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feat: Syntax.updateLeading: also choose "nicer" splits

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This commit is contained in:
Sebastian Ullrich 2020-11-17 17:17:24 +01:00
parent 727816e7fd
commit 871cd105dc
1 changed files with 22 additions and 15 deletions
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37
src/Lean/Syntax.lean
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@ -141,37 +141,44 @@ def getIdAt (stx : Syntax) (i : Nat) : Name :=
@[inline] def rewriteBottomUp (fn : Syntax → Syntax) (stx : Syntax) : Syntax :=
Id.run $ stx.rewriteBottomUpM fn
private def updateInfo : SourceInfo → String.Pos → SourceInfo
| {leading := some {str := s, startPos := _, stopPos := _}, pos := some pos, trailing := trailing}, last =>
{leading := some {str := s, startPos := last, stopPos := pos}, pos := some pos, trailing := trailing}
| info, _ => info
private def updateInfo : SourceInfo → String.Pos → String.Pos → SourceInfo
| {leading := some lead, pos := some pos, trailing := some trail}, leadStart, trailStop =>
{leading := some { lead with startPos := leadStart }, pos := some pos, trailing := some { trail with stopPos := trailStop }}
| info, _, _ => info
private def chooseNiceTrailStop (trail : Substring) : String.Pos :=
trail.startPos + trail.posOf '\n'
/- Remark: the State `String.Pos` is the `SourceInfo.trailing.stopPos` of the previous token,
or the beginning of the String. -/
@[inline]
private def updateLeadingAux : Syntax → StateM String.Pos (Option Syntax)
| atom info@{trailing := some trail, ..} val => do
let last ← get
set trail.stopPos
let newInfo := updateInfo info last
let trailStop := chooseNiceTrailStop trail
let newInfo := updateInfo info (← get) trailStop
set trailStop
pure $ some (atom newInfo val)
| ident info@{trailing := some trail, ..} rawVal val pre => do
let last ← get
set trail.stopPos
let newInfo := updateInfo info last
let trailStop := chooseNiceTrailStop trail
let newInfo := updateInfo info (← get) trailStop
set trailStop
pure $ some (ident newInfo rawVal val pre)
| _ => pure none
/-- Set `SourceInfo.leading` according to the trailing stop of the preceding token.
The Result is a round-tripping Syntax tree IF, in the input Syntax tree,
The result is a round-tripping syntax tree IF, in the input syntax tree,
* all leading stops, atom contents, and trailing starts are correct
* trailing stops are between the trailing start and the next leading stop.
Remark: after parsing all `SourceInfo.leading` fields are Empty.
The Syntax argument is the output produced by the Parser for `source`.
This Function "fixes" the `source.leanding` field.
Remark: after parsing, all `SourceInfo.leading` fields are empty.
The `Syntax` argument is the output produced by the parser for `source`.
This function "fixes" the `source.leading` field.
Note that, the `SourceInfo.trailing` fields are correct.
Additionally, we try to choose "nicer" splits between leading and trailing stops
according to some heuristics so that e.g. comments are associated to the (intuitively)
correct token.
Note that the `SourceInfo.trailing` fields must be correct.
The implementation of this Function relies on this property. -/
def updateLeading : Syntax → Syntax :=
fun stx => (replaceM updateLeadingAux stx).run' 0