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feat: 🎸 native encoding of PlantUML diagram text description
BREAKING CHANGE: 🧨 macOS 10.11 (El Capitan) required previously a network call was initiated to obtain proper encoding for a PlantUML diagram text description. Now the text encoding occurs natively in Swift. Encoding is according to PlantUML definition: 1. encoded in UTF-8, 2. compressed using Deflate, 3. reencoded in ASCII using a transformation close to base64
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,185 @@ | ||
| // | ||
| import Compression | ||
| import Foundation | ||
|
|
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| struct PlantUMLText: RawRepresentable { | ||
| var rawValue: String | ||
|
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| var encodedValue: String { | ||
| let compressedData = deflate(rawValue) | ||
| let encodedText = base64plantuml(compressedData) | ||
| return encodedText | ||
| } | ||
| } | ||
|
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| private extension PlantUMLText { | ||
| /** | ||
| deflates according to IETF RFC 1951 | ||
|
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| https://developer.apple.com/documentation/accelerate/compressing_and_decompressing_data_with_buffer_compression | ||
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| - Parameter text: diagram textual description ("@startuml ... @enduml") | ||
| - Returns: compressed data according to DEFLATE (IETF RFC 1951) a.k.a zlib compression algorithm | ||
| */ | ||
| func deflate(_ text: String) -> NSData { | ||
| let sourceString = text | ||
| let sourceBuffer = Array(sourceString.utf8) | ||
| let destinationBuffer = UnsafeMutablePointer<UInt8>.allocate(capacity: sourceString.count) | ||
| let algorithm = COMPRESSION_ZLIB | ||
| let compressedSize = compression_encode_buffer(destinationBuffer, sourceString.count, | ||
| sourceBuffer, sourceString.count, | ||
| nil, | ||
| algorithm) | ||
| return NSData(bytesNoCopy: destinationBuffer, | ||
| length: compressedSize) | ||
| } | ||
| } | ||
|
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| // implementation based on SwiftyBase64 (Created by Doug Richardson) | ||
| internal extension PlantUMLText { | ||
| /** | ||
| Encode a [UInt8] byte array using Base64 algorithm (as decribed by RFC 4648 section 4) **BUT uses a different translation table / alphabet**. | ||
|
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| For PlantUML, the mapping array for values 0-63 is: | ||
| `0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_` | ||
|
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| See https://plantuml.com/en/text-encoding for more info | ||
|
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| - Parameter compressedData: of a deflated string | ||
| - Returns: encoded string | ||
| */ | ||
| func base64plantuml(_ compressedData: NSData) -> String { // swiftlint:disable:this function_body_length | ||
| let bytes = [UInt8](compressedData) | ||
|
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| let encodingAlphabetTable: [UInt8] = [ | ||
| 48, // 0=0 | ||
| 49, // 1=1 | ||
| 50, // 2=2 | ||
| 51, // 3=3 | ||
| 52, // 4=4 | ||
| 53, // 5=5 | ||
| 54, // 6=6 | ||
| 55, // 7=7 | ||
| 56, // 8=8 | ||
| 57, // 9=9 | ||
| 65, // 10=A | ||
| 66, // 11=B | ||
| 67, // 12=C | ||
| 68, // 13=D | ||
| 69, // 14=E | ||
| 70, // 15=F | ||
| 71, // 16=G | ||
| 72, // 17=H | ||
| 73, // 18=I | ||
| 74, // 19=J | ||
| 75, // 20=K | ||
| 76, // 21=L | ||
| 77, // 22=M | ||
| 78, // 23=N | ||
| 79, // 24=O | ||
| 80, // 25=P | ||
| 81, // 26=Q | ||
| 82, // 27=R | ||
| 83, // 28=S | ||
| 84, // 29=T | ||
| 85, // 30=U | ||
| 86, // 31=V | ||
| 87, // 32=W | ||
| 88, // 33=X | ||
| 89, // 34=Y | ||
| 90, // 35=Z | ||
| 97, // 36=a | ||
| 98, // 37=b | ||
| 99, // 38=c | ||
| 100, // 39=d | ||
| 101, // 40=e | ||
| 102, // 41=f | ||
| 103, // 42=g | ||
| 104, // 43=h | ||
| 105, // 44=i | ||
| 106, // 45=j | ||
| 107, // 46=k | ||
| 108, // 47=l | ||
| 109, // 48=m | ||
| 110, // 49=n | ||
| 111, // 50=o | ||
| 112, // 51=p | ||
| 113, // 52=q | ||
| 114, // 53=r | ||
| 115, // 54=s | ||
| 116, // 55=t | ||
| 117, // 56=u | ||
| 118, // 57=v | ||
| 119, // 58=w | ||
| 120, // 59=x | ||
| 121, // 60=y | ||
| 122, // 61=z | ||
| 45, // 62=- | ||
| 95, // 63=_ | ||
| // PADDING FOLLOWS, not used during lookups | ||
| 61, // 64== | ||
| ] | ||
|
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| var encodedBytes: [UInt8] = [] | ||
| let padding = encodingAlphabetTable[64] | ||
|
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| var i = 0 // swiftlint:disable:this identifier_name | ||
| let count = bytes.count | ||
|
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| while i + 3 <= count { | ||
| let one = bytes[i] >> 2 | ||
| let two = ((bytes[i] & 0b11) << 4) | ((bytes[i + 1] & 0b1111_0000) >> 4) | ||
| let three = ((bytes[i + 1] & 0b0000_1111) << 2) | ((bytes[i + 2] & 0b1100_0000) >> 6) | ||
| let four = bytes[i + 2] & 0b0011_1111 | ||
|
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| encodedBytes.append(encodingAlphabetTable[Int(one)]) | ||
| encodedBytes.append(encodingAlphabetTable[Int(two)]) | ||
| encodedBytes.append(encodingAlphabetTable[Int(three)]) | ||
| encodedBytes.append(encodingAlphabetTable[Int(four)]) | ||
|
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| i += 3 | ||
| } | ||
|
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| if i + 2 == count { | ||
| // (3) The final quantum of encoding input is exactly 16 bits; here, the | ||
| // final unit of encoded output will be three characters followed by | ||
| // one "=" padding character. | ||
| let one = bytes[i] >> 2 | ||
| let two = ((bytes[i] & 0b11) << 4) | ((bytes[i + 1] & 0b1111_0000) >> 4) | ||
| let three = ((bytes[i + 1] & 0b0000_1111) << 2) | ||
| encodedBytes.append(encodingAlphabetTable[Int(one)]) | ||
| encodedBytes.append(encodingAlphabetTable[Int(two)]) | ||
| encodedBytes.append(encodingAlphabetTable[Int(three)]) | ||
| encodedBytes.append(padding) | ||
| } else if i + 1 == count { | ||
| // (2) The final quantum of encoding input is exactly 8 bits; here, the | ||
| // final unit of encoded output will be two characters followed by | ||
| // two "=" padding characters. | ||
| let one = bytes[i] >> 2 | ||
| let two = ((bytes[i] & 0b11) << 4) | ||
| encodedBytes.append(encodingAlphabetTable[Int(one)]) | ||
| encodedBytes.append(encodingAlphabetTable[Int(two)]) | ||
| encodedBytes.append(padding) | ||
| encodedBytes.append(padding) | ||
| } else { | ||
| // (1) The final quantum of encoding input is an integral multiple of 24 | ||
| // bits; here, the final unit of encoded output will be an integral | ||
| // multiple of 4 characters with no "=" padding. | ||
| assert(i == count) | ||
| } | ||
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| return String(decoding: encodedBytes, as: Unicode.UTF8.self) | ||
| } | ||
| } | ||
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| extension PlantUMLText: CustomStringConvertible { | ||
| var description: String { | ||
| encodedValue | ||
| } | ||
| } | ||
|
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| extension PlantUMLText: CustomDebugStringConvertible { | ||
| var debugDescription: String { | ||
| "\(rawValue) encoded is \(encodedValue)" | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,24 @@ | ||
| @testable import SwiftPlantUMLFramework | ||
| import XCTest | ||
|
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| final class PlantUMLTextTests: XCTestCase { | ||
| func testRawValue() { | ||
| let sut = PlantUMLText(rawValue: "test") | ||
| XCTAssertEqual(sut.rawValue, "test") | ||
| } | ||
|
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| func testEncoding() { | ||
| let text = "@startuml\n\' STYLE START\nhide empty members\nskinparam shadowing false\n\' STYLE END\n\n\n\n\n@enduml" | ||
| let expectedResult = "SoWkIImgAStDuL9N20w9z745aev18LmPcIcf2gcv1IML2hcfkKcfHSLSnTcPUGM9HOcv2iKPYIdvvPbvwGffYJd5gN2jhdukN23Wa9gN0ZGI00==" | ||
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| XCTAssertEqual(PlantUMLText(rawValue: text).encodedValue, expectedResult) | ||
| XCTAssertEqual(PlantUMLText(rawValue: text).description, expectedResult) | ||
| } | ||
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| func testDescription() { | ||
| let text = "@startuml\n\' STYLE START\nhide empty members\nskinparam shadowing false\n\' STYLE END\n\n\n\n\n@enduml" | ||
| let expectedResult = "SoWkIImgAStDuL9N20w9z745aev18LmPcIcf2gcv1IML2hcfkKcfHSLSnTcPUGM9HOcv2iKPYIdvvPbvwGffYJd5gN2jhdukN23Wa9gN0ZGI00==" | ||
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| XCTAssertEqual(PlantUMLText(rawValue: text).description, expectedResult) | ||
| } | ||
| } |