dict_decoder_test.go

Documentation: compress/flate

		 1  // Copyright 2016 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package flate
		 6  
		 7  import (
		 8  	"bytes"
		 9  	"strings"
		10  	"testing"
		11  )
		12  
		13  func TestDictDecoder(t *testing.T) {
		14  	const (
		15  		abc	= "ABC\n"
		16  		fox	= "The quick brown fox jumped over the lazy dog!\n"
		17  		poem = "The Road Not Taken\nRobert Frost\n" +
		18  			"\n" +
		19  			"Two roads diverged in a yellow wood,\n" +
		20  			"And sorry I could not travel both\n" +
		21  			"And be one traveler, long I stood\n" +
		22  			"And looked down one as far as I could\n" +
		23  			"To where it bent in the undergrowth;\n" +
		24  			"\n" +
		25  			"Then took the other, as just as fair,\n" +
		26  			"And having perhaps the better claim,\n" +
		27  			"Because it was grassy and wanted wear;\n" +
		28  			"Though as for that the passing there\n" +
		29  			"Had worn them really about the same,\n" +
		30  			"\n" +
		31  			"And both that morning equally lay\n" +
		32  			"In leaves no step had trodden black.\n" +
		33  			"Oh, I kept the first for another day!\n" +
		34  			"Yet knowing how way leads on to way,\n" +
		35  			"I doubted if I should ever come back.\n" +
		36  			"\n" +
		37  			"I shall be telling this with a sigh\n" +
		38  			"Somewhere ages and ages hence:\n" +
		39  			"Two roads diverged in a wood, and I-\n" +
		40  			"I took the one less traveled by,\n" +
		41  			"And that has made all the difference.\n"
		42  	)
		43  
		44  	var poemRefs = []struct {
		45  		dist	 int // Backward distance (0 if this is an insertion)
		46  		length int // Length of copy or insertion
		47  	}{
		48  		{0, 38}, {33, 3}, {0, 48}, {79, 3}, {0, 11}, {34, 5}, {0, 6}, {23, 7},
		49  		{0, 8}, {50, 3}, {0, 2}, {69, 3}, {34, 5}, {0, 4}, {97, 3}, {0, 4},
		50  		{43, 5}, {0, 6}, {7, 4}, {88, 7}, {0, 12}, {80, 3}, {0, 2}, {141, 4},
		51  		{0, 1}, {196, 3}, {0, 3}, {157, 3}, {0, 6}, {181, 3}, {0, 2}, {23, 3},
		52  		{77, 3}, {28, 5}, {128, 3}, {110, 4}, {70, 3}, {0, 4}, {85, 6}, {0, 2},
		53  		{182, 6}, {0, 4}, {133, 3}, {0, 7}, {47, 5}, {0, 20}, {112, 5}, {0, 1},
		54  		{58, 3}, {0, 8}, {59, 3}, {0, 4}, {173, 3}, {0, 5}, {114, 3}, {0, 4},
		55  		{92, 5}, {0, 2}, {71, 3}, {0, 2}, {76, 5}, {0, 1}, {46, 3}, {96, 4},
		56  		{130, 4}, {0, 3}, {360, 3}, {0, 3}, {178, 5}, {0, 7}, {75, 3}, {0, 3},
		57  		{45, 6}, {0, 6}, {299, 6}, {180, 3}, {70, 6}, {0, 1}, {48, 3}, {66, 4},
		58  		{0, 3}, {47, 5}, {0, 9}, {325, 3}, {0, 1}, {359, 3}, {318, 3}, {0, 2},
		59  		{199, 3}, {0, 1}, {344, 3}, {0, 3}, {248, 3}, {0, 10}, {310, 3}, {0, 3},
		60  		{93, 6}, {0, 3}, {252, 3}, {157, 4}, {0, 2}, {273, 5}, {0, 14}, {99, 4},
		61  		{0, 1}, {464, 4}, {0, 2}, {92, 4}, {495, 3}, {0, 1}, {322, 4}, {16, 4},
		62  		{0, 3}, {402, 3}, {0, 2}, {237, 4}, {0, 2}, {432, 4}, {0, 1}, {483, 5},
		63  		{0, 2}, {294, 4}, {0, 2}, {306, 3}, {113, 5}, {0, 1}, {26, 4}, {164, 3},
		64  		{488, 4}, {0, 1}, {542, 3}, {248, 6}, {0, 5}, {205, 3}, {0, 8}, {48, 3},
		65  		{449, 6}, {0, 2}, {192, 3}, {328, 4}, {9, 5}, {433, 3}, {0, 3}, {622, 25},
		66  		{615, 5}, {46, 5}, {0, 2}, {104, 3}, {475, 10}, {549, 3}, {0, 4}, {597, 8},
		67  		{314, 3}, {0, 1}, {473, 6}, {317, 5}, {0, 1}, {400, 3}, {0, 3}, {109, 3},
		68  		{151, 3}, {48, 4}, {0, 4}, {125, 3}, {108, 3}, {0, 2},
		69  	}
		70  
		71  	var got, want bytes.Buffer
		72  	var dd dictDecoder
		73  	dd.init(1<<11, nil)
		74  
		75  	var writeCopy = func(dist, length int) {
		76  		for length > 0 {
		77  			cnt := dd.tryWriteCopy(dist, length)
		78  			if cnt == 0 {
		79  				cnt = dd.writeCopy(dist, length)
		80  			}
		81  
		82  			length -= cnt
		83  			if dd.availWrite() == 0 {
		84  				got.Write(dd.readFlush())
		85  			}
		86  		}
		87  	}
		88  	var writeString = func(str string) {
		89  		for len(str) > 0 {
		90  			cnt := copy(dd.writeSlice(), str)
		91  			str = str[cnt:]
		92  			dd.writeMark(cnt)
		93  			if dd.availWrite() == 0 {
		94  				got.Write(dd.readFlush())
		95  			}
		96  		}
		97  	}
		98  
		99  	writeString(".")
	 100  	want.WriteByte('.')
	 101  
	 102  	str := poem
	 103  	for _, ref := range poemRefs {
	 104  		if ref.dist == 0 {
	 105  			writeString(str[:ref.length])
	 106  		} else {
	 107  			writeCopy(ref.dist, ref.length)
	 108  		}
	 109  		str = str[ref.length:]
	 110  	}
	 111  	want.WriteString(poem)
	 112  
	 113  	writeCopy(dd.histSize(), 33)
	 114  	want.Write(want.Bytes()[:33])
	 115  
	 116  	writeString(abc)
	 117  	writeCopy(len(abc), 59*len(abc))
	 118  	want.WriteString(strings.Repeat(abc, 60))
	 119  
	 120  	writeString(fox)
	 121  	writeCopy(len(fox), 9*len(fox))
	 122  	want.WriteString(strings.Repeat(fox, 10))
	 123  
	 124  	writeString(".")
	 125  	writeCopy(1, 9)
	 126  	want.WriteString(strings.Repeat(".", 10))
	 127  
	 128  	writeString(strings.ToUpper(poem))
	 129  	writeCopy(len(poem), 7*len(poem))
	 130  	want.WriteString(strings.Repeat(strings.ToUpper(poem), 8))
	 131  
	 132  	writeCopy(dd.histSize(), 10)
	 133  	want.Write(want.Bytes()[want.Len()-dd.histSize():][:10])
	 134  
	 135  	got.Write(dd.readFlush())
	 136  	if got.String() != want.String() {
	 137  		t.Errorf("final string mismatch:\ngot	%q\nwant %q", got.String(), want.String())
	 138  	}
	 139  }
	 140
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