6d926c7989
see #371 This commit does not implement all features discussed in this issue. It has implemented it as a macro expansion. Thus, the following is accepted ```lean inductive StrOrNum where | S (s : String) | I (i : Int) def StrOrNum.asString (x : StrOrNum) := match x with | I a | S a => toString a ``` It may confuse the Lean LSP server. The `a` on `toString` shows the information for the first alternative after expansion (i.e., `a` is an `Int`). After expansion, we have ``` def StrOrNum.asString (x : StrOrNum) := match x with | I a => toString a | S a => toString a ```
57 lines
1.6 KiB
Text
57 lines
1.6 KiB
Text
/-
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Copyright (c) 2021 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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Authors: Leonardo de Moura
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-/
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import Lean.Parser.Term
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namespace Lean.Elab.Term
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/-
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Recall that
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```
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def typeSpec := leading_parser " : " >> termParser
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def optType : Parser := optional typeSpec
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```
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-/
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def expandOptType (ref : Syntax) (optType : Syntax) : Syntax :=
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if optType.isNone then
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mkHole ref
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else
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optType[0][1]
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open Lean.Parser.Term
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/- Helper function for `expandEqnsIntoMatch` -/
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def getMatchAltsNumPatterns (matchAlts : Syntax) : Nat :=
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let alt0 := matchAlts[0][0]
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let pats := alt0[1][0].getSepArgs
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pats.size
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/--
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Expand a match alternative such as `| 0 | 1 => rhs` to an array containing `| 0 => rhs` and `| 1 => rhs`.
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-/
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def expandMatchAlt (stx : Syntax) : MacroM (Array Syntax) :=
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match stx with
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| `(matchAltExpr| | $[$patss]|* => $rhs) =>
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if patss.size ≤ 1 then
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return #[stx]
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else
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patss.mapM fun pats => let pats := #[pats]; `(matchAltExpr| | $[$pats]|* => $rhs)
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| _ => return #[stx]
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def shouldExpandMatchAlt (matchAlt : Syntax) : Bool :=
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match matchAlt with
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| `(matchAltExpr| | $[$patss]|* => $rhs) => patss.size > 1
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| _ => false
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def expandMatchAlts? (stx : Syntax) : MacroM (Option Syntax) := do
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match stx with
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| `(match $[$gen]? $[$motive]? $discrs,* with $alts:matchAlt*) =>
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if alts.any shouldExpandMatchAlt then
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let alts ← alts.foldlM (init := #[]) fun alts alt => return alts ++ (← expandMatchAlt alt)
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`(match $[$gen]? $[$motive]? $discrs,* with $alts:matchAlt*)
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else
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return none
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| _ => return none
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end Lean.Elab.Term
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