Add prettyPrintIndentation property on XMLEncoder (CoreOffice#186)

New property can take `XMLEncoder.PrettyPrintIndentation` values such as `.tabs(1)` or `.spaces(2)`.

Resolve CoreOffice#183.

.vscode/tasks.json

@@ -6,7 +6,7 @@
     {
       "label": "swift test",
       "type": "shell",
-      "command": "swift test"
+      "command": "swift test --parallel"
     }
   ]
 }

Dangerfile.swift

@@ -6,3 +6,9 @@
 import Danger
 
 SwiftLint.lint(inline: true, configFile: ".swiftlint.yml", strict: true)
+
+let danger = Danger()
+
+print("Calling SwiftFormat...")
+
+danger.utils.exec("swiftformat", arguments: ["."])

Sources/XMLCoder/Auxiliaries/XMLCoderElement.swift

@@ -122,25 +122,30 @@ struct XMLCoderElement: Equatable {
         return KeyedBox(elements: elements, attributes: attributes)
     }
 
-    func toXMLString(with header: XMLHeader? = nil,
-                     formatting: XMLEncoder.OutputFormatting) -> String {
+    func toXMLString(
+        with header: XMLHeader? = nil,
+        formatting: XMLEncoder.OutputFormatting,
+        indentation: XMLEncoder.PrettyPrintIndentation
+    ) -> String {
         if let header = header, let headerXML = header.toXML() {
-            return headerXML + _toXMLString(formatting: formatting)
+            return headerXML + _toXMLString(formatting, indentation)
         }
-        return _toXMLString(formatting: formatting)
+        return _toXMLString(formatting, indentation)
     }
 
     private func formatUnsortedXMLElements(
         _ string: inout String,
         _ level: Int,
         _ formatting: XMLEncoder.OutputFormatting,
+        _ indentation: XMLEncoder.PrettyPrintIndentation,
         _ prettyPrinted: Bool
     ) {
         formatXMLElements(
             from: elements,
             into: &string,
             at: level,
             formatting: formatting,
+            indentation: indentation,
             prettyPrinted: prettyPrinted
         )
     }
@@ -149,6 +154,7 @@ struct XMLCoderElement: Equatable {
         for element: XMLCoderElement,
         at level: Int,
         formatting: XMLEncoder.OutputFormatting,
+        indentation: XMLEncoder.PrettyPrintIndentation,
         prettyPrinted: Bool
     ) -> String {
         if let stringValue = element.stringValue {
@@ -160,9 +166,7 @@ struct XMLCoderElement: Equatable {
         }
 
         var string = ""
-        string += element._toXMLString(
-            indented: level + 1, formatting: formatting
-        )
+        string += element._toXMLString(indented: level + 1, formatting, indentation)
         string += prettyPrinted ? "\n" : ""
         return string
     }
@@ -171,12 +175,14 @@ struct XMLCoderElement: Equatable {
         _ string: inout String,
         _ level: Int,
         _ formatting: XMLEncoder.OutputFormatting,
+        _ indentation: XMLEncoder.PrettyPrintIndentation,
         _ prettyPrinted: Bool
     ) {
         formatXMLElements(from: elements.sorted { $0.key < $1.key },
                           into: &string,
                           at: level,
                           formatting: formatting,
+                          indentation: indentation,
                           prettyPrinted: prettyPrinted)
     }
 
@@ -198,12 +204,14 @@ struct XMLCoderElement: Equatable {
         into string: inout String,
         at level: Int,
         formatting: XMLEncoder.OutputFormatting,
+        indentation: XMLEncoder.PrettyPrintIndentation,
         prettyPrinted: Bool
     ) {
         for element in elements {
             string += elementString(for: element,
                                     at: level,
                                     formatting: formatting,
+                                    indentation: indentation,
                                     prettyPrinted: prettyPrinted && !containsTextNodes)
         }
     }
@@ -231,30 +239,38 @@ struct XMLCoderElement: Equatable {
 
     private func formatXMLElements(
         _ formatting: XMLEncoder.OutputFormatting,
+        _ indentation: XMLEncoder.PrettyPrintIndentation,
         _ string: inout String,
         _ level: Int,
         _ prettyPrinted: Bool
     ) {
         if formatting.contains(.sortedKeys) {
             formatSortedXMLElements(
-                &string, level, formatting, prettyPrinted
+                &string, level, formatting, indentation, prettyPrinted
             )
             return
         }
         formatUnsortedXMLElements(
-            &string, level, formatting, prettyPrinted
+            &string, level, formatting, indentation, prettyPrinted
         )
     }
 
     private func _toXMLString(
         indented level: Int = 0,
-        formatting: XMLEncoder.OutputFormatting
+        _ formatting: XMLEncoder.OutputFormatting,
+        _ indentation: XMLEncoder.PrettyPrintIndentation
     ) -> String {
         let prettyPrinted = formatting.contains(.prettyPrinted)
-        let indentation = String(
-            repeating: " ", count: (prettyPrinted ? level : 0) * 4
-        )
-        var string = indentation
+        let prefix: String
+        switch indentation {
+        case let .spaces(count) where prettyPrinted:
+            prefix = String(repeating: " ", count: level * count)
+        case let .tabs(count) where prettyPrinted:
+            prefix = String(repeating: "\t", count: level * count)
+        default:
+            prefix = ""
+        }
+        var string = prefix
 
         if !key.isEmpty {
             string += "<\(key)"
@@ -267,9 +283,9 @@ struct XMLCoderElement: Equatable {
             if !key.isEmpty {
                 string += prettyPrintElements ? ">\n" : ">"
             }
-            formatXMLElements(formatting, &string, level, prettyPrintElements)
+            formatXMLElements(formatting, indentation, &string, level, prettyPrintElements)
 
-            if prettyPrintElements { string += indentation }
+            if prettyPrintElements { string += prefix }
             if !key.isEmpty {
                 string += "</\(key)>"
             }

Sources/XMLCoder/Encoder/XMLEncoder.swift

@@ -33,6 +33,12 @@ open class XMLEncoder {
         public static let sortedKeys = OutputFormatting(rawValue: 1 << 1)
     }
 
+    /// The identation to use when XML is pretty-printed.
+    public enum PrettyPrintIndentation {
+        case spaces(Int)
+        case tabs(Int)
+    }
+
     /// A node's encoding type
     public enum NodeEncoding {
         case attribute
@@ -264,6 +270,9 @@ open class XMLEncoder {
     /// The output format to produce. Defaults to `[]`.
     open var outputFormatting: OutputFormatting = []
 
+    /// The indentation to use when XML is printed. Defaults to `.spaces(4)`.
+    open var prettyPrintIndentation: PrettyPrintIndentation = .spaces(4)
+
     /// The strategy to use in encoding dates. Defaults to `.deferredToDate`.
     open var dateEncodingStrategy: DateEncodingStrategy = .deferredToDate
 
@@ -373,8 +382,11 @@ open class XMLEncoder {
             ))
         }
 
-        return element.toXMLString(with: header, formatting: outputFormatting)
-            .data(using: .utf8, allowLossyConversion: true)!
+        return element.toXMLString(
+            with: header,
+            formatting: outputFormatting,
+            indentation: prettyPrintIndentation
+        ).data(using: .utf8, allowLossyConversion: true)!
     }
 
     // MARK: - TopLevelEncoder

Tests/XMLCoderTests/PrettyPrintTest.swift

@@ -0,0 +1,78 @@
+// Copyright (c) 2020 XMLCoder contributors
+//
+// This software is released under the MIT License.
+// https://opensource.org/licenses/MIT
+
+import XCTest
+import XMLCoder
+
+private struct TopContainer: Encodable {
+    let nested: NestedContainer
+}
+
+private struct NestedContainer: Encodable {
+    let values: [String]
+}
+
+final class PrettyPrintTest: XCTestCase {
+    private let testContainer = TopContainer(nested: NestedContainer(values: ["foor", "bar"]))
+
+    func testDefaultIndentation() throws {
+        let encoder = XMLEncoder()
+        encoder.outputFormatting = [.prettyPrinted]
+
+        let encoded = try encoder.encode(testContainer)
+
+        XCTAssertEqual(
+            String(data: encoded, encoding: .utf8)!,
+            """
+            <TopContainer>
+                <nested>
+                    <values>foor</values>
+                    <values>bar</values>
+                </nested>
+            </TopContainer>
+            """
+        )
+    }
+
+    func testSpaces() throws {
+        let encoder = XMLEncoder()
+        encoder.outputFormatting = [.prettyPrinted]
+        encoder.prettyPrintIndentation = .spaces(3)
+
+        let encoded = try encoder.encode(testContainer)
+
+        XCTAssertEqual(
+            String(data: encoded, encoding: .utf8)!,
+            """
+            <TopContainer>
+               <nested>
+                  <values>foor</values>
+                  <values>bar</values>
+               </nested>
+            </TopContainer>
+            """
+        )
+    }
+
+    func testTabs() throws {
+        let encoder = XMLEncoder()
+        encoder.outputFormatting = [.prettyPrinted]
+        encoder.prettyPrintIndentation = .tabs(2)
+
+        let encoded = try encoder.encode(testContainer)
+
+        XCTAssertEqual(
+            String(data: encoded, encoding: .utf8)!,
+            """
+            <TopContainer>
+            \t\t<nested>
+            \t\t\t\t<values>foor</values>
+            \t\t\t\t<values>bar</values>
+            \t\t</nested>
+            </TopContainer>
+            """
+        )
+    }
+}

Tests/XMLCoderTests/XCTestManifests.swift

@@ -125,6 +125,7 @@ extension CDATATest {
     //   `swift test --generate-linuxmain`
     // to regenerate.
     static let __allTests__CDATATest = [
+        ("testCDataTypes", testCDataTypes),
         ("testXML", testXML),
     ]
 }
@@ -585,6 +586,17 @@ extension PlantTest {
     ]
 }
 
+extension PrettyPrintTest {
+    // DO NOT MODIFY: This is autogenerated, use:
+    //   `swift test --generate-linuxmain`
+    // to regenerate.
+    static let __allTests__PrettyPrintTest = [
+        ("testDefaultIndentation", testDefaultIndentation),
+        ("testSpaces", testSpaces),
+        ("testTabs", testTabs),
+    ]
+}
+
 extension QuoteDecodingTest {
     // DO NOT MODIFY: This is autogenerated, use:
     //   `swift test --generate-linuxmain`
@@ -898,6 +910,7 @@ public func __allTests() -> [XCTestCaseEntry] {
         testCase(NullTests.__allTests__NullTests),
         testCase(OptionalTests.__allTests__OptionalTests),
         testCase(PlantTest.__allTests__PlantTest),
+        testCase(PrettyPrintTest.__allTests__PrettyPrintTest),
         testCase(QuoteDecodingTest.__allTests__QuoteDecodingTest),
         testCase(RJITest.__allTests__RJITest),
         testCase(RelationshipsTest.__allTests__RelationshipsTest),