mirror of
https://github.com/golang/go
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90564a9256
manual changes in src/pkg/go/printer, src/cmd/gofix/signal_test.go (cd src/cmd/gofix/testdata; gofmt -w *.in *.out) (cd src/pkg/go/printer; gotest -update) gofmt -w misc src runs all tests R=golang-dev, rsc CC=golang-dev https://golang.org/cl/4715041
92 lines
2.2 KiB
Go
92 lines
2.2 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package strings
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import (
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"os"
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"utf8"
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)
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// A Reader implements the io.Reader, io.ByteScanner, and
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// io.RuneScanner interfaces by reading from a string.
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type Reader struct {
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s string
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i int // current reading index
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prevRune int // index of previous rune; or < 0
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}
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// Len returns the number of bytes of the unread portion of the
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// string.
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func (r *Reader) Len() int {
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return len(r.s) - r.i
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}
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func (r *Reader) Read(b []byte) (n int, err os.Error) {
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if r.i >= len(r.s) {
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return 0, os.EOF
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}
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n = copy(b, r.s[r.i:])
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r.i += n
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r.prevRune = -1
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return
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}
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func (r *Reader) ReadByte() (b byte, err os.Error) {
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if r.i >= len(r.s) {
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return 0, os.EOF
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}
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b = r.s[r.i]
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r.i++
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r.prevRune = -1
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return
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}
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// UnreadByte moves the reading position back by one byte.
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// It is an error to call UnreadByte if nothing has been
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// read yet.
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func (r *Reader) UnreadByte() os.Error {
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if r.i <= 0 {
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return os.NewError("strings.Reader: at beginning of string")
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}
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r.i--
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r.prevRune = -1
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return nil
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}
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// ReadRune reads and returns the next UTF-8-encoded
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// Unicode code point from the buffer.
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// If no bytes are available, the error returned is os.EOF.
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// If the bytes are an erroneous UTF-8 encoding, it
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// consumes one byte and returns U+FFFD, 1.
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func (r *Reader) ReadRune() (rune int, size int, err os.Error) {
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if r.i >= len(r.s) {
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return 0, 0, os.EOF
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}
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r.prevRune = r.i
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if c := r.s[r.i]; c < utf8.RuneSelf {
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r.i++
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return int(c), 1, nil
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}
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rune, size = utf8.DecodeRuneInString(r.s[r.i:])
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r.i += size
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return
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}
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// UnreadRune causes the next call to ReadRune to return the same rune
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// as the previous call to ReadRune.
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// The last method called on r must have been ReadRune.
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func (r *Reader) UnreadRune() os.Error {
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if r.prevRune < 0 {
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return os.NewError("strings.Reader: previous operation was not ReadRune")
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}
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r.i = r.prevRune
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r.prevRune = -1
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return nil
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}
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// NewReader returns a new Reader reading from s.
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// It is similar to bytes.NewBufferString but more efficient and read-only.
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func NewReader(s string) *Reader { return &Reader{s, 0, -1} }
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