From 53ae081cc9a3e61095cab49862658a46b00eacf7 Mon Sep 17 00:00:00 2001
From: Jacek Sieka <jacek@status.im>
Date: Tue, 1 Oct 2024 19:43:11 +0200
Subject: [PATCH] avoid threadvar with const field table (#89)

---
 toml_serialization/private/array_reader.nim |  9 ++++-----
 toml_serialization/reader.nim               | 20 +++++++++++---------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/toml_serialization/private/array_reader.nim b/toml_serialization/private/array_reader.nim
index 58cff67..4991903 100644
--- a/toml_serialization/private/array_reader.nim
+++ b/toml_serialization/private/array_reader.nim
@@ -12,7 +12,6 @@ import
 
 type
   ArrayReader*[RecordType, Reader] = tuple[
-    numRead: int,
     fieldName: string,
     reader: proc (rec: var RecordType, reader: var Reader, idx: int)
                  {.gcsafe, nimcall, raises: [SerializationError].}
@@ -60,7 +59,7 @@ proc makeArrayReadersTable(RecordType, Reader: distinct type, L: static[int]):
             when RecordType is tuple: obj[i] else: field(obj, realFieldName),
             err)
 
-      result[fieldPos] = (0, fieldName, readArrayFieldImpl)
+      result[fieldPos] = (fieldName, readArrayFieldImpl)
       inc fieldPos
 
 template arrayReadersTable*(RecordType, Reader: distinct type): auto =
@@ -77,6 +76,6 @@ proc findArrayReader*(fieldsTable: ArrayReadersTable,
 
   result = BadArrayReader
 
-template readArray*[T, Y](idx: int, fieldsTable: var ArrayReadersTable, rec: var T, r: var Y) =
-  fieldsTable[idx].reader(rec, r, fieldsTable[idx].numRead)
-  inc fieldsTable[idx].numRead
+template readArray*[T, Y](idx: int, fieldsTable: ArrayReadersTable, numRead: var openArray[int], rec: var T, r: var Y) =
+  fieldsTable[idx].reader(rec, r, numRead[idx])
+  inc numRead[idx]
diff --git a/toml_serialization/reader.nim b/toml_serialization/reader.nim
index d48c42a..bf36477 100644
--- a/toml_serialization/reader.nim
+++ b/toml_serialization/reader.nim
@@ -231,13 +231,15 @@ proc decodeRecord[T](r: var TomlReader, value: var T) =
 
   const
     totalFields = T.totalSerializedFields
-    arrayFields = T.totalArrayFields
 
   when  totalFields > 0:
-    let fields = T.fieldReadersTable(TomlReader)
+    const
+      fields = T.fieldReadersTable(TomlReader)
+      arrayFields = T.totalArrayFields
 
     when arrayFields > 0:
-      var arrayReaders = T.arrayReadersTable(TomlReader)
+      const arrayReaders = T.arrayReadersTable(TomlReader)
+      var numRead: array[arrayReaders.len, int]
 
     var
       expectedFieldPos = 0
@@ -287,7 +289,7 @@ proc decodeRecord[T](r: var TomlReader, value: var T) =
         if r.state == ArrayOfTable:
           let reader = findArrayReader(arrayReaders, fieldName, r.tomlCase)
           if reader != BadArrayReader:
-            reader.readArray(arrayReaders, value, r)
+            reader.readArray(arrayReaders, numRead, value, r)
           elif TomlUnknownFields in r.lex.flags:
             r.skipTableBody
           else:
@@ -297,10 +299,10 @@ proc decodeRecord[T](r: var TomlReader, value: var T) =
           continue
 
       when value is tuple:
-        var reader = fields[][expectedFieldPos].reader
+        var reader = fields[expectedFieldPos].reader
         expectedFieldPos += 1
       else:
-        var reader = findFieldReader(fields[],
+        var reader = findFieldReader(fields,
                       fieldName, expectedFieldPos, r.tomlCase)
 
       if reader != nil:
@@ -331,7 +333,7 @@ proc decodeInlineTable[T](r: var TomlReader, value: var T) =
   when  totalFields > 0:
     parseInlineTableImpl(r.lex):
       # initial action
-      let fields = T.fieldReadersTable(TomlReader)
+      const fields = T.fieldReadersTable(TomlReader)
       var
         expectedFieldPos = 0
         fieldName = newStringOfCap(defaultStringCapacity)
@@ -345,10 +347,10 @@ proc decodeInlineTable[T](r: var TomlReader, value: var T) =
     do:
       # value action
       when value is tuple:
-        var reader = fields[][expectedFieldPos].reader
+        var reader = fields[expectedFieldPos].reader
         expectedFieldPos += 1
       else:
-        var reader = findFieldReader(fields[],
+        var reader = findFieldReader(fields,
                       fieldName, expectedFieldPos, r.tomlCase)
 
       if reader != nil: