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Implemented helper object to allow for parsing between List and NSAttributedString - in either direction #52
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| { | ||
| "object": { | ||
| "pins": [ | ||
| { | ||
| "package": "SnapshotTesting", | ||
| "repositoryURL": "https://github.com/pointfreeco/swift-snapshot-testing.git", | ||
| "state": { | ||
| "branch": "master", | ||
| "revision": "641ad58daf62c4577dbcb23a80b1e437a459daf6", | ||
| "version": null | ||
| } | ||
| } | ||
| ] | ||
| }, | ||
| "version": 1 | ||
| } |
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| // | ||
| // ListParser.swift | ||
| // Proton | ||
| // | ||
| // Created by Rajdeep Kwatra on 29/10/20. | ||
| // Copyright © 2020 Rajdeep Kwatra. All rights reserved. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
| // | ||
|
|
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| import Foundation | ||
|
|
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| /// Represents an item in the list. This structure may be used to create `NSAttributedString` from items in an array of `ListItem`. Alternatively, `NSAttributedString` may also be parsed to get an array of `ListItem`s. | ||
| public struct ListItem { | ||
|
|
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| /// Text of the list item. All attributes are preserved as is. | ||
| /// - Note: If the text contains a newline (`\n`), it is preserved as a newline in text by applying `.skipNextListMarker` attribute. | ||
| public let text: NSAttributedString | ||
|
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| /// Level of the list item. This is used with indent to get `paragraphStyle` to be applied with appropriate indentation of the list items. | ||
| public let level: Int | ||
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| /// Attribute value of the list item. | ||
| public let attributeValue: Any | ||
| } | ||
|
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| /// Provides helper function to convert between `NSAttributedString` and `[ListItem]` | ||
| public struct ListParser { | ||
|
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| /// Parses an array of list items into an `NSAttributedString` representation. `NewLines` are automatically added between each list item in the attributed string representation. | ||
| /// - Parameters: | ||
| /// - list: List items to convert | ||
| /// - indent: Indentation to be used. This determines the paragraph indentation for layout. | ||
| /// - Returns: NSAttributedString representation of list items | ||
| public static func parse(list: [ListItem], indent: CGFloat) -> NSAttributedString { | ||
| let attributedString = NSMutableAttributedString() | ||
| for i in 0..<list.count { | ||
| let item = list[i] | ||
| let paraStyle = NSMutableParagraphStyle() | ||
| paraStyle.firstLineHeadIndent = CGFloat(item.level) * indent | ||
| paraStyle.headIndent = paraStyle.firstLineHeadIndent | ||
| let listText = NSMutableAttributedString(attributedString: item.text) | ||
| listText.addAttribute(.listItem, value: item.attributeValue, range: listText.fullRange) | ||
| listText.addAttribute(.paragraphStyle, value: paraStyle, range: listText.fullRange) | ||
| let newLineRanges = listText.rangesOf(characterSet: .newlines) | ||
| for newLineRange in newLineRanges { | ||
| listText.addAttributes([ | ||
| .blockContentType:EditorContentName.newline(), | ||
| .skipNextListMarker: 1 | ||
| ], range: newLineRange) | ||
| } | ||
|
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| if i < list.count - 1 { | ||
| listText.append(NSAttributedString(string: "\n", | ||
| attributes: [ | ||
| NSAttributedString.Key.blockContentType:EditorContentName.newline(), | ||
| NSAttributedString.Key.listItem: item.attributeValue, | ||
| NSAttributedString.Key.paragraphStyle: paraStyle | ||
| ])) | ||
| } | ||
| attributedString.append(listText) | ||
| } | ||
| return attributedString | ||
| } | ||
|
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| /// Parses NSAttributedString to list items | ||
| /// - Parameters: | ||
| /// - attributedString: NSAttributedString to convert to list items. | ||
| /// - indent: Indentation used in list representation in attributedString. This determines the level of list item. | ||
| /// - Returns: Array of list items with corresponding range in attributedString | ||
| /// - Note: If NSAttributedString passed into the function is non continuous i.e. contains multiple lists, the array will contain items from all the list with the range corresponding to range of text in original attributed string. | ||
| public static func parse(attributedString: NSAttributedString, indent: CGFloat = 25) -> [(range: NSRange, listItem: ListItem)] { | ||
| var items = [(range: NSRange, listItem: ListItem)]() | ||
| attributedString.enumerateAttribute(.listItem, in: attributedString.fullRange, options: []) { (value, range, _) in | ||
| if value != nil { | ||
| items.append(contentsOf: parseList(in: attributedString.attributedSubstring(from: range), rangeInOriginalString: range, indent: indent, attributeValue: value)) | ||
| } | ||
| } | ||
| return items | ||
| } | ||
|
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| private static func parseList(in attributedString: NSAttributedString, rangeInOriginalString: NSRange, indent: CGFloat, attributeValue: Any?) -> [(range: NSRange, listItem: ListItem)] { | ||
| var items = [(range: NSRange, listItem: ListItem)]() | ||
|
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| attributedString.enumerateAttribute(.paragraphStyle, in: attributedString.fullRange, options: []) { paraAttribute, paraRange, _ in | ||
| if let paraStyle = paraAttribute as? NSParagraphStyle { | ||
| let level = Int(paraStyle.headIndent/indent) | ||
| let text = attributedString.attributedSubstring(from: paraRange) | ||
| var lines = listLinesFrom(text: text)//text.string.components(separatedBy: .newlines) | ||
|
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| if lines.last?.string.isEmpty ?? false { | ||
| lines.remove(at: lines.count - 1) | ||
| } | ||
| var start = 0 | ||
| for i in 0..<lines.count { | ||
| let line = lines[i] | ||
| let itemRange = NSRange(location: start, length: line.string.count) | ||
| let newlineRange = NSRange(location: max(itemRange.location - 1, 0), length: 1) | ||
| if newlineRange.endLocation < text.length, | ||
| text.attributeValue(for: .skipNextListMarker, at: newlineRange.location) != nil, | ||
| var lastItem = items.last { | ||
| lastItem.range = NSRange(location: lastItem.range.location, length: itemRange.endLocation) | ||
| lastItem.listItem = ListItem(text: text.attributedSubstring(from: lastItem.range), level: level, attributeValue: attributeValue as Any) | ||
| items.remove(at: items.count - 1) | ||
| items.append((range: lastItem.range.shiftedBy(rangeInOriginalString.location), listItem: lastItem.listItem)) | ||
| } else { | ||
| let listLine = text.attributedSubstring(from: itemRange) | ||
| let item = ListItem(text: listLine, level: level, attributeValue: attributeValue as Any) | ||
| items.append((itemRange.shiftedBy(rangeInOriginalString.location), item)) | ||
| } | ||
| start += line.string.count + 1 // + 1 to account for \n | ||
| } | ||
| } | ||
| } | ||
| return items | ||
| } | ||
|
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| private static func listLinesFrom(text: NSAttributedString) -> [NSAttributedString] { | ||
| var listItems = [NSAttributedString]() | ||
|
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| let newlineRanges = text.rangesOf(characterSet: .newlines) | ||
| var startIndex = 0 | ||
|
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| for newlineRange in newlineRanges { | ||
| let isNewlineSkipMarker = text.attributedSubstring(from: newlineRange).attribute(.skipNextListMarker, at: 0, effectiveRange: nil) != nil | ||
|
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| if isNewlineSkipMarker { | ||
| continue | ||
| } | ||
|
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| let itemText = text.attributedSubstring(from: NSRange(location: startIndex, length: newlineRange.location - startIndex)) | ||
| listItems.append(itemText) | ||
| startIndex = newlineRange.endLocation | ||
| } | ||
|
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| let itemText = text.attributedSubstring(from: NSRange(location: startIndex, length: text.length - startIndex)) | ||
| listItems.append(itemText) | ||
| return listItems | ||
| } | ||
| } |
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