Adds Parameters.flatten

CHANGELOG.md

@@ -16,7 +16,10 @@ _None_
 
 ### New Features
 
-_None_
+* Added `Parameters.flatten(dictionary:)` method to do the opposite of
+  `Parameters.parse(items:)` and turn a dictionary into the list of parameters to pass from the command line.  
+  [Olivier Halligon](https://github.com/AliSoftware)
+  [#70](https://github.com/SwiftGen/StencilSwiftKit/pull/70)
 
 ### Internal Changes
 

Sources/Filters+Numbers.swift

@@ -11,7 +11,7 @@ extension Filters {
   enum Numbers {
     static func hexToInt(_ value: Any?) throws -> Any? {
       guard let value = value as? String else { throw Filters.Error.invalidInputType }
-      return Int(value, radix:  16)
+      return Int(value, radix: 16)
     }
 
     static func int255toFloat(_ value: Any?) throws -> Any? {

Sources/Parameters.swift

@@ -37,6 +37,23 @@ public enum Parameters {
     }
   }
 
+  /// Flatten a dictionary into a list of "key.path=value" pairs.
+  /// This method recursively visits the object to build its flat representation.
+  ///
+  /// - Parameters:
+  ///   - dictionary: The dictionary to recursively flatten into key pairs
+  /// - Returns: The list of flatten "key.path=value" pair representations of the object
+  ///
+  /// - Note: flatten is the counterpart of parse. flatten(parse(x)) == parse(flatten(x)) == x
+  ///
+  /// - Example:
+  ///
+  ///       flatten(["a":["b":1,"c":[2,3]]])
+  ///       // ["a.b=1","a.c=2","a.c=3"]
+  public static func flatten(dictionary: StringDict) -> [String] {
+    return flatten(object: dictionary, keyPrefix: "")
+  }
+
   // MARK: - Private methods
 
   /// Parse a single `key=value` (or `key`) string and inserts it into
@@ -115,4 +132,32 @@ public enum Parameters {
       throw Error.invalidSyntax(value: string)
     }
   }
+
+  /// Flatten an object (dictionary, array or single object) into a list of keypath-type k=v pairs.
+  /// This method recursively visits the object to build the flat representation.
+  ///
+  /// - Parameters:
+  ///   - object: The object to recursively flatten
+  ///   - keyPrefix: The prefix to use when creating keys.
+  ///                This is used to build the keyPath via recusrive calls of this function.
+  ///                You should start the root call of this recursive function with an empty keyPrefix.
+  /// - Returns: The list of flatten "key.path=value" pair representations of the object
+  private static func flatten(object: Any, keyPrefix: String = "") -> [String] {
+    var values: [String] = []
+    switch object {
+    case is String, is Int, is Double:
+      values.append("\(keyPrefix)=\(object)")
+    case is Bool:
+      values.append(keyPrefix)
+    case let dict as [String: Any]:
+      for (key, value) in dict {
+        let fullKey = keyPrefix.isEmpty ? key : "\(keyPrefix).\(key)"
+        values += flatten(object: value, keyPrefix: fullKey)
+      }
+    case let array as [Any]:
+      values += array.flatMap { flatten(object: $0, keyPrefix: keyPrefix) }
+    default: break
+    }
+    return values
+  }
 }

Tests/StencilSwiftKitTests/ContextTests.swift

@@ -32,7 +32,7 @@ class ContextTests: XCTestCase {
   }
 
   func testWithContext() throws {
-    let context: [String : Any] = ["foo": "bar", "hello": true]
+    let context: [String: Any] = ["foo": "bar", "hello": true]
 
     let result = try StencilContext.enrich(context: context,
                                            parameters: [],

Tests/StencilSwiftKitTests/ParametersTests.swift

@@ -17,6 +17,13 @@ class ParametersTests: XCTestCase {
     XCTAssertEqual(result["b"] as? String, "hello")
     XCTAssertEqual(result["c"] as? String, "x=y")
     XCTAssertEqual(result["d"] as? Bool, true)
+
+    // Test the opposite operation (flatten) as well
+    let reverse = Parameters.flatten(dictionary: result)
+    XCTAssertEqual(reverse.count, items.count,
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
+    XCTAssertEqual(Set(reverse), Set(items),
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
   }
 
   func testStructured() throws {
@@ -28,6 +35,13 @@ class ParametersTests: XCTestCase {
     XCTAssertEqual(sub["baz"] as? String, "1")
     XCTAssertEqual(sub["bar"] as? String, "2")
     XCTAssertEqual(sub["test"] as? Bool, true)
+
+    // Test the opposite operation (flatten) as well
+    let reverse = Parameters.flatten(dictionary: result)
+    XCTAssertEqual(reverse.count, items.count,
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
+    XCTAssertEqual(Set(reverse), Set(items),
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
   }
 
   func testDeepStructured() throws {
@@ -40,6 +54,13 @@ class ParametersTests: XCTestCase {
     guard let baz = bar["baz"] as? [String: Any] else { XCTFail("Parsed parameter should be a dictionary"); return }
     guard let qux = baz["qux"] as? String else { XCTFail("Parsed parameter should be a string"); return }
     XCTAssertEqual(qux, "1")
+
+    // Test the opposite operation (flatten) as well
+    let reverse = Parameters.flatten(dictionary: result)
+    XCTAssertEqual(reverse.count, items.count,
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
+    XCTAssertEqual(Set(reverse), Set(items),
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
   }
 
   func testRepeated() throws {
@@ -52,9 +73,18 @@ class ParametersTests: XCTestCase {
     XCTAssertEqual(sub[0], "1")
     XCTAssertEqual(sub[1], "2")
     XCTAssertEqual(sub[2], "hello")
+
+    // Test the opposite operation (flatten) as well
+    let reverse = Parameters.flatten(dictionary: result)
+    XCTAssertEqual(reverse.count, items.count,
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
+    XCTAssertEqual(Set(reverse), Set(items),
+                   "Flattening the resulting dictionary back did not result in the equivalent of the original list")
+    XCTAssertEqual(reverse, items,
+                   "The order of arrays are properly preserved when flattened")
   }
 
-  func testInvalidSyntax() {
+  func testParseInvalidSyntax() {
     // invalid character
     do {
       let items = ["foo:1"]
@@ -89,7 +119,7 @@ class ParametersTests: XCTestCase {
     }
   }
 
-  func testInvalidKey() {
+  func testParseInvalidKey() {
     // key may only be alphanumeric or '.'
     do {
       let items = ["foo:bar=1"]
@@ -124,7 +154,7 @@ class ParametersTests: XCTestCase {
     }
   }
 
-  func testInvalidStructure() {
+  func testParseInvalidStructure() {
     // can't switch from string to dictionary
     do {
       let items = ["foo=1", "foo.bar=1"]