130 lines
6.1 KiB
Text
130 lines
6.1 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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builtin_initialize registerBuiltinParserAttribute `builtinDoElemParser `doElem
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builtin_initialize 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 doSeqItem := parser! ppLine >> doElemParser >> optional "; "
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def doSeqIndent := parser! many1Indent doSeqItem
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def doSeqBracketed := parser! "{" >> withoutPosition (many1 doSeqItem) >> ppLine >> "}"
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def doSeq := doSeqBracketed <|> doSeqIndent
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def termBeforeDo := withForbidden "do" termParser
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attribute [runBuiltinParserAttributeHooks] doSeq termBeforeDo
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builtin_initialize
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registerParserAlias! "doSeq" doSeq
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registerParserAlias! "termBeforeDo" termBeforeDo
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def notFollowedByRedefinedTermToken :=
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notFollowedBy ("if" <|> "match" <|> "let" <|> "have" <|> "do" <|> "dbgTrace!" <|> "assert!" <|> "for" <|> "unless" <|> "return" <|> symbol "try") "token at 'do' element"
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@[builtinDoElemParser] def doLet := parser! "let " >> optional "mut " >> letDecl
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@[builtinDoElemParser] def doLetRec := parser! group ("let " >> nonReservedSymbol "rec ") >> letRecDecls
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def doIdDecl := parser! atomic (ident >> optType >> leftArrow) >> doElemParser
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def doPatDecl := parser! atomic (termParser >> leftArrow) >> doElemParser >> optional (checkColGt >> " | " >> doElemParser)
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@[builtinDoElemParser] def doLetArrow := parser! withPosition ("let " >> optional "mut " >> (doIdDecl <|> doPatDecl))
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-- We use `letIdDeclNoBinders` to define `doReassign`.
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-- Motivation: we do not reassign functions, and avoid parser conflict
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def letIdDeclNoBinders := node `Lean.Parser.Term.letIdDecl $ atomic (ident >> pushNone >> optType >> " := ") >> termParser
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@[builtinDoElemParser] def doReassign := parser! notFollowedByRedefinedTermToken >> (letIdDeclNoBinders <|> letPatDecl)
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@[builtinDoElemParser] def doReassignArrow := parser! notFollowedByRedefinedTermToken >> withPosition (doIdDecl <|> doPatDecl)
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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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def elseIf := atomic (group (withPosition (" else " >> checkLineEq >> " if ")))
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-- ensure `if $e then ...` still binds to `e:term`
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def doIfLetPure := parser! " := " >> termParser
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def doIfLetBind := parser! " ← " >> termParser
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def doIfLet := nodeWithAntiquot "doIfLet" `Lean.Parser.Term.doIfLet <| "let " >> termParser >> (doIfLetPure <|> doIfLetBind)
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def doIfProp := nodeWithAntiquot "doIfProp" `Lean.Parser.Term.doIfProp <| optIdent >> termParser
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def doIfCond := withAntiquot (mkAntiquot "doIfCond" none (anonymous := false)) <| doIfLet <|> doIfProp
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@[builtinDoElemParser] def doIf := parser! withPosition $
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"if " >> doIfCond >> " then " >> doSeq
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>> many (checkColGe "'else if' in 'do' must be indented" >> group (elseIf >> doIfCond >> " 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 " >> withForbidden "do" termParser >> "do " >> doSeq
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def doForDecl := parser! termParser >> " in " >> withForbidden "do" termParser
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@[builtinDoElemParser] def doFor := parser! "for " >> sepBy1 doForDecl ", " >> "do " >> doSeq
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def doMatchAlts := matchAlts (rhsParser := doSeq)
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@[builtinDoElemParser] def doMatch := parser!:leadPrec "match " >> sepBy1 matchDiscr ", " >> optType >> " with " >> doMatchAlts
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def doCatch := parser! atomic ("catch " >> binderIdent) >> optional (" : " >> termParser) >> 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 doBreak := parser! "break"
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@[builtinDoElemParser] def doContinue := parser! "continue"
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@[builtinDoElemParser] def doReturn := parser!:leadPrec withPosition ("return " >> optional (checkLineEq >> termParser))
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@[builtinDoElemParser] def doDbgTrace := parser!:leadPrec "dbgTrace! " >> ((interpolatedStr termParser) <|> 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! notFollowedByRedefinedTermToken >> termParser
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@[builtinDoElemParser] def doNested := parser! "do " >> doSeq
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@[builtinTermParser] def «do» := parser!:maxPrec "do " >> doSeq
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@[builtinTermParser] def doElem.quot : Parser := parser! "`(doElem|" >> toggleInsideQuot doElemParser >> ")"
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/- macros for using `unless`, `for`, `try`, `return` as terms. They expand into `do unless ...`, `do for ...`, `do try ...`, and `do return ...` -/
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@[builtinTermParser] def termUnless := parser! "unless " >> withForbidden "do" termParser >> "do " >> doSeq
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@[builtinTermParser] def termFor := parser! "for " >> sepBy1 doForDecl ", " >> "do " >> doSeq
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@[builtinTermParser] def termTry := parser! "try " >> doSeq >> many (doCatch <|> doCatchMatch) >> optional doFinally
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@[builtinTermParser] def termReturn := parser!:leadPrec withPosition ("return " >> optional (checkLineEq >> termParser))
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end Term
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end Parser
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end Lean
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