Data.Loc.Span

Documentation

data Span

A Span consists of a start location (start) and an end location (end). The end location must be greater than the start location; in other words, empty or backwards spans are not permitted.

Construct and combine spans using fromTo, fromToMay, +, and -.

Instances

Eq Span

Methods

(==) :: Span -> Span -> Bool

(/=) :: Span -> Span -> Bool

Ord Span

Methods

compare :: Span -> Span -> Ordering

(<) :: Span -> Span -> Bool

(<=) :: Span -> Span -> Bool

(>) :: Span -> Span -> Bool

(>=) :: Span -> Span -> Bool

max :: Span -> Span -> Span

min :: Span -> Span -> Span

Read Span

readPrec = spanReadPrec

Methods

readsPrec :: Int -> ReadS Span

readList :: ReadS [Span]

readPrec :: ReadPrec Span

readListPrec :: ReadPrec [Span]

Show Span

showsPrec = spanShowsPrec

Methods

showsPrec :: Int -> Span -> ShowS

show :: Span -> String

showList :: [Span] -> ShowS

Constructing

fromTo :: Loc -> Loc -> Span

Attempt to construct a Span from two Locs. The lesser loc will be the start, and the greater loc will be the end. The two locs must not be equal, or else this throws EmptySpan.

The safe version of this function is fromToMay.

fromToMay :: Loc -> Loc -> Maybe Span

Attempt to construct a Span from two Locs. The lesser loc will be the start, and the greater loc will be the end. If the two locs are not equal, the result is Nothing, because a span cannot be empty.

This is the safe version of fromTo, which throws an exception instead.

Querying

start :: Span -> Loc

end :: Span -> Loc

Calculations

lines :: Span -> NonEmpty Line

All of the lines that a span touches.

>>> NonEmpty.toList (lines (read "2:6-2:10"))
[2]

>>> NonEmpty.toList (lines (read "2:6-8:4"))
[2,3,4,5,6,7,8]

overlapping :: Span -> Span -> Bool

Spans that are directly abutting do not count as overlapping.

>>> overlapping (read "1:5-1:8") (read "1:8-1:12")
False

But these spans overlap by a single character:

>>> overlapping (read "1:5-1:9") (read "1:8-1:12")
True

Spans are overlapping if one is contained entirely within another.

>>> overlapping (read "1:5-1:15") (read "1:6-1:10")
True

Spans are overlapping if they are identical.

>>> overlapping (read "1:5-1:15") (read "1:5-1:15")
True

linesOverlapping :: Span -> Span -> Bool

Determines whether the two spans touch any of the same lines.

>>> linesOverlapping (read "1:1-1:2") (read "1:1-1:2")
True

>>> linesOverlapping (read "1:1-1:2") (read "1:1-2:1")
True

>>> linesOverlapping (read "1:1-1:2") (read "2:1-2:2")
False

touching :: Span -> Span -> Bool

Two spans are considered to "touch" if they are overlapping or abutting; in other words, if there is no space between them.

>>> touching (read "1:1-1:2") (read "1:2-1:3")
True

>>> touching (read "1:1-1:2") (read "1:1-1:3")
True

>>> touching (read "1:1-1:2") (read "1:3-1:4")
False

join :: Span -> Span -> Span

>>> join (read "1:1-1:2") (read "1:2-1:3")
1:1-1:3

>>> join (read "1:1-1:2") (read "1:1-1:3")
1:1-1:3

joinAsc

Arguments

:: [Span]

A list of Spans sorted in ascending order.

This precondition is not checked.

-> [Span]

Given an ascending list of Spans, combine those which abut or overlap.

(+) :: Span -> Span -> OneToTwo Span

Combine two Spans, merging them if they abut or overlap.

>>> read "1:1-1:2" + read "1:2-1:3"
One 1:1-1:3

>>> read "1:1-1:2" + read "1:1-3:1"
One 1:1-3:1

>>> read "1:1-1:2" + read "1:1-11:1"
One 1:1-11:1

If the spans are not overlapping or abutting, they are returned unmodified in the same order in which they were given as parameters.

>>> read "1:1-1:2" + read "2:1-2:5"
Two 1:1-1:2 2:1-2:5

>>> read "2:1-2:5" + read "1:1-1:2"
Two 2:1-2:5 1:1-1:2

(-) :: Span -> Span -> ZeroToTwo Span

The difference between two Spanss. a - b contains what is covered by a and not covered by b.

>>> read "2:5-4:1" - read "2:9-3:5"
Two 2:5-2:9 3:5-4:1

>>> read "2:5-4:1" - read "2:5-3:5"
One 3:5-4:1

>>> read "2:5-4:1" - read "2:2-3:5"
One 3:5-4:1

Subtracting a thing from itself yields nothing.

>>> let x = read "2:5-4:1" in x - x
Zero

>>> read "2:5-4:1" - read "2:2-4:4"
Zero

>>> read "1:1-8:1" - read "1:2-8:1"
One 1:1-1:2

Show and Read

spanShowsPrec :: Int -> Span -> ShowS

>>> spanShowsPrec minPrec (fromTo (read "3:14") (read "6:5")) ""
"3:14-6:5"

spanReadPrec :: ReadPrec Span

>>> readPrec_to_S spanReadPrec minPrec "3:14-6:5"
[(3:14-6:5,"")]

>>> readPrec_to_S spanReadPrec minPrec "6:5-3:14"
[(3:14-6:5,"")]

>>> readPrec_to_S spanReadPrec minPrec "6:5-6:5"
[]