reader support for stringlikes

json_serialization/lexer.nim

@@ -1,6 +1,6 @@
 import
   unicode,
-  faststreams/input_stream, stew/objects,
+  faststreams/input_stream,
   types
 
 export

json_serialization/reader.nim

@@ -169,6 +169,12 @@ func maxAbsValue(T: type[SomeInteger]): uint64 {.compileTime.} =
 proc isNotNilCheck[T](x: ref T not nil) {.compileTime.} = discard
 proc isNotNilCheck[T](x: ptr T not nil) {.compileTime.} = discard
 
+# this construct catches `array[N, char]` which otherwise won't decompose into
+# openArray[char] - we treat any array-like thing-of-characters as a string in
+# the output
+template isCharArray[N](v: array[N, char]): bool = true
+template isCharArray(v: auto): bool = false
+
 proc readValue*(r: var JsonReader, value: var auto) =
   mixin readValue
 
@@ -178,7 +184,20 @@ proc readValue*(r: var JsonReader, value: var auto) =
     r.requireToken tkString
     value = r.lexer.strVal
     r.lexer.next()
-
+  elif value is seq[char]:
+    r.requireToken tkString
+    value.setLen(r.lexer.strVal.len)
+    for i in 0..<r.lexer.strVal.len:
+      value[i] = r.lexer.strVal[i]
+    r.lexer.next()
+  elif isCharArray(value):
+    r.requireToken tkString
+    if r.lexer.strVal.len != value.len:
+      # Raise tkString because we expected a `"` earlier
+      r.raiseUnexpectedToken(etString)
+    for i in 0..<value.len:
+      value[i] = r.lexer.strVal[i]
+    r.lexer.next()
   elif value is bool:
     case tok
     of tkTrue: value = true

tests/test_serialization.nim

@@ -149,8 +149,16 @@ suite "toJson tests":
     check:
        $original == $decoded
 
-  test "openArray[char]":
+  test "stringLike":
     check:
       "abc" == Json.decode(Json.encode(['a', 'b', 'c']), string)
       "abc" == Json.decode(Json.encode(@['a', 'b', 'c']), string)
+      ['a', 'b', 'c'] == Json.decode(Json.encode(@['a', 'b', 'c']), seq[char])
+      ['a', 'b', 'c'] == Json.decode(Json.encode("abc"), seq[char])
+      ['a', 'b', 'c'] == Json.decode(Json.encode(@['a', 'b', 'c']), array[3, char])
 
+    expect JsonReaderError: # too short
+      discard Json.decode(Json.encode(@['a', 'b']), array[3, char])
+
+    expect JsonReaderError: # too long
+      discard Json.decode(Json.encode(@['a', 'b']), array[1, char])