Fix parsing of floats with long mantissa (#222)

zio · Mar 24, 2021 · c184f0e · c184f0e
1 parent bd8bb12
commit c184f0e
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Showing 2 changed files with 53 additions and 2 deletions.
diff --git a/zio-json/jvm/src/test/scala/zio/json/internal/SafeNumbersSpec.scala b/zio-json/jvm/src/test/scala/zio/json/internal/SafeNumbersSpec.scala
@@ -151,6 +151,10 @@ object SafeNumbersSpec extends DefaultRunnableSpec {
         testM("valid") {
           check(Gen.anyFloat.filterNot(_.isNaN))(d => assert(SafeNumbers.float(d.toString))(equalTo(FloatSome(d))))
         },
+        test("large mantissa") {
+          // https://github.com/zio/zio-json/issues/221
+          assert(SafeNumbers.float("1.199999988079071"))(equalTo(FloatSome(1.1999999f)))
+        },
         testM("valid (from Int)") {
           check(Gen.anyInt)(i => assert(SafeNumbers.float(i.toString))(equalTo(FloatSome(i.toFloat))))
         },

diff --git a/zio-json/shared/src/main/scala/zio/json/internal/numbers.scala b/zio-json/shared/src/main/scala/zio/json/internal/numbers.scala
@@ -263,11 +263,58 @@ object UnsafeNumbers {
 
   def float(num: String, max_bits: Int): Float =
     float_(new FastStringReader(num), true, max_bits)
-  def float_(in: Reader, consume: Boolean, max_bits: Int): Float =
-    double_(in, consume, max_bits).toFloat
+
+  def float_(in: Reader, consume: Boolean, max_bits: Int): Float = {
+    var current: Int = in.read()
+    var negative     = false
+
+    def readAll(s: String): Unit = {
+      var i   = 0
+      val len = s.length
+
+      while (i < len) {
+        current = in.read()
+        if (current != s(i)) throw UnsafeNumber
+        i += 1
+      }
+
+      current = in.read() // to be consistent read the terminator
+
+      if (consume && current != -1)
+        throw UnsafeNumber
+    }
+
+    if (current == 'N') {
+      readAll("aN")
+      return Float.NaN
+    }
+
+    if (current == '-') {
+      negative = true
+      current = in.read()
+    } else if (current == '+') {
+      current = in.read()
+    }
+
+    if (current == 'I') {
+      readAll("nfinity")
+
+      if (negative) return Float.NegativeInfinity
+      else return Float.PositiveInfinity
+    }
+
+    if (current == -1)
+      throw UnsafeNumber
+
+    val res = bigDecimal__(in, consume, negative = negative, initial = current, int_only = false, max_bits = max_bits)
+
+    if (negative && res.unscaledValue == java.math.BigInteger.ZERO) -0.0f
+    else res.floatValue
+  }
 
   def double(num: String, max_bits: Int): Double =
     double_(new FastStringReader(num), true, max_bits)
+
   def double_(in: Reader, consume: Boolean, max_bits: Int): Double = {
     var current: Int = in.read()
     var negative     = false