Add Arborix section directory byte readers

lib/arborix.tri

@@ -20,3 +20,58 @@ readArborixHeader = (bs :
                     (pair majorVersion
                       (pair minorVersion sectionCount))
                     afterSectionCount)))))
+
+readSectionRecord = (bs :
+  bindResult (readBytes 2 bs)
+    (sectionId afterSectionId :
+      bindResult (readBytes 4 afterSectionId)
+        (offset afterOffset :
+          bindResult (readBytes 4 afterOffset)
+            (length afterLength :
+              ok
+                (pair sectionId
+                  (pair offset length))
+                afterLength))))
+
+readSectionDirectory_ = y (self sectionCount i bs acc :
+  matchBool
+    (ok (reverse acc) bs)
+    (bindResult (readSectionRecord bs)
+      (sectionRecord afterSectionRecord :
+        self sectionCount (succ i) afterSectionRecord (pair sectionRecord acc)))
+    (equal? i sectionCount))
+
+readSectionDirectory = (sectionCount bs : readSectionDirectory_ sectionCount 0 bs t)
+
+sectionRecordId = (sectionRecord :
+  matchPair
+    (sectionId _ : sectionId)
+    sectionRecord)
+
+sectionRecordOffset = (sectionRecord :
+  matchPair
+    (_ payload :
+      matchPair
+        (offset _ : offset)
+        payload)
+    sectionRecord)
+
+sectionRecordLength = (sectionRecord :
+  matchPair
+    (_ payload :
+      matchPair
+        (_ length : length)
+        payload)
+    sectionRecord)
+
+lookupSectionRecord = y (self sectionId directory :
+  matchList
+    nothing
+    (sectionRecord rest :
+      matchBool
+        (just sectionRecord)
+        (self sectionId rest)
+        (bytesEq? sectionId (sectionRecordId sectionRecord)))
+    directory)
+
+byteSlice = (offset length bytes : bytesTake length (bytesDrop offset bytes))

test/Spec.hs

@@ -1554,4 +1554,126 @@ binaryReaderTests = testGroup "Binary Reader Tests"
       library <- evaluateFile "./lib/arborix.tri"
       let env = evalTricu library (parseTricu input)
       result env @?= errT eofT (bytesT [65,82])
+
+  -- ------------------------------------------------------------------------
+  -- Arborix section directory record parsing
+  -- ------------------------------------------------------------------------
+
+  , testCase "readSectionRecord: parses raw section id offset and length" $ do
+      let input = "readSectionRecord [(0) (2) (0) (0) (0) (16) (0) (0) (0) (32)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= okT
+        (pairT (bytesT [0,2])
+          (pairT (bytesT [0,0,0,16])
+            (bytesT [0,0,0,32])))
+        (bytesT [])
+
+  , testCase "readSectionRecord: preserves trailing bytes" $ do
+      let input = "readSectionRecord [(0) (2) (0) (0) (0) (16) (0) (0) (0) (32) (9) (8)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= okT
+        (pairT (bytesT [0,2])
+          (pairT (bytesT [0,0,0,16])
+            (bytesT [0,0,0,32])))
+        (bytesT [9,8])
+
+  , testCase "readSectionRecord: empty input returns EOF" $ do
+      let input = "readSectionRecord []"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= errT eofT (bytesT [])
+
+  , testCase "readSectionRecord: short section id returns EOF preserving input" $ do
+      let input = "readSectionRecord [(0)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= errT eofT (bytesT [0])
+
+  , testCase "readSectionRecord: missing offset returns EOF preserving unread offset bytes" $ do
+      let input = "readSectionRecord [(0) (2)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= errT eofT (bytesT [])
+
+  , testCase "readSectionRecord: short offset returns EOF preserving unread offset bytes" $ do
+      let input = "readSectionRecord [(0) (2) (0) (0) (0)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= errT eofT (bytesT [0,0,0])
+
+  , testCase "readSectionRecord: missing length returns EOF preserving unread length bytes" $ do
+      let input = "readSectionRecord [(0) (2) (0) (0) (0) (16)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= errT eofT (bytesT [])
+
+  , testCase "readSectionRecord: short length returns EOF preserving unread length bytes" $ do
+      let input = "readSectionRecord [(0) (2) (0) (0) (0) (16) (0) (0) (0)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= errT eofT (bytesT [0,0,0])
+
+  -- ------------------------------------------------------------------------
+  -- Arborix section directory parsing
+  -- ------------------------------------------------------------------------
+
+  , testCase "readSectionDirectory: zero records preserves input" $ do
+      let input = "readSectionDirectory 0 [(9) (8)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= okT (ofList []) (bytesT [9,8])
+
+  , testCase "readSectionDirectory: reads requested records and preserves trailing bytes" $ do
+      let input = "readSectionDirectory 2 [(0) (1) (0) (0) (0) (10) (0) (0) (0) (20) (0) (2) (0) (0) (0) (30) (0) (0) (0) (40) (9)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= okT
+        (ofList
+          [ pairT (bytesT [0,1])
+              (pairT (bytesT [0,0,0,10])
+                (bytesT [0,0,0,20]))
+          , pairT (bytesT [0,2])
+              (pairT (bytesT [0,0,0,30])
+                (bytesT [0,0,0,40]))
+          ])
+        (bytesT [9])
+
+  , testCase "readSectionDirectory: truncated record returns EOF" $ do
+      let input = "readSectionDirectory 2 [(0) (1) (0) (0) (0) (10) (0) (0) (0) (20) (0) (2) (0) (0)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= errT eofT (bytesT [0,0])
+
+  -- ------------------------------------------------------------------------
+  -- Arborix section lookup and raw byte slicing
+  -- ------------------------------------------------------------------------
+
+  , testCase "lookupSectionRecord: finds record by raw section id" $ do
+      let input = "lookupSectionRecord [(0) (2)] [(pair [(0) (1)] (pair [(0) (0) (0) (10)] [(0) (0) (0) (20)])) (pair [(0) (2)] (pair [(0) (0) (0) (30)] [(0) (0) (0) (40)]))]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= justT
+        (pairT (bytesT [0,2])
+          (pairT (bytesT [0,0,0,30])
+            (bytesT [0,0,0,40])))
+
+  , testCase "lookupSectionRecord: missing section id returns nothing" $ do
+      let input = "lookupSectionRecord [(0) (3)] [(pair [(0) (1)] (pair [(0) (0) (0) (10)] [(0) (0) (0) (20)])) (pair [(0) (2)] (pair [(0) (0) (0) (30)] [(0) (0) (0) (40)]))]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= nothingT
+
+  , testCase "byteSlice: extracts requested byte range" $ do
+      let input = "byteSlice 2 3 [(10) (11) (12) (13) (14) (15)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= bytesT [12,13,14]
+
+  , testCase "byteSlice: overlong length returns remaining bytes" $ do
+      let input = "byteSlice 4 9 [(10) (11) (12) (13) (14) (15)]"
+      library <- evaluateFile "./lib/arborix.tri"
+      let env = evalTricu library (parseTricu input)
+      result env @?= bytesT [14,15]
   ]