library except as expressly provided under this License.
+        Any attempt otherwise to copy, modify, sublicense, link with,
+        or distribute the Library is void, and will automatically
+        terminate your rights under this License. However, parties who
+        have received copies, or rights, from you under this License
+        will not have their licenses terminated so long as such
+        parties remain in full compliance.
+ 
+     9. You are not required to accept this License, since you have
+        not signed it. However, nothing else grants you permission to
+        modify or distribute the Library or its derivative works.
+        These actions are prohibited by law if you do not accept this
+        License. Therefore, by modifying or distributing the Library
+        (or any work based on the Library), you indicate your
+        acceptance of this License to do so, and all its terms and
+        conditions for copying, distributing or modifying the Library
+        or works based on it.
+    10. Each time you redistribute the Library (or any work based on
+        the Library), the recipient automatically receives a license
+        from the original licensor to copy, distribute, link with or
+        modify the Library subject to these terms and conditions. You
+        may not impose any further restrictions on the recipients'
+        exercise of the rights granted herein. You are not responsible
+        for enforcing compliance by third parties with this License.
+    11. If, as a consequence of a court judgment or allegation of
+        patent infringement or for any other reason (not limited to
+        patent issues), conditions are imposed on you (whether by
+        court order, agreement or otherwise) that contradict the
+        conditions of this License, they do not excuse you from the
+        conditions of this License. If you cannot distribute so as to
+        satisfy simultaneously your obligations under this License and
+        any other pertinent obligations, then as a consequence you may
+        not distribute the Library at all. For example, if a patent
+        license would not permit royalty-free redistribution of the
+        Library by all those who receive copies directly or indirectly
+        through you, then the only way you could satisfy both it and
+        this License would be to refrain entirely from distribution of
+        the Library.
+        If any portion of this section is held invalid or
+        unenforceable under any particular circumstance, the balance
+        of the section is intended to apply, and the section as a
+        whole is intended to apply in other circumstances.
+        It is not the purpose of this section to induce you to
+        infringe any patents or other property right claims or to
+        contest validity of any such claims; this section has the sole
+        purpose of protecting the integrity of the free software
+        distribution system which is implemented by public license
+        practices. Many people have made generous contributions to the
+        wide range of software distributed through that system in
+        reliance on consistent application of that system; it is up to
+        the author/donor to decide if he or she is willing to
+        distribute software through any other system and a licensee
+        cannot impose that choice.
+        This section is intended to make thoroughly clear what is
+        believed to be a consequence of the rest of this License.
+    12. If the distribution and/or use of the Library is restricted in
+        certain countries either by patents or by copyrighted
+        interfaces, the original copyright holder who places the
+        Library under this License may add an explicit geographical
+        distribution limitation excluding those countries, so that
+        distribution is permitted only in or among countries not thus
+        excluded. In such case, this License incorporates the
+        limitation as if written in the body of this License.
+    13. The Free Software Foundation may publish revised and/or new
+        versions of the Lesser General Public License from time to
+        time. Such new versions will be similar in spirit to the
+        present version, but may differ in detail to address new
+        problems or concerns.
+        Each version is given a distinguishing version number. If the
+        Library specifies a version number of this License which
+        applies to it and "any later version", you have the option of
+        following the terms and conditions either of that version or
+        of any later version published by the Free Software
+        Foundation. If the Library does not specify a license version
+        number, you may choose any version ever published by the Free
+        Software Foundation.
+    14. If you wish to incorporate parts of the Library into other
+        free programs whose distribution conditions are incompatible
+        with these, write to the author to ask for permission. For
+        software which is copyrighted by the Free Software Foundation,
+        write to the Free Software Foundation; we sometimes make
+        exceptions for this. Our decision will be guided by the two
+        goals of preserving the free status of all derivatives of our
+        free software and of promoting the sharing and reuse of
+        software generally.
+    NO WARRANTY
+    15. BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE, THERE IS NO
+        WARRANTY FOR THE LIBRARY, TO THE EXTENT PERMITTED BY
+        APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
+        COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE LIBRARY "AS
+        IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
+        INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+        MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
+        ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE LIBRARY
+        IS WITH YOU. SHOULD THE LIBRARY PROVE DEFECTIVE, YOU ASSUME
+        THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+    16. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
+        WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
+        MODIFY AND/OR REDISTRIBUTE THE LIBRARY AS PERMITTED ABOVE, BE
+        LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
+        INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
+        INABILITY TO USE THE LIBRARY (INCLUDING BUT NOT LIMITED TO
+        LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES
+        SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE LIBRARY
+        TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR
+        OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+        DAMAGES.