lean4-htt/src/Lean/InternalExceptionId.lean
2020-12-22 18:10:20 -08:00

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/-
Copyright (c) 2020 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
namespace Lean
structure InternalExceptionId where
idx : Nat := 0
deriving Inhabited, BEq
builtin_initialize internalExceptionsRef : IO.Ref (Array Name) ← IO.mkRef #[]
def registerInternalExceptionId (name : Name) : IO InternalExceptionId := do
let exs ← internalExceptionsRef.get
if exs.contains name then throw $ IO.userError s!"invalid internal exception id, '{name}' has already been used"
let nextIdx := exs.size
internalExceptionsRef.modify fun a => a.push name
pure { idx := nextIdx }
def InternalExceptionId.toString (id : InternalExceptionId) : String :=
s!"internal exception #{id.idx}"
def InternalExceptionId.getName (id : InternalExceptionId) : IO Name := do
let exs ← internalExceptionsRef.get
let i := id.idx;
if h : i < exs.size then
pure $ exs.get ⟨i, h⟩
else
throw $ IO.userError "invalid internal exception id"
end Lean