update code to Swift 4.1

Sources/ForTag.swift

@@ -23,7 +23,7 @@ class ForNode : NodeType {
       throw TemplateSyntaxError("'for' statements should use the syntax: `for <x> in <y> [where <condition>]`.")
     }
 
-    let loopVariables = components[1].characters
+    let loopVariables = components[1]
       .split(separator: ",")
       .map(String.init)
       .map { $0.trim(character: " ") }

Sources/Inheritence.swift

@@ -64,7 +64,7 @@ class ExtendsNode : NodeType {
       throw TemplateSyntaxError("'extends' cannot appear more than once in the same template")
     }
 
-    let blockNodes = parsedNodes.flatMap { $0 as? BlockNode }
+    let blockNodes = parsedNodes.compactMap { $0 as? BlockNode }
 
     let nodes = blockNodes.reduce([String: BlockNode]()) { (accumulator, node) -> [String: BlockNode] in
       var dict = accumulator
@@ -159,8 +159,8 @@ class BlockNode : NodeType {
   }
 
   // child node is a block node from child template that extends this node (has the same name)
-  func childContext(_ child: BlockNode, blockContext: BlockContext, context: Context) throws -> [String: Any?] {
-    var childContext: [String: Any?] = [BlockContext.contextKey: blockContext]
+  func childContext(_ child: BlockNode, blockContext: BlockContext, context: Context) throws -> [String: Any] {
+    var childContext: [String: Any] = [BlockContext.contextKey: blockContext]
 
     if let blockSuperNode = child.nodes.first(where: {
       if case .variable(let variable, _)? = $0.token, variable == "block.super" { return true }

Sources/KeyPath.swift

@@ -24,7 +24,7 @@ final class KeyPath {
       subscriptLevel = 0
     }
 
-    for c in variable.characters {
+    for c in variable {
       switch c {
       case "." where subscriptLevel == 0:
         try foundSeparator()

Sources/Parser.swift

@@ -108,7 +108,7 @@ public class TokenParser {
     let filtersWithDistance = allFilters
                 .map({ (filterName: $0, distance: $0.levenshteinDistance(name)) })
                 // do not suggest filters which names are shorter than the distance
-                .filter({ $0.filterName.characters.count > $0.distance })
+                .filter({ $0.filterName.count > $0.distance })
     guard let minDistance = filtersWithDistance.min(by: { $0.distance < $1.distance })?.distance else {
       return []
     }
@@ -167,10 +167,10 @@ extension String {
     // initialize v0 (the previous row of distances)
     // this row is A[0][i]: edit distance for an empty s
     // the distance is just the number of characters to delete from t
-    last = [Int](0...target.characters.count)
-    current = [Int](repeating: 0, count: target.characters.count + 1)
+    last = [Int](0...target.count)
+    current = [Int](repeating: 0, count: target.count + 1)
 
-    for i in 0..<self.characters.count {
+    for i in 0..<self.count {
       // calculate v1 (current row distances) from the previous row v0
 
       // first element of v1 is A[i+1][0]
@@ -178,7 +178,7 @@ extension String {
       current[0] = i + 1
 
       // use formula to fill in the rest of the row
-      for j in 0..<target.characters.count {
+      for j in 0..<target.count {
         current[j+1] = Swift.min(
           last[j+1] + 1,
           current[j] + 1,
@@ -190,7 +190,7 @@ extension String {
       last = current
     }
 
-    return current[target.characters.count]
+    return current[target.count]
   }
 
 }

Sources/Tokenizer.swift

@@ -13,7 +13,7 @@ extension String {
     let specialCharacters = ",|:"
     func appendWord(_ word: String) {
       if components.count > 0 {
-        if let precedingChar = components.last?.characters.last, specialCharacters.characters.contains(precedingChar) {
+        if let precedingChar = components.last?.last, specialCharacters.contains(precedingChar) {
           components[components.count-1] += word
         } else if specialCharacters.contains(word) {
           components[components.count-1] += word
@@ -25,7 +25,7 @@ extension String {
       }
     }
 
-    for character in self.characters {
+    for character in self {
       if character == "'" { singleQuoteCount += 1 }
       else if character == "\"" { doubleQuoteCount += 1 }
 

Sources/Variable.swift

@@ -9,7 +9,7 @@ class FilterExpression : Resolvable {
   let variable: Variable
 
   init(token: String, parser: TokenParser) throws {
-    let bits = token.characters.split(separator: "|").map({ String($0).trim(character: " ") })
+    let bits = token.split(separator: "|").map({ String($0).trim(character: " ") })
     if bits.isEmpty {
       throw TemplateSyntaxError("Variable tags must include at least 1 argument")
     }
@@ -60,7 +60,7 @@ public struct Variable : Equatable, Resolvable {
 
     if (variable.hasPrefix("'") && variable.hasSuffix("'")) || (variable.hasPrefix("\"") && variable.hasSuffix("\"")) {
       // String literal
-      return String(variable[variable.characters.index(after: variable.startIndex) ..< variable.characters.index(before: variable.endIndex)])
+      return String(variable[variable.index(after: variable.startIndex) ..< variable.index(before: variable.endIndex)])
     }
 
     // Number literal

Tests/StencilTests/ForNodeSpec.swift

@@ -189,7 +189,7 @@ func testForNode() {
       let template = Template(templateString: templateString)
       let result = try template.render(context)
 
-      let sortedResult = result.characters.split(separator: ",").map(String.init).sorted(by: <)
+      let sortedResult = result.split(separator: ",").map(String.init).sorted(by: <)
       try expect(sortedResult) == ["one: I", "two: II"]
     }
 
@@ -202,7 +202,7 @@ func testForNode() {
       let node = ForNode(resolvable: Variable("dict"), loopVariables: ["key"], nodes: nodes, emptyNodes: emptyNodes, where: nil)
       let result = try node.render(context)
 
-      let sortedResult = result.characters.split(separator: ",").map(String.init).sorted(by: <)
+      let sortedResult = result.split(separator: ",").map(String.init).sorted(by: <)
       try expect(sortedResult) == ["one", "two"]
     }
 
@@ -218,7 +218,7 @@ func testForNode() {
 
       let result = try node.render(context)
 
-      let sortedResult = result.characters.split(separator: ",").map(String.init).sorted(by: <)
+      let sortedResult = result.split(separator: ",").map(String.init).sorted(by: <)
       try expect(sortedResult) == ["one=I", "two=II"]
     }