Suppport preservesTupleTail pragma within objects

preserves.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version = "20230825"
+version = "20230912"
 author        = "Emery Hemingway"
 description   = "data model and serialization format"
 license       = "Unlicense"

src/preserves.nim

@@ -1101,10 +1101,19 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool {.gcsafe.} =
       if pr.isRecord and pr.label.isSymbol(T.getCustomPragmaVal(preservesRecord)):
         result = true
         var i: int
-        for key, val in fieldPairs(v):
-          if result and i <= pr.len:
-            result = result and fieldFromPreserve(key, val, pr.record[i])
-          inc i
+        for name, field in fieldPairs(v):
+          when v.dot(name).hasCustomPragma(preservesTupleTail):
+            v.dot(name).setLen(pr.record.len.pred - i)
+            var j: int
+            while result and i < pr.record.high:
+              result = result and fromPreserve(v.dot(name)[j], pr.record[i])
+              inc i
+              inc j
+            break
+          else:
+            if result and i <= pr.len:
+              result = result and fieldFromPreserve(name, field, pr.record[i])
+            inc i
         result = result and (i <= pr.len)
     elif T.hasCustomPragma(preservesTuple):
       if pr.isSequence:

tests/test_conversions.nim

@@ -4,6 +4,11 @@
 import std/[options, tables, unittest, xmlparser, xmltree]
 import preserves, preserves/xmlhooks
 
+type
+  Route {.preservesRecord: "route".} = object
+    `transports`*: seq[Preserve[void]]
+    `pathSteps`* {.preservesTupleTail.}: seq[Preserve[void]]
+
 suite "conversions":
   test "dictionary":
     type Bar = tuple
@@ -60,6 +65,11 @@ suite "conversions":
     checkpoint $pr
     check fromPreserve(a, pr)
 
+  test "preservesTupleTail":
+    let pr = parsePreserves """<route [<tcp "localhost" 1024>] <ref {oid: "syndicate" sig: #x"69ca300c1dbfa08fba692102dd82311a"}>>"""
+    var route: Route
+    check route.fromPreserve(pr)
+
 suite "toPreserve":
   template check(p: Preserve; s: string) =
     test s: check($p == s)