{-|
Module      : Toml.Position
Description : File position representation
Copyright   : (c) Eric Mertens, 2023
License     : ISC
Maintainer  : emertens@gmail.com

This module provides the 'Position' type for tracking locations
in files while doing lexing and parsing for providing more useful
error messages.

-}
module Toml.Position (
    Position(..),
    startPos,
    move,
    ) where

-- | A position in a text file
data Position = Position
    { Position -> Int
posIndex, Position -> Int
posLine, Position -> Int
posColumn :: {-# UNPACK #-} !Int }
    deriving (ReadPrec [Position]
ReadPrec Position
Int -> ReadS Position
ReadS [Position]
forall a.
(Int -> ReadS a)
-> ReadS [a] -> ReadPrec a -> ReadPrec [a] -> Read a
readListPrec :: ReadPrec [Position]
$creadListPrec :: ReadPrec [Position]
readPrec :: ReadPrec Position
$creadPrec :: ReadPrec Position
readList :: ReadS [Position]
$creadList :: ReadS [Position]
readsPrec :: Int -> ReadS Position
$creadsPrec :: Int -> ReadS Position
Read, Int -> Position -> ShowS
[Position] -> ShowS
Position -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [Position] -> ShowS
$cshowList :: [Position] -> ShowS
show :: Position -> String
$cshow :: Position -> String
showsPrec :: Int -> Position -> ShowS
$cshowsPrec :: Int -> Position -> ShowS
Show, Eq Position
Position -> Position -> Bool
Position -> Position -> Ordering
Position -> Position -> Position
forall a.
Eq a
-> (a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
min :: Position -> Position -> Position
$cmin :: Position -> Position -> Position
max :: Position -> Position -> Position
$cmax :: Position -> Position -> Position
>= :: Position -> Position -> Bool
$c>= :: Position -> Position -> Bool
> :: Position -> Position -> Bool
$c> :: Position -> Position -> Bool
<= :: Position -> Position -> Bool
$c<= :: Position -> Position -> Bool
< :: Position -> Position -> Bool
$c< :: Position -> Position -> Bool
compare :: Position -> Position -> Ordering
$ccompare :: Position -> Position -> Ordering
Ord, Position -> Position -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: Position -> Position -> Bool
$c/= :: Position -> Position -> Bool
== :: Position -> Position -> Bool
$c== :: Position -> Position -> Bool
Eq)

-- | The initial 'Position' for the start of a file
startPos :: Position
startPos :: Position
startPos = Position { posIndex :: Int
posIndex = Int
0, posLine :: Int
posLine = Int
1, posColumn :: Int
posColumn = Int
1 }

-- | Adjust a file position given a single character handling
-- newlines and tabs. All other characters are considered to fill
-- exactly one column.
move :: Char -> Position -> Position
move :: Char -> Position -> Position
move Char
x Position{ posIndex :: Position -> Int
posIndex = Int
i, posLine :: Position -> Int
posLine = Int
l, posColumn :: Position -> Int
posColumn = Int
c} =
    case Char
x of
        Char
'\n' -> Position{ posIndex :: Int
posIndex = Int
iforall a. Num a => a -> a -> a
+Int
1, posLine :: Int
posLine = Int
lforall a. Num a => a -> a -> a
+Int
1, posColumn :: Int
posColumn = Int
1 }
        Char
'\t' -> Position{ posIndex :: Int
posIndex = Int
iforall a. Num a => a -> a -> a
+Int
1, posLine :: Int
posLine = Int
l, posColumn :: Int
posColumn = (Int
c forall a. Num a => a -> a -> a
+ Int
7) forall a. Integral a => a -> a -> a
`quot` Int
8 forall a. Num a => a -> a -> a
* Int
8 forall a. Num a => a -> a -> a
+ Int
1 }
        Char
_    -> Position{ posIndex :: Int
posIndex = Int
iforall a. Num a => a -> a -> a
+Int
1, posLine :: Int
posLine = Int
l, posColumn :: Int
posColumn = Int
cforall a. Num a => a -> a -> a
+Int
1 }