40640b85bd
It was failing to parse
```
def f2 (x : Nat) : IO Nat := do {
let y := 1;
if x > 0 then
y := y + 1;
IO.println y
}
```
cc @Kha
100 lines
4.1 KiB
Text
100 lines
4.1 KiB
Text
/-
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Copyright (c) 2020 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
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namespace Parser
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@[init] def regBuiltinDoElemParserAttr : IO Unit :=
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registerBuiltinParserAttribute `builtinDoElemParser `doElem
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@[init] def regDoElemParserAttribute : IO Unit :=
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registerBuiltinDynamicParserAttribute `doElemParser `doElem
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@[inline] def doElemParser (rbp : Nat := 0) : Parser :=
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categoryParser `doElem rbp
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namespace Term
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def leftArrow : Parser := unicodeSymbol " ← " " <- "
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@[builtinTermParser] def liftMethod := parser!:0 leftArrow >> termParser
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def doSeqIndent := many1Indent $ doElemParser >> optional "; "
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def doSeqBracketed := parser! "{" >> withoutPosition (many1 (doElemParser >> optional "; ")) >> "}"
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def doSeq := doSeqBracketed <|> doSeqIndent
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@[builtinDoElemParser] def doLet := parser! "let " >> letDecl
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@[builtinDoElemParser] def doLetRec := parser! group ("let " >> nonReservedSymbol "rec ") >> letRecDecls
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def doId := parser! «try» (ident >> optType >> leftArrow) >> termParser
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def doPat := parser! «try» (termParser >> leftArrow) >> termParser >> optional (" | " >> termParser)
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@[builtinDoElemParser] def doLetArrow := parser! "let " >> (doId <|> doPat)
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@[builtinDoElemParser] def doReassign := parser! letIdDecl <|> letPatDecl
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@[builtinDoElemParser] def doReassignArrow := doId <|> doPat
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@[builtinDoElemParser] def doHave := parser! "have " >> Term.haveDecl
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/-
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In `do` blocks, we support `if` without an `else`. Thus, we use indentation to prevent examples such as
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```
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if c_1 then
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if c_2 then
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action_1
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else
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action_2
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```
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from being parsed as
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```
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if c_1 then {
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if c_2 then {
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action_1
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} else {
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action_2
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}
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}
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```
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We also have special support for `else if` because we don't want to write
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```
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if c_1 then
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action_1
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else if c_2 then
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action_2
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else
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action_3
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```
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-/
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@[builtinDoElemParser] def doIf := parser! withPosition $
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"if " >> optIdent >> termParser >> " then " >> doSeq
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>> many (checkColGe "'else if' in 'do' must be indented" >> «try» (" else " >> " if ") >> optIdent >> termParser >> " then " >> doSeq)
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>> optional (checkColGe "'else' in 'do' must be indented" >> " else " >> doSeq)
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@[builtinDoElemParser] def doUnless := parser! "unless " >> termParser >> "do " >> doSeq
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@[builtinDoElemParser] def doFor := parser! "for " >> termParser >> " in " >> termParser >> "do " >> doSeq
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/- `match`-expression where the right-hand-side of alternatives is a `doSeq` instead of a `term` -/
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def doMatchAlt : Parser := sepBy1 termParser ", " >> darrow >> doSeq
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def doMatchAlts : Parser := parser! withPosition $ (optional "| ") >> sepBy1 doMatchAlt (checkColGe "alternatives must be indented" >> "|")
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@[builtinDoElemParser] def doMatch := parser!:leadPrec "match " >> sepBy1 matchDiscr ", " >> optType >> " with " >> doMatchAlts
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def doCatch := parser! «try» ("catch " >> binderIdent) >> optional binderType >> darrow >> doSeq
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def doCatchMatch := parser! "catch " >> doMatchAlts
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def doFinally := parser! "finally " >> doSeq
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@[builtinDoElemParser] def doTry := parser! "try " >> doSeq >> many (doCatch <|> doCatchMatch) >> optional doFinally
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@[builtinDoElemParser] def «break» := parser! "break"
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@[builtinDoElemParser] def «continue» := parser! "continue"
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@[builtinDoElemParser] def «return» := parser!:leadPrec "return " >> termParser
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@[builtinDoElemParser] def doDbgTrace := parser!:leadPrec "dbgTrace! " >> termParser
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@[builtinDoElemParser] def doAssert := parser!:leadPrec "assert! " >> termParser
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/-
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We use `notFollowedBy` to avoid counterintuitive behavior. For example, the `if`-term parser
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doesn't enforce indentation restrictions, but we don't want it to be used when `doIf` fails.
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Note that parser priorities would not solve this problem since the `doIf` parser is failing while the `if`
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parser is succeeding.
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-/
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@[builtinDoElemParser] def doExpr := parser! notFollowedBy ("if" <|> "match" <|> "let" <|> "have" <|> "do") >> termParser
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@[builtinTermParser] def «do» := parser!:maxPrec "do " >> doSeq
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end Term
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end Parser
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end Lean
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