Add support for dictionary expressions. (swiftlang#120)

Author: dabelknap

Diff for: Sources/PrettyPrint/TokenStreamCreator.swift

@@ -96,12 +96,38 @@ private final class TokenStreamCreator: SyntaxVisitor {
   }
 
   override func visit(_ node: ArrayExprSyntax) {
-    after(node.leftSquare, tokens: .break(size: 0, offset: 2), .open(.consistent, 0), .break(size: 0), .open(.consistent, 0))
+    after(
+      node.leftSquare,
+      tokens: .break(size: 0, offset: 2), .open(.consistent, 0), .break(size: 0),
+        .open(.consistent, 0)
+    )
     before(node.rightSquare, tokens: .close, .break(size: 0, offset: -2), .close)
     super.visit(node)
   }
 
   override func visit(_ node: DictionaryExprSyntax) {
+    after(
+      node.leftSquare,
+      tokens: .break(size: 0, offset: 2), .open(.consistent, 0), .break(size: 0),
+      .open(.consistent, 0)
+    )
+    before(node.rightSquare, tokens: .close, .break(size: 0, offset: -2), .close)
+    super.visit(node)
+  }
+
+  override func visit(_ node: DictionaryTypeSyntax) {
+    after(node.colon, tokens: .space)
+    super.visit(node)
+  }
+
+  override func visit(_ node: DictionaryElementSyntax) {
+    before(node.firstToken, tokens: .open)
+    after(node.colon, tokens: .break(offset: 2))
+    if let trailingComma = node.trailingComma {
+      after(trailingComma, tokens: .close, .break)
+    } else {
+      after(node.lastToken, tokens: .close)
+    }
     super.visit(node)
   }
 
@@ -331,10 +357,6 @@ private final class TokenStreamCreator: SyntaxVisitor {
     super.visit(node)
   }
 
-  override func visit(_ node: DictionaryTypeSyntax) {
-    super.visit(node)
-  }
-
   override func visit(_ node: TupleTypeSyntax) {
     after(node.leftParen, tokens: .open(.consistent, 2), .break(size: 0))
     before(node.rightParen, tokens: .break(size: 0), .close)
@@ -830,10 +852,6 @@ private final class TokenStreamCreator: SyntaxVisitor {
     super.visit(node)
   }
 
-  override func visit(_ node: DictionaryElementSyntax) {
-    super.visit(node)
-  }
-
   override func visit(_ node: ExpressionPatternSyntax) {
     super.visit(node)
   }

Diff for: Tests/PrettyPrinterTests/DictionaryDeclTests.swift

@@ -0,0 +1,32 @@
+public class DictionaryDeclTests: PrettyPrintTestCase {
+  public func testBasicDictionaries() {
+    let input =
+      """
+      let a = [1: "a", 2: "b", 3: "c"]
+      let a: [Int: String] = [1: "a", 2: "b", 3: "c"]
+      let a: [Int: String] = [1: "a", 2: "b", 3: "c", 4: "d"]
+      let a: [Int: String] = [1: "a", 2: "b", 3: "c", 4: "d", 5: "e", 6: "f", 7: "g"]
+      """
+
+    let expected =
+      """
+      let a = [1: "a", 2: "b", 3: "c"]
+      let a: [Int: String] = [1: "a", 2: "b", 3: "c"]
+      let a: [Int: String] = [
+        1: "a", 2: "b", 3: "c", 4: "d"
+      ]
+      let a: [Int: String] = [
+        1: "a",
+        2: "b",
+        3: "c",
+        4: "d",
+        5: "e",
+        6: "f",
+        7: "g"
+      ]
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 50)
+  }
+}