Fix parsing of large integer doubles (#504)

Fixes #240 The basic problem appears to be that we are using a `parseLong` fast-path inside `ujson.Value.visitFloat64StringParts`. This is only valid for numbers of a certain digit-length. We should be checking for numbers larger than that length, and falling back to the `toDouble` slow path for those
com-lihaoyi · Jul 9, 2023 · 1e75232 · 1e75232
1 parent 8723cae
commit 1e75232
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Showing 3 changed files with 51 additions and 2 deletions.
diff --git a/ujson/src/ujson/Value.scala b/ujson/src/ujson/Value.scala
@@ -180,7 +180,9 @@ object Value extends AstTransformer[Value]{
 
   override def visitFloat64StringParts(s: CharSequence, decIndex: Int, expIndex: Int, index: Int) = {
     ujson.Num(
-      if (decIndex != -1 || expIndex != -1) s.toString.toDouble
+      if (decIndex != -1 || expIndex != -1 || s.length() >= 19 /*digit count of largest positive long*/) {
+        s.toString.toDouble
+      }
       else ParseUtils.parseIntegralNum(s, decIndex, expIndex, index).toDouble
     )
   }

diff --git a/ujson/test/src/ujson/SmallJsonTests.scala b/ujson/test/src/ujson/SmallJsonTests.scala
@@ -23,6 +23,50 @@ object SmallJsonTests extends TestSuite {
 
       }
     }
+    test("largeDouble"){
+      test("longMaxValue") {
+        assert(
+          ujson.read("9223372036854775807").num ==
+          "9223372036854775807".toDouble
+        )
+      }
+      test("longMinValue") {
+        assert(
+          ujson.read("-9223372036854775808").num ==
+          "-9223372036854775808".toDouble
+        )
+      }
+      test("longMaxValuePlusOne") {
+        assert(
+          ujson.read("9223372036854775808").num ==
+          "9223372036854775808".toDouble
+        )
+      }
+      test("longMinValueMinusOne") {
+        assert(
+          ujson.read("-9223372036854775809").num ==
+          "-9223372036854775809".toDouble
+        )
+      }
+      test("issue240"){
+        assert(
+          ujson.read("28291041994989161181883157038606177750").num ==
+            "28291041994989161181883157038606177750".toDouble
+        )
+      }
+      test("largeDecimalPoint"){
+        assert(
+          ujson.read("28291041994989161181883157038606177750.28291041994989161181883157038606177750").num ==
+            "28291041994989161181883157038606177750.28291041994989161181883157038606177750".toDouble
+        )
+      }
+      test("largeDecimalPointExponent"){
+        assert(
+          ujson.read("28291041994989161181883157038606177750.28291041994989161181883157038606177750E123456789").num ==
+            "28291041994989161181883157038606177750.28291041994989161181883157038606177750E123456789".toDouble
+        )
+      }
+    }
     test("inputsEu"){
       TestUtil.checkParse(
         """{

diff --git a/upickle/core/templates/ElemUtils.scala b/upickle/core/templates/ElemUtils.scala
@@ -174,7 +174,10 @@ object ElemUtils{
     }
 
     val size = end - i
-    if (size <= 0 || size > 19) throw new NumberFormatException(new String(cs))
+
+    if (size <= 0 || size > 19 /*digit count of largest positive long*/) {
+      throw new NumberFormatException(new String(cs))
+    }
 
     while (i < end) {
       val digit = cs(i).toInt - 48