From 77caa626f0e59d9a5eab3bcd37c17c4a4b746539 Mon Sep 17 00:00:00 2001
From: Emil Lerch <emil@lerch.org>
Date: Wed, 23 Jun 2021 18:18:42 -0700
Subject: [PATCH] allow parsing of exponential numbers if they resolve to int

---
 src/json.zig | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/json.zig b/src/json.zig
index fcb4b72..7548f6c 100644
--- a/src/json.zig
+++ b/src/json.zig
@@ -1543,8 +1543,13 @@ fn parseInternal(comptime T: type, token: Token, tokens: *TokenStream, options:
                 .Number => |n| n,
                 else => return error.UnexpectedToken,
             };
-            if (!numberToken.is_integer) return error.UnexpectedToken;
-            return try std.fmt.parseInt(T, numberToken.slice(tokens.slice, tokens.i - 1), 10);
+            // This is a bug. you can still potentially have an integer that has exponents
+            // if (!numberToken.is_integer) return error.UnexpectedToken;
+            if (numberToken.is_integer)
+                return try std.fmt.parseInt(T, numberToken.slice(tokens.slice, tokens.i - 1), 10);
+            const float = try std.fmt.parseFloat(f128, numberToken.slice(tokens.slice, tokens.i - 1));
+            if (std.math.round(float) != float) return error.InvalidNumber;
+            return @floatToInt(T, float);
         },
         .Optional => |optionalInfo| {
             if (token == .Null) {
@@ -2002,6 +2007,11 @@ test "parse into struct with no fields" {
     const T = struct {};
     try testing.expectEqual(T{}, try parse(T, &TokenStream.init("{}"), ParseOptions{}));
 }
+test "parse exponential into int" {
+    const T = struct { int: i64 };
+    const r = try parse(T, &TokenStream.init("{ \"int\": 4.2e2 }"), ParseOptions{});
+    try testing.expectEqual(@as(i64, 420), r.int);
+}
 
 test "parse into struct with misc fields" {
     @setEvalBranchQuota(10000);