/
transition.ex
656 lines (547 loc) · 21.2 KB
/
transition.ex
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defmodule Finitomata.Transition do
@moduledoc """
The internal representation of `Transition`.
It includes `from` and `to` states, and the `event`, all represented as atoms.
"""
alias Finitomata.Transition
@typedoc "The state of FSM"
@type state :: atom()
@typedoc "The event in FSM"
@type event :: atom()
@typedoc "The kind of event"
@type event_kind :: :soft | :hard | :normal
@typedoc """
The transition is represented by `from` and `to` states _and_ the `event`.
"""
@type t :: %{
__struct__: Transition,
from: state(),
to: state() | [state()],
event: event()
}
@enforce_keys [:from, :to, :event]
defstruct [:from, :to, :event]
defmodule Path do
@moduledoc "The path from one state to another one"
alias Finitomata.Transition
@type t :: %{
__struct__: Path,
from: Transition.state(),
to: Transition.state(),
path: [{Transition.event(), Transition.state()}]
}
@enforce_keys [:from, :to, :path]
defstruct [:from, :to, :path]
defimpl Inspect do
@moduledoc false
import Inspect.Algebra
def inspect(%Finitomata.Transition.Path{from: from, to: to, path: path}, opts) do
fancy =
case Keyword.get(opts.custom_options, :fancy, true) do
false -> false
{from, to} -> %{from: from, to: to}
%{} = map -> Map.merge(%{from: " ⇥ ", to: " ↦ "}, map)
_ -> %{from: " ⇥ ", to: " ↦ "}
end
fancy_path =
if is_map(fancy) do
path
|> Enum.reduce([], fn {event, to}, acc ->
[to_doc(to, opts), fancy.to, to_doc(event, opts), fancy.from | acc]
end)
|> Enum.reverse()
end
case {from == to and from != :*, is_map(fancy)} do
{true, false} ->
inner = [around: from, path: path]
concat(["#Finitomata.Loop<", to_doc(inner, opts), ">"])
{false, false} ->
inner = [from: from, to: to, path: path]
concat(["#Finitomata.Path<", to_doc(inner, opts), ">"])
{true, _} ->
concat(["↺‹", to_doc(from, opts) | fancy_path] ++ ["›"])
{false, _} ->
concat(["↝‹", to_doc(from, opts) | fancy_path] ++ ["›"])
end
end
end
end
@doc false
@spec from_parsed([binary()]) :: t()
def from_parsed([from, to, event])
when is_binary(from) and is_binary(to) and is_binary(event) do
[from, to, event] =
Enum.map(
[from, to, event],
&(&1 |> String.trim_leading("[") |> String.trim_trailing("]") |> String.to_atom())
)
%Transition{from: from, to: to, event: event}
end
@doc ~S"""
Returns the kind of event.
If event ends up with an exclamation sign, it’s `:hard`, meaning the respective
transition would be initiated automatically when the `from` state of such a transition
is reached.
If event ends up with a question mark, it’s `:soft`, meaning no error would have
been reported in a case transition fails.
Otherwise the event is `:normal`.
iex> {:ok, [_, hard, _]} =
...> Finitomata.PlantUML.parse("[*] --> entry : foo\nentry --> exit : go!\nexit --> [*] : terminate")
...> Finitomata.Transition.event_kind(hard)
:hard
"""
@spec event_kind(event() | t()) :: event_kind()
def event_kind(%Transition{event: event}), do: event_kind(event)
def event_kind(event) do
event = to_string(event)
cond do
String.ends_with?(event, "!") -> :hard
String.ends_with?(event, "?") -> :soft
true -> :normal
end
end
@doc ~S"""
Returns the state _after_ starting one, so-called `entry` state.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> entry : foo\nentry --> exit : go\nexit --> [*] : terminate")
...> Finitomata.Transition.entry(transitions)
:entry
"""
@spec entry(:state | :transition, [t()]) :: state()
def entry(what \\ :state, transitions)
def entry(:transition, transitions),
do: Enum.find(transitions, &match?(%Transition{from: :*}, &1))
def entry(:state, transitions), do: entry(:transition, transitions).to
@doc ~S"""
Returns the states _before_ ending one, so-called `exit` states.
iex> {:ok, transitions} =
...> Finitomata.Mermaid.parse(
...> "entry --> |process| processing\nprocessing --> |ok| success\nprocessing --> |ko| error"
...> )
...> Finitomata.Transition.exit(transitions)
[:error, :success]
"""
@spec exit(:states | :transitions, [t()]) :: [state()]
def exit(what \\ :states, transitions)
def exit(:transitions, transitions) do
Enum.reduce(transitions, [], fn
%Transition{to: :*} = t, acc -> [t | acc]
_, acc -> acc
end)
end
def exit(:states, transitions),
do: :transitions |> Transition.exit(transitions) |> Enum.map(& &1.from)
@doc ~S"""
Returns all the hard transitions which inevitably lead to the next state
(events ending with an exclamation sign,)
which makes the _FSM_ to go to the next state with `:continue` callback.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> entry : start\nentry --> exit : go!\nexit --> [*] : terminate")
...> Finitomata.Transition.hard(transitions)
[entry: :go!]
...> Finitomata.Transition.hard(:transitions, transitions)
[%Finitomata.Transition{from: :entry, to: :exit, event: :go!}]
"""
@spec hard(:states | :transitions, [t()]) :: Enumerable.t(t()) | [Path.t()]
def hard(states \\ :states, transitions)
def hard(:states, transitions) do
:transitions
|> hard(transitions)
|> Enum.map(&{&1.from, &1.event})
end
def hard(:transitions, transitions) do
Enum.filter(transitions, &(event_kind(&1) == :hard))
end
@doc ~S"""
Returns the continuation from the state given which inevitably lead to other state(s).
All the transitions from this state are hard (ending with `!`,)
which makes the _FSM_ to go through all these states in `:continue` callbacks.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> entry : start\nentry --> exit : go!\nexit --> done : finish\ndone --> [*] : terminate")
...> Finitomata.Transition.continuation(:entry, Finitomata.Transition.hard(:transitions, transitions))
%Finitomata.Transition.Path{from: :entry, to: :exit, path: [go!: :exit]}
"""
@spec continuation(:states | :transitions, state(), [t()]) :: nil | Path.t() | [t()]
def continuation(states \\ :states, from, transitions)
def continuation(:states, from, transitions) do
:transitions
|> continuation(from, transitions)
|> case do
[] -> nil
path -> [path] |> to_path() |> hd()
end
end
def continuation(:transitions, from, transitions) do
do_continuation(from, transitions, [])
end
defp do_continuation(from, transitions, path) do
transitions
|> Enum.filter(&match?(%Transition{from: ^from}, &1))
|> case do
[%Transition{from: from, to: to} = t] when from != to ->
do_continuation(to, transitions, [t | path])
_ ->
Enum.reverse(path)
end
end
@doc ~S"""
Returns all the states which inevitably lead to the ending one.
All the transitions from these states to the ending one are hard (ending with `!`,)
which makes the _FSM_ to go through all these states in `:continue` callbacks.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> entry : start\nentry --> exit : go!\nexit --> [*] : terminate")
...> Finitomata.Transition.exiting(transitions)
[%Finitomata.Transition.Path{from: :entry, to: :*, path: [go!: :exit, terminate: :*]}]
"""
@spec exiting(:states | :transitions, [t()]) :: Enumerable.t([t()]) | [Path.t()]
def exiting(what \\ :states, transitions)
def exiting(:states, transitions) do
:transitions
|> exiting(transitions)
|> to_path()
end
def exiting(:transitions, transitions) do
:transitions
|> paths(transitions)
|> Stream.filter(fn path ->
path
|> Enum.reverse()
|> then(&match?([%Transition{to: :*} | _], &1))
end)
|> Stream.map(fn path ->
[last | rest] = Enum.reverse(path)
rest = Enum.take_while(rest, &(event_kind(&1) == :hard))
Enum.reverse([last | rest])
end)
|> Stream.uniq()
end
@doc ~S"""
Returns all the loops aka internal paths where starting and ending states are the same one.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> s1 : foo\ns1 --> s2 : ok\ns2 --> s1 : ok\ns2 --> [*] : ko")
...> Finitomata.Transition.loops(transitions)
[%Finitomata.Transition.Path{from: :s1, to: :s1, path: [ok: :s2, ok: :s1]},
%Finitomata.Transition.Path{from: :s2, to: :s2, path: [ok: :s1, ok: :s2]}]
"""
@spec loops(:states | :transitions, [t()]) :: Enumerable.t(t()) | [Path.t()]
def loops(what \\ :states, transitions)
def loops(:transitions, transitions) do
transitions
|> states(true)
|> Stream.flat_map(&do_loop(&1, transitions, [], []))
end
def loops(:states, transitions) do
:transitions
|> loops(transitions)
|> to_path()
end
defp do_loop(state, _transitions, [%Transition{from: state} | _] = path, paths),
do: [path | paths]
defp do_loop(state, transitions, path, paths) do
transitions
|> Stream.reject(&(&1 in path))
|> Stream.filter(&match?(%Transition{from: ^state, to: to} when to != :*, &1))
|> Stream.flat_map(&do_loop(&1.to, transitions, path ++ [&1], paths))
end
@doc ~S"""
Returns all the paths from starting to ending state.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> s1 : foo\ns1 --> s2 : ok\ns1 --> s3 : ok\ns2 --> [*] : ko\ns3 --> [*] : ko")
...> Finitomata.Transition.paths(transitions)
[%Finitomata.Transition.Path{from: :*, to: :*, path: [foo: :s1, ok: :s2, ko: :*]},
%Finitomata.Transition.Path{from: :*, to: :*, path: [foo: :s1, ok: :s3, ko: :*]}]
"""
@spec paths(:states | :transitions, [t()], state(), state()) :: Enumerable.t(t()) | [Path.t()]
def paths(what \\ :states, transitions, from \\ :*, to \\ :*)
def paths(:states, transitions, from, to) do
:transitions
|> paths(transitions, from, to)
|> to_path()
end
def paths(:transitions, transitions, :*, to) do
entry = entry(:transition, transitions)
do_path(entry.to, to, transitions, [entry], [])
end
def paths(:transitions, transitions, from, to) do
do_path(from, to, transitions, [], [])
end
defp do_path(to, to, _transitions, [_ | _] = path, paths), do: [Enum.reverse(path) | paths]
defp do_path(to, to, _transitions, [], paths), do: paths
defp do_path(:*, _, _transitions, _, paths), do: paths
defp do_path(from, to, transitions, path, paths) do
transitions
|> Stream.reject(&(&1 in path))
|> Stream.filter(&match?(%Transition{from: ^from}, &1))
|> Stream.flat_map(&do_path(&1.to, to, transitions, [&1 | path], paths))
end
@doc ~S"""
Returns `true` if the transition `from` → `to` is allowed, `false` otherwise.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> s1 : foo\ns1 --> s2 : ok\ns2 --> [*] : ko")
...> Finitomata.Transition.allowed?(transitions, :s1, :s2)
true
...> Finitomata.Transition.allowed?(transitions, :s1, :*)
false
"""
@spec allowed?([t()], state(), state()) :: boolean()
def allowed?(transitions, from, to) do
Enum.any?(transitions, &match?(%Transition{from: ^from, to: ^to}, &1))
end
@doc ~S"""
Returns `true` if the state `from` hsa an outgoing transition with `event`, false otherwise.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> s1 : foo\ns1 --> s2 : ok\ns2 --> [*] : ko")
...> Finitomata.Transition.responds?(transitions, :s1, :ok)
true
...> Finitomata.Transition.responds?(transitions, :s1, :ko)
false
"""
@spec responds?([t()], state(), event()) :: boolean()
def responds?(transitions, from, event) do
Enum.any?(transitions, &match?(%Transition{from: ^from, event: ^event}, &1))
end
@doc ~S"""
Returns the list of all the transitions, matching the options.
Used internally for the validations.
iex> {:ok, transitions} =
...> Finitomata.Mermaid.parse(
...> "idle --> |to_s1| s1\n" <>
...> "s1 --> |to_s2| s2\n" <>
...> "s1 --> |to_s3| s3\n" <>
...> "s2 --> |to_s3| s3")
...> Finitomata.Transition.allowed(transitions, to: [:idle, :*])
[{:*, :idle, :__start__}, {:s3, :*, :__end__}]
iex> Finitomata.Transition.allowed(transitions, from: :s1)
[{:s1, :s2, :to_s2}, {:s1, :s3, :to_s3}]
iex> Finitomata.Transition.allowed(transitions, from: :s1, to: :s3)
[{:s1, :s3, :to_s3}]
iex> Finitomata.Transition.allowed(transitions, from: :s1, with: :to_s3)
[{:s1, :s3, :to_s3}]
iex> Finitomata.Transition.allowed(transitions, from: :s2, with: :to_s2)
[]
"""
@spec allowed([t()], [
{:from, state()} | {:to, state()} | {:with, event()} | {:as, :states | :transitions}
]) :: [
{state(), state(), event()}
]
def allowed(transitions, options \\ []) do
{as, options} = Keyword.pop(options, :as, :states)
from = List.wrap(options[:from])
to = List.wrap(options[:to])
event = List.wrap(options[:with])
do_allowed(as, {from, to, event}, transitions)
end
defp do_allowed(:states, fte, transitions) do
:transitions
|> do_allowed(fte, transitions)
|> Enum.map(&{&1.from, &1.to, &1.event})
end
defp do_allowed(:transitions, fte, transitions) do
case fte do
{[], [], []} ->
transitions
{fa, [], []} ->
for %Transition{from: from} = t <- transitions, from in fa, do: t
{[], ta, []} ->
for %Transition{to: to} = t <- transitions, to in ta, do: t
{[], [], ea} ->
for %Transition{event: event} = t <- transitions, event in ea, do: t
{fa, ta, []} ->
for %Transition{from: from, to: to} = t <- transitions, from in fa and to in ta, do: t
{fa, [], ea} ->
for %Transition{from: from, event: event} = t <- transitions,
from in fa and event in ea,
do: t
{[], ta, ea} ->
for %Transition{to: to, event: event} = t <- transitions, to in ta and event in ea, do: t
{fa, ta, ea} ->
for %Transition{from: from, to: to, event: event} = t <- transitions,
from in fa and to in ta and event in ea,
do: t
end
end
@doc ~S"""
Returns the list of all the transitions, matching the `from` state and the `event`.
Used internally for the validations.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> s1 : foo\ns1 --> s2 : ok\ns2 --> [*] : ko")
...> Finitomata.Transition.allowed(transitions, :s1, :foo)
[:s2]
...> Finitomata.Transition.allowed(transitions, :s1, :*)
[]
"""
@spec allowed([t()], state(), event()) :: [state()]
def allowed(transitions, from, event) do
for %Transition{from: ^from, to: to, event: ^event} <- transitions, do: to
end
@doc ~S"""
Returns keyword list of
`{Finitomata.Transition.state(), Finitomata.Transition.event()}` tuples
for determined transition from the current state.
The transition is determined, if it is the only transition allowed from the state.
Used internally for the validations.
iex> {:ok, transitions} =
...> Finitomata.Mermaid.parse(
...> "idle --> |to_s1| s1\n" <>
...> "s1 --> |to_s2| s2\n" <>
...> "s1 --> |to_s3| s3\n" <>
...> "s2 --> |to_s1| s3\n" <>
...> "s2 --> |ambiguous| s3\n" <>
...> "s2 --> |ambiguous| s4\n" <>
...> "s3 --> |determined| s3\n" <>
...> "s3 --> |determined| s4\n")
...> Finitomata.Transition.determined(transitions)
[s4: :__end__, s3: :determined, idle: :to_s1]
"""
@spec determined([t()]) :: [{state(), {event(), state()}}]
def determined(transitions) do
transitions
|> states(true)
|> Enum.reduce([], fn state, acc ->
transitions
|> allowed(from: state)
|> Enum.group_by(fn {state, _, event} -> {state, event} end)
|> Map.to_list()
|> case do
[{{^state, event}, [_ | _]}] -> [{state, event} | acc]
_ -> acc
end
end)
end
@doc ~S"""
Returns `{:ok, {event(), state()}}` tuple if there is a determined transition
from the current state, `:error` otherwise.
The transition is determined, if it is the only transition allowed from the state.
Used internally for the validations.
iex> {:ok, transitions} =
...> Finitomata.Mermaid.parse(
...> "idle --> |to_s1| s1\n" <>
...> "s1 --> |to_s2| s2\n" <>
...> "s1 --> |to_s3| s3\n" <>
...> "s2 --> |to_s3| s3")
...> Finitomata.Transition.determined(transitions, :s1)
:error
iex> Finitomata.Transition.determined(transitions, :s2)
{:ok, {:to_s3, :s3}}
iex> Finitomata.Transition.determined(transitions, :s3)
{:ok, {:__end__, :*}}
"""
@spec determined([t()], state()) :: {:ok, {event(), state()}} | :error
def determined(transitions, state) do
transitions
|> allowed(from: state)
|> case do
[{^state, target, event}] -> {:ok, {event, target}}
_ -> :error
end
end
@doc ~S"""
Returns keyword list of
`{Finitomata.Transition.state(), [Finitomata.Transition.event()]}` for transitions
which do not have a determined _to_ state.
Used internally for the validations.
iex> {:ok, transitions} =
...> Finitomata.Mermaid.parse(
...> "idle --> |to_s1| s1\n" <>
...> "s1 --> |to_s2| s2\n" <>
...> "s1 --> |to_s3| s3\n" <>
...> "s2 --> |to_s1| s3\n" <>
...> "s2 --> |ambiguous| s3\n" <>
...> "s2 --> |ambiguous| s4\n" <>
...> "s3 --> |determined| s3\n" <>
...> "s3 --> |determined| s4\n")
...> Finitomata.Transition.ambiguous(transitions)
[s3: {:determined, [:s3, :s4]}, s2: {:ambiguous, [:s3, :s4]}]
"""
@spec ambiguous([t()]) :: [{state(), {event(), state()}}]
def ambiguous(transitions) do
transitions
|> states()
|> Enum.reduce([], fn state, acc ->
transitions
|> allowed(from: state)
|> Enum.group_by(fn {state, _, event} -> {state, event} end)
|> Enum.filter(&match?({_, [_, _ | _]}, &1))
|> case do
[{{^state, event}, ambiguous}] ->
[{state, {event, Enum.map(ambiguous, &elem(&1, 1))}} | acc]
_ ->
acc
end
end)
end
@doc ~S"""
Returns the not ordered list of states, including or excluding
the starting and ending states `:*` according to the second argument.
iex> {:ok, transitions} =
...> Finitomata.PlantUML.parse("[*] --> s1 : foo\ns1 --> s2 : ok\ns2 --> [*] : ko")
...> Finitomata.Transition.states(transitions, true)
[:s1, :s2]
...> Finitomata.Transition.states(transitions)
[:*, :s1, :s2]
"""
@spec states([t()], boolean()) :: [state()]
def states(transitions, purge_internal \\ false)
def states(transitions, false) do
transitions
|> Enum.flat_map(fn %Transition{from: from, to: to} -> [from, to] end)
|> Enum.uniq()
end
def states(transitions, true), do: transitions |> states(false) |> Enum.reject(&(&1 == :*))
@doc ~S"""
Returns the not ordered list of events, including or excluding
the internal starting and ending transitions `:__start__` and `__end__`
according to the second argument.
iex> {:ok, transitions} =
...> Finitomata.Mermaid.parse("s1 --> |ok| s2\ns1 --> |ko| s3")
...> Finitomata.Transition.events(transitions, true)
[:ok, :ko]
...> Finitomata.Transition.events(transitions)
[:__start__, :ok, :ko, :__end__]
"""
@spec events([t()], boolean()) :: [state()]
def events(transitions, purge_internal \\ false)
def events(transitions, false) do
transitions
|> Enum.map(fn %Transition{event: event} -> event end)
|> Enum.uniq()
end
def events(transitions, true),
do: transitions |> events(false) |> Enum.reject(&(&1 in ~w|__start__ __end__|a))
@spec to_path(Enumerable.t([t()])) :: [Path.t()]
defp to_path(transitions) do
Enum.map(transitions, fn [%Transition{from: from} | _] = transitions ->
transitions
|> Enum.reduce([], fn
%Transition{event: event, to: to}, [] ->
[{event, to}]
%Transition{event: event, to: to, from: from}, [{_, from} | _] = acc ->
[{event, to} | acc]
end)
|> then(fn [{_, to} | _] = path -> %Path{from: from, to: to, path: Enum.reverse(path)} end)
end)
end
defimpl Inspect do
@moduledoc false
import Inspect.Algebra
def inspect(%Finitomata.Transition{from: from, to: to, event: event}, opts) do
case Keyword.get(opts.custom_options, :fancy, true) do
false ->
inner = [from: from, to: to, event: event]
concat(["#Finitomata.Transition<", to_doc(inner, opts), ">"])
_ ->
# ‹#{from} -- <#{event}> --> #{inspect(tos)}›
concat([
"↹‹",
to_doc(from, opts),
" ⇥ ",
to_doc(event, opts),
" ↦ ",
to_doc(to, opts),
"›"
])
end
end
end
end