Initial commit

CHANGELOG

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+# HTTPHeaders 0.x
+
+## HTTPHeaders 0.0.1
+
+*Dec 9, 2021*
+
+- Initial relase

Package.swift

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+// swift-tools-version:5.5
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "HTTPHeaders",
+    platforms: [
+        .macOS(.v10_15),
+        .iOS(.v13),
+        .tvOS(.v13),
+        .watchOS(.v6)
+    ],
+    products: [
+        // Products define the executables and libraries a package produces, and make them visible to other packages.
+        .library(
+            name: "HTTPHeaders",
+            targets: ["HTTPHeaders"]),
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages this package depends on.
+        .target(
+            name: "HTTPHeaders",
+            dependencies: []),
+        .testTarget(
+            name: "HTTPHeadersTests",
+            dependencies: ["HTTPHeaders"]),
+    ]
+)

README.md

@@ -1,2 +1,15 @@
-# Headers
-Parsing Simple HTTP Headers
+# HTTP Headers
+
+Parsing simple HTTP headers.
+
+Examples:
+
+```swift
+let response = HTTPURLRseponse(..., headers: [
+    "X-RateLimit-Reset": "2015-01-01T00:00:00Z"
+])
+
+let header = HTTPHeader<Date>(field: "X-RateLimit-Reset")
+let date = try header.parse(from: response)
+// let date = try header.parseIfPresent(from: response)
+```

Sources/HTTPHeaders/HTTPHeader.swift

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+// The MIT License (MIT)
+//
+// Copyright (c) 2021 Alexander Grebenyuk (github.com/kean).
+
+import Foundation
+
+public struct HTTPHeader<T> {
+    public let field: String
+    private let _parse: (String) -> T?
+
+    public init(field: String, parse: @escaping (String) -> T?) {
+        self.field = field
+        self._parse = parse
+    }
+
+    public func parse(from response: HTTPURLResponse) throws -> T {
+        guard let value = response.value(forHTTPHeaderField: field) else {
+            throw ParsingError.valueNotFound(field: field)
+        }
+        return try parse(value)
+    }
+
+    public func parseIfPresent(from response: HTTPURLResponse) throws -> T? {
+        guard let value = response.value(forHTTPHeaderField: field) else {
+            return nil
+        }
+        return try parse(value)
+    }
+
+    private func parse(_ value: String) throws -> T {
+        guard let value = _parse(value) else {
+            throw ParsingError.typeMismatch(field: field, value: value, type: T.self)
+        }
+        return value
+    }
+
+    public enum ParsingError: Error {
+        case valueNotFound(field: String)
+        case typeMismatch(field: String, value: String, type: Any.Type)
+    }
+}
+
+extension HTTPHeader where T == String {
+    public init(field: String) {
+        self.init(field: field) { $0 }
+    }
+}
+
+extension HTTPHeader where T == Int {
+    public init(field: String) {
+        self.init(field: field) { Int($0) }
+    }
+}
+
+extension HTTPHeader where T == Date {
+    public init(field: String, options: ISO8601DateFormatter.Options? = nil) {
+        self.init(field: field) {
+            let formatter = ISO8601DateFormatter()
+            if let options = options {
+                formatter.formatOptions = options
+            }
+            return formatter.date(from: $0)
+        }
+    }
+}
+
+extension HTTPHeader where T == Double {
+    public init(field: String) {
+        self.init(field: field) { Double($0) }
+    }
+}

Tests/HTTPHeadersTests/HTTPHeadersTests.swift

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+// The MIT License (MIT)
+//
+// Copyright (c) 2021 Alexander Grebenyuk (github.com/kean).
+
+import XCTest
+@testable import HTTPHeaders
+
+final class HTTPHeadersTests: XCTestCase {
+    func testParseString() throws {
+        // Given
+        let response = makeResponse(headers: ["X-RateLimit-Reset": "2015-01-01T00:00:00Z"])
+        let header = HTTPHeader<String>(field: "X-RateLimit-Reset")
+
+        // When/Then
+        let value = try header.parse(from: response)
+        XCTAssertEqual(value, "2015-01-01T00:00:00.000Z")
+    }
+
+    func testParseOptionalString() throws {
+        // Given
+        let response = makeResponse(headers: ["X-RateLimit-Reset": "2015-01-01T00:00:00Z"])
+        let header = HTTPHeader<String>(field: "non-existing-key")
+
+        // When/Then
+        let value = try header.parseIfPresent(from: response)
+        XCTAssertNil(value)
+    }
+
+    func testParseDate() throws {
+        // Given
+        let response = makeResponse(headers: ["X-RateLimit-Reset": "2015-01-01T00:00:00Z"])
+        let header = HTTPHeader<Date>(field: "X-RateLimit-Reset")
+
+        // When/Then
+        let value = try header.parse(from: response)
+        XCTAssertEqual(value, Date.init(timeIntervalSinceReferenceDate: 441763200.0))
+    }
+
+    func testParseDateWithCustomOptions() throws {
+        // Given
+        let response = makeResponse(headers: ["X-RateLimit-Reset": "2015-01-01T01:20:30.25Z"])
+        let header = HTTPHeader<Date>(field: "X-RateLimit-Reset", options: [.withInternetDateTime, .withFractionalSeconds])
+
+        // When/Then
+        let value = try header.parse(from: response)
+        print(value.timeIntervalSinceReferenceDate)
+        XCTAssertEqual(value, Date.init(timeIntervalSinceReferenceDate: 441768030.25))
+    }
+
+    private func makeResponse(headers: [String: String]) -> HTTPURLResponse {
+        HTTPURLResponse(url: URL(string: "https://api.github.com/user")!, statusCode: 200, httpVersion: nil, headerFields: headers)!
+    }
+}