Add method to apply text transformations in a document

Sources/CommonMark/Core/Block.swift

@@ -47,4 +47,23 @@ public enum Block: Equatable {
  fatalError("Unhandled cmark node '\(node.typeString)'")
  }
  }
+
+ /// Returns a new block created by applying the specified transform to this block's text elements.
+ public func applyingTransform(_ transform: (String) -> String) -> Block {
+ switch self {
+ case let .blockQuote(blocks):
+ return .blockQuote(blocks.map { $0.applyingTransform(transform) })
+ case let .list(list):
+ return .list(list.applyingTransform(transform))
+ case let .paragraph(inlines):
+ return .paragraph(inlines.map { $0.applyingTransform(transform) })
+ case let .heading(inlines, level):
+ return .heading(
+ inlines.map { $0.applyingTransform(transform) },
+ level: level
+ )
+ case .code, .html, .thematicBreak:
+ return self
+ }
+ }
 }

Sources/CommonMark/Core/Document.swift

@@ -36,6 +36,11 @@ public struct Document {
  self.init(blocks: content())
  }
  #endif
+
+ /// Returns a new document created by applying the specified transform to this document's text elements.
+ public func applyingTransform(_ transform: (String) -> String) -> Document {
+ Document(blocks: blocks.map { $0.applyingTransform(transform) })
+ }
 }
 
 extension Document: Equatable {

Sources/CommonMark/Core/Inline.swift

@@ -54,4 +54,30 @@ public enum Inline: Equatable {
  fatalError("Unhandled cmark node '\(node.typeString)'")
  }
  }
+
+ /// Returns a new inline created by applying the specified transform to this inline's text elements.
+ public func applyingTransform(_ transform: (String) -> String) -> Inline {
+ switch self {
+ case let .text(text):
+ return .text(transform(text))
+ case let .emphasis(inlines):
+ return .emphasis(inlines.map { $0.applyingTransform(transform) })
+ case let .strong(inlines):
+ return .strong(inlines.map { $0.applyingTransform(transform) })
+ case let .link(inlines, url, title):
+ return .link(
+ inlines.map { $0.applyingTransform(transform) },
+ url: url,
+ title: title
+ )
+ case let .image(inlines, url, title):
+ return .image(
+ inlines.map { $0.applyingTransform(transform) },
+ url: url,
+ title: title
+ )
+ case .softBreak, .lineBreak, .code, .html:
+ return self
+ }
+ }
 }

Sources/CommonMark/Core/Item.swift

@@ -23,6 +23,11 @@ public struct Item: Equatable {
  guard case CMARK_NODE_ITEM = node.type else { return nil }
  self.init(blocks: node.children.map(Block.init))
  }
+
+ /// Returns a new list item created by applying the specified transform to this item's text elements.
+ public func applyingTransform(_ transform: (String) -> String) -> Item {
+ Item(blocks: blocks.map { $0.applyingTransform(transform) })
+ }
 }
 
 #if swift(>=5.4)

Sources/CommonMark/Core/List.swift

@@ -47,6 +47,15 @@ public struct List: Equatable {
  items: node.children.compactMap(Item.init)
  )
  }
+
+ /// Returns a new list created by applying the specified transform to this list's text elements.
+ public func applyingTransform(_ transform: (String) -> String) -> List {
+ List(
+ style: style,
+ spacing: spacing,
+ items: items.map { $0.applyingTransform(transform) }
+ )
+ }
 }
 
 #if swift(>=5.4)

Tests/CommonMarkTests/DocumentTests.swift

@@ -37,6 +37,54 @@ final class DocumentTests: XCTestCase {
  XCTAssertEqual([], result)
  }
 
+ func testApplyTransform() {
+ // given
+ let text = """
+ ## Try CommonMark
+
+ You can try CommonMark here. This dingus is powered by
+ [commonmark.js](https://github.com/jgm/commonmark.js), the
+ `JavaScript` reference implementation.
+
+ ```swift
+ let a = b
+ ```
+
+ 1. item one
+ 2. item two
+ - sublist
+ - sublist
+ """
+
+ // when
+ let result = Document(text).applyingTransform { text in
+ text.uppercased()
+ }
+
+ // then
+ XCTAssertEqual(
+ Document(
+ """
+ ## TRY COMMONMARK
+
+ YOU CAN TRY COMMONMARK HERE. THIS DINGUS IS POWERED BY
+ [COMMONMARK.JS](https://github.com/jgm/commonmark.js), THE
+ `JavaScript` REFERENCE IMPLEMENTATION.
+
+ ``` swift
+ let a = b
+ ```
+
+ 1. ITEM ONE
+ 2. ITEM TWO
+ - SUBLIST
+ - SUBLIST
+ """
+ ),
+ result
+ )
+ }
+
  func testBlockQuote() {
  // given
  let text = """