90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
// Copyright 2013 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 util contains utility types and functions for godoc.
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package util
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import (
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pathpkg "path"
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"sync"
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"time"
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"unicode/utf8"
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"golang.org/x/tools/godoc/vfs"
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)
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// An RWValue wraps a value and permits mutually exclusive
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// access to it and records the time the value was last set.
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type RWValue struct {
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mutex sync.RWMutex
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value interface{}
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timestamp time.Time // time of last set()
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}
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func (v *RWValue) Set(value interface{}) {
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v.mutex.Lock()
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v.value = value
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v.timestamp = time.Now()
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v.mutex.Unlock()
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}
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func (v *RWValue) Get() (interface{}, time.Time) {
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v.mutex.RLock()
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defer v.mutex.RUnlock()
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return v.value, v.timestamp
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}
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// IsText reports whether a significant prefix of s looks like correct UTF-8;
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// that is, if it is likely that s is human-readable text.
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func IsText(s []byte) bool {
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const max = 1024 // at least utf8.UTFMax
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if len(s) > max {
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s = s[0:max]
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}
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for i, c := range string(s) {
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if i+utf8.UTFMax > len(s) {
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// last char may be incomplete - ignore
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break
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}
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if c == 0xFFFD || c < ' ' && c != '\n' && c != '\t' && c != '\f' {
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// decoding error or control character - not a text file
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return false
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}
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}
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return true
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}
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// textExt[x] is true if the extension x indicates a text file, and false otherwise.
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var textExt = map[string]bool{
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".css": false, // must be served raw
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".js": false, // must be served raw
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}
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// IsTextFile reports whether the file has a known extension indicating
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// a text file, or if a significant chunk of the specified file looks like
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// correct UTF-8; that is, if it is likely that the file contains human-
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// readable text.
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func IsTextFile(fs vfs.Opener, filename string) bool {
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// if the extension is known, use it for decision making
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if isText, found := textExt[pathpkg.Ext(filename)]; found {
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return isText
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}
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// the extension is not known; read an initial chunk
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// of the file and check if it looks like text
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f, err := fs.Open(filename)
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if err != nil {
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return false
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}
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defer f.Close()
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var buf [1024]byte
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n, err := f.Read(buf[0:])
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if err != nil {
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return false
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}
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return IsText(buf[0:n])
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}
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