Add "literal" parsers (#56)

* Add "literal" parsers

* fix

Parsing.playground/Contents.swift

@@ -4,21 +4,21 @@ struct Color {
   let red, green, blue: UInt8
 }
 
-let hexPrimary = Prefix<Substring.UTF8View>(2)
-  .compactMap { UInt8(Substring($0), radix: 16) }
+let hexPrimary = Prefix<Substring>(2)
+  .compactMap { UInt8($0, radix: 16) }
 
-let hexColor = StartsWith("#".utf8)
+let hexColor = "#"
   .take(hexPrimary)
   .take(hexPrimary)
   .take(hexPrimary)
   .map(Color.init)
 
 do {
-  var hex = "#000000"[...].utf8
+  var hex = "#000000"[...]
   print(hexColor.parse(&hex)!)
 }
 
 do {
-  var hex = "#FF0000"[...].utf8
+  var hex = "#FF0000"[...]
   print(hexColor.parse(&hex)!)
 }

README.md

@@ -97,7 +97,7 @@ We can start by describing what it means to parse a single row, first by parsing
 
 ```swift
 let user = Int.parser()
-  .skip(StartsWith(","))
+  .skip(",")
 ```
 
 Already this can consume the beginning of the input:
@@ -111,9 +111,9 @@ Next we want to take everything up until the next comma for the user's name, and
 
 ```swift
 let user = Int.parser()
-  .skip(StartsWith(","))
+  .skip(",")
   .take(Prefix { $0 != "," })
-  .skip(StartsWith(","))
+  .skip(",")
 ```
 
 Here the `.take` operator has combined parsed values together into a tuple, `(Int, Substring)`.
@@ -122,19 +122,19 @@ And then we want to take the boolean at the end of the row for the user's admin
 
 ```swift
 let user = Int.parser()
-  .skip(StartsWith(","))
+  .skip(",")
   .take(Prefix { $0 != "," })
-  .skip(StartsWith(","))
+  .skip(",")
   .take(Bool.parser())
 ```
 
 Currently this will parse a tuple `(Int, Substring, Bool)` from the input, and we can `.map` on that to turn it into a `User`:
 
 ```swift
 let user = Int.parser()
-  .skip(StartsWith(","))
+  .skip(",")
   .take(Prefix { $0 != "," })
-  .skip(StartsWith(","))
+  .skip(",")
   .take(Bool.parser())
   .map { User(id: $0, name: String($1), isAdmin: $2) }
 ```
@@ -149,7 +149,7 @@ input // => "\n2,Blob Jr.,false\n3,Blob Sr.,true"
 To parse multiple users from the input we can use the `Many` parser:
 
 ```swift
-let users = Many(user, separator: StartsWith("\n"))
+let users = Many(user, separator: "\n")
 
 users.parse(&input) // => [User(id: 1, name: "Blob", isAdmin: true), ...]
 input // => ""

Sources/Parsing/Parsers/Literal.swift

@@ -0,0 +1,35 @@
+extension Array: Parser where Element: Equatable {
+  @inlinable
+  public func parse(_ input: inout ArraySlice<Element>) -> Void? {
+    guard input.starts(with: self) else { return nil }
+    input.removeFirst(self.count)
+    return ()
+  }
+}
+
+extension String: Parser {
+  @inlinable
+  public func parse(_ input: inout Substring) -> Void? {
+    guard input.starts(with: self) else { return nil }
+    input.removeFirst(self.count)
+    return ()
+  }
+}
+
+extension String.UnicodeScalarView: Parser {
+  @inlinable
+  public func parse(_ input: inout Substring.UnicodeScalarView) -> Void? {
+    guard input.starts(with: self) else { return nil }
+    input.removeFirst(self.count)
+    return ()
+  }
+}
+
+extension String.UTF8View: Parser {
+  @inlinable
+  public func parse(_ input: inout Substring.UTF8View) -> Void? {
+    guard input.starts(with: self) else { return nil }
+    input.removeFirst(self.count)
+    return ()
+  }
+}

Sources/Parsing/Parsers/Many.swift

@@ -6,7 +6,7 @@
 ///
 /// ```swift
 /// var input = "1,2,3"[...]
-/// let output = Many(Int.parser(), separator: StartsWith(",")).parse(&input)
+/// let output = Many(Int.parser(), separator: ",").parse(&input)
 /// precondition(input == "")
 /// precondition(output == [1, 2, 3])
 /// ```
@@ -23,7 +23,7 @@
 ///   +=
 /// )
 /// var input = "1,2,3"[...]
-/// let output = Many(Int.parser(), into: 0, separator: StartsWith(",")).parse(&input)
+/// let output = Many(Int.parser(), into: 0, separator: ",").parse(&input)
 /// precondition(input == "")
 /// precondition(output == 6)
 /// ```

Sources/Parsing/Parsers/Take.swift

@@ -13,7 +13,7 @@ extension Parser {
   ///
   /// var input = "-1.5,1"[...].utf8
   /// let output = Double.parser()
-  ///   .skip(StartsWith(","))
+  ///   .skip(",")
   ///   .take(Double.parser())
   ///   .map(Point.init)
   ///   .parse(&input) // => Point(x: -1.5, y: 1)

Sources/swift-parsing-benchmark/ReadmeExample.swift

@@ -23,12 +23,12 @@ let readmeExampleSuite = BenchmarkSuite(name: "README Example") { suite in
 
   do {
     let user = Int.parser()
-      .skip(StartsWith(","))
+      .skip(",")
       .take(Prefix { $0 != "," })
-      .skip(StartsWith(","))
+      .skip(",")
       .take(Bool.parser())
       .map { User(id: $0, name: String($1), isAdmin: $2) }
-    let users = Many(user, separator: StartsWith("\n"))
+    let users = Many(user, separator: "\n")
 
     suite.benchmark(
       name: "Parser: Substring",
@@ -44,12 +44,12 @@ let readmeExampleSuite = BenchmarkSuite(name: "README Example") { suite in
 
   do {
     let user = Int.parser(of: Substring.UTF8View.self)
-      .skip(StartsWith(","[...].utf8))
+      .skip(",".utf8)
       .take(Prefix { $0 != .init(ascii: ",") })
-      .skip(StartsWith(","[...].utf8))
+      .skip(",".utf8)
       .take(Bool.parser())
       .map { User(id: $0, name: String(Substring($1)), isAdmin: $2) }
-    let users = Many(user, separator: StartsWith("\n"[...].utf8))
+    let users = Many(user, separator: "\n".utf8)
 
     suite.benchmark(
       name: "Parser: UTF8",

Sources/swift-parsing-benchmark/Routing.swift

@@ -22,28 +22,28 @@ let routingSuite = BenchmarkSuite(name: "Routing") { suite in
     .map { Route.home }
     .orElse(
       Method("GET")
-        .skip(Path(StartsWith("contact-us".utf8)))
+        .skip(Path("contact-us".utf8))
         .skip(End())
         .map { Route.contactUs }
     )
     .orElse(
       Method("GET")
-        .skip(Path(StartsWith("episodes".utf8)))
+        .skip(Path("episodes".utf8))
         .skip(End())
         .map { Route.episodes }
     )
     .orElse(
       Method("GET")
-        .skip(Path(StartsWith("episodes".utf8)))
+        .skip(Path("episodes".utf8))
         .take(Path(Int.parser()))
         .skip(End())
         .map(Route.episode(id:))
     )
     .orElse(
       Method("GET")
-        .skip(Path(StartsWith("episodes".utf8)))
+        .skip(Path("episodes".utf8))
         .take(Path(Int.parser()))
-        .skip(Path(StartsWith("comments".utf8)))
+        .skip(Path("comments".utf8))
         .skip(End())
         .map(Route.episodeComments(id:))
     )