lean4-htt/tests/playground/lowtech_expander.lean
2020-10-27 18:29:19 -07:00

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import init.lean.name
open Lean (Name NameMap)
def MacroScope := Nat
abbrev MacroScopes := List MacroScope
structure SourceInfo :=
(leading : Substring)
(pos : Nat)
(trailing : Substring)
def mkUniqIdRef : IO (IO.Ref Nat) :=
IO.mkRef 0
@[init mkUniqIdRef]
constant nextUniqId : IO.Ref Nat := default _
structure SyntaxNodeKind :=
(name : Name) (id : Nat)
instance : Inhabited SyntaxNodeKind :=
⟨{name := default _, id := default _}⟩
instance : BEq SyntaxNodeKind :=
⟨λ k₁ k₂, k₁.id == k₂.id⟩
def mkNameToKindTable : IO (IO.Ref (NameMap Nat)) :=
IO.mkRef {}
@[init mkNameToKindTable]
constant nameToKindTable : IO.Ref (NameMap Nat) := default _
def nextKind (k : Name) : IO SyntaxNodeKind :=
do m ← nameToKindTable.get,
when (m.contains k) (throw $ IO.userError ("Error kind '" ++ toString k ++ "' already exists")),
id ← nextUniqId.get,
nameToKindTable.set (m.insert k id),
nextUniqId.set (id+1),
pure { name := k, id := id }
def mkNullKind : IO SyntaxNodeKind := nextKind `null
@[init mkNullKind] constant nullKind : SyntaxNodeKind := default _
inductive Syntax
| missing
| node (kind : SyntaxNodeKind) (args : Array Syntax) (scopes : MacroScopes)
| atom (info : Option SourceInfo) (val : String)
| ident (info : Option SourceInfo) (rawVal : Substring) (val : Name) (preresolved : List Name) (scopes : MacroScopes)
instance : Inhabited Syntax :=
⟨Syntax.missing⟩
def SyntaxNodeKind.fix : SyntaxNodeKind → IO SyntaxNodeKind
| {name := n, ..} := do
m ← nameToKindTable.get,
match m.find n with
| some id := pure {name := n, id := id}
| none := throw $ IO.userError ("Error unknown Syntax kind '" ++ toString n ++ "'")
partial def Syntax.fixKinds : Syntax → IO Syntax
| (Syntax.node k args scopes) := do
k ← k.fix,
args ← args.mmap Syntax.fixKinds,
pure (Syntax.node k args scopes)
| other := pure other
inductive IsNode : Syntax → Prop
| mk (kind : SyntaxNodeKind) (args : Array Syntax) (scopes : MacroScopes) : IsNode (Syntax.node kind args scopes)
def SyntaxNode : Type := {s : Syntax // IsNode s }
def notIsNodeMissing (h : IsNode Syntax.missing) : False := match h with end
def notIsNodeAtom {info val} (h : IsNode (Syntax.atom info val)) : False := match h with end
def notIsNodeIdent {info rawVal val preresolved scopes} (h : IsNode (Syntax.ident info rawVal val preresolved scopes)) : False := match h with end
def unreachIsNodeMissing {α : Type} (h : IsNode Syntax.missing) : α := False.elim (notIsNodeMissing h)
def unreachIsNodeAtom {α : Type} {info val} (h : IsNode (Syntax.atom info val)) : α := False.elim (notIsNodeAtom h)
def unreachIsNodeIdent {α : Type} {info rawVal val preresolved scopes} (h : IsNode (Syntax.ident info rawVal val preresolved scopes)) : α := False.elim (match h with end)
@[inline] def toSyntaxNode {α : Type} (s : Syntax) (base : α) (fn : SyntaxNode → α) : α :=
match s with
| Syntax.node kind args scopes := fn ⟨Syntax.node kind args scopes, IsNode.mk kind args scopes⟩
| other := base
@[inline] def toSyntaxNodeOf {α : Type} (kind : SyntaxNodeKind) (s : Syntax) (base : α) (fn : SyntaxNode → α) : α :=
match s with
| Syntax.node k args scopes :=
if k == kind then fn ⟨Syntax.node kind args scopes, IsNode.mk kind args scopes⟩
else base
| other := base
@[inline] def mkAtom (val : String) : Syntax :=
Syntax.atom none val
def mkOptionSomeKind : IO SyntaxNodeKind := nextKind `some
@[init mkOptionSomeKind] constant optionSomeKind : SyntaxNodeKind := default _
def mkOptionNoneKind : IO SyntaxNodeKind := nextKind `none
@[init mkOptionSomeKind] constant optionNoneKind : SyntaxNodeKind := default _
def mkManyKind : IO SyntaxNodeKind := nextKind `many
@[init mkManyKind] constant manyKind : SyntaxNodeKind := default _
def mkHoleKind : IO SyntaxNodeKind := nextKind `hole
@[init mkHoleKind] constant holeKind : SyntaxNodeKind := default _
def mkNotKind : IO SyntaxNodeKind := nextKind `not
@[init mkNotKind] constant notKind : SyntaxNodeKind := default _
def mkIfKind : IO SyntaxNodeKind := nextKind `if
@[init mkIfKind] constant ifKind : SyntaxNodeKind := default _
def mkLetKind : IO SyntaxNodeKind := nextKind `let
@[init mkLetKind] constant letKind : SyntaxNodeKind := default _
def mkLetLhsIdKind : IO SyntaxNodeKind := nextKind `letLhsId
@[init mkLetLhsIdKind] constant letLhsIdKind : SyntaxNodeKind := default _
def mkLetLhsPatternKind : IO SyntaxNodeKind := nextKind `letLhsPattern
@[init mkLetLhsPatternKind] constant letLhsPatternKind : SyntaxNodeKind := default _
@[inline] def withArgs {α : Type} (n : SyntaxNode) (fn : Array Syntax → α) : α :=
match n with
| ⟨Syntax.node _ args _, _⟩ := fn args
| ⟨Syntax.missing, h⟩ := unreachIsNodeMissing h
| ⟨Syntax.atom _ _, h⟩ := unreachIsNodeAtom h
| ⟨Syntax.ident _ _ _ _ _, h⟩ := unreachIsNodeIdent h
@[inline] def updateArgs (n : SyntaxNode) (fn : Array Syntax → Array Syntax) : Syntax :=
match n with
| ⟨Syntax.node kind args scopes, _⟩ := Syntax.node kind (fn args) scopes
| ⟨Syntax.missing, h⟩ := unreachIsNodeMissing h
| ⟨Syntax.atom _ _, h⟩ := unreachIsNodeAtom h
| ⟨Syntax.ident _ _ _ _ _, h⟩ := unreachIsNodeIdent h
@[inline] def mkNotAux (tk : Syntax) (c : Syntax) : Syntax :=
Syntax.node notKind [tk, c].toArray []
@[inline] def mkNot (c : Syntax) : Syntax :=
mkNotAux (mkAtom "not") c
@[inline] def withNot {α : Type} (n : SyntaxNode) (fn : Syntax → α) : α :=
withArgs n $ λ args, fn (args.get 1)
@[inline] def updateNot (src : SyntaxNode) (c : Syntax) : Syntax :=
updateArgs src $ λ args, args.set 1 c
@[inline] def mkIfAux (ifTk : Syntax) (condNode : Syntax) (thenTk : Syntax) (thenNode : Syntax) (elseTk : Syntax) (elseNode: Syntax) : Syntax :=
Syntax.node ifKind [ifTk, condNode, thenTk, thenNode, elseTk, elseNode].toArray []
@[inline] def mkIf (c t e : Syntax) : Syntax :=
mkIfAux (mkAtom "if") c (mkAtom "then") t (mkAtom "else") e
@[inline] def withIf {α : Type} (n : SyntaxNode) (fn : Syntax → Syntax → Syntax → α) : α :=
withArgs n $ λ args, fn (args.get 1) (args.get 3) (args.get 5)
@[inline] def updateIf (src : SyntaxNode) (c t e : Syntax) : Syntax :=
updateArgs src $ λ args,
let args := args.set 1 c in
let args := args.set 3 t in
let args := args.set 5 e in
args
@[inline] def mkLetAux (letTk : Syntax) (lhs : Syntax) (assignTk : Syntax) (val : Syntax) (inTk : Syntax) (body : Syntax) : Syntax :=
Syntax.node letKind [letTk, lhs, assignTk, val, inTk, body].toArray []
@[inline] def mkLet (lhs : Syntax) (val : Syntax) (body : Syntax) : Syntax :=
mkLetAux (mkAtom "let") lhs (mkAtom ":=") val (mkAtom "in") body
@[inline] def withLet {α : Type} (n : SyntaxNode) (fn : Syntax → Syntax → Syntax → α) : α :=
withArgs n $ λ args, fn (args.get 1) (args.get 3) (args.get 5)
@[inline] def updateLet (src : SyntaxNode) (lhs val body : Syntax) : Syntax :=
updateArgs src $ λ args,
let args := args.set 1 lhs in
let args := args.set 3 val in
let args := args.set 5 body in
args
@[inline] def mkLetLhsId (id : Syntax) (binders : Syntax) (type : Syntax) : Syntax :=
Syntax.node letLhsIdKind [id, binders, type].toArray []
@[inline] def withLetLhsId {α : Type} (n : SyntaxNode) (fn : Syntax → Syntax → Syntax → α) : α :=
withArgs n $ λ args, fn (args.get 0) (args.get 1) (args.get 2)
@[inline] def updateLhsId (src : SyntaxNode) (id binders type : Syntax) : Syntax :=
updateArgs src $ λ args,
let args := args.set 0 id in
let args := args.set 1 binders in
let args := args.set 2 type in
args
@[inline] def mkLetLhsPattern (pattern : Syntax) : Syntax :=
Syntax.node letLhsPatternKind [pattern].toArray []
@[inline] def withLetLhsPattern {α : Type} (n : SyntaxNode) (fn : Syntax → α) : α :=
withArgs n $ λ args, fn (args.get 0)
@[inline] def withOptionSome {α : Type} (n : SyntaxNode) (fn : Syntax → α) : α :=
withArgs n $ λ args, fn (args.get 0)
def Syntax.getNumChildren (n : Syntax) : Nat :=
match n with
| Syntax.node _ args _ := args.size
| _ := 0
def hole : Syntax := Syntax.node holeKind ∅ []
def mkOptionSome (s : Syntax) := Syntax.node optionSomeKind [s].toArray []
abbrev FrontendConfig := Bool -- placeholder
abbrev Message := String -- placeholder
abbrev TransformM := ReaderT FrontendConfig $ ExceptT Message Id
abbrev Transformer := SyntaxNode → TransformM (Option Syntax)
def noExpansion : TransformM (Option Syntax) := pure none
@[inline] def Syntax.case {α : Type} (n : Syntax) (k : SyntaxNodeKind) (fn : SyntaxNode → TransformM (Option α)) : TransformM (Option α) :=
match n with
| Syntax.node k' args s := if k == k' then fn ⟨Syntax.node k' args s, IsNode.mk _ _ _⟩ else pure none
| _ := pure none
@[inline] def TransformM.orCase {α : Type} (x y : TransformM (Option α)) : TransformM (Option α) :=
λ cfg, match x cfg with
| Except.ok none := y cfg
| other := other
infix `<?>`:2 := TransformM.orCase
set_option pp.implicit true
set_option trace.compiler.boxed true
def flipIf : Transformer :=
λ n, withIf n $ λ c t e,
c.case notKind $ λ c, withNot c $ λ c',
pure $ updateIf n c' e t
def letTransformer : Transformer :=
λ n, withLet n $ λ lhs val body,
(lhs.case letLhsIdKind $ λ lhs, withLetLhsId lhs $ λ id binders type,
if binders.getNumChildren == 0 then
type.case optionNoneKind $ λ _,
let newLhs := updateLhsId lhs id binders (mkOptionSome hole) in
pure (some (updateLet n newLhs val body))
else
-- TODO
noExpansion)
<?>
(lhs.case letLhsPatternKind $ λ lhs,
-- TODO
noExpansion)
@[inline] def Syntax.isNode {α : Type} (n : Syntax) (fn : SyntaxNodeKind → SyntaxNode → TransformM (Option α)) : TransformM (Option α) :=
match n with
| Syntax.node k args s := fn k ⟨Syntax.node k args s, IsNode.mk _ _ _⟩
| other := pure none
/- Version without using the combinator <?>. -/
def letTransformer' : Transformer :=
λ n, withLet n $ λ lhs val body,
lhs.isNode $ λ k lhs, -- lhs is now a SyntaxNode
if k == letLhsIdKind then withLetLhsId lhs $ λ id binders type,
if binders.getNumChildren == 0 then
type.case optionNoneKind $ λ _,
let newLhs := updateLhsId lhs id binders (mkOptionSome hole) in
pure (some (updateLet n newLhs val body))
else
-- TODO
noExpansion
else withLetLhsPattern lhs $ λ pattern,
-- TODO
noExpansion