Theorem: Regex.VM.captureNext_spec.go
Proof state before:
nfa : NFA
saveSize : ℕ
it : String.Iterator
current next : SparseSet nfa.nodes.size
saveSlots : Vec (Array (Option String.Pos)) nfa.nodes.size
lastMatch matched : Option (Array (Option String.Pos))
haystack : String
inv : captureNext.go.Inv nfa it haystack current lastMatch
v : it.Valid
eqs : haystack = it.toString
hemp : next.isEmpty = true
atEnd : ¬it.atEnd = true
h✝ : ¬(current.isEmpty && lastMatch.isSome) = true
hm : ¬lastMatch.isNone = true
stepped : Option (Array (Option String.Pos)) × SparseSet nfa.nodes.size × Vec (Array (Option String.Pos)) nfa.nodes.size
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots'' : Vec (Array (Option String.Pos)) nfa.nodes.size
hs : eachStepChar nfa it.curr it.next.i current next saveSlots = (matched', next', saveSlots'')
h :
  captureNext.go nfa saveSize it.next next' current.clear saveSlots'' (HOrElse.hOrElse matched' fun x => lastMatch) =
    matched
currentPath' :
  ∀ k ∈ next',
    ∃ s l m r,
      Substring.ValidFor l m r s ∧ String.Iterator.ValidFor (m.reverse ++ l.reverse) r it.next ∧ nfa.reaches k m
⊢ matched.isSome = true →
    ∃ s l m r,
      Substring.ValidFor l m r s ∧ haystack = { data := l ++ m ++ r } ∧ ∃ i, nfa.reaches i m ∧ nfa[i] = Node.done
Tactic:
have acceptOfLastMatch' (h : (matched' <|> lastMatch).isSome) :
  ∃ (s : Substring) (l m r : List Char), s.ValidFor l m r ∧ haystack = ⟨l ++ m ++ r⟩ ∧ ∃ i, nfa.reaches i m ∧ nfa[i] = .done := by
  cases matched' with
  | none =>
    simp at h
    exact eqs ▸ inv.acceptOfLastMatch h
  | some =>
    have ⟨i, hi, hdone⟩ := (eachStepChar_spec.mem_done_iff hs hemp).mpr rfl
    have ⟨s, l, m, r, sv, iv, reaches⟩ := currentPath' i hi
    have eqs' := iv.toString
    simp [String.Iterator.next, List.reverseAux_eq] at eqs'
    exact ⟨s, l, m, r, sv, by simp [eqs, eqs'], ⟨i, reaches, hdone⟩⟩
Proof state after:
nfa : NFA
saveSize : ℕ
it : String.Iterator
current next : SparseSet nfa.nodes.size
saveSlots : Vec (Array (Option String.Pos)) nfa.nodes.size
lastMatch matched : Option (Array (Option String.Pos))
haystack : String
inv : captureNext.go.Inv nfa it haystack current lastMatch
v : it.Valid
eqs : haystack = it.toString
hemp : next.isEmpty = true
atEnd : ¬it.atEnd = true
h✝ : ¬(current.isEmpty && lastMatch.isSome) = true
hm : ¬lastMatch.isNone = true
stepped : Option (Array (Option String.Pos)) × SparseSet nfa.nodes.size × Vec (Array (Option String.Pos)) nfa.nodes.size
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots'' : Vec (Array (Option String.Pos)) nfa.nodes.size
hs : eachStepChar nfa it.curr it.next.i current next saveSlots = (matched', next', saveSlots'')
h :
  captureNext.go nfa saveSize it.next next' current.clear saveSlots'' (HOrElse.hOrElse matched' fun x => lastMatch) =
    matched
currentPath' :
  ∀ k ∈ next',
    ∃ s l m r,
      Substring.ValidFor l m r s ∧ String.Iterator.ValidFor (m.reverse ++ l.reverse) r it.next ∧ nfa.reaches k m
acceptOfLastMatch' :
  (HOrElse.hOrElse matched' fun x => lastMatch).isSome = true →
    ∃ s l m r,
      Substring.ValidFor l m r s ∧ haystack = { data := l ++ m ++ r } ∧ ∃ i, nfa.reaches i m ∧ nfa[i] = Node.done
⊢ matched.isSome = true →
    ∃ s l m r,
      Substring.ValidFor l m r s ∧ haystack = { data := l ++ m ++ r } ∧ ∃ i, nfa.reaches i m ∧ nfa[i] = Node.done