Add escaping to $ operator for Symbol

preserves.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version = "20230611"
+version = "20230612"
 author        = "Emery Hemingway"
 description   = "data model and serialization format"
 license       = "Unlicense"

src/preserves.nim

@@ -33,7 +33,33 @@ proc hash*(s: Symbol): Hash {.borrow.}
 proc len*(s: Symbol): int {.borrow.}
 
 proc `$`*(s: Symbol): string =
-  if s.len == 0: "||" else: string(s)
+  let sym = string s
+  if sym.len > 0 and sym.string[0] in {'A'..'z'} and not sym.anyIt(char(it) in { '\x00'..'\x19', '"', '\\', '|' }):
+    result = string sym
+  else:
+    result = newStringOfCap(sym.len shl 1)
+    result.add('|')
+    for c in sym.string:
+      case c
+      of '\\':
+        result.add("\\\\")
+      of '/':
+        result.add("\\/")
+      of '\x08':
+        result.add("\\b")
+      of '\x0c':
+        result.add("\\f")
+      of '\x0a':
+        result.add("\\n")
+      of '\x0d':
+        result.add("\\r")
+      of '\x09':
+        result.add("\\t")
+      of '|':
+        result.add("\\|")
+      else:
+        result.add(c)
+    result.add('|')
 
 type
   Preserve*[E] = object