Convert SourceKit snippet syntax to TextMate snippet syntax

Sources/LanguageServerProtocol/Functions/Convert.swift

@@ -0,0 +1,36 @@
+//
+//  Convert.swift
+//  langserver-swift
+//
+//  Created by Ryan Lovelett on 12/10/16.
+//
+//
+
+import Argo
+import Foundation
+import Regex
+
+fileprivate let pattern = try! Regex(pattern: "<#T##([^#]+)#(?:#[^#]+#)?>", groupNames: "type")
+
+/// Convert a SourceKit (read: Xcode) style snippet to a
+/// [TextMate snippet syntax](https://manual.macromates.com/en/snippets).
+///
+/// Example:
+/// ========
+///
+/// ```
+/// let str = "fatalError(<#T##message: String##String#>)"
+/// convert(str).value! // "fatalError({{1:message: String}})"
+/// ```
+///
+/// - Parameter sourceKit: A `String` possibly containing an SourceKit style snippet.
+/// - Returns: A `String` where any SourceKit style snippets have been converted to TextMate
+/// snippets.
+func convert(_ sourceKit: String) -> Decoded<String> {
+    var cursorIndex = 0
+    return pure(pattern.replaceAll(in: sourceKit) { match in
+        guard let group = match.group(at: 1) else { return nil }
+        cursorIndex += 1
+        return "{{\(cursorIndex):\(group)}}"
+    })
+}

Sources/LanguageServerProtocol/Types/CompletionItem.swift

@@ -122,7 +122,7 @@ extension CompletionItem : Decodable {
         documentation = brief
         sortText = nil
         filterText = nil
-        insertText = nil
+        insertText = sourcetext
         textEdit = nil
         additionalTextEdits = nil
         command = nil
@@ -177,7 +177,7 @@ extension CompletionItem : Decodable {
     public static func decode(_ json: JSON) -> Decoded<CompletionItem> {
         let description: Decoded<String> = json <| "key.description"
         let kind: Decoded<CompletionItemKind?> = json <|? "key.kind"
-        let sourcetext: Decoded<String> = json <| "key.sourcetext"
+        let sourcetext: Decoded<String> = (json <| "key.sourcetext").flatMap(convert)
         let type: Decoded<String?> = json <|? "key.typename"
         let brief: Decoded<String?> = json <|? "key.doc.brief"
         let context: Decoded<String> = json <| "key.context"

Tests/LanguageServerProtocolTests/Functions/ConvertTests.swift

@@ -0,0 +1,22 @@
+//
+//  ConvertTests.swift
+//  langserver-swift
+//
+//  Created by Ryan Lovelett on 12/10/16.
+//
+//
+
+@testable import LanguageServerProtocol
+import XCTest
+
+class ConvertTests: XCTestCase {
+
+    func testExample() {
+        XCTAssertEqual(convert("fatalError(<#T##message: String##String#>)").value, "fatalError({{1:message: String}})")
+        XCTAssertEqual(convert("x: <#T##Int#>, y: <#T##String#>)").value, "x: {{1:Int}}, y: {{2:String}})")
+        XCTAssertEqual(convert("debugPrint(<#T##items: Any...##Any#>, to: &<#T##Target#>)").value, "debugPrint({{1:items: Any...}}, to: &{{2:Target}})")
+        XCTAssertEqual(convert("isKnownUniquelyReferenced(&<#T##object: T?##T?#>)").value, "isKnownUniquelyReferenced(&{{1:object: T?}})")
+        XCTAssertEqual(convert("getVaList(<#T##args: [CVarArg]##[CVarArg]#>)").value, "getVaList({{1:args: [CVarArg]}})")
+    }
+
+}