Improve name unmangling in ProductFormats, closes #138

1 files changed, 44 insertions, 19 deletions

diff --git a/src/main/scala/spray/json/ProductFormats.scala b/src/main/scala/spray/json/ProductFormats.scala
index 9e494ff..b1aac8e 100644
--- a/src/main/scala/spray/json/ProductFormats.scala
+++ b/src/main/scala/spray/json/ProductFormats.scala
@@ -17,6 +17,7 @@
 package spray.json
 
 import java.lang.reflect.Modifier
+import scala.annotation.tailrec
 import scala.util.control.NonFatal
 
 /**
@@ -87,26 +88,50 @@ trait ProductFormats extends ProductFormatsInstances {
 }
 
 object ProductFormats {
-  private val operators = Map(
-    "$eq" -> "=",
-    "$greater" -> ">",
-    "$less" -> "<",
-    "$plus" -> "+",
-    "$minus" -> "-",
-    "$times" -> "*",
-    "$div" -> "/",
-    "$bang" -> "!",
-    "$at" -> "@",
-    "$hash" -> "#",
-    "$percent" -> "%",
-    "$up" -> "^",
-    "$amp" -> "&",
-    "$tilde" -> "~",
-    "$qmark" -> "?",
-    "$bar" -> "|")
 
-  private def unmangle(name: String) = operators.foldLeft(name) { case (n, (mangled, unmangled)) =>
-    if (n.indexOf(mangled) >= 0) n.replace(mangled, unmangled) else n
+  private def unmangle(name: String) = {
+    import java.lang.{StringBuilder => JStringBuilder}
+    @tailrec def rec(ix: Int, builder: JStringBuilder): String = {
+      val rem = name.length - ix
+      if (rem > 0) {
+        var ch = name.charAt(ix)
+        var ni = ix + 1
+        val sb = if (ch == '$' && rem > 1) {
+          def c(offset: Int, ch: Char) = name.charAt(ix + offset) == ch
+          ni = name.charAt(ix + 1) match {
+            case 'a' if rem > 3 && c(2, 'm') && c(3, 'p') => { ch = '&'; ix + 4 }
+            case 'a' if rem > 2 && c(2, 't') => { ch = '@'; ix + 3 }
+            case 'b' if rem > 4 && c(2, 'a') && c(3, 'n') && c(4, 'g') => { ch = '!'; ix + 5 }
+            case 'b' if rem > 3 && c(2, 'a') && c(3, 'r') => { ch = '|'; ix + 4 }
+            case 'd' if rem > 3 && c(2, 'i') && c(3, 'v') => { ch = '/'; ix + 4 }
+            case 'e' if rem > 2 && c(2, 'q') => { ch = '='; ix + 3 }
+            case 'g' if rem > 7 && c(2, 'r') && c(3, 'e') && c(4, 'a') && c(5, 't') && c(6, 'e') && c(7, 'r') => { ch = '>'; ix + 8 }
+            case 'h' if rem > 4 && c(2, 'a') && c(3, 's') && c(4, 'h') => { ch = '#'; ix + 5 }
+            case 'l' if rem > 4 && c(2, 'e') && c(3, 's') && c(4, 's') => { ch = '<'; ix + 5 }
+            case 'm' if rem > 5 && c(2, 'i') && c(3, 'n') && c(4, 'u') && c(5, 's') => { ch = '-'; ix + 6 }
+            case 'p' if rem > 7 && c(2, 'e') && c(3, 'r') && c(4, 'c') && c(5, 'e') && c(6, 'n') && c(7, 't') => { ch = '%'; ix + 8 }
+            case 'p' if rem > 4 && c(2, 'l') && c(3, 'u') && c(4, 's') => { ch = '+'; ix + 5 }
+            case 'q' if rem > 5 && c(2, 'm') && c(3, 'a') && c(4, 'r') && c(5, 'k') => { ch = '?'; ix + 6 }
+            case 't' if rem > 5 && c(2, 'i') && c(3, 'l') && c(4, 'd') && c(5, 'e') => { ch = '~'; ix + 6 }
+            case 't' if rem > 5 && c(2, 'i') && c(3, 'm') && c(4, 'e') && c(5, 's') => { ch = '*'; ix + 6 }
+            case 'u' if rem > 2 && c(2, 'p') => { ch = '^'; ix + 3 }
+            case 'u' if rem > 5 =>
+              def hexValue(offset: Int): Int = {
+                val c = name.charAt(ix + offset)
+                if ('0' <= c && c <= '9') c - '0'
+                else if ('a' <= c && c <= 'f') c - 87
+                else if ('A' <= c && c <= 'F') c - 55 else -0xFFFF
+              }
+              val ci = (hexValue(2) << 12) + (hexValue(3) << 8) + (hexValue(4) << 4) + hexValue(5)
+              if (ci >= 0) { ch = ci.toChar; ix + 6 } else ni
+            case _ => ni
+          }
+          if (ni > ix + 1 && builder == null) new JStringBuilder(name.substring(0, ix)) else builder
+        } else builder
+        rec(ni, if (sb != null) sb.append(ch) else null)
+      } else if (builder != null) builder.toString else name
+    }
+    rec(0, null)
   }
 }