Check-in [47b221d5b4]
Overview
Comment:Added MinReader to ioutils, CC at 100%
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1:47b221d5b405e27881cf8846370ca5025aade422
User & Date: spaskalev on 2014-12-23 10:38:30
Other Links: manifest | tags
Context
2014-12-23
14:27
minReader fixes check-in: 4195e7817d user: spaskalev tags: trunk
10:38
Added MinReader to ioutils, CC at 100% check-in: 47b221d5b4 user: spaskalev tags: trunk
09:32
Removed the compressor alias type from predictor, use ioutil.WriterFunc check-in: c62581c2a6 user: spaskalev tags: trunk
Changes

Modified src/0dev.org/ioutil/ioutil.go from [404db9969d] to [edab0c9e76].

1
2




3
4
5
6
7
8
9
..
12
13
14
15
16
17
18














































// Package ioutil contains various constructs for io operations
package ioutil





// An function alias type that implements io.Writer
type WriterFunc func([]byte) (int, error)

// Delegates the call to the WriterFunc while implementing io.Writer
func (w WriterFunc) Write(b []byte) (int, error) {
	return w(b)
................................................................................
// An function alias type that implements io.Reader
type ReaderFunc func([]byte) (int, error)

// Delegates the call to the WriterFunc while implementing io.Reader
func (r ReaderFunc) Read(b []byte) (int, error) {
	return r(b)
}
















































>
>
>
>







 







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
1
2
3
4
5
6
7
8
9
10
11
12
13
..
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
// Package ioutil contains various constructs for io operations
package ioutil

import (
	"io"
)

// An function alias type that implements io.Writer
type WriterFunc func([]byte) (int, error)

// Delegates the call to the WriterFunc while implementing io.Writer
func (w WriterFunc) Write(b []byte) (int, error) {
	return w(b)
................................................................................
// An function alias type that implements io.Reader
type ReaderFunc func([]byte) (int, error)

// Delegates the call to the WriterFunc while implementing io.Reader
func (r ReaderFunc) Read(b []byte) (int, error) {
	return r(b)
}

// Returns a reader that will delegate calls to Read(...) while ensuring
// that the output buffer will never be smaller than the required size
func MinReader(reader io.Reader, size int) io.Reader {
	var buffer []byte = make([]byte, 0, size)

	return ReaderFunc(func(output []byte) (readCount int, e error) {
		var (
			bufferLength int = len(buffer)
			err          error
		)

	start:
		// Reply with the buffered data if there is any
		if bufferLength > 0 {
			readCount = copy(output, buffer)

			if readCount < bufferLength {
				// Advance the data in the buffer
				buffer = buffer[:copy(buffer, buffer[:readCount])]
			} else {
				// Clear the buffer
				buffer = buffer[:0]
			}

			// Stage any error for returning
			e, err = err, nil

			return readCount, e
		}

		// Delegate if the buffer is empty and the destination buffer is large enough
		if len(output) >= size {
			return reader.Read(output)
		}

		// Extend the buffer up to the desired size and perform a Read
		buffer = buffer[:size]
		readCount, err = reader.Read(buffer)

		// Size the buffer down to the read data size and restart
		buffer = buffer[:readCount]
		bufferLength = len(buffer)
		goto start
	})
}

Modified src/0dev.org/ioutil/ioutil_test.go from [e21bc31120] to [8530a31260].

1
2
3
4
5

6
7
8
9
10
11
12
..
41
42
43
44
45
46
47














































package ioutil

import (
	diff "0dev.org/diff"
	"bytes"

	"testing"
)

func TestWriter(t *testing.T) {
	var (
		input  []byte = []byte{0, 1, 2, 3, 4, 5, 6, 7}
		output []byte
................................................................................
	// Diff the result against the initial input
	delta := diff.Diff(diff.D{len(input), len(output),
		func(i, j int) bool { return input[i] == output[j] }})
	if len(delta.Added) > 0 || len(delta.Removed) > 0 {
		t.Error("Differences detected ", delta)
	}
}



















































>







 







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
1
2
3
4
5
6
7
8
9
10
11
12
13
..
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
package ioutil

import (
	diff "0dev.org/diff"
	"bytes"
	"io"
	"testing"
)

func TestWriter(t *testing.T) {
	var (
		input  []byte = []byte{0, 1, 2, 3, 4, 5, 6, 7}
		output []byte
................................................................................
	// Diff the result against the initial input
	delta := diff.Diff(diff.D{len(input), len(output),
		func(i, j int) bool { return input[i] == output[j] }})
	if len(delta.Added) > 0 || len(delta.Removed) > 0 {
		t.Error("Differences detected ", delta)
	}
}

func TestMinReader(t *testing.T) {
	var (
		input  []byte = []byte{0, 1, 2, 3, 4, 5, 6, 7}
		output []byte = make([]byte, 16)

		reader *bytes.Reader = bytes.NewReader(input)
		min    io.Reader     = MinReader(reader, 4)
	)

	// Expecting a read count of 2
	count, err := min.Read(output[:2])
	if count != 2 {
		t.Error("Invalid read count from MinReader", count)
	}
	if err != nil {
		t.Error("Unexpected error from MinReader", err)
	}

	// Expecting a read count of 2 as it should have 2 bytes in its buffer
	count, err = min.Read(output[:3])
	if count != 2 {
		t.Error("Invalid read count from MinReader", count)
	}
	if err != nil {
		t.Error("Unexpected error from MinReader", err)
	}

	// Expecting a read count of 4 as the buffer should be empty
	count, err = min.Read(output[:4])
	if count != 4 {
		t.Error("Invalid read count from MinReader", count)
	}
	if err != nil {
		t.Error("Unexpected error from MinReader", err)
	}

	// Expecting a read count of 0 with an EOF as the buffer should be empty
	count, err = min.Read(output[:4])
	if count != 0 {
		t.Error("Invalid read count from MinReader", count)
	}
	if err != io.EOF {
		t.Error("Unexpected error from MinReader", err)
	}
}