| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Distribution.Types.CondTree
- data CondTree v c a = CondNode {
- condTreeData :: a
- condTreeConstraints :: c
- condTreeComponents :: [CondBranch v c a]
- data CondBranch v c a = CondBranch {
- condBranchCondition :: Condition v
- condBranchIfTrue :: CondTree v c a
- condBranchIfFalse :: Maybe (CondTree v c a)
- condIfThen :: Condition v -> CondTree v c a -> CondBranch v c a
- condIfThenElse :: Condition v -> CondTree v c a -> CondTree v c a -> CondBranch v c a
- mapCondTree :: (a -> b) -> (c -> d) -> (Condition v -> Condition w) -> CondTree v c a -> CondTree w d b
- mapTreeConstrs :: (c -> d) -> CondTree v c a -> CondTree v d a
- mapTreeConds :: (Condition v -> Condition w) -> CondTree v c a -> CondTree w c a
- mapTreeData :: (a -> b) -> CondTree v c a -> CondTree v c b
- extractCondition :: Eq v => (a -> Bool) -> CondTree v c a -> Condition v
- simplifyCondTree :: (Monoid a, Monoid d) => (v -> Either v Bool) -> CondTree v d a -> (d, a)
- ignoreConditions :: (Monoid a, Monoid c) => CondTree v c a -> (a, c)
Documentation
A CondTree is used to represent the conditional structure of
a Cabal file, reflecting a syntax element subject to constraints,
and then any number of sub-elements which may be enabled subject
to some condition. Both a and c are usually Monoids.
To be more concrete, consider the following fragment of a Cabal
file:
build-depends: base >= 4.0
if flag(extra)
build-depends: base >= 4.2
One way to represent this is to have CondTree ConfVar
[Dependency] BuildInfocondTreeData represents
the actual fields which are not behind any conditional, while
condTreeComponents recursively records any further fields
which are behind a conditional. condTreeConstraints records
the constraints (in this case, base >= 4.0) which would
be applied if you use this syntax; in general, this is
derived off of targetBuildInfo (perhaps a good refactoring
would be to convert this into an opaque type, with a smart
constructor that pre-computes the dependencies.)
Constructors
| CondNode | |
Fields
| |
Instances
| Functor (CondTree v c) # | |
| Foldable (CondTree v c) # | |
| Traversable (CondTree v c) # | |
| (Eq v, Eq c, Eq a) => Eq (CondTree v c a) # | |
| (Data a, Data c, Data v) => Data (CondTree v c a) # | |
| (Show v, Show c, Show a) => Show (CondTree v c a) # | |
| Generic (CondTree v c a) # | |
| (Binary v, Binary c, Binary a) => Binary (CondTree v c a) # | |
| type Rep (CondTree v c a) # | |
data CondBranch v c a #
A CondBranch represents a conditional branch, e.g., if
flag(foo) on some syntax a. It also has an optional false
branch.
Constructors
| CondBranch | |
Fields
| |
Instances
| Functor (CondBranch v c) # | |
| Foldable (CondBranch v c) # | |
| Traversable (CondBranch v c) # | |
| (Eq a, Eq c, Eq v) => Eq (CondBranch v c a) # | |
| (Data a, Data c, Data v) => Data (CondBranch v c a) # | |
| (Show a, Show c, Show v) => Show (CondBranch v c a) # | |
| Generic (CondBranch v c a) # | |
| (Binary v, Binary c, Binary a) => Binary (CondBranch v c a) # | |
| type Rep (CondBranch v c a) # | |
condIfThen :: Condition v -> CondTree v c a -> CondBranch v c a #
condIfThenElse :: Condition v -> CondTree v c a -> CondTree v c a -> CondBranch v c a #
mapCondTree :: (a -> b) -> (c -> d) -> (Condition v -> Condition w) -> CondTree v c a -> CondTree w d b #
mapTreeConstrs :: (c -> d) -> CondTree v c a -> CondTree v d a #
mapTreeData :: (a -> b) -> CondTree v c a -> CondTree v c b #
extractCondition :: Eq v => (a -> Bool) -> CondTree v c a -> Condition v #
Extract the condition matched by the given predicate from a cond tree.
We use this mainly for extracting buildable conditions (see the Note above), but the function is in fact more general.
simplifyCondTree :: (Monoid a, Monoid d) => (v -> Either v Bool) -> CondTree v d a -> (d, a) #
Flattens a CondTree using a partial flag assignment. When a condition cannot be evaluated, both branches are ignored.
ignoreConditions :: (Monoid a, Monoid c) => CondTree v c a -> (a, c) #
Flatten a CondTree. This will resolve the CondTree by taking all possible paths into account. Note that since branches represent exclusive choices this may not result in a "sane" result.