A wrapper around Text for fast line/column navigation. Concatenation takes linear time.

This is a building block for Rope, which provides logarithmic concatenation.

Create from Text, linear time.

Extract Text, O(1).

Check whether a text is empty, O(1).

Get line with given 0-based index, O(1). The result does not contain \n characters.. Returns mempty if the line index is out of bounds.

>>> :set -XOverloadedStrings >>> map (\l -> getLine l "fя𐀀\n☺bar\n\n") [0..3] ["fя𐀀","☺bar","",""] 

Since: 0.3

Split into lines by \n, similar to Data.Text.lines. Each line is produced in O(1).

>>> :set -XOverloadedStrings >>> lines "" [] >>> lines "foo" ["foo"] >>> lines "foo\n" ["foo"] >>> lines "foo\n\n" ["foo",""] >>> lines "foo\nbar" ["foo","bar"] 

Equivalent to length . lines, but in O(1).

>>> :set -XOverloadedStrings >>> lengthInLines "" 0 >>> lengthInLines "foo" 1 >>> lengthInLines "foo\n" 1 >>> lengthInLines "foo\n\n" 2 >>> lengthInLines "foo\nbar" 2 

Split at given line, O(1).

>>> :set -XOverloadedStrings >>> map (\l -> splitAtLine l "foo\nbar") [0..3] [("","foo\nbar"),("foo\n","bar"),("foo\nbar",""),("foo\nbar","")] 

Length in UTF-8 code units aka bytes. Takes linear time.

>>> :set -XOverloadedStrings >>> length "fя𐀀" 7 >>> Data.Text.Lines.length "fя𐀀" 3 

Split at given UTF-8 code unit aka byte. If requested number of code units splits a code point in half, return Nothing. Takes linear time.

>>> :set -XOverloadedStrings >>> map (\c -> splitAt c "fя𐀀") [0..7] [Just ("","fя𐀀"),Just ("f","я𐀀"),Nothing,Just ("fя","𐀀"),Nothing,Nothing,Nothing,Just ("fя𐀀","")] 

Represent a position in a text.

Measure text length as an amount of lines and columns. Time is proportional to the length of the last line.

>>> :set -XOverloadedStrings >>> lengthAsPosition "f𐀀" Position {posLine = 0, posColumn = 7} >>> lengthAsPosition "f\n𐀀" Position {posLine = 1, posColumn = 4} >>> lengthAsPosition "f\n𐀀\n" Position {posLine = 2, posColumn = 0} 

Combination of splitAtLine and subsequent splitAt. If requested number of code units splits a code point in half, return Nothing. Time is linear in posColumn, but does not depend on posLine.

>>> :set -XOverloadedStrings >>> splitAtPosition (Position 1 0) "f\n𐀀я" Just ("f\n","𐀀я") >>> splitAtPosition (Position 1 1) "f\n𐀀я" Nothing >>> splitAtPosition (Position 1 2) "f\n𐀀я" Nothing >>> splitAtPosition (Position 0 2) "f\n𐀀я" Just ("f\n","𐀀я") >>> splitAtPosition (Position 0 3) "f\n𐀀я" Nothing >>> splitAtPosition (Position 0 4) "f\n𐀀я" Nothing >>> splitAtPosition (Position 0 6) "f\n𐀀я" Just ("f\n𐀀","я")