69 lines
2.5 KiB
Text
69 lines
2.5 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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Macro expander for the Lean language
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-/
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prelude
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import init.lean.parser.module
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namespace lean
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namespace expander
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open parser
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open parser.term
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open parser.command
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open parser.command.notation_spec
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@[derive monad]
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def transform_m := option_t $ except message
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abbreviation transformer := syntax → transform_m syntax
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section
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local attribute [reducible] transform_m
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instance coe_option_transform_m {α : Type} : has_coe (option α) (transform_m α) :=
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⟨λ o, match o with some a := pure a | none := failure⟩
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end
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def mixfix.transform (stx : tysyntax mixfix.view) : transform_m (tysyntax notation.view) :=
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do v ← view stx,
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-- TODO: reserved token case
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notation_symbol.view.quoted quoted ← view v.symbol,
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quoted ← view quoted,
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prec ← view quoted.prec,
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-- `notation` allows more syntax after `:` than mixfix commands, so we have to do a small conversion
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let prec_to_action : precedence.view → action.view :=
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λ prec, {action := review $ action_kind.view.prec prec.prec, ..prec},
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k ← view v.kind,
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let (spec, term) := match k : _ → (notation_spec.view × syntax) with
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| mixfix.kind.view.prefix _ :=
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let b : tysyntax parser.ident.view := review {part := review $ ident_part.view.default "b"} in
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(notation_spec.view.rules $ review {
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rules := review [review {
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symbol := v.symbol,
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transition := review $ some $ review $ transition.view.arg $ review {
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id := b,
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action := review $ do prec ← prec, prec ← view prec, pure $ review $ prec_to_action prec}}]},
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review {lambda.view . op := review lambda_op.view.«λ», binders := review [review $
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binder.view.unbracketed $ review {
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ids := review [review $ binder_id.view.id $ review {id := b}]}
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],
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body := review_as app.view {fn := v.term, arg := b}})
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| _ := sorry,
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pure $ review {spec := review spec, term := term}
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local attribute [instance] name.has_lt_quick
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-- TODO(Sebastian): replace with attribute
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def transformers : rbmap name transformer (<) := rbmap.from_list [
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(mixfix.name, mixfix.transform)
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] _
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def expand (stx : syntax) : except message syntax :=
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--TODO(Sebastian): recursion, hygiene, error messages
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do syntax.node {kind := some k, ..} ← pure stx | pure stx,
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some t ← pure $ transformers.find k.name | pure stx,
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flip option.get_or_else stx <$> t stx
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end expander
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end lean
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