UP | HOME

# Upgrading from Spot 1.2.6

## Table of Contents

- Overview of the changes
- Upgrading to C++11
- Upgrading `#include` directives
  - Adjusting the search path
  - Renaming headers files
- BuDDy was renamed
- New implementation for temporal logic formulas
- Many objects are now returned as `std::shared_ptr`
- The `twa` class replaces `tgba`
- Various renamings

This page is for people who have code written for Spot 1.2.6, and would like to upgrade to Spot 2.0. The changes listed here will probably also apply to code written using older Spot 1.x versions.

This page is in no way exhaustive. The main intent is just to list the major changes that have occurred in the library since version 1.2.6, so that one can more easily update existing code. The focus is based on features that appear to be commonly used, based on our the experience of updating a couple of projects that are using Spot.

## Overview of the changes

Let's begin by just trying to summarize what has changed between Spot 1.2.6 and Spot 2.0, just to get an idea of what will need to be updated.

1. Spot now compiles using the C++11 standard. Compliant compiler are sufficiently widespread now that this should not be an issue.
2. The layout of the source-tree and the layout of the installed header files have been completely overhauled, and several header files have been renamed. An early step of upgrading existing code dependent on Spot will therefore be to update all the `#include`.
3. The customized version of BuDDy distributed with Spot has been renamed to not clash with any regular version installed on the system.
4. The implementation of LTL formulas has been rewritten.

   They are no longer pointers but plain objects that performs their own reference counting, freeing the programmer from this tedious and error-prone task. They could be handled as if they were shared pointer, with the small difference that they are not using C++'s standard shared pointers.

   All operators are now implemented using a single type of node, with a field that can be used to make a switch instead of what used to require visitors.

5. Allocated object that are large or expected to have a long life (such as automata, BDD dictionaries, accepting runs) are now returned using shared pointers.
6. Spot used to be centered around the concept of TGBA (Transition-based Generalized Büchi Automata), i.e., ω-automata in which a run is accepting if it visits infinitely often one transition in each defined accepting set of transitions. This was implemented as a `tgba` class.

   In Spot 2.0, each automaton can have a different acceptance condition: this includes well known acceptance conditions such as Büchi, co-Büchi, Rabin, Streett, or parity, but it could also be an arbitrarily complex Boolean combination of those. The central automaton concept is now called TωA (for Transition-based ω-Automata), and implemented as a `twa` class. The `tgba` class does not exist anymore: a TGBA is just a TωA in which the acceptance condition has been set to "generalized Büchi".

   While the gained generality on acceptance conditions allows us to write algorithms that may work on any acceptance condition, Spot still contains algorithms that work only on a particular acceptance condition. Those restrictions have to be ensured using preconditions: the acceptance condition does not appear in the type of the C++ object representing the automaton.

7. Several class, functions, and methods, have been renamed. Some have been completely reimplemented, with different interfaces. In particular the `tgba_explicit_*` familly of classes (`tgba_explicit_formula`, `tgba_explicit_number`, `tgba_explicit_string` used to encode a TGBA using a graph whose state was named using LTL formulas, integers, or strings) are replaced by a `twa_graph` class in which the representation is more complact and efficient, but where states are necessarily numbered. Many algorithms have been rewritten on top of this `twa_graph` class, and this simplified them a lot.

## Upgrading to C++11

Because Spot now relies on C++11 features, programs that use Spot should at least be compiled using this version (or a later one) of the language.

Before the `g++` 6.0, the default C++ standard used was C++98, and enabling C++11 is usually done by passing the option `-std=c++11`. In `g++` 6.0 the default C++ standard used is C++14, so passing `-std=c++11` is only necessary in projects that are incompatible with C++14.

Upgrading from C++98 or C++03 to C++11 should be relatively smooth as the language is mostly backward compatible.

## Upgrading `#include` directives

### Adjusting the search path

If Spot 1.2.6 was installed in `/usr/local`, its headers are in `/usr/local/include/spot`. One would to write include statements such as

    #include <tgba/tgba.hh>
    #include <ltl/formula.hh>

and then compile with `-I /usr/local/include/spot/` to make sure that the Spot headers were found. Headers in Spot would also include other header in Spot by using names relative to the `/usr/local/include/spot/` directory.

If Spot 2.0 is installed in `/usr/local`, its headers are still in `/usr/local/include/spot` however the `spot/` directory is and should always be used to refer to the header:

    #include <spot/twa/twa.hh>      // the new name of tgba/tgba.hh
    #include <spot/tl/formula.hh>   // the new name of ltl/formula.hh

Now compilation should only be done with option `-I /usr/local/include`, which is usually already included by default.

### Renaming headers files

The following table shows all the headers installed by Spot 1.2.6, and the corresponding name to include in Spot 2.0. Some of the new names do not exactly correspond to a renaming, but instead correspond to headers that provide a function with a similar service.

old name | new name or suggested replacement | comment
--- | --- | ---
`bdd.h` | `bddx.h` | customized version of BuDDy
`bvec.h` | `bvecx.h` | customized version of BuDDy
`fdd.h` | `fddx.h` | customized version of BuDDy
`dstarparse/public.hh` | `spot/parseaut/public.hh` | single parser for all automata
`eltlparse/public.hh` |  | not supported anymore
`iface/dve2/dve2.hh` | `spot/ltsmin/ltsmin.hh` |
`kripke/fairkripke.hh` | `spot/kripke/fairkripke.hh` |
`kripke/kripkeexplicit.hh` | `spot/kripke/kripkegraph.hh` | new implementation
`kripke/kripke.hh` | `spot/kripke/kripke.hh` |
`kripke/kripkeprint.hh` | `spot/twaalgos/hoa.hh` | adhoc output format replaced by HOA
`kripkeparse/public.hh` | `spot/parseaut/public.hh` | single parser for all automata
`ltlast/allnodes.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/atomic_prop.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/automatop.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/binop.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/bunop.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/constant.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/formula.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/multop.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/nfa.hh` |  | not supported anymore
`ltlast/predecl.hh` |  | not needed anymore
`ltlast/refformula.hh` |  | not needed anymore
`ltlast/unop.hh` | `spot/tl/formula.hh` | new implementation of formulas
`ltlast/visitor.hh` |  | not supported anymore
`ltlenv/declenv.hh` | `spot/tl/declenv.hh` |
`ltlenv/defaultenv.hh` | `spot/tl/defaultenv.hh` |
`ltlenv/environment.hh` | `spot/tl/environment.hh` |
`ltlparse/ltlfile.hh` |  | not supported anymore
`ltlparse/public.hh` | `spot/tl/parse.hh` |
`ltlvisit/apcollect.hh` | `spot/tl/apcollect.hh` |
`ltlvisit/clone.hh` |  | not needed anymore
`ltlvisit/contain.hh` | `spot/tl/contain.hh` |
`ltlvisit/destroy.hh` |  | not needed anymore
`ltlvisit/dotty.hh` | `spot/tl/dot.hh` |
`ltlvisit/dump.hh` | `spot/tl/formula.hh` | member of the formula class
`ltlvisit/lbt.hh` | `spot/tl/print.hh` |
`ltlvisit/length.hh` | `spot/tl/length.hh` |
`ltlvisit/lunabbrev.hh` | `spot/tl/unabbrev.hh` | generalized
`ltlvisit/nenoform.hh` | `spot/tl/nenoform.hh` |
`ltlvisit/postfix.hh` |  | not supported anymore
`ltlvisit/randomltl.hh` | `spot/tl/randomltl.hh` |
`ltlvisit/reduce.hh` | `spot/tl/simplify.hh` | was already deprecated
`ltlvisit/relabel.hh` | `spot/tl/relabel.hh` |
`ltlvisit/remove_x.hh` | `spot/tl/remove_x.hh` |
`ltlvisit/simpfg.hh` | `spot/tl/unabbrev.hh` | generalized
`ltlvisit/simplify.hh` | `spot/tl/simplify.hh` |
`ltlvisit/snf.hh` | `spot/tl/snf.hh` |
`ltlvisit/tostring.hh` | `spot/tl/print.hh` |
`ltlvisit/tunabbrev.hh` | `spot/tl/unabbrev.hh` | generalized
`ltlvisit/wmunabbrev.hh` | `spot/lt/wmunabbrev.hh` | generalized
`misc/bareword.hh` | `spot/misc/bareword.hh` |
`misc/bddlt.hh` | `spot/misc/bddlt.hh` |
`misc/bddop.hh` |  | not needed anymore
`misc/bitvect.hh` | `spot/misc/bitvect.hh` |
`misc/casts.hh` | `spot/misc/casts.hh` |
`misc/common.hh` | `spot/misc/common.hh` |
`misc/_config.h` | `spot/misc/_config.h` |
`misc/escape.hh` | `spot/misc/escape.hh` |
`misc/fixpool.hh` | `spot/misc/fixpool.hh` |
`misc/formater.hh` | `spot/misc/formater.hh` |
`misc/hashfunc.hh` | `spot/misc/hashfunc.hh` |
`misc/hash.hh` | `spot/misc/hash.hh` |
`misc/intvcmp2.hh` | `spot/misc/intvcmp2.hh` |
`misc/intvcomp.hh` | `spot/misc/intvcomp.hh` |
`misc/location.hh` | `spot/misc/location.hh` |
`misc/ltstr.hh` | `spot/misc/ltstr.hh` |
`misc/memusage.hh` | `spot/misc/memusage.hh` |
`misc/minato.hh` | `spot/misc/minato.hh` |
`misc/mspool.hh` | `spot/misc/mspool.hh` |
`misc/optionmap.hh` | `spot/misc/optionmap.hh` |
`misc/position.hh` | `spot/misc/position.hh` |
`misc/random.hh` | `spot/misc/random.hh` |
`misc/satsolver.hh` | `spot/misc/satsolver.hh` |
`misc/timer.hh` | `spot/misc/timer.hh` |
`misc/tmpfile.hh` | `spot/misc/tmpfile.hh` |
`misc/unique_ptr.hh` | `memory` | use `std::unique_ptr` from C++11
`misc/version.hh` | `spot/misc/version.hh` |
`neverparse/public.hh` | `spot/parseaut/public.hh` | single parser for all automata
`sabaalgos/sabadotty.hh` |  | not supported anymore
`sabaalgos/sabareachiter.hh` |  | not supported anymore
`saba/explicitstateconjunction.hh` |  | not supported anymore
`saba/sabacomplementtgba.hh` |  | not supported anymore
`saba/saba.hh` |  | not supported anymore
`saba/sabastate.hh` |  | not supported anymore
`saba/sabasucciter.hh` |  | not supported anymore
`taalgos/dotty.hh` | `spot/taalgos/dot.hh` |
`taalgos/emptinessta.hh` | `spot/taalgos/emptinessta.hh` |
`taalgos/minimize.hh` | `spot/taalgos/minimize.hh` |
`taalgos/reachiter.hh` | `spot/taalgos/reachiter.hh` |
`taalgos/statessetbuilder.hh` | `spot/taalgos/statesetbuilder.hh` |
`taalgos/stats.hh` | `spot/taalgos/stats.hh` |
`taalgos/tgba2ta.hh` | `spot/taalgos/tgba2ta.hh` |
`ta/taexplicit.hh` | `spot/ta/taexplicit.hh` | old implementation (ought to be changed)
`ta/ta.hh` | `spot/ta/ta.hh` |
`ta/taproduct.hh` | `spot/ta/taproduct.hh` |
`ta/tgtaexplicit.hh` | `spot/ta/tgtaexplicit.hh` | old implementation (ought to be changed)
`ta/tgta.hh` | `spot/ta/tgta.hh` |
`ta/tgtaproduct.hh` | `spot/ta/tgtaproduct.hh` |
`tgbaalgos/bfssteps.hh` | `spot/twaalgos/bfssteps.hh` |
`tgbaalgos/complete.hh` | `spot/twaalgos/complete.hh` |
`tgbaalgos/compsusp.hh` | `spot/twaalgos/compsusp.hh` |
`tgbaalgos/cutscc.hh` |  | not supported anymore
`tgbaalgos/cycles.hh` | `spot/twaalgos/cycles.hh` |
`tgbaalgos/degen.hh` | `spot/twaalgos/degen.hh` |
`tgbaalgos/dottydec.hh` |  | not supported anymore
`tgbaalgos/dotty.hh` | `spot/twaalgos/dot.hh` |
`tgbaalgos/dtbasat.hh` | `spot/twaalgos/dtbasat.hh` |
`tgbaalgos/dtgbacomp.hh` | `spot/twaalgos/complement.hh` |
`tgbaalgos/dtgbasat.hh` | `spot/twaalgos/dtwasat.hh` |
`tgbaalgos/dupexp.hh` | `spot/twaalgos/copy.hh` | also a copy constructor of twa
`tgbaalgos/eltl2tgba_lacim.hh` |  | not supported anymore
`tgbaalgos/emptiness.hh` | `spot/twaalgos/emptiness.hh` |
`tgbaalgos/emptiness_stats.hh` | `spot/twaalgos/emptiness_stats.hh` |
`tgbaalgos/gtec/ce.hh` | `spot/twaalgos/gtec/ce.hh` |
`tgbaalgos/gtec/explscc.hh` |  | not supported anymore
`tgbaalgos/gtec/gtec.hh` | `spot/twaalgos/gtec/gtec.hh` |
`tgbaalgos/gtec/nsheap.hh` |  | not supported anymore
`tgbaalgos/gtec/sccstack.hh` | `spot/twaalgos/gtec/sccstack.hh` |
`tgbaalgos/gtec/status.hh` | `spot/twaalgos/gtec/status.hh` |
`tgbaalgos/gv04.hh` | `spot/twaalgos/gv04.hh` |
`tgbaalgos/hoaf.hh` | `spot/twaalgos/hoa.hh` |
`tgbaalgos/isdet.hh` | `spot/twaalgos/isdet.hh` |
`tgbaalgos/isweakscc.hh` | `spot/twaalgos/isweakscc.hh` |
`tgbaalgos/lbtt.hh` | `spot/twaalgos/lbtt.hh` |
`tgbaalgos/ltl2taa.hh` | `spot/twaalgos/ltl2taa.hh` |
`tgbaalgos/ltl2tgba_fm.hh` | `spot/twaalgos/ltl2tgba_fm.hh` |
`tgbaalgos/ltl2tgba_lacim.hh` |  | not supported anymore
`tgbaalgos/magic.hh` | `spot/twaalgos/magic.hh` |
`tgbaalgos/minimize.hh` | `spot/twaalgos/minimize.hh` |
`tgbaalgos/neverclaim.hh` | `spot/twaalgos/neverclaim.hh` |
`tgbaalgos/postproc.hh` | `spot/twaalgos/postproc.hh` |
`tgbaalgos/powerset.hh` | `spot/twaalgos/powerset.hh` |
`tgbaalgos/projrun.hh` | `spot/twaalgos/emptiness.hh` | use `twa_run::project()` since Spot 2.1
`tgbaalgos/randomgraph.hh` | `spot/twaalgos/randomgraph.hh` |
`tgbaalgos/reachiter.hh` | `spot/twaalgos/reachiter.hh` |
`tgbaalgos/reducerun.hh` | `spot/twaalgos/emptiness.hh` | now `twa_run::reduce()`
`tgbaalgos/reductgba_sim.hh` | `spot/twaalgos/simulation.hh` | was already deprecated
`tgbaalgos/replayrun.hh` | `spot/twaalgos/emptiness.hh` | now `twa_run::replay()`
`tgbaalgos/rundotdec.hh` | `spot/twaalgos/emptiness.hh` | now `twa_run::highlight()`
`tgbaalgos/safety.hh` | `spot/twaalgos/strength.hh` |
`tgbaalgos/save.hh` | `spot/twaalgos/hoa.hh` | adhoc output format replaced by HOA
`tgbaalgos/sccfilter.hh` | `spot/twaalgos/sccfilter.hh` |
`tgbaalgos/scc.hh` | `spot/twaalgos/sccinfo.hh` | new implementation restricted to `twa_graph`
`tgbaalgos/se05.hh` | `spot/twaalgos/se05.hh` |
`tgbaalgos/simulation.hh` | `spot/twaalgos/simulation.hh` |
`tgbaalgos/stats.hh` | `spot/twaalgos/stats.hh` |
`tgbaalgos/stripacc.hh` | `spot/twaalgos/stripacc.hh` |
`tgbaalgos/tau03.hh` | `spot/twaalgos/tau03.hh` |
`tgbaalgos/tau03opt.hh` | `spot/twaalgos/tau03opt.hh` |
`tgbaalgos/translate.hh` | `spot/twaalgos/translate.hh` |
`tgbaalgos/word.hh` | `spot/twaalgos/word.hh` |
`tgba/bdddict.hh` | `spot/twa/bdddict.hh` |
`tgba/bddprint.hh` | `spot/twa/bddprint.hh` |
`tgba/formula2bdd.hh` | `spot/twa/formula2bdd.hh` |
`tgba/futurecondcol.hh` |  | not supported anymore
`tgba/public.hh` | `spot/twa/twa.hh` |
`tgba/sba.hh` |  | replaced by a flag in `twa`
`tgba/statebdd.hh` |  | not supported anymore
`tgba/state.hh` | `spot/twa/twa.hh` |
`tgba/succiterconcrete.hh` |  | not supported anymore
`tgba/succiter.hh` | `spot/twa/twa.hh` |
`tgba/taatgba.hh` | `spot/twa/taatgba.hh` |
`tgba/tgbabddconcretefactory.hh` |  | not supported anymore
`tgba/tgbabddconcrete.hh` |  | not supported anymore
`tgba/tgbabddconcreteproduct.hh` |  | not supported anymore
`tgba/tgbabddcoredata.hh` |  | not supported anymore
`tgba/tgbabddfactory.hh` |  | not supported anymore
`tgba/tgbaexplicit.hh` | `spot/twa/twagraph.hh` |
`tgba/tgba.hh` | `spot/twa/twa.hh` |
`tgba/tgbakvcomplement.hh` |  | use `tgba_determinize()` and `dtwa_complement()`
`tgba/tgbamask.hh` | `spot/twa/tgbamask.hh` |
`tgba/tgbaproduct.hh` | `spot/twa/tgbaproduct.hh` |
`tgba/tgbaproxy.hh` |  | not supported anymore
`tgba/tgbasafracomplement.hh` | `spot/twaalgos/determinize.hh` |
`tgba/tgbascc.hh` | `spot/twaalgos/mask.hh` |
`tgba/tgbasgba.hh` | `spot/twaalgos/sbacc.hh` |
`tgba/tgbatba.hh` | `spot/twaalgos/degen.hh` |
`tgba/tgbaunion.hh` |  | not yet reimplemented
`tgba/wdbacomp.hh` | `spot/twaalgos/complement.hh` | use `dtwa_complement()` instead
`tgbaparse/public.hh` | `spot/parseaut/public.hh` | single parser for all automata

## BuDDy was renamed

Spot install a customized version of the BDD library BuDDy.

As shown in the table of renamed header files, the header files for this library were all renamed: they have an `x` appended (`bddx.h`, `bvecx.h`, `fddx.h`). The name of the library was renamed as well: `libbdd.so` and `libbdd.a` are now respectively `libbddx.so` and `libbddx.a`. This means one should now pass `-lspot -lbddx` to the linker (instead of `-lspot -lbdd`) when linking against Spot.

## New implementation for temporal logic formulas

As can be guessed from the the table of renamed header files, the class hierarchy for temporal formulas has been entirely rewritten. This change is actually quite massive (~13200 lines removed, ~8200 lines added), and brings some nice benefits:

- LTL/PSL formulas are now represented by lightweight formula objects (instead of pointers to children of an abstract formula class) that perform reference counting automatically.
- There is no hierachy anymore: all operators are represented by a single type of node in the syntax tree, and an enumerator is used to distinguish between operators.
- Visitors have been replaced by member functions such as `map()` or `traverse()`, that take a function (usually written as a lambda function) and apply it to the nodes of the tree.
- As a consequence, writing algorithms that manipulate formula is more friendly, and several algorithms that spanned a few pages have been reduced to a few lines. This page illustrates the new interface.

Also the `spot::ltl` namespace has been removed: everything is directly in `spot` now.

In code where formulas are just parsed from input string, and then passed on to other algorithms (e.g., translation to automata): it will suffice to change all occurrences of `const spot::ltl::formula*` into a plain `spot::formula`, and remove all calls to `->destroy()` or `->clone()` (that were used to perform explicit reference counting).

## Many objects are now returned as `std::shared_ptr`

By convention `foo_ptr` is a `typedef` for `std::share_ptr<foo>`. The following typedefs are provided:

    typedef std::shared_ptr<bdd_dict> bdd_dict_ptr;
    typedef std::shared_ptr<const fair_kripke> const_fair_kripke_ptr;
    typedef std::shared_ptr<const kripke> const_kripke_ptr;
    typedef std::shared_ptr<const kripke_explicit> const_kripke_explicit_ptr;
    typedef std::shared_ptr<const parsed_aut> const_parsed_aut_ptr;
    typedef std::shared_ptr<const taa_tgba_formula> const_taa_tgba_formula_ptr;
    typedef std::shared_ptr<const taa_tgba_string> const_taa_tgba_string_ptr;
    typedef std::shared_ptr<const ta> const_ta_ptr;
    typedef std::shared_ptr<const ta_explicit> const_ta_explicit_ptr;
    typedef std::shared_ptr<const ta_product> const_ta_product_ptr;
    typedef std::shared_ptr<const tgta> const_tgta_ptr;
    typedef std::shared_ptr<const tgta_explicit> const_tgta_explicit_ptr;
    typedef std::shared_ptr<const twa> const_twa_ptr;
    typedef std::shared_ptr<const twa_graph> const_twa_graph_ptr;
    typedef std::shared_ptr<const twa_product> const_twa_product_ptr;
    typedef std::shared_ptr<const twa_run> const_twa_run_ptr;
    typedef std::shared_ptr<emptiness_check> emptiness_check_ptr;
    typedef std::shared_ptr<emptiness_check_result> emptiness_check_result_ptr;
    typedef std::shared_ptr<fair_kripke> fair_kripke_ptr;
    typedef std::shared_ptr<kripke_explicit> kripke_explicit_ptr;
    typedef std::shared_ptr<kripke_graph> kripke_graph_ptr;
    typedef std::shared_ptr<kripke> kripke_ptr;
    typedef std::shared_ptr<parsed_aut> parsed_aut_ptr;
    typedef std::shared_ptr<taa_tgba_formula> taa_tgba_formula_ptr;
    typedef std::shared_ptr<taa_tgba_string> taa_tgba_string_ptr;
    typedef std::shared_ptr<ta_explicit> ta_explicit_ptr;
    typedef std::shared_ptr<ta_product> ta_product_ptr;
    typedef std::shared_ptr<ta> ta_ptr;
    typedef std::shared_ptr<tgta_explicit> tgta_explicit_ptr;
    typedef std::shared_ptr<tgta> tgta_ptr;
    typedef std::shared_ptr<twa_graph> twa_graph_ptr;
    typedef std::shared_ptr<twa_product> twa_product_ptr;
    typedef std::shared_ptr<twa_run> twa_run_ptr;
    typedef std::shared_ptr<twa> twa_ptr;
    typedef std::shared_ptr<twa_word> twa_word_ptr;

You should update any `foo*` to `foo_ptr` if it appears in this list, and remove any explicit call to `delete`. Additionally, if `foo` is a class, there is usually a `make_foo(...)` function that calls `std::make_shared<foo>(...)`.

As an example of usage, see this example of creating an automaton explicitly where `spot::make_bdd_dict()` is used to create a BDD dictionary that is then passed to `spot::make_twa_graph()`.

## The `twa` class replaces `tgba`

The change has several implications besides just the changing the name:

- `twa` can represent a larger class of automata than `tgba` could, since the acceptance condition can be arbitrarily complex. Algorithm that used to input `tgba` can be either generalized to handle those larger acceptance conditions, or restricted to generalized Büchi acceptance. The typical way to ensure that an `input` automaton has generalized Büchi acceptance is

    if (!input->acc().is_generalized_buchi())
       throw std::runtime_error
         ("myalgorithm() can only works with generalized Büchi acceptance");

- Some methods of the `tgba` class have been removed, include some pure virtual methods. If you wrote a subclass, you may simply remove the following methods:
  - `compute_support_conditions()`,
  - `compute_support_variables()`,
  - `transition_annotation()`,
  - `neg_acceptance_conditions()`.
- The `succ_iter()` method lost its last two (optional) arguments.
- The badly named `number_of_acceptance_conditions()` has been renamed to `num_sets()`.
- The `tgba_succ_iterator` class was renamed to `twa_succ_iterator`, and its interface was changed:
  - `current_state()`, `current_condition()`, and `current_acceptance_conditions()` are now named respectively `dst()`, `cond()`, `acc()`.
  - the `first()` and `next()` method now return a Boolean that indicates whether we moved to a new successor (`true`), or reached the end of the list of successors (`false`). This return value should be the same as what `!done()` would return, and can be used to avoid some costly calls to the `done()` virtual function.
- Membership to acceptance sets is now represented using a bit set (instead of BDDs). An TωA `aut` uses `aut->num_sets()` acceptance sets numbered from `0` to `aut->num_sets()-1`. The bit sets are implemented as instances of `spot::acc_cond::mark_t`, so they are also called "acceptance marks".
- The `twa::release_iter()` method allow iterators to be recycled. Each `twa` now contains a mutable field `iter_cache_` where `release_iter()` stores the last returned iterator. If this field is not equal to `nullptr`, then `succ_iter()` can use it to allocate a new iterator more efficiently.

  In the code for `succ_iter()`, instead of:

      // ...
      return new my_iterator(arg1, arg2, arg3);

  we can now have

      // ...
      if (iter_cache_)
        {
           my_iterator* it = static_cast<my_iterator*>(iter_cache_);
           iter_cache_ = nullptr;
           // Some method to change the member that need changing.
           // (Here we assume that arg2 is the same for all iterators
           // built on this automaton.)
           it->recycle(arg1, arg3);
           return it;
        }
      return new my_iterator(arg1, arg2, arg3);

  So not only do we save the calls to `new` and `delete`, but we also save the time it takes to construct the objects (including setting up the virtual table), and via a `recycle()` method that has to be added to the iterator, we update only the attributes that needs to be updated (for instance if the iterator contains a pointer back to the automaton, this pointer requires no update when the iterator is recycled).

  The iterator stored in `twa::iter_cache_` is destroyed by `twa::~twa()`. In some case, this is too late. For instance the class `twa_product` uses a custom memory pool to allocate new iterators more efficiently, and this memory pool is destroyed in `twa_product::~twa_product()`. In this case, referencing `twa::iter_cache_` for its deletion in `twa::~tgba()` would be incorrect: it has to be done in `twa_product::~twa_product()` before destroying the pool.

For a TGBA `aut`, and a state `s`, the original way to loop over the successors of `s` was:

    tgba_succ_iterator* i = aut->succ_iter(s);
    for (i->first(); !i->done(); i->next())
      {
         // use i->current_state()
         //     i->current_condition()
         //     i->current_acceptance_conditions()
      }
    delete i;

While the above would still run after a few renamings, it can now be written more efficiently as:

    twa_succ_iterator* i = aut->succ_iter(s);
    if (i->first())
      do
        {
          // use i->dst()
          //     i->cond()
          //     i->acc()
        }
      while (i->next());
    aut->release_iter(i);

If the original code did \(1\) virtual call to `first()`, \(n+1\) virtual calls to `done()`, and \(n\) virtual calls to `next()`, the new version does as many calls to `first()` and `done()` while avoiding all the calls to `done()`. Furthermore the call `release_iter()` makes it possible for the next call to `succ_iter()` to reuse the same iterator.

Because the the above loop is quite common we also have some syntactic sugar via the new `succ()` method that returns a fake container with `begin()` and `end()` methods so that this works:

    for (auto i: aut->succ(s))
      {
        // use i->dst()
        //     i->cond()
        //     i->acc()
      }

- Each `twa` now has a BDD dictionary, so the `get_dict()` method is implemented once for all in `twa`, and should not be implemented anymore in sub-classes.
- There should now be very few cases where it is necessary to call methods of the BDD dictionary attached to a `twa`. Registering the atomic proposition used by a `twa` should now be done via the `twa::register_ap()` or `twa::copy_ap_of()` methods. Accessing all registered propositions is achievable with `twa::ap()` or `twa::ap_vars()`. All propositions registered by an automaton are automatically unregistered when the automaton is destroyed.

## Various renamings

The following is a non-exhaustive list of functions or classes that have been renamed.

old name | new name | comment
--- | --- | ---
`dstar_parse()` | `parse_aut()` | single parser for all automata
`dtgba_complement()` | `dtwa_complement()` |
`dupexp_bfs()` |  | deleted
`dupexp_dfs()` | `copy()` |
`format_parse_aut_errors()` | `parsed_aut::format_errors()` |
`emptiness_check_instantiator::construct()` | `make_emptiness_check_instantiator()` |
`emptiness_check_instantiator::max_acceptance_conditions()` | `emptiness_check_instantiator::max_sets()` |
`emptiness_check_instantiator::min_acceptance_conditions()` | `emptiness_check_instantiator::min_sets()` |
`hoaf_reachable()` | `print_hoa()` |
`is_guarantee_automaton()` | `is_terminal_automaton()` |
`kripke_parse()` | `parse_aut()` | single parser for all automata
`kripke_save_reachable()` | `print_hoa()` | adhoc output format replaced by HOA
`kripke_save_reachable_renumbered()` | `print_hoa()` | adhoc output format replaced by HOA
`lbtt_parse()` | `parse_aut()` | single parser for all automata
`lbtt_reachable()` | `print_lbtt()` |
`ltl::formula::is_X_free()` | `formula::is_syntactic_stutter_invariant()` |
`ltl::ltl_simplifier` | `tl_simplifier` |
`ltl::parse_boolean()` | `parse_infix_boolean()` |
`ltl::parse_lbt()` | `parse_prefix_ltl()` |
`ltl::parse()` | `parse_infix_psl()` |
`ltl::parse_sere()` | `parse_infix_sere()` |
`ltl::to_latex_string()` | `print_latex_psl()` | also `str_latex_psl()`
`ltl::to_lbt_string()` | `print_lbt_ltl()` | also `str_lbt_ltl()`
`ltl::to_sclatex_string()` | `print_sclatex_psl()` | also `str_sclatex_psl()`
`ltl::to_spin_string()` | `print_spin_ltl()` | also `str_spin_ltl()`
`ltl::to_string()` | `print_psl()`, `print_sere()` | also `str_psl()` or `str_sere()`
`ltl::to_ut8_string()` | `print_utg8_psl()`, `print_utf8_sere()` | also `str_utf8_psl()` or `str_utf8_sere()`
`ltl::to_wring_string()` | `print_wring_ltl()` | also `str_wring_ltl()`
`neverclaim_parse()` | `parse_aut()` | single parser for all automata
`never_claim_reachable()` | `print_never_claim()` |
`print_tgba_run()` | `tgba_run::operator<<()` |
`reduce_run()` | `twa_run::reduce()` |
`replay_tgba_run()` | `twa_run::replay()` |
`scc_map` | `scc_info` | new implementation restricted to `twa_graph`
`ta_succ_iterator::current_acceptance_conditions()` | `ta_succ_iterator::acc()` |
`ta_succ_iterator::current_condition()` | `ta_succ_iterator::cond()` |
`ta_succ_iterator::current_state()` | `ta_succ_iterator::dst()` |
`tgba` | `twa` |
`tgba::all_acceptance_conditions()` |  | use `tgba::acc().accepting()` or `tgba::acc().all_sets()`
`tgba::neg_acceptance_conditions()` |  | deleted
`tgba::number_of_acceptance_conditions()` | `tgba::num_sets()` |
`tgba::support_conditions()` |  | deleted
`tgba::support_variables()` |  | deleted
`tgba_explicit_formula` |  | deleted
`tgba_explicit_number` | `twa_graph` | new implementation
`tgba_explicit_string` |  | deleted
`tgba_parse()` | `parse_aut()` | single parser for all automata
`tgba_reachable_iterator` | `twa_reachable_iterator` |
`tgba_reachable_iterator_breadth_first` | `twa_reachable_iterator_breadth_first` |
`tgba_reachable_iterator_depth_first` | `twa_reachable_iterator_depth_first` |
`tgba_run_to_tgba()` | `twa_run::as_twa()` |
`tgba_run` | `twa_run` |
`tgba_save_reachable()` | `print_hoa()` | adhoc output format replaced by HOA
`tgba_statistics::transitions()` | `twa_statistics::edges()` |
`tgba_sub_statistics::sub_transitions()` | `twa_sub_statistics::transitions()` |
`tgba_succ_iterator::current_acceptance_conditions()` | `twa_succ_iterator::acc()` |
`tgba_succ_iterator::current_condition()` | `twa_succ_iterator::cond()` |
`tgba_succ_iterator::current_state()` | `twa_succ_iterator::dst()` |