feat: add support for date format

Author: Jack Newcombe

Sources/Draft201909Validator.swift

@@ -63,6 +63,7 @@ public class Draft201909Validator: Validator {
     "json-pointer": validateJSONPointer,
     "duration": validateDuration,
     "time": validateTime,
+    "date": validateDate,
   ]
 
   public required init(schema: Bool) {

Sources/Draft202012Validator.swift

@@ -64,6 +64,7 @@ public class Draft202012Validator: Validator {
     "json-pointer": validateJSONPointer,
     "duration": validateDuration,
     "time": validateTime,
+    "date": validateDate,
   ]
 
   public required init(schema: Bool) {

Sources/Draft7Validator.swift

@@ -51,6 +51,7 @@ public class Draft7Validator: Validator {
     "json-pointer": validateJSONPointer,
     "regex": validateRegex,
     "time": validateTime,
+    "date": validateDate,
   ]
 
   public required init(schema: Bool) {

Sources/Format/date.swift

@@ -0,0 +1,33 @@
+import Foundation
+
+
+func validateDate(_ context: Context, _ value: String) -> AnySequence<ValidationError> {
+  if let regularExpression = try? NSRegularExpression(pattern: "^\\d{4}-\\d{2}-\\d{2}$", options: []) {
+    let range = NSRange(location: 0, length: value.utf16.count)
+    let result = regularExpression.matches(in: value, options: [], range: range)
+    if result.isEmpty  {
+      return AnySequence([
+        ValidationError(
+          "'\(value)' is not a valid RFC 3339 formatted date.",
+          instanceLocation: context.instanceLocation,
+          keywordLocation: context.keywordLocation
+        )
+      ])
+    }
+  }
+
+  let rfc3339DateTimeFormatter = DateFormatter()
+
+  rfc3339DateTimeFormatter.dateFormat = "yyyy-MM-dd"
+  if rfc3339DateTimeFormatter.date(from: value) != nil {
+    return AnySequence(EmptyCollection())
+  }
+
+  return AnySequence([
+    ValidationError(
+      "'\(value)' is not a valid RFC 3339 formatted date.",
+      instanceLocation: context.instanceLocation,
+      keywordLocation: context.keywordLocation
+    )
+  ])
+}

Tests/JSONSchemaTests/JSONSchemaCases.swift

@@ -138,7 +138,6 @@ class JSONSchemaCases: XCTestCase {
 
       // optional, format
       "date-time.json",
-      "date.json",
       "email.json",
       "hostname.json",
       "idn-email.json",
@@ -173,7 +172,6 @@ class JSONSchemaCases: XCTestCase {
       // optional, format
       "format.json",
       "date-time.json",
-      "date.json",
       "email.json",
       "hostname.json",
       "idn-email.json",
@@ -207,7 +205,6 @@ class JSONSchemaCases: XCTestCase {
       // optional, format
       "format.json",
       "date-time.json",
-      "date.json",
       "email.json",
       "hostname.json",
       "idn-email.json",