From 717cba24991e1a173eed534ed3674b6cf49c9b31 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Sun, 17 May 2026 12:10:04 +0200
Subject: Watch branches using more generic expression structure

---
 src/Expression.hs | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 src/Expression.hs

(limited to 'src/Expression.hs')

diff --git a/src/Expression.hs b/src/Expression.hs
new file mode 100644
index 0000000..cd6c9dc
--- /dev/null
+++ b/src/Expression.hs
@@ -0,0 +1,109 @@
+module Expression (
+    StaticRef',
+    WatchedRef(..),
+    WatchedRef',
+
+    RevisionExpression'(..), RevisionExpression, DeclaredRevisionExpression,
+    RangeExpression'(..), RangeExpression, DeclaredRangeExpression,
+    CommitRange(..),
+    evaluateDeclaredRevision, evaluateDeclaredRange,
+    evaluateRevision, evaluateRange,
+    getRangeCommits, getAddedRangeCommits,
+) where
+
+import Control.Concurrent.STM
+import Control.Monad.IO.Class
+
+import Data.Kind
+import Data.Maybe
+import Data.Text (Text)
+
+import Job.Types
+import Repo
+
+
+type family StaticRef' d :: Type where
+    StaticRef' Declared = Text
+    StaticRef' Evaluated = Commit
+
+data WatchedRef
+    = BranchRef (STM (Maybe Commit))
+
+type family WatchedRef' d :: Type where
+    WatchedRef' Declared = Text
+    WatchedRef' Evaluated = WatchedRef
+
+
+data RevisionExpression' d
+    = StaticRef (StaticRef' d)
+    | WatchedRef (WatchedRef' d)
+    | ModifiedRevision Text (RevisionExpression' d)
+
+type RevisionExpression = RevisionExpression' Evaluated
+type DeclaredRevisionExpression = RevisionExpression' Declared
+
+
+data RangeExpression' d
+    = RangeExpression (RevisionExpression' d) {- tip -} (RevisionExpression' d) {- except -}
+
+type RangeExpression = RangeExpression' Evaluated
+type DeclaredRangeExpression = RangeExpression' Declared
+
+
+data CommitRef = CommitRef Text {- suffix -} CommitId
+    deriving (Eq)
+
+data CommitRange
+    = EmptyCommitRange
+    | CommitRange CommitRef {- tip -} CommitRef {- except -}
+    deriving (Eq)
+
+textCommitRef :: CommitRef -> Text
+textCommitRef (CommitRef suffix cid) = textCommitId cid <> suffix
+
+
+evaluateDeclaredRevision :: (MonadIO m, MonadFail m) => Repo -> DeclaredRevisionExpression -> m RevisionExpression
+evaluateDeclaredRevision repo = \case
+    StaticRef ref -> StaticRef <$> readCommit repo ref
+    WatchedRef ref -> WatchedRef . BranchRef <$> watchBranch repo ref
+    ModifiedRevision suffix rev -> ModifiedRevision suffix <$> evaluateDeclaredRevision repo rev
+
+evaluateDeclaredRange :: (MonadIO m, MonadFail m) => Repo -> DeclaredRangeExpression -> m RangeExpression
+evaluateDeclaredRange repo (RangeExpression a b) =
+    RangeExpression <$> evaluateDeclaredRevision repo a <*> evaluateDeclaredRevision repo b
+
+evaluateRevision :: RevisionExpression -> STM (Maybe CommitRef)
+evaluateRevision = \case
+    StaticRef commit -> return $ Just $ CommitRef "" $ commitId commit
+    WatchedRef (BranchRef getter) -> fmap (CommitRef "" . commitId) <$> getter
+    ModifiedRevision suffix rev ->
+        fmap (\(CommitRef suffix' ref) -> CommitRef (suffix' <> suffix) ref) <$> evaluateRevision rev
+
+evaluateRange :: RangeExpression -> STM CommitRange
+evaluateRange (RangeExpression tipExpr exceptExpr) = do
+    tip <- evaluateRevision tipExpr
+    except <- evaluateRevision exceptExpr
+    return $ fromMaybe EmptyCommitRange $ CommitRange <$> tip <*> except
+
+getCommitIdFromRef :: MonadIO m => Repo -> CommitRef -> m (Maybe CommitId)
+getCommitIdFromRef repo = liftIO . fmap (fmap commitId) . tryReadCommit repo . textCommitRef
+
+getRangeCommits :: MonadIO m => Repo -> CommitRange -> m [ Commit ]
+getRangeCommits _ EmptyCommitRange = return []
+getRangeCommits repo (CommitRange tip except) = do
+    tipId <- getCommitIdFromRef repo tip
+    excId <- getCommitIdFromRef repo except
+    listCommitsFrom repo (catMaybes [ tipId ]) (catMaybes [ excId ])
+
+getAddedRangeCommits :: MonadIO m => Repo -> CommitRange -> CommitRange -> m [ Commit ]
+getAddedRangeCommits _    _ EmptyCommitRange = return []
+getAddedRangeCommits repo EmptyCommitRange r = getRangeCommits repo r
+getAddedRangeCommits repo (CommitRange ar br) (CommitRange ar' br') = do
+    a <- getCommitIdFromRef repo ar
+    b <- getCommitIdFromRef repo br
+    a' <- getCommitIdFromRef repo ar'
+    b' <- getCommitIdFromRef repo br'
+    a'b <- fmap (map commitId) $ mergeBase repo $ catMaybes [ a', b ]
+    (++)
+        <$> listCommitsFrom repo a'b (catMaybes [ b' ]) -- added by moving B to B'
+        <*> listCommitsFrom repo (catMaybes [ a' ]) (catMaybes [ a, b, b' ]) -- added by moving A to A'
-- 
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