Do not leak null characters into the #"" encoding

src/preserves.nim

@@ -1039,7 +1039,11 @@ proc concat[E](result: var string; pr: Preserve[E]) =
   of pkString:
     result.add escapeJson(pr.string)
   of pkByteString:
-    if sequtils.any(pr.bytes, proc (b: byte): bool = b.char in {'\20'..'\21', '#'..'[', ']'..'~'}):
+    if pr.bytes.allIt(char(it) in {' '..'!', '#'..'~'}):
+      result.add("#\"")
+      result.add(cast[string](pr.bytes))
+      result.add('"')
+    else:
       if pr.bytes.len > 64:
         result.add("#[") #]#
         result.add(base64.encode(pr.bytes))
@@ -1051,10 +1055,6 @@ proc concat[E](result: var string; pr: Preserve[E]) =
           result.add(alphabet[int(b shr 4)])
           result.add(alphabet[int(b and 0xf)])
         result.add('"')
-    else:
-      result.add("#\"")
-      result.add(cast[string](pr.bytes))
-      result.add('"')
   of pkSymbol:
     result.add(escapeJsonUnquoted(pr.symbol))
   of pkRecord:

src/preserves/pegs.nim

@@ -38,8 +38,7 @@ grammar "Preserves":
   exp <- 'e' * ?('-'|'+') * +Digit
   flt <- int * ((frac * exp) | frac | exp)
 
-  stringBody <- ?escape * *( +( {'\x20'..'\xff'} - {'"'} - {'\\'}) * *escape)
-  String <- '"' * stringBody * '"'
+  String <- '"' * *(escaped | (utf8.any - '"')) * '"'
 
   ByteString <- charByteString | hexByteString | b64ByteString
   charByteString <- '#' * >('"' * >(*binchar) * '"')

src/preserves/preserves_schema_nim.nim

@@ -418,10 +418,13 @@ proc typeDef(scm: Schema; name: string; pat: Pattern; ty: PNode): PNode =
 proc typeDef(scm: Schema; name: string; def: Definition; ty: PNode): PNode =
   case def.orKind
   of DefinitionKind.or:
+    let pragma = nn(nkPragma, ident"preservesOr")
+    if isSymbolEnum(scm, def):
+      pragma.add ident"pure"
     nn(nkTypeDef,
       nn(nkPragmaExpr,
         name.ident.accQuote.toExport,
-        nn(nkPragma, ident"preservesOr")),
+        pragma),
       embeddingParams(isEmbeddable(scm, def)),
       ty)
   of DefinitionKind.and:

tests/test_parser.nim

@@ -9,6 +9,7 @@ const examples = [
 ("""[1 2 3 4]""", "\xB5\x91\x92\x93\x94\x84"),
 ("""[-2 -1 0 1]""", "\xB5\x9E\x9F\x90\x91\x84"),
 (""""hello"""", "\xB1\x05hello"),
+("""" \"hello\" """", "\xB1\x09 \"hello\" "),
 ("""["a" b #"c" [] #{} #t #f]""", "\xB5\xB1\x01a\xB3\x01b\xB2\x01c\xB5\x84\xB6\x84\x81\x80\x84"),
 ("""-257""", "\xA1\xFE\xFF"),
 ("""-1""", "\x9F"),