[JSON] Misc improvements

Author: rintaro

Sources/SwiftCompilerPluginMessageHandling/JSON/JSONDecoding.swift

@@ -55,19 +55,19 @@ func decodeFromJSON<T: Decodable>(json: UnsafeBufferPointer<UInt8>) throws -> T
  map: [
    0: <OM>,      -- object marker
    1: 15,        |  `- number of *map* elements in this collection
-   2: <SS>,      | --- key 1 'array'
+   2: <SS>,      | --- key 1: 'array'
    3: <int_ptr>, | |   |- pointer in the payload
    4: 5,         | |   `- length
-   5: <AM>,      | --- value1 array
+   5: <AM>,      | --- value 1: array
    6: 4,         | |   `- number of *map* elements in the array
-   7: <NM>,      | | -- arr elm 1 '-1.3'
+   7: <NM>,      | | -- arr elm 1: '-1.3'
    8: <int_ptr>, | | |
    9: 4,         | | |
-  10: <TL>,      | | -- arr elm 2 'true'
-  11: <SS>,      | --- key 2 'number'
+  10: <TL>,      | | -- arr elm 2: 'true'
+  11: <SS>,      | --- key 2: 'number'
   12: <int_ptr>, | |
   13: 6,         | |
-  14: <NM>       | --- value1: '42'
+  14: <NM>       | --- value 2: '42'
   15: <int_ptr>, | |
   16: 2,         | |
  ]

Sources/SwiftCompilerPluginMessageHandling/JSON/JSONEncoding.swift

@@ -167,23 +167,15 @@ private struct JSONWriter {
         case 0x0D:
           flush()
           write(string: "\\r")
-        case 0x0...0xF:
+        case 0x00...0x1F:
           let c = cursor.pointee
           flush()
-          write(string: "\\u000")
-          if (c < 10) {
-            write(ascii: UInt8(ascii: "0") &+ c)
-          } else {
-            write(ascii: UInt8(ascii: "A") &+ (c &- 10))
-          }
-        case 0x10...0x1F:
-          let c = cursor.pointee & 0xF
-          flush()
-          write(string: "\\u001")
-          if (c < 10) {
-            write(ascii: UInt8(ascii: "0") &+ c)
-          } else {
-            write(ascii: UInt8(ascii: "A") &+ (c &- 10))
+          write(string: "\\u00")
+          let _0 = UInt8(ascii: "0")
+          let _A = UInt8(ascii: "A")
+          for shift in stride(from: 4, through: 0, by: -4) {
+            let d = (c >> shift) & 0xF
+            write(ascii: d < 10 ? (_0 + d) : (_A + d - 10))
           }
         default:
           // Accumulate this byte.

Tests/SwiftCompilerPluginTest/JSONTests.swift

@@ -61,8 +61,8 @@ final class JSONTests: XCTestCase {
   }
 
   func testComplexStruct() {
-    let empty = ComplexStruct(result: nil, diagnostics: [])
-    _testRoundTrip(of: empty, expectedJSON: #"{"diagnostics":[]}"#)
+    let empty = ComplexStruct(result: nil, diagnostics: [], elapsed: 0.0)
+    _testRoundTrip(of: empty, expectedJSON: #"{"diagnostics":[],"elapsed":0.0}"#)
 
     let value = ComplexStruct(
       result: "\tresult\nfoo",
@@ -72,12 +72,13 @@ final class JSONTests: XCTestCase {
           animal: .cat,
           data: [nil, 42]
         )
-      ]
+      ],
+      elapsed: 42.3
     )
     _testRoundTrip(
       of: value,
       expectedJSON: #"""
-        {"diagnostics":[{"animal":"cat","data":[null,42],"message":"error 🛑"}],"result":"\tresult\nfoo"}
+        {"diagnostics":[{"animal":"cat","data":[null,42],"message":"error 🛑"}],"elapsed":42.3,"result":"\tresult\nfoo"}
         """#
     )
   }
@@ -214,4 +215,5 @@ fileprivate struct ComplexStruct: Codable, Equatable {
 
   var result: String?
   var diagnostics: [Diagnostic]
+  var elapsed: Double
 }