lean4-htt/src/Lean/Compiler/CSimpAttr.lean
2024-02-18 14:55:17 -08:00

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/-
Copyright (c) 2021 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import Lean.ScopedEnvExtension
import Lean.Util.Recognizers
import Lean.Util.ReplaceExpr
namespace Lean.Compiler
namespace CSimp
structure Entry where
fromDeclName : Name
toDeclName : Name
thmName : Name
deriving Inhabited
structure State where
map : SMap Name Name := {}
thmNames : SSet Name := {}
deriving Inhabited
def State.switch : State → State
| { map, thmNames } => { map := map.switch, thmNames := thmNames.switch }
builtin_initialize ext : SimpleScopedEnvExtension Entry State ←
registerSimpleScopedEnvExtension {
initial := {}
addEntry := fun { map, thmNames } { fromDeclName, toDeclName, thmName } => { map := map.insert fromDeclName toDeclName, thmNames := thmNames.insert thmName }
finalizeImport := fun s => s.switch
}
private def isConstantReplacement? (declName : Name) : CoreM (Option Entry) := do
let info ← getConstInfo declName
match info.type.eq? with
| some (_, Expr.const fromDeclName us .., Expr.const toDeclName vs ..) =>
if us == vs then
return some { fromDeclName, toDeclName, thmName := declName }
else
return none
| _ => return none
def add (declName : Name) (kind : AttributeKind) : CoreM Unit := do
if let some entry ← isConstantReplacement? declName then
ext.add entry kind
else
throwError "invalid 'csimp' theorem, only constant replacement theorems (e.g., `@f = @g`) are currently supported."
builtin_initialize
registerBuiltinAttribute {
name := `csimp
descr := "simplification theorem for the compiler"
add := fun declName stx attrKind => do
Attribute.Builtin.ensureNoArgs stx
discard <| add declName attrKind
}
@[export lean_csimp_replace_constants]
def replaceConstants (env : Environment) (e : Expr) : Expr :=
let s := ext.getState env
e.replace fun e =>
if e.isConst then
match s.map.find? e.constName! with
| some declNameNew => some (mkConst declNameNew e.constLevels!)
| none => none
else
none
end CSimp
def hasCSimpAttribute (env : Environment) (declName : Name) : Bool :=
CSimp.ext.getState env |>.thmNames.contains declName
end Lean.Compiler