lean4-htt/src/Lean/Elab/Tactic/Cache.lean
2022-04-17 13:47:28 -07:00

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/-
Copyright (c) 2022 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
import Lean.Elab.Tactic.Basic
namespace Lean.Elab.Tactic
open Meta
private def equivMVarDecl (d₁ d₂ : MetavarDecl) : Bool :=
d₁.type == d₂.type
-- The following additional check does not seem to be necessary
/-
&&
d₁.lctx.decls.size == d₂.lctx.decls.size &&
Id.run do
for i in [:d₁.lctx.decls.size] do
match d₁.lctx.decls[i], d₂.lctx.decls[i] with
| some localDecl₁, some localDecl₂ => if localDecl₁.type != localDecl₂.type then return false
| none, none => pure ()
| _, _ => return false
return true
-/
register_builtin_option tactic.dbg_cache : Bool := {
defValue := false
group := "tactic"
descr := "enable tactic cache debug messages (remark: they are sent to the standard error)"
}
private def dbg_cache (msg : String) : TacticM Unit := do
if tactic.dbg_cache.get (← getOptions) then
dbg_trace msg
private def dbg_cache' (cacheRef : IO.Ref Cache) (pos : String.Pos) (mvarId : MVarId) (msg : String) : TacticM Unit := do
if tactic.dbg_cache.get (← getOptions) then
let {line, column} := (← getFileMap).toPosition pos
dbg_trace "{msg}, cache size: {(← cacheRef.get).pre.size}, line: {line}, column: {column}, contains entry: {(← cacheRef.get).pre.find? { mvarId, pos } |>.isSome}"
private def findCache? (cacheRef : IO.Ref Cache) (mvarId : MVarId) (stx : Syntax) (pos : String.Pos) : TacticM (Option Snapshot) := do
let some s := (← cacheRef.get).pre.find? { mvarId, pos } | do dbg_cache "cache key not found"; return none
let mvarDecl ← getMVarDecl mvarId
let some mvarDeclOld := s.meta.mctx.findDecl? mvarId | return none
if equivMVarDecl mvarDecl mvarDeclOld then
if stx == s.stx then
return some s
else
dbg_cache "syntax is different"
return none
else
dbg_cache "cached state is not compatible"
return none
@[builtinTactic checkpoint] def evalCheckpoint : Tactic := fun stx =>
focus do
let mvarId ← getMainGoal
let some cacheRef := (← readThe Term.Context).tacticCache? | evalTactic stx[1]
let some pos := stx.getPos? | evalTactic stx[1]
match (← findCache? cacheRef mvarId stx[1] pos) with
| some s =>
cacheRef.modify fun { pre, post } => { pre, post := post.insert { mvarId, pos } s }
set s.core
set s.meta
set s.term
set s.tactic
dbg_cache' cacheRef pos mvarId "cache hit"
| none =>
evalTactic stx[1]
let s := {
stx := stx[1]
core := (← getThe Core.State)
meta := (← getThe Meta.State)
term := (← getThe Term.State)
tactic := (← get)
}
dbg_cache' cacheRef pos mvarId "cache miss"
cacheRef.modify fun { pre, post } => { pre, post := post.insert { mvarId, pos } s }
end Lean.Elab.Tactic