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Extract HuffmanLength array creation code into Deflate specific file

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This commit is contained in:
Timofey Solomko
2017-09-03 22:46:00 +03:00
parent cebf0555e5
commit a70e557f38
4 changed files with 54 additions and 33 deletions
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SWCompression.xcodeproj/project.pbxproj
+10
View File
@@ -147,6 +147,10 @@
0681B3E11E44F674001A9D79 /* BitWriter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0681B3DD1E44F674001A9D79 /* BitWriter.swift */; };
0685E6241F123F0D008655AA /* test_zip_bzip2.zip in Resources */ = {isa = PBXBuildFile; fileRef = 0685E6231F123F0D008655AA /* test_zip_bzip2.zip */; };
068B36791ED0AC050016269E /* full_test.tar in Resources */ = {isa = PBXBuildFile; fileRef = 068B36781ED0AC050016269E /* full_test.tar */; };
06912BD21F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */ = {isa = PBXBuildFile; fileRef = 06912BD11F5C8F3D0070BB60 /* Deflate+Lengths.swift */; };
06912BD31F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */ = {isa = PBXBuildFile; fileRef = 06912BD11F5C8F3D0070BB60 /* Deflate+Lengths.swift */; };
06912BD41F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */ = {isa = PBXBuildFile; fileRef = 06912BD11F5C8F3D0070BB60 /* Deflate+Lengths.swift */; };
06912BD51F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */ = {isa = PBXBuildFile; fileRef = 06912BD11F5C8F3D0070BB60 /* Deflate+Lengths.swift */; };
0691B9401EBE3E100037EE58 /* test.tar in Resources */ = {isa = PBXBuildFile; fileRef = 0691B93F1EBE3E100037EE58 /* test.tar */; };
0693DF521F2E499F00602300 /* test_empty_dir.7z in Resources */ = {isa = PBXBuildFile; fileRef = 0693DF501F2E499F00602300 /* test_empty_dir.7z */; };
0693DF531F2E499F00602300 /* test_empty_file.7z in Resources */ = {isa = PBXBuildFile; fileRef = 0693DF511F2E499F00602300 /* test_empty_file.7z */; };
@@ -398,6 +402,7 @@
0681B3DD1E44F674001A9D79 /* BitWriter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = BitWriter.swift; path = Sources/BitWriter.swift; sourceTree = SOURCE_ROOT; };
0685E6231F123F0D008655AA /* test_zip_bzip2.zip */ = {isa = PBXFileReference; lastKnownFileType = archive.zip; path = test_zip_bzip2.zip; sourceTree = "<group>"; };
068B36781ED0AC050016269E /* full_test.tar */ = {isa = PBXFileReference; lastKnownFileType = archive.tar; path = full_test.tar; sourceTree = "<group>"; };
06912BD11F5C8F3D0070BB60 /* Deflate+Lengths.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "Deflate+Lengths.swift"; sourceTree = "<group>"; };
0691B93F1EBE3E100037EE58 /* test.tar */ = {isa = PBXFileReference; lastKnownFileType = archive.tar; path = test.tar; sourceTree = "<group>"; };
0693DF501F2E499F00602300 /* test_empty_dir.7z */ = {isa = PBXFileReference; lastKnownFileType = file; path = test_empty_dir.7z; sourceTree = "<group>"; };
0693DF511F2E499F00602300 /* test_empty_file.7z */ = {isa = PBXFileReference; lastKnownFileType = file; path = test_empty_file.7z; sourceTree = "<group>"; };
@@ -882,6 +887,7 @@
061FCE251DBCC4BE0052F7BE /* Deflate.swift */,
06CDFCA71F111D9700292758 /* DeflateError.swift */,
06CDFC9D1F111D2600292758 /* DeflateCompression.swift */,
06912BD11F5C8F3D0070BB60 /* Deflate+Lengths.swift */,
);
name = Deflate;
sourceTree = "<group>";
@@ -1238,6 +1244,7 @@
0681B3DF1E44F674001A9D79 /* BitWriter.swift in Sources */,
061C063E1F0E8AB700832F0C /* ZipError.swift in Sources */,
069D0FE71E0D6C6400D8AA87 /* LZMADecoder.swift in Sources */,
06912BD31F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */,
06A9606B1F1E7E0D0078E6D1 /* 7zSubstreamInfo.swift in Sources */,
06FED40D1DD7717E0013DFB2 /* BZip2.swift in Sources */,
06A960611F1E7DE20078E6D1 /* 7zFileInfo.swift in Sources */,
@@ -1298,6 +1305,7 @@
0681B3E01E44F674001A9D79 /* BitWriter.swift in Sources */,
061C063F1F0E8AB700832F0C /* ZipError.swift in Sources */,
069D0FE81E0D6C6400D8AA87 /* LZMADecoder.swift in Sources */,
06912BD41F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */,
06A9606C1F1E7E0D0078E6D1 /* 7zSubstreamInfo.swift in Sources */,
065569711DC65C2B00A47E66 /* Deflate.swift in Sources */,
06A960621F1E7DE20078E6D1 /* 7zFileInfo.swift in Sources */,
@@ -1358,6 +1366,7 @@
0681B3E11E44F674001A9D79 /* BitWriter.swift in Sources */,
061C06401F0E8AB700832F0C /* ZipError.swift in Sources */,
069D0FE91E0D6C6400D8AA87 /* LZMADecoder.swift in Sources */,
06912BD51F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */,
06A9606D1F1E7E0D0078E6D1 /* 7zSubstreamInfo.swift in Sources */,
06FED40F1DD7717E0013DFB2 /* BZip2.swift in Sources */,
06A960631F1E7DE20078E6D1 /* 7zFileInfo.swift in Sources */,
@@ -1418,6 +1427,7 @@
0681B3DE1E44F674001A9D79 /* BitWriter.swift in Sources */,
061C063D1F0E8AB700832F0C /* ZipError.swift in Sources */,
069D0FE61E0D6C6400D8AA87 /* LZMADecoder.swift in Sources */,
06912BD21F5C8F3D0070BB60 /* Deflate+Lengths.swift in Sources */,
06A9606A1F1E7E0D0078E6D1 /* 7zSubstreamInfo.swift in Sources */,
06A3933B1DE0709300182E12 /* Deflate.swift in Sources */,
06A960601F1E7DE20078E6D1 /* 7zFileInfo.swift in Sources */,
Sources/Deflate+Lengths.swift
+39
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@@ -0,0 +1,39 @@
// Copyright (c) 2017 Timofey Solomko
// Licensed under MIT License
//
// See LICENSE for license information
import Foundation
// Deflate specific functions for generation of HuffmanLength arrays from different inputs.
extension Deflate {
static func lengths(from bootStrap: [(symbol: Int, codeLength: Int)]) -> [HuffmanLength] {
// Fills the 'lengths' array with pairs of (symbol, codeLength) from a 'bootstrap'.
var lengths = [HuffmanLength]()
var start = bootStrap[0].symbol
var bits = bootStrap[0].codeLength
for pair in bootStrap[1..<bootStrap.count] {
let finish = pair.symbol
let endbits = pair.codeLength
if bits > 0 {
for i in start..<finish {
lengths.append(HuffmanLength(symbol: i, codeLength: bits))
}
}
start = finish
bits = endbits
}
return lengths
}
/// - Note: Skips zero codeLengths.
static func lengths(from orderedCodeLengths: [Int]) -> [HuffmanLength] {
var lengths = [HuffmanLength]()
for (i, codeLength) in orderedCodeLengths.enumerated() where codeLength > 0 {
lengths.append(HuffmanLength(symbol: i, codeLength: codeLength))
}
return lengths
}
}
Sources/Deflate.swift
+5 -5
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@@ -10,8 +10,8 @@ public class Deflate: DecompressionAlgorithm {
struct Constants {
// Bootstraps for Static Huffman trees (first element in tuple is code, second is number of bits).
static let staticHuffmanBootstrap = HuffmanLength.lengths(from: [(0, 8), (144, 9), (256, 7), (280, 8), (288, -1)])
static let staticHuffmanDistancesBootstrap = HuffmanLength.lengths(from: [(0, 5), (32, -1)])
static let staticHuffmanBootstrap = Deflate.lengths(from: [(0, 8), (144, 9), (256, 7), (280, 8), (288, -1)])
static let staticHuffmanDistancesBootstrap = Deflate.lengths(from: [(0, 5), (32, -1)])
static let codeLengthOrders: [Int] =
[16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15]
@@ -122,7 +122,7 @@ public class Deflate: DecompressionAlgorithm {
lengthsForOrder[Constants.codeLengthOrders[i]] = bitReader.intFromBits(count: 3)
}
/// Huffman tree for code lengths. Each code in the main alphabets is coded with this tree.
let dynamicCodes = DecodingHuffmanTree(lengths: HuffmanLength.lengths(from: lengthsForOrder), bitReader)
let dynamicCodes = DecodingHuffmanTree(lengths: Deflate.lengths(from: lengthsForOrder), bitReader)
// Now we need to read codes (code lengths) for two main alphabets (trees).
var codeLengths: [Int] = []
@@ -164,9 +164,9 @@ public class Deflate: DecompressionAlgorithm {
// We have read codeLengths for both trees at once.
// Now we need to split them and make corresponding trees.
mainLiterals = DecodingHuffmanTree(lengths:
HuffmanLength.lengths(from: Array(codeLengths[0..<literals])), bitReader)
Deflate.lengths(from: Array(codeLengths[0..<literals])), bitReader)
mainDistances = DecodingHuffmanTree(lengths:
HuffmanLength.lengths(from: Array(codeLengths[literals..<codeLengths.count])), bitReader)
Deflate.lengths(from: Array(codeLengths[literals..<codeLengths.count])), bitReader)
}
// Main loop of data decompression.
Sources/HuffmanLength.swift
-28
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@@ -10,34 +10,6 @@ struct HuffmanLength {
let symbol: Int
let codeLength: Int
static func lengths(from bootStrap: [(symbol: Int, codeLength: Int)]) -> [HuffmanLength] {
// Fills the 'lengths' array with pairs of (symbol, codeLength) from a 'bootstrap'.
var lengths = [HuffmanLength]()
var start = bootStrap[0].symbol
var bits = bootStrap[0].codeLength
for pair in bootStrap[1..<bootStrap.count] {
let finish = pair.symbol
let endbits = pair.codeLength
if bits > 0 {
for i in start..<finish {
lengths.append(HuffmanLength(symbol: i, codeLength: bits))
}
}
start = finish
bits = endbits
}
return lengths
}
/// - Note: Skips zero codeLengths.
static func lengths(from orderedCodeLengths: [Int]) -> [HuffmanLength] {
var lengths = [HuffmanLength]()
for (i, codeLength) in orderedCodeLengths.enumerated() where codeLength > 0 {
lengths.append(HuffmanLength(symbol: i, codeLength: codeLength))
}
return lengths
}
}
extension HuffmanLength: Comparable {