lean4-htt/tests/playground/parser/filemap.lean

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structure Position :=
(line : Nat := 1)
(column : Nat := 0)
instance : Inhabited Position :=
⟨{}⟩
structure FileMap :=
(source : String)
(positions : Array String.Pos)
(lines : Array Nat)
namespace FileMap
instance : Inhabited FileMap :=
⟨{ source := "", positions := Array.empty, lines := Array.empty }⟩
private partial def ofStringAux (s : String) : String.Pos → Nat → Array String.Pos → Array Nat → FileMap
| i line ps lines :=
if s.atEnd i then { source := s, positions := ps.push i, lines := lines.push line }
else
let c := s.get i in
let i := s.next i in
if c == '\n' then ofStringAux i (line+1) (ps.push i) (lines.push (line+1))
else ofStringAux i line ps lines
def ofString (s : String) : FileMap :=
ofStringAux s 0 1 (Array.empty.push 0) (Array.empty.push 1)
private partial def toColumnAux (str : String) (lineBeginPos : String.Pos) (pos : String.Pos) : String.Pos → Nat → Nat
| i c :=
if i == pos || str.atEnd i then c
else toColumnAux (str.next i) (c+1)
/- Remark: `pos` is in `[ps.get b, ps.get e]` and `b < e` -/
private partial def toPositionAux (str : String) (ps : Array Nat) (lines : Array Nat) (pos : String.Pos) : Nat → Nat → Position
| b e :=
let posB := ps.get b in
if e == b + 1 then { line := lines.get b, column := toColumnAux str posB pos posB 0 }
else
let m := (b + e) / 2 in
let posM := ps.get m in
if pos == posM then { line := lines.get m, column := 0 }
else if pos > posM then toPositionAux m e
else toPositionAux b m
def toPosition : FileMap → String.Pos → Position
| { source := str, positions := ps, lines := lines } pos := toPositionAux str ps lines pos 0 (ps.size-1)
end FileMap
def String.toFileMap (s : String) : FileMap :=
FileMap.ofString s