Add string interpolation support for SourceFileSyntax

Author: DougGregor

Sources/SwiftParser/Syntax+StringInterpolation.swift

@@ -117,6 +117,12 @@ extension PatternSyntaxProtocol {
 }
 
 // String interpolation support for the primary node kinds.
+extension SourceFileSyntax: SyntaxExpressibleByStringInterpolation {
+  public static func parse(from parser: inout Parser) -> Self {
+    return Syntax(raw: parser.parseSourceFile().raw).as(Self.self)!
+  }
+}
+
 extension DeclSyntax: SyntaxExpressibleByStringInterpolation { }
 extension ExprSyntax: SyntaxExpressibleByStringInterpolation { }
 extension StmtSyntax: SyntaxExpressibleByStringInterpolation { }

Tests/SwiftParserTest/StringInterpolation.swift

@@ -65,6 +65,14 @@ final class StringInterpolationTests: XCTestCase {
     XCTAssertTrue(structNode.is(StructDeclSyntax.self))
   }
 
+  func testSourceFile() throws {
+    let _: SourceFileSyntax =
+      """
+      print("Hello, world!")
+      """
+  }
+
+
   func testRewriter() throws {
     let sourceFile = try Parser.parse(source: """
       class Foo {