More efficient encoding of primitives and java.time._ values (#1293)

zio-json/js/src/main/scala/zio/json/internal/FastStringWrite.scala

@@ -0,0 +1,84 @@
+package zio.json.internal
+
+final class FastStringWrite(initial: Int) extends Write {
+  require(initial >= 8)
+  private[this] var chars: String = ""
+
+  @inline def reset(): Unit = chars = ""
+
+  @inline private[internal] def length: Int = chars.length
+
+  @inline private[internal] def getChars: Array[Char] = chars.toCharArray
+
+  @inline def write(s: String): Unit = chars += s
+
+  @inline def write(c: Char): Unit = chars += c
+
+  @inline override def write(cs: Array[Char], from: Int, to: Int): Unit = {
+    var i = from
+    while (i < to) {
+      chars += cs(i)
+      i += 1
+    }
+  }
+
+  @inline override def write(c1: Char, c2: Char): Unit = {
+    chars += c1
+    chars += c2
+  }
+
+  @inline override def write(c1: Char, c2: Char, c3: Char): Unit = {
+    chars += c1
+    chars += c2
+    chars += c3
+  }
+
+  @inline override def write(c1: Char, c2: Char, c3: Char, c4: Char): Unit = {
+    chars += c1
+    chars += c2
+    chars += c3
+    chars += c4
+  }
+
+  @inline override def write(c1: Char, c2: Char, c3: Char, c4: Char, c5: Char): Unit = {
+    chars += c1
+    chars += c2
+    chars += c3
+    chars += c4
+    chars += c5
+  }
+
+  @inline override def write(s: Short): Unit = {
+    chars += (s & 0xff).toChar
+    chars += (s >> 8).toChar
+  }
+
+  @inline override def write(s1: Short, s2: Short): Unit = {
+    chars += (s1 & 0xff).toChar
+    chars += (s1 >> 8).toChar
+    chars += (s2 & 0xff).toChar
+    chars += (s2 >> 8).toChar
+  }
+
+  @inline override def write(s1: Short, s2: Short, s3: Short): Unit = {
+    chars += (s1 & 0xff).toChar
+    chars += (s1 >> 8).toChar
+    chars += (s2 & 0xff).toChar
+    chars += (s2 >> 8).toChar
+    chars += (s3 & 0xff).toChar
+    chars += (s3 >> 8).toChar
+  }
+
+  @inline override def write(s1: Short, s2: Short, s3: Short, s4: Short): Unit = {
+    chars += (s1 & 0xff).toChar
+    chars += (s1 >> 8).toChar
+    chars += (s2 & 0xff).toChar
+    chars += (s2 >> 8).toChar
+    chars += (s3 & 0xff).toChar
+    chars += (s3 >> 8).toChar
+    chars += (s4 & 0xff).toChar
+    chars += (s4 >> 8).toChar
+  }
+
+  @inline def buffer: CharSequence = chars
+}