Merge pull request #114 from jolt-lang/refactor-phase3c-dedups

Refactor phase 3c: dedup collection readers + phm bucket scans (jolt-26dm)

src/jolt/phm.janet

@@ -39,25 +39,26 @@
 (defn- hash-idx [m k]
   (if (nil? k) 0 (mod (hash (ck k)) (length (m :buckets)))))
 
-(defn- phm-bucket-find [bucket k]
+# Index of key k in a bucket (entries are stored stride-2: k v k v ...), or nil.
-  (var i 0) (var n (length bucket)) (var found nil)
+# The single scan all the bucket ops share — keeping it one place stops the
+# stride logic drifting between them.
+(defn- bucket-index-of [bucket k]
+  (var i 0) (def n (length bucket)) (var found nil)
   (while (< i n)
-    (if (key= k (in bucket i)) (do (set found (in bucket (+ i 1))) (break)))
+    (if (key= k (in bucket i)) (do (set found i) (break)))
     (+= i 2))
   found)
 
+(defn- phm-bucket-find [bucket k]
+  (let [i (bucket-index-of bucket k)]
+    (if i (in bucket (+ i 1)) nil)))
+
 (defn phm-bucket-contains? [bucket k]
-  (var i 0) (var n (length bucket)) (var found false)
+  (not (nil? (bucket-index-of bucket k))))
-  (while (< i n)
-    (if (key= k (in bucket i)) (do (set found true) (break)))
-    (+= i 2))
-  found)
 
 (defn- phm-bucket-assoc [bucket k v]
-  (var i 0) (var n (length bucket)) (var found-i nil)
+  (def n (length bucket))
-  (while (< i n)
+  (def found-i (bucket-index-of bucket k))
-    (if (key= k (in bucket i)) (do (set found-i i) (break)))
-    (+= i 2))
   (if (not (nil? found-i))
     (let [nb @[]] (var j 0)
       (while (< j n) (array/push nb (if (= j (+ found-i 1)) v (in bucket j))) (++ j)) nb)
@@ -66,10 +67,8 @@
       (array/push nb k) (array/push nb v) nb)))
 
 (defn- phm-bucket-dissoc [bucket k]
-  (var i 0) (var n (length bucket)) (var found-i nil)
+  (def n (length bucket))
-  (while (< i n)
+  (def found-i (bucket-index-of bucket k))
-    (if (key= k (in bucket i)) (do (set found-i i) (break)))
-    (+= i 2))
   (if (nil? found-i) bucket
     (if (= n 2) nil
       (let [nb @[]] (var j 0)
@@ -82,12 +81,8 @@
     # Single pass with a presence flag (not nil-of-value): a key mapped to nil
     # is still present, so return nil (not the default) when it exists.
     (if bucket
-      (do
+      (let [i (bucket-index-of bucket k)]
-        (var i 0) (var n (length bucket)) (var result default)
+        (if i (in bucket (+ i 1)) default))
-        (while (< i n)
-          (if (key= k (in bucket i)) (do (set result (in bucket (+ i 1))) (break)))
-          (+= i 2))
-        result)
       default)))
 
 # Rehash every entry of `buckets` into a fresh array of `nb` buckets.

src/jolt/reader.janet

@@ -298,39 +298,35 @@
                       (+ exp-end 1) exp-end)]
             [(if neg (- val) val) fin]))))))
 
-(defn read-list [s pos]
+# Read forms until `close` (a byte), returning [items end-pos]. Shared by the
-  # pos is at opening paren
+# list/vector/set readers: skip #_ discards and splice #?@ items uniformly, so the
-  (defn read-list-items [s pos items]
+# skip/splice handling can't drift between them (it did once). The map reader
+# keeps its own loop — its key/value pairing needs a different value-slot scan.
+(defn read-delimited [s start-pos close err]
+  (defn read-items [s pos items]
     (let [pos (skip-whitespace s pos)]
       (if (>= pos (length s))
-        (reader-error "Unterminated list" pos))
+        (reader-error err pos))
-      (if (= (s pos) 41) # )
+      (if (= (s pos) close)
         [items (+ pos 1)]
         (let [[form new-pos] (read-form s pos)]
           # skip #_ discarded forms
           (if (and (struct? form) (= :jolt/skip (form :jolt/type)))
-            (read-list-items s new-pos items)
+            (read-items s new-pos items)
-            # splice #?@ items into the list
+            # splice #?@ items into the collection
             (if (and (struct? form) (= :jolt/splice (form :jolt/type)))
-              (read-list-items s new-pos (array/concat items (form :items)))
+              (read-items s new-pos (array/concat items (form :items)))
-              (read-list-items s new-pos (array/push items form))))))))
+              (read-items s new-pos (array/push items form))))))))
-  (read-list-items s (+ pos 1) @[]))
+  (read-items s start-pos @[]))
+
+(defn read-list [s pos]
+  # pos is at opening paren
+  (read-delimited s (+ pos 1) 41 "Unterminated list"))  # )
 
 (defn read-vector [s pos]
   # pos is at opening bracket
-  (defn read-vec-items [s pos items]
+  (let [[items end] (read-delimited s (+ pos 1) 93 "Unterminated vector")]  # ]
-    (let [pos (skip-whitespace s pos)]
+    [(tuple/slice (tuple ;items)) end]))
-      (if (>= pos (length s))
-        (reader-error "Unterminated vector" pos))
-      (if (= (s pos) 93) # ]
-        [(tuple/slice (tuple ;items)) (+ pos 1)]
-        (let [[form new-pos] (read-form s pos)]
-          (if (and (struct? form) (= :jolt/skip (form :jolt/type)))
-            (read-vec-items s new-pos items)
-            (if (and (struct? form) (= :jolt/splice (form :jolt/type)))
-              (read-vec-items s new-pos (array/concat items (form :items)))
-              (read-vec-items s new-pos (array/push items form))))))))
-  (read-vec-items s (+ pos 1) @[]))
 
 # A map-literal form. Janet structs drop nil keys/values, so when a key or value
 # is nil (e.g. {:a nil}) build a phm — it preserves nil, matching Clojure. The
@@ -400,19 +396,8 @@
 
 (defn read-set [s pos]
   # pos is at #, next char is {
-  (defn read-set-items [s pos items]
+  (let [[items end] (read-delimited s (+ pos 2) 125 "Unterminated set")]  # }
-    (let [pos (skip-whitespace s pos)]
+    [{:jolt/type :jolt/set :value (tuple/slice (tuple ;items))} end]))
-      (if (>= pos (length s))
-        (reader-error "Unterminated set" pos))
-      (if (= (s pos) 125) # }
-        [{:jolt/type :jolt/set :value (tuple/slice (tuple ;items))} (+ pos 1)]
-        (let [[form new-pos] (read-form s pos)]
-          (if (and (struct? form) (= :jolt/skip (form :jolt/type)))
-            (read-set-items s new-pos items)
-            (if (and (struct? form) (= :jolt/splice (form :jolt/type)))
-              (read-set-items s new-pos (array/concat items (form :items)))
-              (read-set-items s new-pos (array/push items form))))))))
-  (read-set-items s (+ pos 2) @[]))
 
 (defn read-char-name-end [s pos]
   (if (and (< pos (length s)) (symbol-char? (s pos)))