internal/compress: Add

1 files changed, 284 insertions, 0 deletions

diff --git a/internal/compress/flate/dict_decoder_test.go b/internal/compress/flate/dict_decoder_test.go
new file mode 100644
index 00000000..8bc48a3e
--- /dev/null
+++ b/internal/compress/flate/dict_decoder_test.go
@@ -0,0 +1,284 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestDictDecoder(t *testing.T) {
+	const (
+		abc  = "ABC\n"
+		fox  = "The quick brown fox jumped over the lazy dog!\n"
+		poem = "The Road Not Taken\nRobert Frost\n" +
+			"\n" +
+			"Two roads diverged in a yellow wood,\n" +
+			"And sorry I could not travel both\n" +
+			"And be one traveler, long I stood\n" +
+			"And looked down one as far as I could\n" +
+			"To where it bent in the undergrowth;\n" +
+			"\n" +
+			"Then took the other, as just as fair,\n" +
+			"And having perhaps the better claim,\n" +
+			"Because it was grassy and wanted wear;\n" +
+			"Though as for that the passing there\n" +
+			"Had worn them really about the same,\n" +
+			"\n" +
+			"And both that morning equally lay\n" +
+			"In leaves no step had trodden black.\n" +
+			"Oh, I kept the first for another day!\n" +
+			"Yet knowing how way leads on to way,\n" +
+			"I doubted if I should ever come back.\n" +
+			"\n" +
+			"I shall be telling this with a sigh\n" +
+			"Somewhere ages and ages hence:\n" +
+			"Two roads diverged in a wood, and I-\n" +
+			"I took the one less traveled by,\n" +
+			"And that has made all the difference.\n"
+	)
+
+	poemRefs := []struct {
+		dist   int // Backward distance (0 if this is an insertion)
+		length int // Length of copy or insertion
+	}{
+		{0, 38},
+		{33, 3},
+		{0, 48},
+		{79, 3},
+		{0, 11},
+		{34, 5},
+		{0, 6},
+		{23, 7},
+		{0, 8},
+		{50, 3},
+		{0, 2},
+		{69, 3},
+		{34, 5},
+		{0, 4},
+		{97, 3},
+		{0, 4},
+		{43, 5},
+		{0, 6},
+		{7, 4},
+		{88, 7},
+		{0, 12},
+		{80, 3},
+		{0, 2},
+		{141, 4},
+		{0, 1},
+		{196, 3},
+		{0, 3},
+		{157, 3},
+		{0, 6},
+		{181, 3},
+		{0, 2},
+		{23, 3},
+		{77, 3},
+		{28, 5},
+		{128, 3},
+		{110, 4},
+		{70, 3},
+		{0, 4},
+		{85, 6},
+		{0, 2},
+		{182, 6},
+		{0, 4},
+		{133, 3},
+		{0, 7},
+		{47, 5},
+		{0, 20},
+		{112, 5},
+		{0, 1},
+		{58, 3},
+		{0, 8},
+		{59, 3},
+		{0, 4},
+		{173, 3},
+		{0, 5},
+		{114, 3},
+		{0, 4},
+		{92, 5},
+		{0, 2},
+		{71, 3},
+		{0, 2},
+		{76, 5},
+		{0, 1},
+		{46, 3},
+		{96, 4},
+		{130, 4},
+		{0, 3},
+		{360, 3},
+		{0, 3},
+		{178, 5},
+		{0, 7},
+		{75, 3},
+		{0, 3},
+		{45, 6},
+		{0, 6},
+		{299, 6},
+		{180, 3},
+		{70, 6},
+		{0, 1},
+		{48, 3},
+		{66, 4},
+		{0, 3},
+		{47, 5},
+		{0, 9},
+		{325, 3},
+		{0, 1},
+		{359, 3},
+		{318, 3},
+		{0, 2},
+		{199, 3},
+		{0, 1},
+		{344, 3},
+		{0, 3},
+		{248, 3},
+		{0, 10},
+		{310, 3},
+		{0, 3},
+		{93, 6},
+		{0, 3},
+		{252, 3},
+		{157, 4},
+		{0, 2},
+		{273, 5},
+		{0, 14},
+		{99, 4},
+		{0, 1},
+		{464, 4},
+		{0, 2},
+		{92, 4},
+		{495, 3},
+		{0, 1},
+		{322, 4},
+		{16, 4},
+		{0, 3},
+		{402, 3},
+		{0, 2},
+		{237, 4},
+		{0, 2},
+		{432, 4},
+		{0, 1},
+		{483, 5},
+		{0, 2},
+		{294, 4},
+		{0, 2},
+		{306, 3},
+		{113, 5},
+		{0, 1},
+		{26, 4},
+		{164, 3},
+		{488, 4},
+		{0, 1},
+		{542, 3},
+		{248, 6},
+		{0, 5},
+		{205, 3},
+		{0, 8},
+		{48, 3},
+		{449, 6},
+		{0, 2},
+		{192, 3},
+		{328, 4},
+		{9, 5},
+		{433, 3},
+		{0, 3},
+		{622, 25},
+		{615, 5},
+		{46, 5},
+		{0, 2},
+		{104, 3},
+		{475, 10},
+		{549, 3},
+		{0, 4},
+		{597, 8},
+		{314, 3},
+		{0, 1},
+		{473, 6},
+		{317, 5},
+		{0, 1},
+		{400, 3},
+		{0, 3},
+		{109, 3},
+		{151, 3},
+		{48, 4},
+		{0, 4},
+		{125, 3},
+		{108, 3},
+		{0, 2},
+	}
+
+	var got, want bytes.Buffer
+	var dd dictDecoder
+	dd.init(1<<11, nil)
+
+	writeCopy := func(dist, length int) {
+		for length > 0 {
+			cnt := dd.tryWriteCopy(dist, length)
+			if cnt == 0 {
+				cnt = dd.writeCopy(dist, length)
+			}
+
+			length -= cnt
+			if dd.availWrite() == 0 {
+				got.Write(dd.readFlush())
+			}
+		}
+	}
+	writeString := func(str string) {
+		for len(str) > 0 {
+			cnt := copy(dd.writeSlice(), str)
+			str = str[cnt:]
+			dd.writeMark(cnt)
+			if dd.availWrite() == 0 {
+				got.Write(dd.readFlush())
+			}
+		}
+	}
+
+	writeString(".")
+	want.WriteByte('.')
+
+	str := poem
+	for _, ref := range poemRefs {
+		if ref.dist == 0 {
+			writeString(str[:ref.length])
+		} else {
+			writeCopy(ref.dist, ref.length)
+		}
+		str = str[ref.length:]
+	}
+	want.WriteString(poem)
+
+	writeCopy(dd.histSize(), 33)
+	want.Write(want.Bytes()[:33])
+
+	writeString(abc)
+	writeCopy(len(abc), 59*len(abc))
+	want.WriteString(strings.Repeat(abc, 60))
+
+	writeString(fox)
+	writeCopy(len(fox), 9*len(fox))
+	want.WriteString(strings.Repeat(fox, 10))
+
+	writeString(".")
+	writeCopy(1, 9)
+	want.WriteString(strings.Repeat(".", 10))
+
+	writeString(strings.ToUpper(poem))
+	writeCopy(len(poem), 7*len(poem))
+	want.WriteString(strings.Repeat(strings.ToUpper(poem), 8))
+
+	writeCopy(dd.histSize(), 10)
+	want.Write(want.Bytes()[want.Len()-dd.histSize():][:10])
+
+	got.Write(dd.readFlush())
+	if got.String() != want.String() {
+		t.Errorf("final string mismatch:\ngot  %q\nwant %q", got.String(), want.String())
+	}
+}