Improve Date parser demo (#305)

* Improve `Date` parser demo Incorporates a helper from @juri's [parser](https://github.com/juri/Parse3339) to improve things a bit. * wip * wip
pointfreeco · Jul 24, 2023 · 27a3a86 · 27a3a86
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diff --git a/Package.resolved b/Package.resolved
@@ -1,52 +1,41 @@
 {
-  "object": {
-    "pins": [
-      {
-        "package": "swift-argument-parser",
-        "repositoryURL": "https://github.com/apple/swift-argument-parser",
-        "state": {
-          "branch": null,
-          "revision": "6b2aa2748a7881eebb9f84fb10c01293e15b52ca",
-          "version": "0.5.0"
-        }
-      },
-      {
-        "package": "Benchmark",
-        "repositoryURL": "https://github.com/google/swift-benchmark",
-        "state": {
-          "branch": null,
-          "revision": "a0564bf88df5f94eec81348a2f089494c6b28d80",
-          "version": "0.1.1"
-        }
-      },
-      {
-        "package": "swift-case-paths",
-        "repositoryURL": "https://github.com/pointfreeco/swift-case-paths",
-        "state": {
-          "branch": null,
-          "revision": "241301b67d8551c26d8f09bd2c0e52cc49f18007",
-          "version": "0.8.0"
-        }
-      },
-      {
-        "package": "SwiftDocCPlugin",
-        "repositoryURL": "https://github.com/apple/swift-docc-plugin",
-        "state": {
-          "branch": null,
-          "revision": "3303b164430d9a7055ba484c8ead67a52f7b74f6",
-          "version": "1.0.0"
-        }
-      },
-      {
-        "package": "xctest-dynamic-overlay",
-        "repositoryURL": "https://github.com/pointfreeco/xctest-dynamic-overlay",
-        "state": {
-          "branch": null,
-          "revision": "50a70a9d3583fe228ce672e8923010c8df2deddd",
-          "version": "0.2.1"
-        }
+  "pins" : [
+    {
+      "identity" : "swift-argument-parser",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-argument-parser",
+      "state" : {
+        "revision" : "6b2aa2748a7881eebb9f84fb10c01293e15b52ca",
+        "version" : "0.5.0"
       }
-    ]
-  },
-  "version": 1
+    },
+    {
+      "identity" : "swift-benchmark",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/google/swift-benchmark",
+      "state" : {
+        "revision" : "a0564bf88df5f94eec81348a2f089494c6b28d80",
+        "version" : "0.1.1"
+      }
+    },
+    {
+      "identity" : "swift-case-paths",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/pointfreeco/swift-case-paths",
+      "state" : {
+        "revision" : "241301b67d8551c26d8f09bd2c0e52cc49f18007",
+        "version" : "0.8.0"
+      }
+    },
+    {
+      "identity" : "swift-docc-plugin",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-docc-plugin",
+      "state" : {
+        "revision" : "3303b164430d9a7055ba484c8ead67a52f7b74f6",
+        "version" : "1.0.0"
+      }
+    }
+  ],
+  "version" : 2
 }
diff --git a/README.md b/README.md
@@ -317,7 +317,7 @@ Bool.Scanner.scanBool                             916.000 ns ±  30.55 %    1000
 Color.Parser                                      208.000 ns ±  28.34 %    1000000
 CSV.Parser                                    3675250.000 ns ±   1.16 %        380
 CSV.Ad hoc mutating methods                    651333.000 ns ±   1.00 %       2143
-Date.Parser                                      5833.000 ns ±   5.65 %     238924
+Date.Parser                                      3500.000 ns ±   5.65 %     238924
 Date.DateFormatter                              23542.000 ns ±   5.50 %      58766
 Date.ISO8601DateFormatter                       29041.000 ns ±   3.31 %      48028
 HTTP.HTTP                                       10250.000 ns ±   6.24 %     135657

diff --git a/Sources/swift-parsing-benchmark/Date.swift b/Sources/swift-parsing-benchmark/Date.swift
@@ -2,6 +2,76 @@ import Benchmark
 import Foundation
 import Parsing
 
+#if swift(>=5.8)
+  struct DateTime: Parser {
+    var body: some Parser<Substring.UTF8View, Date> {
+      Parse(Date.init(year:month:day:hour:minute:second:nanosecond:timeZone:)) {
+        Digits(4)
+        "-".utf8
+        Digits(2).filter { (1...12).contains($0) }
+        "-".utf8
+        Digits(2).filter { (1...31).contains($0) }
+        "T".utf8
+        Digits(2).filter { $0 < 24 }
+        ":".utf8
+        Digits(2).filter { $0 < 60 }
+        ":".utf8
+        Digits(2).filter { $0 <= 60 }
+        Parse {
+          ".".utf8
+          Prefix(1...9, while: (UInt8(ascii: "0")...UInt8(ascii: "9")).contains)
+            .compactMap { n in Int(Substring(n)).map { $0 * Int(pow(10, 9 - Double(n.count))) } }
+        }
+        .replaceError(with: 0)
+        OneOf {
+          "Z".utf8.map { 0 }
+          Parse {
+            OneOf {
+              "+".utf8.map { 1 }
+              "-".utf8.map { -1 }
+            }
+            Digits(2).filter { $0 < 24 }.map { $0 * 60 * 60 }
+            ":".utf8
+            Digits(2).filter { $0 < 60 }.map { $0 * 60 }
+          }
+          .map { $0 * ($1 + $2) }
+        }
+      }
+    }
+  }
+
+  private extension Date {
+    init(
+      year: Int,
+      month: Int,
+      day: Int,
+      hour: Int,
+      minute: Int,
+      second: Int,
+      nanosecond: Int,
+      timeZone: Int
+    ) {
+      var components = tm(
+        tm_sec: Int32(second),
+        tm_min: Int32(minute),
+        tm_hour: Int32(hour),
+        tm_mday: Int32(day),
+        tm_mon: Int32(month - 1),
+        tm_year: Int32(year - 1900),
+        tm_wday: 0,
+        tm_yday: 0,
+        tm_isdst: 0,
+        tm_gmtoff: 0,
+        tm_zone: nil
+      )
+      let time = timegm(&components)
+      var timeIntervalSince1970 = TimeInterval(time - timeZone)
+      timeIntervalSince1970 += TimeInterval(nanosecond) / 1_000_000_000
+      self.init(timeIntervalSince1970: timeIntervalSince1970)
+    }
+  }
+#endif
+
 /// This benchmarks implements an [RFC-3339-compliant](https://www.ietf.org/rfc/rfc3339.txt) date
 /// parser in a relatively naive way and pits it against `DateFormatter` and `ISO8601DateFormatter`.
 ///
@@ -10,62 +80,12 @@ import Parsing
 /// nanosecond, while the formatters do not parse beyond the millisecond.
 let dateSuite = BenchmarkSuite(name: "Date") { suite in
   #if swift(>=5.8)
-    struct DateTime: Parser {
-      var body: some Parser<Substring.UTF8View, DateComponents> {
-        Parse { year, month, day, hour, minute, second, nanosecond, timeZone in
-          DateComponents(
-            timeZone: timeZone,
-            year: year,
-            month: month,
-            day: day,
-            hour: hour,
-            minute: minute,
-            second: second,
-            nanosecond: nanosecond
-          )
-        } with: {
-          Digits(4)
-          "-".utf8
-          Digits(2)
-          "-".utf8
-          Digits(2)
-          "T".utf8
-          Digits(2)
-          ":".utf8
-          Digits(2)
-          ":".utf8
-          Digits(2)
-          Optionally {
-            ".".utf8
-            Prefix(1...9, while: (UInt8(ascii: "0")...UInt8(ascii: "9")).contains)
-              .compactMap { n in Int(Substring(n)).map { $0 * Int(pow(10, 9 - Double(n.count))) } }
-          }
-          OneOf {
-            "Z".utf8.map { 0 }
-            Parse {
-              OneOf {
-                "+".utf8.map { 1 }
-                "-".utf8.map { -1 }
-              }
-              Digits(2).map { $0 * 60 * 60 }
-              ":".utf8
-              Digits(2).map { $0 * 60 }
-            }
-            .map { $0 * ($1 + $2) }
-          }
-          .map { TimeZone(secondsFromGMT: $0) }
-        }
-      }
-    }
-
     let input = "1979-05-27T00:32:00Z"
     let expected = Date(timeIntervalSince1970: 296_613_120)
     var output: Date!
 
-    let dateTimeParser = DateTime().compactMap(Calendar.current.date(from:))
     suite.benchmark("Parser") {
-      var input = input[...].utf8
-      output = try dateTimeParser.parse(&input)
+      output = try DateTime().parse(input)
     } tearDown: {
       precondition(output == expected)
     }