223 lines
8.3 KiB
Text
223 lines
8.3 KiB
Text
/-
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Copyright (c) 2018 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Sebastian Ullrich
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-/
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prelude
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import init.lean.name init.lean.parser.parsec
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namespace Lean
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namespace Parser
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--TODO(Sebastian): move
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structure Substring :=
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(start : String.OldIterator)
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(stop : String.OldIterator)
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structure SourceInfo :=
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/- Will be inferred after parsing by `Syntax.updateLeading`. During parsing,
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it is not at all clear what the preceding token was, especially with backtracking. -/
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(leading : Substring)
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(pos : Parsec.Position)
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(trailing : Substring)
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structure SyntaxAtom :=
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(info : Option SourceInfo := none) (val : String)
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/-- A simple wrapper that should remind you to use the static Declaration instead
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of hard-coding the Node Name. -/
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structure SyntaxNodeKind :=
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-- should be equal to the Name of the Declaration this structure instance was bound to
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(name : Name)
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/-- Signifies ambiguous Syntax to be disambiguated by the Elaborator. Should have at least two children.
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This Node kind is special-cased by `Syntax.reprint` since its children's outputs should not be concatenated. -/
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@[pattern] def choice : SyntaxNodeKind := ⟨`Lean.Parser.choice⟩
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/-- A nondescriptive kind that can be used for merely grouping Syntax trees into a Node.
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This Node kind is special-cased by `Syntax.Format` to be printed as brackets `[...]` without a Node kind. -/
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@[pattern] def noKind : SyntaxNodeKind := ⟨`Lean.Parser.noKind⟩
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/-- A hygiene marker introduced by a macro expansion. -/
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@[derive DecidableEq HasFormat]
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def MacroScope := Nat
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abbrev macroScopes := List MacroScope
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/-
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Parsers create `SyntaxNode`'s with the following properties (see implementation of `Combinators.Node`):
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- If `args` contains a `Syntax.missing`, then all subsequent elements are also `Syntax.missing`.
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- The first argument in `args` is not `Syntax.missing`
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Remark: We do create `SyntaxNode`'s with an Empty `args` field (e.g. for representing `Option.none`).
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-/
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structure SyntaxNode (Syntax : Type) :=
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(kind : SyntaxNodeKind)
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(args : List Syntax)
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-- Lazily propagated scopes. Scopes are pushed inwards when a Node is destructed via `Syntax.asNode`,
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-- until an ident or an atom (in which the scopes vanish) is reached.
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-- Scopes are stored in a stack with the most recent Scope at the top.
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(scopes : macroScopes := [])
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structure SyntaxIdent :=
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(info : Option SourceInfo := none)
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(rawVal : Substring)
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(val : Name)
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/- A List of overloaded, global names that this identifier could have referred to in the lexical context
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where it was parsed.
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If the identifier does not resolve to a local binding, it should instead resolve to one of
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these preresolved constants. -/
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(preresolved : List Name := [])
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(scopes : macroScopes := [])
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inductive Syntax
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| atom (val : SyntaxAtom)
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| ident (val : SyntaxIdent)
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-- note: use `Syntax.asNode` instead of matching against this Constructor so that
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-- macro scopes are propagated
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| rawNode (val : SyntaxNode Syntax)
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| missing
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instance : Inhabited Syntax :=
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⟨Syntax.missing⟩
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def Substring.toString (s : Substring) : String :=
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s.start.extract s.stop
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def Substring.ofString (s : String) : Substring :=
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⟨s.mkOldIterator, s.mkOldIterator.toEnd⟩
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instance Substring.HasToString : HasToString Substring :=
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⟨Substring.toString⟩
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-- TODO(Sebastian): exhaustively argue why (if?) this is correct
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-- The basic idea is List concatenation with elimination of adjacent identical scopes
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def macroScopes.flip : macroScopes → macroScopes → macroScopes
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| ys (x::xs) := match macroScopes.flip ys xs with
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| y::ys := if x = y then ys else x::y::ys
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| [] := [x]
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| ys [] := ys
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namespace Syntax
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open Lean.Format
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def flipScopes (scopes : macroScopes) : Syntax → Syntax
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| (Syntax.ident n) := Syntax.ident {n with scopes := n.scopes.flip scopes}
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| (Syntax.rawNode n) := Syntax.rawNode {n with scopes := n.scopes.flip scopes}
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| stx := stx
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def mkNode (kind : SyntaxNodeKind) (args : List Syntax) :=
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Syntax.rawNode { kind := kind, args := args }
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/-- Match against `Syntax.rawNode`, propagating lazy macro scopes. -/
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def asNode : Syntax → Option (SyntaxNode Syntax)
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| (Syntax.rawNode n) := some {n with args := n.args.map (flipScopes n.scopes), scopes := []}
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| _ := none
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protected def list (args : List Syntax) :=
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mkNode noKind args
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def kind : Syntax → Option SyntaxNodeKind
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| (Syntax.rawNode n) := some n.kind
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| _ := none
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def isOfKind (k : SyntaxNodeKind) : Syntax → Bool
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| (Syntax.rawNode n) := k.name = n.kind.name
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| _ := false
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section
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variables {m : Type → Type} [Monad m] (r : Syntax → m (Option Syntax))
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local attribute [instance] monadInhabited
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partial def mreplace : Syntax → m Syntax
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| stx@(rawNode n) := do
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o ← r stx,
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match o with
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| some stx' := pure stx'
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| none := do args' ← n.args.mmap mreplace, pure $ rawNode {n with args := args'}
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| stx := do
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o ← r stx,
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pure $ o.getOrElse stx
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def replace := @mreplace Id _
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end
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/- Remark: the State `String.Iterator` is the `SourceInfo.trailing.stop` of the previous token,
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or the beginning of the String. -/
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private def updateLeadingAux : Syntax → State String.OldIterator (Option Syntax)
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| (atom a@{info := some info, ..}) := do
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last ← get,
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set info.trailing.stop,
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pure $ some $ atom {a with info := some {info with leading := ⟨last, last.nextn (info.pos - last.offset)⟩}}
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| (ident id@{info := some info, ..}) := do
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last ← get,
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set info.trailing.stop,
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pure $ some $ ident {id with info := some {info with leading := ⟨last, last.nextn (info.pos - last.offset)⟩}}
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| _ := pure none
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/-- Set `SourceInfo.leading` according to the trailing stop of the preceding token.
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The Result is a round-tripping Syntax tree IF, in the input Syntax tree,
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* all leading stops, atom contents, and trailing starts are correct
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* trailing stops are between the trailing start and the next leading stop.
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Remark: after parsing all `SourceInfo.leading` fields are Empty.
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The Syntax argument is the output produced by the Parser for `source`.
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This Function "fixes" the `source.leanding` field.
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Note that, the `SourceInfo.trailing` fields are correct.
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The implementation of this Function relies on this property. -/
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def updateLeading (source : String) : Syntax → Syntax :=
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λ stx, Prod.fst $ (mreplace updateLeadingAux stx).run source.mkOldIterator
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/-- Retrieve the left-most leaf's info in the Syntax tree. -/
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partial def getHeadInfo : Syntax → Option SourceInfo
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| (atom a) := a.info
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| (ident id) := id.info
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| (rawNode n) := n.args.foldr (λ s r, getHeadInfo s <|> r) none
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| _ := none
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def getPos (stx : Syntax) : Option Parsec.Position :=
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do i ← stx.getHeadInfo,
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pure i.pos
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def reprintAtom : SyntaxAtom → String
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| ⟨some info, s⟩ := info.leading.toString ++ s ++ info.trailing.toString
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| ⟨none, s⟩ := s
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partial def reprint : Syntax → Option String
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| (atom ⟨some info, s⟩) := pure $ info.leading.toString ++ s ++ info.trailing.toString
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| (atom ⟨none, s⟩) := pure s
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| (ident id@{info := some info, ..}) := pure $ info.leading.toString ++ id.rawVal.toString ++ info.trailing.toString
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| (ident id@{info := none, ..}) := pure id.rawVal.toString
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| (rawNode n) :=
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if n.kind.name = choice.name then match n.args with
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-- should never happen
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| [] := failure
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-- check that every choice prints the same
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| n::ns := do
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s ← reprint n,
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ss ← ns.mmap reprint,
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guard $ ss.all (= s),
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pure s
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else String.join <$> n.args.mmap reprint
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| missing := ""
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protected partial def format : Syntax → Format
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| (atom ⟨_, s⟩) := fmt $ repr s
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| (ident id) :=
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let scopes := id.preresolved.map fmt ++ id.scopes.reverse.map fmt in
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let scopes := match scopes with [] := fmt "" | _ := bracket "{" (joinSep scopes ", ") "}" in
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fmt "`" ++ fmt id.val ++ scopes
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| stx@(rawNode n) :=
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let scopes := match n.scopes with [] := fmt "" | _ := bracket "{" (joinSep n.scopes.reverse ", ") "}" in
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if n.kind.name = `Lean.Parser.noKind then sbracket $ scopes ++ joinSep (n.args.map format) line
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else let shorterName := n.kind.name.replacePrefix `Lean.Parser Name.anonymous
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in paren $ joinSep ((fmt shorterName ++ scopes) :: n.args.map format) line
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| missing := "<missing>"
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instance : HasFormat Syntax := ⟨Syntax.format⟩
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instance : HasToString Syntax := ⟨toString ∘ fmt⟩
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end Syntax
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end Parser
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end Lean
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