1// Copyright 2010 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package token 6 7import ( 8 "fmt" 9 "sort" 10 "sync" 11) 12 13// ----------------------------------------------------------------------------- 14// Positions 15 16// Position describes an arbitrary source position 17// including the file, line, and column location. 18// A Position is valid if the line number is > 0. 19// 20type Position struct { 21 Filename string // filename, if any 22 Offset int // offset, starting at 0 23 Line int // line number, starting at 1 24 Column int // column number, starting at 1 (byte count) 25} 26 27// IsValid reports whether the position is valid. 28func (pos *Position) IsValid() bool { return pos.Line > 0 } 29 30// String returns a string in one of several forms: 31// 32// file:line:column valid position with file name 33// file:line valid position with file name but no column (column == 0) 34// line:column valid position without file name 35// line valid position without file name and no column (column == 0) 36// file invalid position with file name 37// - invalid position without file name 38// 39func (pos Position) String() string { 40 s := pos.Filename 41 if pos.IsValid() { 42 if s != "" { 43 s += ":" 44 } 45 s += fmt.Sprintf("%d", pos.Line) 46 if pos.Column != 0 { 47 s += fmt.Sprintf(":%d", pos.Column) 48 } 49 } 50 if s == "" { 51 s = "-" 52 } 53 return s 54} 55 56// Pos is a compact encoding of a source position within a file set. 57// It can be converted into a Position for a more convenient, but much 58// larger, representation. 59// 60// The Pos value for a given file is a number in the range [base, base+size], 61// where base and size are specified when a file is added to the file set. 62// The difference between a Pos value and the corresponding file base 63// corresponds to the byte offset of that position (represented by the Pos value) 64// from the beginning of the file. Thus, the file base offset is the Pos value 65// representing the first byte in the file. 66// 67// To create the Pos value for a specific source offset (measured in bytes), 68// first add the respective file to the current file set using FileSet.AddFile 69// and then call File.Pos(offset) for that file. Given a Pos value p 70// for a specific file set fset, the corresponding Position value is 71// obtained by calling fset.Position(p). 72// 73// Pos values can be compared directly with the usual comparison operators: 74// If two Pos values p and q are in the same file, comparing p and q is 75// equivalent to comparing the respective source file offsets. If p and q 76// are in different files, p < q is true if the file implied by p was added 77// to the respective file set before the file implied by q. 78// 79type Pos int 80 81// The zero value for Pos is NoPos; there is no file and line information 82// associated with it, and NoPos.IsValid() is false. NoPos is always 83// smaller than any other Pos value. The corresponding Position value 84// for NoPos is the zero value for Position. 85// 86const NoPos Pos = 0 87 88// IsValid reports whether the position is valid. 89func (p Pos) IsValid() bool { 90 return p != NoPos 91} 92 93// ----------------------------------------------------------------------------- 94// File 95 96// A File is a handle for a file belonging to a FileSet. 97// A File has a name, size, and line offset table. 98// 99type File struct { 100 set *FileSet 101 name string // file name as provided to AddFile 102 base int // Pos value range for this file is [base...base+size] 103 size int // file size as provided to AddFile 104 105 // lines and infos are protected by mutex 106 mutex sync.Mutex 107 lines []int // lines contains the offset of the first character for each line (the first entry is always 0) 108 infos []lineInfo 109} 110 111// Name returns the file name of file f as registered with AddFile. 112func (f *File) Name() string { 113 return f.name 114} 115 116// Base returns the base offset of file f as registered with AddFile. 117func (f *File) Base() int { 118 return f.base 119} 120 121// Size returns the size of file f as registered with AddFile. 122func (f *File) Size() int { 123 return f.size 124} 125 126// LineCount returns the number of lines in file f. 127func (f *File) LineCount() int { 128 f.mutex.Lock() 129 n := len(f.lines) 130 f.mutex.Unlock() 131 return n 132} 133 134// AddLine adds the line offset for a new line. 135// The line offset must be larger than the offset for the previous line 136// and smaller than the file size; otherwise the line offset is ignored. 137// 138func (f *File) AddLine(offset int) { 139 f.mutex.Lock() 140 if i := len(f.lines); (i == 0 || f.lines[i-1] < offset) && offset < f.size { 141 f.lines = append(f.lines, offset) 142 } 143 f.mutex.Unlock() 144} 145 146// MergeLine merges a line with the following line. It is akin to replacing 147// the newline character at the end of the line with a space (to not change the 148// remaining offsets). To obtain the line number, consult e.g. Position.Line. 149// MergeLine will panic if given an invalid line number. 150// 151func (f *File) MergeLine(line int) { 152 if line < 1 { 153 panic(fmt.Sprintf("invalid line number %d (should be >= 1)", line)) 154 } 155 f.mutex.Lock() 156 defer f.mutex.Unlock() 157 if line >= len(f.lines) { 158 panic(fmt.Sprintf("invalid line number %d (should be < %d)", line, len(f.lines))) 159 } 160 // To merge the line numbered <line> with the line numbered <line+1>, 161 // we need to remove the entry in lines corresponding to the line 162 // numbered <line+1>. The entry in lines corresponding to the line 163 // numbered <line+1> is located at index <line>, since indices in lines 164 // are 0-based and line numbers are 1-based. 165 copy(f.lines[line:], f.lines[line+1:]) 166 f.lines = f.lines[:len(f.lines)-1] 167} 168 169// SetLines sets the line offsets for a file and reports whether it succeeded. 170// The line offsets are the offsets of the first character of each line; 171// for instance for the content "ab\nc\n" the line offsets are {0, 3}. 172// An empty file has an empty line offset table. 173// Each line offset must be larger than the offset for the previous line 174// and smaller than the file size; otherwise SetLines fails and returns 175// false. 176// Callers must not mutate the provided slice after SetLines returns. 177// 178func (f *File) SetLines(lines []int) bool { 179 // verify validity of lines table 180 size := f.size 181 for i, offset := range lines { 182 if i > 0 && offset <= lines[i-1] || size <= offset { 183 return false 184 } 185 } 186 187 // set lines table 188 f.mutex.Lock() 189 f.lines = lines 190 f.mutex.Unlock() 191 return true 192} 193 194// SetLinesForContent sets the line offsets for the given file content. 195// It ignores position-altering //line comments. 196func (f *File) SetLinesForContent(content []byte) { 197 var lines []int 198 line := 0 199 for offset, b := range content { 200 if line >= 0 { 201 lines = append(lines, line) 202 } 203 line = -1 204 if b == '\n' { 205 line = offset + 1 206 } 207 } 208 209 // set lines table 210 f.mutex.Lock() 211 f.lines = lines 212 f.mutex.Unlock() 213} 214 215// LineStart returns the Pos value of the start of the specified line. 216// It ignores any alternative positions set using AddLineColumnInfo. 217// LineStart panics if the 1-based line number is invalid. 218func (f *File) LineStart(line int) Pos { 219 if line < 1 { 220 panic(fmt.Sprintf("invalid line number %d (should be >= 1)", line)) 221 } 222 f.mutex.Lock() 223 defer f.mutex.Unlock() 224 if line > len(f.lines) { 225 panic(fmt.Sprintf("invalid line number %d (should be < %d)", line, len(f.lines))) 226 } 227 return Pos(f.base + f.lines[line-1]) 228} 229 230// A lineInfo object describes alternative file, line, and column 231// number information (such as provided via a //line directive) 232// for a given file offset. 233type lineInfo struct { 234 // fields are exported to make them accessible to gob 235 Offset int 236 Filename string 237 Line, Column int 238} 239 240// AddLineInfo is like AddLineColumnInfo with a column = 1 argument. 241// It is here for backward-compatibility for code prior to Go 1.11. 242// 243func (f *File) AddLineInfo(offset int, filename string, line int) { 244 f.AddLineColumnInfo(offset, filename, line, 1) 245} 246 247// AddLineColumnInfo adds alternative file, line, and column number 248// information for a given file offset. The offset must be larger 249// than the offset for the previously added alternative line info 250// and smaller than the file size; otherwise the information is 251// ignored. 252// 253// AddLineColumnInfo is typically used to register alternative position 254// information for line directives such as //line filename:line:column. 255// 256func (f *File) AddLineColumnInfo(offset int, filename string, line, column int) { 257 f.mutex.Lock() 258 if i := len(f.infos); i == 0 || f.infos[i-1].Offset < offset && offset < f.size { 259 f.infos = append(f.infos, lineInfo{offset, filename, line, column}) 260 } 261 f.mutex.Unlock() 262} 263 264// Pos returns the Pos value for the given file offset; 265// the offset must be <= f.Size(). 266// f.Pos(f.Offset(p)) == p. 267// 268func (f *File) Pos(offset int) Pos { 269 if offset > f.size { 270 panic(fmt.Sprintf("invalid file offset %d (should be <= %d)", offset, f.size)) 271 } 272 return Pos(f.base + offset) 273} 274 275// Offset returns the offset for the given file position p; 276// p must be a valid Pos value in that file. 277// f.Offset(f.Pos(offset)) == offset. 278// 279func (f *File) Offset(p Pos) int { 280 if int(p) < f.base || int(p) > f.base+f.size { 281 panic(fmt.Sprintf("invalid Pos value %d (should be in [%d, %d[)", p, f.base, f.base+f.size)) 282 } 283 return int(p) - f.base 284} 285 286// Line returns the line number for the given file position p; 287// p must be a Pos value in that file or NoPos. 288// 289func (f *File) Line(p Pos) int { 290 return f.Position(p).Line 291} 292 293func searchLineInfos(a []lineInfo, x int) int { 294 return sort.Search(len(a), func(i int) bool { return a[i].Offset > x }) - 1 295} 296 297// unpack returns the filename and line and column number for a file offset. 298// If adjusted is set, unpack will return the filename and line information 299// possibly adjusted by //line comments; otherwise those comments are ignored. 300// 301func (f *File) unpack(offset int, adjusted bool) (filename string, line, column int) { 302 f.mutex.Lock() 303 defer f.mutex.Unlock() 304 filename = f.name 305 if i := searchInts(f.lines, offset); i >= 0 { 306 line, column = i+1, offset-f.lines[i]+1 307 } 308 if adjusted && len(f.infos) > 0 { 309 // few files have extra line infos 310 if i := searchLineInfos(f.infos, offset); i >= 0 { 311 alt := &f.infos[i] 312 filename = alt.Filename 313 if i := searchInts(f.lines, alt.Offset); i >= 0 { 314 // i+1 is the line at which the alternative position was recorded 315 d := line - (i + 1) // line distance from alternative position base 316 line = alt.Line + d 317 if alt.Column == 0 { 318 // alternative column is unknown => relative column is unknown 319 // (the current specification for line directives requires 320 // this to apply until the next PosBase/line directive, 321 // not just until the new newline) 322 column = 0 323 } else if d == 0 { 324 // the alternative position base is on the current line 325 // => column is relative to alternative column 326 column = alt.Column + (offset - alt.Offset) 327 } 328 } 329 } 330 } 331 return 332} 333 334func (f *File) position(p Pos, adjusted bool) (pos Position) { 335 offset := int(p) - f.base 336 pos.Offset = offset 337 pos.Filename, pos.Line, pos.Column = f.unpack(offset, adjusted) 338 return 339} 340 341// PositionFor returns the Position value for the given file position p. 342// If adjusted is set, the position may be adjusted by position-altering 343// //line comments; otherwise those comments are ignored. 344// p must be a Pos value in f or NoPos. 345// 346func (f *File) PositionFor(p Pos, adjusted bool) (pos Position) { 347 if p != NoPos { 348 if int(p) < f.base || int(p) > f.base+f.size { 349 panic(fmt.Sprintf("invalid Pos value %d (should be in [%d, %d[)", p, f.base, f.base+f.size)) 350 } 351 pos = f.position(p, adjusted) 352 } 353 return 354} 355 356// Position returns the Position value for the given file position p. 357// Calling f.Position(p) is equivalent to calling f.PositionFor(p, true). 358// 359func (f *File) Position(p Pos) (pos Position) { 360 return f.PositionFor(p, true) 361} 362 363// ----------------------------------------------------------------------------- 364// FileSet 365 366// A FileSet represents a set of source files. 367// Methods of file sets are synchronized; multiple goroutines 368// may invoke them concurrently. 369// 370// The byte offsets for each file in a file set are mapped into 371// distinct (integer) intervals, one interval [base, base+size] 372// per file. Base represents the first byte in the file, and size 373// is the corresponding file size. A Pos value is a value in such 374// an interval. By determining the interval a Pos value belongs 375// to, the file, its file base, and thus the byte offset (position) 376// the Pos value is representing can be computed. 377// 378// When adding a new file, a file base must be provided. That can 379// be any integer value that is past the end of any interval of any 380// file already in the file set. For convenience, FileSet.Base provides 381// such a value, which is simply the end of the Pos interval of the most 382// recently added file, plus one. Unless there is a need to extend an 383// interval later, using the FileSet.Base should be used as argument 384// for FileSet.AddFile. 385// 386type FileSet struct { 387 mutex sync.RWMutex // protects the file set 388 base int // base offset for the next file 389 files []*File // list of files in the order added to the set 390 last *File // cache of last file looked up 391} 392 393// NewFileSet creates a new file set. 394func NewFileSet() *FileSet { 395 return &FileSet{ 396 base: 1, // 0 == NoPos 397 } 398} 399 400// Base returns the minimum base offset that must be provided to 401// AddFile when adding the next file. 402// 403func (s *FileSet) Base() int { 404 s.mutex.RLock() 405 b := s.base 406 s.mutex.RUnlock() 407 return b 408 409} 410 411// AddFile adds a new file with a given filename, base offset, and file size 412// to the file set s and returns the file. Multiple files may have the same 413// name. The base offset must not be smaller than the FileSet's Base(), and 414// size must not be negative. As a special case, if a negative base is provided, 415// the current value of the FileSet's Base() is used instead. 416// 417// Adding the file will set the file set's Base() value to base + size + 1 418// as the minimum base value for the next file. The following relationship 419// exists between a Pos value p for a given file offset offs: 420// 421// int(p) = base + offs 422// 423// with offs in the range [0, size] and thus p in the range [base, base+size]. 424// For convenience, File.Pos may be used to create file-specific position 425// values from a file offset. 426// 427func (s *FileSet) AddFile(filename string, base, size int) *File { 428 s.mutex.Lock() 429 defer s.mutex.Unlock() 430 if base < 0 { 431 base = s.base 432 } 433 if base < s.base { 434 panic(fmt.Sprintf("invalid base %d (should be >= %d)", base, s.base)) 435 } 436 if size < 0 { 437 panic(fmt.Sprintf("invalid size %d (should be >= 0)", size)) 438 } 439 // base >= s.base && size >= 0 440 f := &File{set: s, name: filename, base: base, size: size, lines: []int{0}} 441 base += size + 1 // +1 because EOF also has a position 442 if base < 0 { 443 panic("token.Pos offset overflow (> 2G of source code in file set)") 444 } 445 // add the file to the file set 446 s.base = base 447 s.files = append(s.files, f) 448 s.last = f 449 return f 450} 451 452// Iterate calls f for the files in the file set in the order they were added 453// until f returns false. 454// 455func (s *FileSet) Iterate(f func(*File) bool) { 456 for i := 0; ; i++ { 457 var file *File 458 s.mutex.RLock() 459 if i < len(s.files) { 460 file = s.files[i] 461 } 462 s.mutex.RUnlock() 463 if file == nil || !f(file) { 464 break 465 } 466 } 467} 468 469func searchFiles(a []*File, x int) int { 470 return sort.Search(len(a), func(i int) bool { return a[i].base > x }) - 1 471} 472 473func (s *FileSet) file(p Pos) *File { 474 s.mutex.RLock() 475 // common case: p is in last file 476 if f := s.last; f != nil && f.base <= int(p) && int(p) <= f.base+f.size { 477 s.mutex.RUnlock() 478 return f 479 } 480 // p is not in last file - search all files 481 if i := searchFiles(s.files, int(p)); i >= 0 { 482 f := s.files[i] 483 // f.base <= int(p) by definition of searchFiles 484 if int(p) <= f.base+f.size { 485 s.mutex.RUnlock() 486 s.mutex.Lock() 487 s.last = f // race is ok - s.last is only a cache 488 s.mutex.Unlock() 489 return f 490 } 491 } 492 s.mutex.RUnlock() 493 return nil 494} 495 496// File returns the file that contains the position p. 497// If no such file is found (for instance for p == NoPos), 498// the result is nil. 499// 500func (s *FileSet) File(p Pos) (f *File) { 501 if p != NoPos { 502 f = s.file(p) 503 } 504 return 505} 506 507// PositionFor converts a Pos p in the fileset into a Position value. 508// If adjusted is set, the position may be adjusted by position-altering 509// //line comments; otherwise those comments are ignored. 510// p must be a Pos value in s or NoPos. 511// 512func (s *FileSet) PositionFor(p Pos, adjusted bool) (pos Position) { 513 if p != NoPos { 514 if f := s.file(p); f != nil { 515 return f.position(p, adjusted) 516 } 517 } 518 return 519} 520 521// Position converts a Pos p in the fileset into a Position value. 522// Calling s.Position(p) is equivalent to calling s.PositionFor(p, true). 523// 524func (s *FileSet) Position(p Pos) (pos Position) { 525 return s.PositionFor(p, true) 526} 527 528// ----------------------------------------------------------------------------- 529// Helper functions 530 531func searchInts(a []int, x int) int { 532 // This function body is a manually inlined version of: 533 // 534 // return sort.Search(len(a), func(i int) bool { return a[i] > x }) - 1 535 // 536 // With better compiler optimizations, this may not be needed in the 537 // future, but at the moment this change improves the go/printer 538 // benchmark performance by ~30%. This has a direct impact on the 539 // speed of gofmt and thus seems worthwhile (2011-04-29). 540 // TODO(gri): Remove this when compilers have caught up. 541 i, j := 0, len(a) 542 for i < j { 543 h := i + (j-i)/2 // avoid overflow when computing h 544 // i ≤ h < j 545 if a[h] <= x { 546 i = h + 1 547 } else { 548 j = h 549 } 550 } 551 return i - 1 552} 553