[Support] Make JSON handle doubles and int64s losslessly
Summary:
This patch adds a new "integer" ValueType, and renames Number -> Double.
This allows us to preserve the full precision of int64_t when parsing integers
from the wire, or constructing from an integer.
The API is unchanged, other than giving asInteger() a clearer contract.
In addition, always output doubles with enough precision that parsing will
reconstruct the same double.
Reviewers: simon_tatham
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D46209
llvm-svn: 336541
diff --git a/llvm/unittests/Support/JSONTest.cpp b/llvm/unittests/Support/JSONTest.cpp
index bf7f4ae..08307c1 100644
--- a/llvm/unittests/Support/JSONTest.cpp
+++ b/llvm/unittests/Support/JSONTest.cpp
@@ -227,6 +227,66 @@
}
}
+// Verify special integer handling - we try to preserve exact int64 values.
+TEST(JSONTest, Integers) {
+ struct {
+ const char *Desc;
+ Value Val;
+ const char *Str;
+ llvm::Optional<int64_t> AsInt;
+ llvm::Optional<double> AsNumber;
+ } TestCases[] = {
+ {
+ "Non-integer. Stored as double, not convertible.",
+ double{1.5},
+ "1.5",
+ llvm::None,
+ 1.5,
+ },
+
+ {
+ "Integer, not exact double. Stored as int64, convertible.",
+ int64_t{0x4000000000000001},
+ "4611686018427387905",
+ int64_t{0x4000000000000001},
+ double{0x4000000000000000},
+ },
+
+ {
+ "Negative integer, not exact double. Stored as int64, convertible.",
+ int64_t{-0x4000000000000001},
+ "-4611686018427387905",
+ int64_t{-0x4000000000000001},
+ double{-0x4000000000000000},
+ },
+
+ {
+ "Dynamically exact integer. Stored as double, convertible.",
+ double{0x6000000000000000},
+ "6.9175290276410819e+18",
+ int64_t{0x6000000000000000},
+ double{0x6000000000000000},
+ },
+
+ {
+ "Dynamically integer, >64 bits. Stored as double, not convertible.",
+ 1.5 * double{0x8000000000000000},
+ "1.3835058055282164e+19",
+ llvm::None,
+ 1.5 * double{0x8000000000000000},
+ },
+ };
+ for (const auto &T : TestCases) {
+ EXPECT_EQ(T.Str, s(T.Val)) << T.Desc;
+ llvm::Expected<Value> Doc = parse(T.Str);
+ EXPECT_TRUE(!!Doc) << T.Desc;
+ EXPECT_EQ(Doc->getAsInteger(), T.AsInt) << T.Desc;
+ EXPECT_EQ(Doc->getAsNumber(), T.AsNumber) << T.Desc;
+ EXPECT_EQ(T.Val, *Doc) << T.Desc;
+ EXPECT_EQ(T.Str, s(*Doc)) << T.Desc;
+ }
+}
+
// Sample struct with typical JSON-mapping rules.
struct CustomStruct {
CustomStruct() : B(false) {}