More efficient decoding of string values (#1280)

zio · Feb 3, 2025 · e56066d · e56066d
1 parent fec8e2c
commit e56066d
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Showing 2 changed files with 7 additions and 4 deletions.
diff --git a/zio-json/shared/src/main/scala/zio/json/internal/lexer.scala b/zio-json/shared/src/main/scala/zio/json/internal/lexer.scala
@@ -203,7 +203,8 @@ object Lexer {
   def string(trace: List[JsonError], in: OneCharReader): CharSequence = {
     var c = in.nextNonWhitespace()
     if (c != '"') error("'\"'", c, trace)
-    val sb = new FastStringBuilder(64)
+    var cs = new Array[Char](64)
+    var i  = 0
     while ({
       c = in.readChar()
       c != '"'
@@ -222,9 +223,11 @@ object Lexer {
           case _    => error(c, trace)
         }
       } else if (c < ' ') error("invalid control in string", trace)
-      sb.append(c)
+      if (i == cs.length) cs = java.util.Arrays.copyOf(cs, i << 1)
+      cs(i) = c
+      i += 1
     }
-    sb.buffer
+    new String(cs, 0, i)
   }
 
   def char(trace: List[JsonError], in: OneCharReader): Char = {

diff --git a/zio-json/shared/src/main/scala/zio/json/internal/writers.scala b/zio-json/shared/src/main/scala/zio/json/internal/writers.scala
@@ -43,7 +43,7 @@ final class FastStringWrite(initial: Int) extends Write {
   def buffer: CharSequence = sb
 }
 
-// like StringBuilder but doesn't have any encoding or range checks
+// FIXME: remove in the next major version
 private[zio] final class FastStringBuilder(initial: Int) {
   private[this] var chars: Array[Char] = new Array[Char](initial)
   private[this] var i: Int             = 0