Merge pull request #223 from ahoppen/constructor-from-syntax-protocol

Add an initializer to construct Syntax nodes from syntax protocol types

Author: akyrtzi

Sources/SwiftSyntax/Syntax.swift

@@ -39,6 +39,15 @@ public struct Syntax: SyntaxProtocol, SyntaxHashable {
     guard let syntax = syntax else { return nil }
     self = syntax._syntaxNode
   }
+  
+  public init(fromProtocol syntax: SyntaxProtocol) {
+    self = syntax._syntaxNode
+  }
+  
+  public init?(fromProtocol syntax: SyntaxProtocol?) {
+    guard let syntax = syntax else { return nil }
+    self = syntax._syntaxNode
+  }
 
   public func hash(into hasher: inout Hasher) {
     return data.nodeId.hash(into: &hasher)

Tests/SwiftSyntaxTest/SyntaxTests.swift

@@ -135,4 +135,13 @@ public class SyntaxTests: XCTestCase {
     XCTAssertTrue(integerExpr.syntaxNodeType == node.syntaxNodeType)
     XCTAssertEqual("\(integerExpr.syntaxNodeType)", "IntegerLiteralExprSyntax")
   }
+
+  public func testConstructFromSyntaxProtocol() {
+    let integerExpr = IntegerLiteralExprSyntax {
+      $0.useDigits(SyntaxFactory.makeIntegerLiteral("1", trailingTrivia: .spaces(1)))
+    }
+
+    XCTAssertEqual(Syntax(integerExpr), Syntax(fromProtocol: integerExpr as SyntaxProtocol))
+    XCTAssertEqual(Syntax(integerExpr), Syntax(fromProtocol: integerExpr as ExprSyntaxProtocol))
+  }
 }