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