[Feature] Custom list prefixes for AttributedStringVisitor

Down.xcodeproj/project.pbxproj

@@ -9,6 +9,7 @@
 /* Begin PBXBuildFile section */
 		14C5E33521877CE900D5380C /* DownView.bundle in Resources */ = {isa = PBXBuildFile; fileRef = D41689B51CFFE6BB00E5802B /* DownView.bundle */; };
 		26CABB93252B4D490032183C /* ChildSequence.swift in Sources */ = {isa = PBXBuildFile; fileRef = 26CABB92252B4D490032183C /* ChildSequence.swift */; };
+		6A66ABDE262E082C007C65CA /* ListItemPrefixGeneratorBuilder.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6A66ABDD262E082C007C65CA /* ListItemPrefixGeneratorBuilder.swift */; };
 		8A569F481E6B3ED2008BE2AC /* DownView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D43AE5D91CFFD0D0006E1522 /* DownView.swift */; };
 		8A569F491E6B3ED9008BE2AC /* blocks.c in Sources */ = {isa = PBXBuildFile; fileRef = D4201EF71CFA5D63008EEC6E /* blocks.c */; settings = {COMPILER_FLAGS = "-w -Xanalyzer -analyzer-disable-all-checks"; }; };
 		8A569F4A1E6B3ED9008BE2AC /* buffer.c in Sources */ = {isa = PBXBuildFile; fileRef = D4201EF81CFA5D63008EEC6E /* buffer.c */; settings = {COMPILER_FLAGS = "-w -Xanalyzer -analyzer-disable-all-checks"; }; };
@@ -201,6 +202,7 @@
 /* Begin PBXFileReference section */
 		14C5E33621877FCD00D5380C /* DownView (macOS).bundle */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.plug-in"; path = "DownView (macOS).bundle"; sourceTree = "<group>"; };
 		26CABB92252B4D490032183C /* ChildSequence.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ChildSequence.swift; sourceTree = "<group>"; };
+		6A66ABDD262E082C007C65CA /* ListItemPrefixGeneratorBuilder.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ListItemPrefixGeneratorBuilder.swift; sourceTree = "<group>"; };
 		8A569F401E6B3E50008BE2AC /* Down.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Down.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		8AFAEAFB1E6E32E900E09B68 /* DownTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = DownTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		8C73B9B522A687C400C8E60F /* module.modulemap */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = "sourcecode.module-map"; path = module.modulemap; sourceTree = "<group>"; };
@@ -712,6 +714,7 @@
 			children = (
 				EEEBEE71225D2F9200AE438D /* AttributedStringVisitor.swift */,
 				EE8F38CD22BFEDE50056270E /* ListItemPrefixGenerator.swift */,
+				6A66ABDD262E082C007C65CA /* ListItemPrefixGeneratorBuilder.swift */,
 				EEEBEE6F225D2B9D00AE438D /* DebugVisitor.swift */,
 				EEF137702259E7E700D7DDE0 /* Visitor.swift */,
 			);
@@ -1002,6 +1005,7 @@
 				8A569F671E6B3ED9008BE2AC /* render.c in Sources */,
 				EEEBEE49225D29C200AE438D /* BlockQuote.swift in Sources */,
 				8A569F651E6B3ED9008BE2AC /* references.c in Sources */,
+				6A66ABDE262E082C007C65CA /* ListItemPrefixGeneratorBuilder.swift in Sources */,
 				EEEBEE67225D2AF900AE438D /* Emphasis.swift in Sources */,
 				EEA2BDCA22F7152B00D0C72C /* ThematicBreakOptions.swift in Sources */,
 			);

Sources/Down/AST/Visitors/AttributedStringVisitor.swift

@@ -20,17 +20,23 @@ public class AttributedStringVisitor {
 
     private let styler: Styler
     private let options: DownOptions
+    private let listPrefixGeneratorBuilder: ListItemPrefixGeneratorBuilder
     private var listPrefixGenerators = [ListItemPrefixGenerator]()
 
     /// Creates a new instance with the given styler and options.
     ///
     /// - parameters:
     ///     - styler: used to style the markdown elements.
     ///     - options: may be used to modify rendering.
+    ///     - listPrefixGeneratorBuilder: may be used to modify list prefixes.
 
-    public init(styler: Styler, options: DownOptions = .default) {
+    public init(
+        styler: Styler,
+        options: DownOptions = .default,
+        listPrefixGeneratorBuilder: ListItemPrefixGeneratorBuilder = StaticListItemPrefixGeneratorBuilder()) {
         self.styler = styler
         self.options = options
+        self.listPrefixGeneratorBuilder = listPrefixGeneratorBuilder
     }
 
 }
@@ -53,7 +59,12 @@ extension AttributedStringVisitor: Visitor {
     }
 
     public func visit(list node: List) -> NSMutableAttributedString {
-        listPrefixGenerators.append(ListItemPrefixGenerator(list: node))
+
+        listPrefixGenerators.append(
+            listPrefixGeneratorBuilder.build(
+            listType: node.listType,
+            numberOfItems: node.numberOfItems,
+            nestDepth: node.nestDepth))
         defer { listPrefixGenerators.removeLast() }
 
         let items = visitChildren(of: node)

Sources/Down/AST/Visitors/ListItemPrefixGenerator.swift

@@ -8,34 +8,43 @@
 
 import Foundation
 
-class ListItemPrefixGenerator {
+/// A ListItemPrefixGenerator is an object used to generate list item prefix.
+///
+/// ListItemPrefixGenerator are created by `ListItemPrefixGeneratorBuilder`, the later used in
+/// conjunction with an instance of `AttributedStringVisitor`.
+public protocol ListItemPrefixGenerator {
+    init(listType: List.ListType, numberOfItems: Int, nestDepth: Int)
+    func next() -> String?
+}
+
+/// Default implementation of `ListItemPrefixGenerator`.
+/// Generating the following symbol based on `List.ListType`:
+/// - List.ListType is bullet => "•"
+/// - List.ListType is ordered => "X." (where is the item number)
+public class StaticListItemPrefixGenerator: ListItemPrefixGenerator {
 
     // MARK: - Properties
 
     private var prefixes: IndexingIterator<[String]>
 
     // MARK: - Life cycle
 
-    convenience init(list: List) {
-        self.init(listType: list.listType, numberOfItems: list.numberOfItems)
-    }
-
-    init(listType: List.ListType, numberOfItems: Int) {
-        switch listType {
-        case .bullet:
-            prefixes = [String](repeating: "•", count: numberOfItems)
-                .makeIterator()
-
-        case .ordered(let start):
-            prefixes = (start..<(start + numberOfItems))
-                .map { "\($0)." }
-                .makeIterator()
+    required public init(listType: List.ListType, numberOfItems: Int, nestDepth: Int) {
+            switch listType {
+            case .bullet:
+                prefixes = [String](repeating: "•", count: numberOfItems)
+                    .makeIterator()
+
+            case .ordered(let start):
+                prefixes = (start..<(start + numberOfItems))
+                    .map { "\($0)." }
+                    .makeIterator()
+            }
         }
-    }
 
     // MARK: - Methods
 
-    func next() -> String? {
+    public func next() -> String? {
         prefixes.next()
     }
 

Sources/Down/AST/Visitors/ListItemPrefixGeneratorBuilder.swift

@@ -0,0 +1,25 @@
+//
+//  ListItemPrefixGeneratorBuilder.swift
+//  Down
+//
+//  Created by Loïc DARDANT on 2021-04-19.
+//  Copyright © 2021 Down. All rights reserved.
+//
+
+import Foundation
+
+/// Builder of `ListItemPrefixGeneratorBuilder` used in `AttributedStringVisitor`.
+/// Visitor is creating one ListItemPrefixGenerator per list.
+public protocol ListItemPrefixGeneratorBuilder {
+    func build(listType: List.ListType, numberOfItems: Int, nestDepth: Int) -> ListItemPrefixGenerator
+}
+
+/// Default implementation of `StaticListItemPrefixGeneratorBuilder`, using `StaticListItemPrefixGenerator`.
+public class StaticListItemPrefixGeneratorBuilder: ListItemPrefixGeneratorBuilder {
+
+    public init() {}
+
+    public func build(listType: List.ListType, numberOfItems: Int, nestDepth: Int) -> ListItemPrefixGenerator {
+        return StaticListItemPrefixGenerator(listType: listType, numberOfItems: numberOfItems, nestDepth: nestDepth)
+    }
+}

Tests/DownTests/AST/ListItemPrefixGeneratorTests.swift

@@ -11,9 +11,9 @@ import XCTest
 
 class ListItemPrefixGeneratorTests: XCTestCase {
 
-    func testNumberPrefixGeneration() {
+    func testNumberStaticPrefixGeneration() {
         // Given
-        let sut = ListItemPrefixGenerator(listType: .ordered(start: 3), numberOfItems: 3)
+        let sut = StaticListItemPrefixGenerator(listType: .ordered(start: 3), numberOfItems: 3, nestDepth: 1)
 
         // Then
         XCTAssertEqual("3.", sut.next())
@@ -22,9 +22,9 @@ class ListItemPrefixGeneratorTests: XCTestCase {
         XCTAssertNil(sut.next())
     }
 
-    func testBulletPrefixGeneration() {
+    func testBulletStaticPrefixGeneration() {
         // Given
-        let sut = ListItemPrefixGenerator(listType: .bullet, numberOfItems: 3)
+        let sut = StaticListItemPrefixGenerator(listType: .bullet, numberOfItems: 3, nestDepth: 1)
 
         // Then
         XCTAssertEqual("•", sut.next())