document io
R=rsc
DELTA=44 (30 added, 4 deleted, 10 changed)
OCL=25819
CL=25835
diff --git a/src/lib/io/bytebuffer.go b/src/lib/io/bytebuffer.go
index fa11b37..cb2d448 100644
--- a/src/lib/io/bytebuffer.go
+++ b/src/lib/io/bytebuffer.go
@@ -4,15 +4,13 @@
package io
-// Byte buffer for marshaling nested messages.
+// Simple byte buffer for marshaling data.
import (
"io";
"os";
)
-// A simple implementation of the io.Read and io.Write interfaces.
-// A newly allocated ByteBuffer is ready to use.
// TODO(r): Do better memory management.
@@ -24,6 +22,9 @@
}
}
+// A ByteBuffer is a simple implementation of the io.Read and io.Write interfaces
+// connected to a buffer of bytes.
+// The zero value for ByteBuffer is an empty buffer ready to use.
type ByteBuffer struct {
buf []byte;
off int; // Read from here
@@ -31,11 +32,14 @@
cap int;
}
+// Reset resets the buffer so it has no content.
func (b *ByteBuffer) Reset() {
b.off = 0;
b.len = 0;
}
+// Write appends the contents of p to the buffer. The return
+// value is the length of p; err is always nil.
func (b *ByteBuffer) Write(p []byte) (n int, err *os.Error) {
plen := len(p);
if len(b.buf) == 0 {
@@ -54,6 +58,8 @@
return plen, nil;
}
+// Read reads the next len(p) bytes from the buffer or until the buffer
+// is drained. The return value is the number of bytes read; err is always nil.
func (b *ByteBuffer) Read(p []byte) (n int, err *os.Error) {
plen := len(p);
if len(b.buf) == 0 {
@@ -71,22 +77,23 @@
return plen, nil;
}
+// Len returns the length of the underlying buffer.
func (b *ByteBuffer) Len() int {
return b.len
}
+// Off returns the location within the buffer of the next byte to be read.
func (b *ByteBuffer) Off() int {
return b.off
}
+// Data returns the contents of the unread portion of the buffer.
func (b *ByteBuffer) Data() []byte {
return b.buf[b.off:b.len]
}
-func (b *ByteBuffer) AllData() []byte {
- return b.buf[0:b.len]
-}
-
+// NewByteBufferFromArray creates and initializes a new ByteBuffer
+// with buf as its initial contents.
func NewByteBufferFromArray(buf []byte) *ByteBuffer {
b := new(ByteBuffer);
b.buf = buf;
diff --git a/src/lib/io/io.go b/src/lib/io/io.go
index e5f02eb..37acab4 100644
--- a/src/lib/io/io.go
+++ b/src/lib/io/io.go
@@ -2,6 +2,11 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
+// This package provides basic interfaces to I/O primitives.
+// Its primary job is to wrap existing implementations of such primitives,
+// such as those in package os, into shared public interfaces that
+// abstract the functionality.
+// It also provides buffering primitives and some other basic operations.
package io
import (
@@ -9,35 +14,43 @@
"syscall";
)
+// ErrEOF is the error returned by Readn and Copyn when they encounter EOF.
var ErrEOF = os.NewError("EOF")
+// Read is the interface that wraps the basic Read method.
type Read interface {
Read(p []byte) (n int, err *os.Error);
}
+// Write is the interface that wraps the basic Write method.
type Write interface {
Write(p []byte) (n int, err *os.Error);
}
+// Close is the interface that wraps the basic Close method.
type Close interface {
Close() *os.Error;
}
+// ReadWrite is the interface that groups the basic Read and Write methods.
type ReadWrite interface {
Read;
Write;
}
+// ReadClose is the interface that groups the basic Read and Close methods.
type ReadClose interface {
Read;
Close;
}
+// WriteClose is the interface that groups the basic Write and Close methods.
type WriteClose interface {
Write;
Close;
}
+// ReadWriteClose is the interface that groups the basic Read, Write and Close methods.
type ReadWriteClose interface {
Read;
Write;
@@ -53,11 +66,12 @@
return b;
}
+// WriteString writes the contents of the string s to w, which accepts an array of bytes.
func WriteString(w Write, s string) (n int, err *os.Error) {
return w.Write(StringBytes(s))
}
-// Read until buffer is full, EOF, or error
+// Readn reads r until the buffer buf is full, or until EOF or error.
func Readn(r Read, buf []byte) (n int, err *os.Error) {
n = 0;
for n < len(buf) {
@@ -86,6 +100,8 @@
return n, err
}
+// MakeFullReader takes r, an implementation of Read, and returns an object
+// that still implements Read but always calls Readn underneath.
func MakeFullReader(r Read) Read {
if fr, ok := r.(*fullRead); ok {
// already a fullRead
@@ -94,8 +110,8 @@
return &fullRead{r}
}
-// Copies n bytes (or until EOF is reached) from src to dst.
-// Returns the number of bytes copied and the error, if any.
+// Copy n copies n bytes (or until EOF is reached) from src to dst.
+// It returns the number of bytes copied and the error, if any.
func Copyn(src Read, dst Write, n int64) (written int64, err *os.Error) {
buf := make([]byte, 32*1024);
for written < n {
@@ -130,8 +146,8 @@
return written, err
}
-// Copies from src to dst until EOF is reached.
-// Returns the number of bytes copied and the error, if any.
+// Copy copies from src to dst until EOF is reached.
+// It returns the number of bytes copied and the error, if any.
func Copy(src Read, dst Write) (written int64, err *os.Error) {
buf := make([]byte, 32*1024);
for {
diff --git a/src/lib/io/pipe.go b/src/lib/io/pipe.go
index 6ef080f..427717b 100644
--- a/src/lib/io/pipe.go
+++ b/src/lib/io/pipe.go
@@ -169,7 +169,10 @@
w.Close();
}
-// Create a synchronous in-memory pipe.
+// Pipe creates a synchronous in-memory pipe.
+// Used to connect code expecting an io.Read
+// with code expecting an io.Write.
+//
// Reads on one end are matched by writes on the other.
// Writes don't complete until all the data has been
// written or the read end is closed. Reads return
