113 lines
2.1 KiB
Go
113 lines
2.1 KiB
Go
package source
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import (
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"sort"
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"sync"
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)
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type FileSet struct {
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mutex sync.RWMutex // protects the file set
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base int // base offset for the next file
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files []*File // list of files in the order added to the set
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last *File // cache of last file looked up
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}
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func NewFileSet() *FileSet {
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return &FileSet{
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base: 1, // 0 == NoPos
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}
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}
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func (s *FileSet) Base() int {
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s.mutex.RLock()
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b := s.base
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s.mutex.RUnlock()
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return b
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}
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func (s *FileSet) AddFile(filename string, base, size int) *File {
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s.mutex.Lock()
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defer s.mutex.Unlock()
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if base < 0 {
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base = s.base
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}
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if base < s.base || size < 0 {
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panic("illegal base or size")
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}
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f := &File{
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set: s,
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name: filename,
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base: base,
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size: size,
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lines: []int{0},
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}
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base += size + 1 // +1 because EOF also has a position
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if base < 0 {
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panic("offset overflow (> 2G of source code in file set)")
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}
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// add the file to the file set
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s.base = base
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s.files = append(s.files, f)
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s.last = f
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return f
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}
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// File returns the file that contains the position p.
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// If no such file is found (for instance for p == NoPos),
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// the result is nil.
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//
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func (s *FileSet) File(p Pos) (f *File) {
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if p != NoPos {
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f = s.file(p)
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}
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return
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}
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// PositionFor converts a Pos p in the fileset into a FilePos value.
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func (s *FileSet) Position(p Pos) (pos FilePos) {
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if p != NoPos {
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if f := s.file(p); f != nil {
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return f.position(p)
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}
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}
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return
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}
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func (s *FileSet) file(p Pos) *File {
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s.mutex.RLock()
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// common case: p is in last file
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if f := s.last; f != nil && f.base <= int(p) && int(p) <= f.base+f.size {
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s.mutex.RUnlock()
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return f
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}
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// p is not in last file - search all files
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if i := searchFiles(s.files, int(p)); i >= 0 {
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f := s.files[i]
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// f.base <= int(p) by definition of searchFiles
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if int(p) <= f.base+f.size {
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s.mutex.RUnlock()
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s.mutex.Lock()
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s.last = f // race is ok - s.last is only a cache
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s.mutex.Unlock()
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return f
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}
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}
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s.mutex.RUnlock()
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return nil
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}
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func searchFiles(a []*File, x int) int {
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return sort.Search(len(a), func(i int) bool { return a[i].base > x }) - 1
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}
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