| // Copyright 2010 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package token |
| |
| import ( |
| "fmt" |
| "sort" |
| "sync" |
| "sync/atomic" |
| ) |
| |
| // ----------------------------------------------------------------------------- |
| // Positions |
| |
| // Position describes an arbitrary source position |
| // including the file, line, and column location. |
| // A Position is valid if the line number is > 0. |
| type Position struct { |
| Filename string // filename, if any |
| Offset int // offset, starting at 0 |
| Line int // line number, starting at 1 |
| Column int // column number, starting at 1 (byte count) |
| } |
| |
| // IsValid reports whether the position is valid. |
| func (pos *Position) IsValid() bool { return pos.Line > 0 } |
| |
| // String returns a string in one of several forms: |
| // |
| // file:line:column valid position with file name |
| // file:line valid position with file name but no column (column == 0) |
| // line:column valid position without file name |
| // line valid position without file name and no column (column == 0) |
| // file invalid position with file name |
| // - invalid position without file name |
| func (pos Position) String() string { |
| s := pos.Filename |
| if pos.IsValid() { |
| if s != "" { |
| s += ":" |
| } |
| s += fmt.Sprintf("%d", pos.Line) |
| if pos.Column != 0 { |
| s += fmt.Sprintf(":%d", pos.Column) |
| } |
| } |
| if s == "" { |
| s = "-" |
| } |
| return s |
| } |
| |
| // Pos is a compact encoding of a source position within a file set. |
| // It can be converted into a Position for a more convenient, but much |
| // larger, representation. |
| // |
| // The Pos value for a given file is a number in the range [base, base+size], |
| // where base and size are specified when a file is added to the file set. |
| // The difference between a Pos value and the corresponding file base |
| // corresponds to the byte offset of that position (represented by the Pos value) |
| // from the beginning of the file. Thus, the file base offset is the Pos value |
| // representing the first byte in the file. |
| // |
| // To create the Pos value for a specific source offset (measured in bytes), |
| // first add the respective file to the current file set using FileSet.AddFile |
| // and then call File.Pos(offset) for that file. Given a Pos value p |
| // for a specific file set fset, the corresponding Position value is |
| // obtained by calling fset.Position(p). |
| // |
| // Pos values can be compared directly with the usual comparison operators: |
| // If two Pos values p and q are in the same file, comparing p and q is |
| // equivalent to comparing the respective source file offsets. If p and q |
| // are in different files, p < q is true if the file implied by p was added |
| // to the respective file set before the file implied by q. |
| type Pos int |
| |
| // The zero value for Pos is NoPos; there is no file and line information |
| // associated with it, and NoPos.IsValid() is false. NoPos is always |
| // smaller than any other Pos value. The corresponding Position value |
| // for NoPos is the zero value for Position. |
| const NoPos Pos = 0 |
| |
| // IsValid reports whether the position is valid. |
| func (p Pos) IsValid() bool { |
| return p != NoPos |
| } |
| |
| // ----------------------------------------------------------------------------- |
| // File |
| |
| // A File is a handle for a file belonging to a FileSet. |
| // A File has a name, size, and line offset table. |
| type File struct { |
| name string // file name as provided to AddFile |
| base int // Pos value range for this file is [base...base+size] |
| size int // file size as provided to AddFile |
| |
| // lines and infos are protected by mutex |
| mutex sync.Mutex |
| lines []int // lines contains the offset of the first character for each line (the first entry is always 0) |
| infos []lineInfo |
| } |
| |
| // Name returns the file name of file f as registered with AddFile. |
| func (f *File) Name() string { |
| return f.name |
| } |
| |
| // Base returns the base offset of file f as registered with AddFile. |
| func (f *File) Base() int { |
| return f.base |
| } |
| |
| // Size returns the size of file f as registered with AddFile. |
| func (f *File) Size() int { |
| return f.size |
| } |
| |
| // LineCount returns the number of lines in file f. |
| func (f *File) LineCount() int { |
| f.mutex.Lock() |
| n := len(f.lines) |
| f.mutex.Unlock() |
| return n |
| } |
| |
| // AddLine adds the line offset for a new line. |
| // The line offset must be larger than the offset for the previous line |
| // and smaller than the file size; otherwise the line offset is ignored. |
| func (f *File) AddLine(offset int) { |
| f.mutex.Lock() |
| if i := len(f.lines); (i == 0 || f.lines[i-1] < offset) && offset < f.size { |
| f.lines = append(f.lines, offset) |
| } |
| f.mutex.Unlock() |
| } |
| |
| // MergeLine merges a line with the following line. It is akin to replacing |
| // the newline character at the end of the line with a space (to not change the |
| // remaining offsets). To obtain the line number, consult e.g. Position.Line. |
| // MergeLine will panic if given an invalid line number. |
| func (f *File) MergeLine(line int) { |
| if line < 1 { |
| panic(fmt.Sprintf("invalid line number %d (should be >= 1)", line)) |
| } |
| f.mutex.Lock() |
| defer f.mutex.Unlock() |
| if line >= len(f.lines) { |
| panic(fmt.Sprintf("invalid line number %d (should be < %d)", line, len(f.lines))) |
| } |
| // To merge the line numbered <line> with the line numbered <line+1>, |
| // we need to remove the entry in lines corresponding to the line |
| // numbered <line+1>. The entry in lines corresponding to the line |
| // numbered <line+1> is located at index <line>, since indices in lines |
| // are 0-based and line numbers are 1-based. |
| copy(f.lines[line:], f.lines[line+1:]) |
| f.lines = f.lines[:len(f.lines)-1] |
| } |
| |
| // SetLines sets the line offsets for a file and reports whether it succeeded. |
| // The line offsets are the offsets of the first character of each line; |
| // for instance for the content "ab\nc\n" the line offsets are {0, 3}. |
| // An empty file has an empty line offset table. |
| // Each line offset must be larger than the offset for the previous line |
| // and smaller than the file size; otherwise SetLines fails and returns |
| // false. |
| // Callers must not mutate the provided slice after SetLines returns. |
| func (f *File) SetLines(lines []int) bool { |
| // verify validity of lines table |
| size := f.size |
| for i, offset := range lines { |
| if i > 0 && offset <= lines[i-1] || size <= offset { |
| return false |
| } |
| } |
| |
| // set lines table |
| f.mutex.Lock() |
| f.lines = lines |
| f.mutex.Unlock() |
| return true |
| } |
| |
| // SetLinesForContent sets the line offsets for the given file content. |
| // It ignores position-altering //line comments. |
| func (f *File) SetLinesForContent(content []byte) { |
| var lines []int |
| line := 0 |
| for offset, b := range content { |
| if line >= 0 { |
| lines = append(lines, line) |
| } |
| line = -1 |
| if b == '\n' { |
| line = offset + 1 |
| } |
| } |
| |
| // set lines table |
| f.mutex.Lock() |
| f.lines = lines |
| f.mutex.Unlock() |
| } |
| |
| // LineStart returns the Pos value of the start of the specified line. |
| // It ignores any alternative positions set using AddLineColumnInfo. |
| // LineStart panics if the 1-based line number is invalid. |
| func (f *File) LineStart(line int) Pos { |
| if line < 1 { |
| panic(fmt.Sprintf("invalid line number %d (should be >= 1)", line)) |
| } |
| f.mutex.Lock() |
| defer f.mutex.Unlock() |
| if line > len(f.lines) { |
| panic(fmt.Sprintf("invalid line number %d (should be < %d)", line, len(f.lines))) |
| } |
| return Pos(f.base + f.lines[line-1]) |
| } |
| |
| // A lineInfo object describes alternative file, line, and column |
| // number information (such as provided via a //line directive) |
| // for a given file offset. |
| type lineInfo struct { |
| // fields are exported to make them accessible to gob |
| Offset int |
| Filename string |
| Line, Column int |
| } |
| |
| // AddLineInfo is like AddLineColumnInfo with a column = 1 argument. |
| // It is here for backward-compatibility for code prior to Go 1.11. |
| func (f *File) AddLineInfo(offset int, filename string, line int) { |
| f.AddLineColumnInfo(offset, filename, line, 1) |
| } |
| |
| // AddLineColumnInfo adds alternative file, line, and column number |
| // information for a given file offset. The offset must be larger |
| // than the offset for the previously added alternative line info |
| // and smaller than the file size; otherwise the information is |
| // ignored. |
| // |
| // AddLineColumnInfo is typically used to register alternative position |
| // information for line directives such as //line filename:line:column. |
| func (f *File) AddLineColumnInfo(offset int, filename string, line, column int) { |
| f.mutex.Lock() |
| if i := len(f.infos); i == 0 || f.infos[i-1].Offset < offset && offset < f.size { |
| f.infos = append(f.infos, lineInfo{offset, filename, line, column}) |
| } |
| f.mutex.Unlock() |
| } |
| |
| // Pos returns the Pos value for the given file offset; |
| // the offset must be <= f.Size(). |
| // f.Pos(f.Offset(p)) == p. |
| func (f *File) Pos(offset int) Pos { |
| if offset > f.size { |
| panic(fmt.Sprintf("invalid file offset %d (should be <= %d)", offset, f.size)) |
| } |
| return Pos(f.base + offset) |
| } |
| |
| // Offset returns the offset for the given file position p; |
| // p must be a valid Pos value in that file. |
| // f.Offset(f.Pos(offset)) == offset. |
| func (f *File) Offset(p Pos) int { |
| if int(p) < f.base || int(p) > f.base+f.size { |
| panic(fmt.Sprintf("invalid Pos value %d (should be in [%d, %d])", p, f.base, f.base+f.size)) |
| } |
| return int(p) - f.base |
| } |
| |
| // Line returns the line number for the given file position p; |
| // p must be a Pos value in that file or NoPos. |
| func (f *File) Line(p Pos) int { |
| return f.Position(p).Line |
| } |
| |
| func searchLineInfos(a []lineInfo, x int) int { |
| return sort.Search(len(a), func(i int) bool { return a[i].Offset > x }) - 1 |
| } |
| |
| // unpack returns the filename and line and column number for a file offset. |
| // If adjusted is set, unpack will return the filename and line information |
| // possibly adjusted by //line comments; otherwise those comments are ignored. |
| func (f *File) unpack(offset int, adjusted bool) (filename string, line, column int) { |
| f.mutex.Lock() |
| defer f.mutex.Unlock() |
| filename = f.name |
| if i := searchInts(f.lines, offset); i >= 0 { |
| line, column = i+1, offset-f.lines[i]+1 |
| } |
| if adjusted && len(f.infos) > 0 { |
| // few files have extra line infos |
| if i := searchLineInfos(f.infos, offset); i >= 0 { |
| alt := &f.infos[i] |
| filename = alt.Filename |
| if i := searchInts(f.lines, alt.Offset); i >= 0 { |
| // i+1 is the line at which the alternative position was recorded |
| d := line - (i + 1) // line distance from alternative position base |
| line = alt.Line + d |
| if alt.Column == 0 { |
| // alternative column is unknown => relative column is unknown |
| // (the current specification for line directives requires |
| // this to apply until the next PosBase/line directive, |
| // not just until the new newline) |
| column = 0 |
| } else if d == 0 { |
| // the alternative position base is on the current line |
| // => column is relative to alternative column |
| column = alt.Column + (offset - alt.Offset) |
| } |
| } |
| } |
| } |
| return |
| } |
| |
| func (f *File) position(p Pos, adjusted bool) (pos Position) { |
| offset := int(p) - f.base |
| pos.Offset = offset |
| pos.Filename, pos.Line, pos.Column = f.unpack(offset, adjusted) |
| return |
| } |
| |
| // PositionFor returns the Position value for the given file position p. |
| // If adjusted is set, the position may be adjusted by position-altering |
| // //line comments; otherwise those comments are ignored. |
| // p must be a Pos value in f or NoPos. |
| func (f *File) PositionFor(p Pos, adjusted bool) (pos Position) { |
| if p != NoPos { |
| if int(p) < f.base || int(p) > f.base+f.size { |
| panic(fmt.Sprintf("invalid Pos value %d (should be in [%d, %d])", p, f.base, f.base+f.size)) |
| } |
| pos = f.position(p, adjusted) |
| } |
| return |
| } |
| |
| // Position returns the Position value for the given file position p. |
| // Calling f.Position(p) is equivalent to calling f.PositionFor(p, true). |
| func (f *File) Position(p Pos) (pos Position) { |
| return f.PositionFor(p, true) |
| } |
| |
| // ----------------------------------------------------------------------------- |
| // FileSet |
| |
| // A FileSet represents a set of source files. |
| // Methods of file sets are synchronized; multiple goroutines |
| // may invoke them concurrently. |
| // |
| // The byte offsets for each file in a file set are mapped into |
| // distinct (integer) intervals, one interval [base, base+size] |
| // per file. Base represents the first byte in the file, and size |
| // is the corresponding file size. A Pos value is a value in such |
| // an interval. By determining the interval a Pos value belongs |
| // to, the file, its file base, and thus the byte offset (position) |
| // the Pos value is representing can be computed. |
| // |
| // When adding a new file, a file base must be provided. That can |
| // be any integer value that is past the end of any interval of any |
| // file already in the file set. For convenience, FileSet.Base provides |
| // such a value, which is simply the end of the Pos interval of the most |
| // recently added file, plus one. Unless there is a need to extend an |
| // interval later, using the FileSet.Base should be used as argument |
| // for FileSet.AddFile. |
| type FileSet struct { |
| mutex sync.RWMutex // protects the file set |
| base int // base offset for the next file |
| files []*File // list of files in the order added to the set |
| last atomic.Pointer[File] // cache of last file looked up |
| } |
| |
| // NewFileSet creates a new file set. |
| func NewFileSet() *FileSet { |
| return &FileSet{ |
| base: 1, // 0 == NoPos |
| } |
| } |
| |
| // Base returns the minimum base offset that must be provided to |
| // AddFile when adding the next file. |
| func (s *FileSet) Base() int { |
| s.mutex.RLock() |
| b := s.base |
| s.mutex.RUnlock() |
| return b |
| |
| } |
| |
| // AddFile adds a new file with a given filename, base offset, and file size |
| // to the file set s and returns the file. Multiple files may have the same |
| // name. The base offset must not be smaller than the FileSet's Base(), and |
| // size must not be negative. As a special case, if a negative base is provided, |
| // the current value of the FileSet's Base() is used instead. |
| // |
| // Adding the file will set the file set's Base() value to base + size + 1 |
| // as the minimum base value for the next file. The following relationship |
| // exists between a Pos value p for a given file offset offs: |
| // |
| // int(p) = base + offs |
| // |
| // with offs in the range [0, size] and thus p in the range [base, base+size]. |
| // For convenience, File.Pos may be used to create file-specific position |
| // values from a file offset. |
| func (s *FileSet) AddFile(filename string, base, size int) *File { |
| // Allocate f outside the critical section. |
| f := &File{name: filename, size: size, lines: []int{0}} |
| |
| s.mutex.Lock() |
| defer s.mutex.Unlock() |
| if base < 0 { |
| base = s.base |
| } |
| if base < s.base { |
| panic(fmt.Sprintf("invalid base %d (should be >= %d)", base, s.base)) |
| } |
| f.base = base |
| if size < 0 { |
| panic(fmt.Sprintf("invalid size %d (should be >= 0)", size)) |
| } |
| // base >= s.base && size >= 0 |
| base += size + 1 // +1 because EOF also has a position |
| if base < 0 { |
| panic("token.Pos 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.last.Store(f) |
| return f |
| } |
| |
| // Iterate calls f for the files in the file set in the order they were added |
| // until f returns false. |
| func (s *FileSet) Iterate(f func(*File) bool) { |
| for i := 0; ; i++ { |
| var file *File |
| s.mutex.RLock() |
| if i < len(s.files) { |
| file = s.files[i] |
| } |
| s.mutex.RUnlock() |
| if file == nil || !f(file) { |
| break |
| } |
| } |
| } |
| |
| func searchFiles(a []*File, x int) int { |
| return sort.Search(len(a), func(i int) bool { return a[i].base > x }) - 1 |
| } |
| |
| func (s *FileSet) file(p Pos) *File { |
| // common case: p is in last file. |
| if f := s.last.Load(); f != nil && f.base <= int(p) && int(p) <= f.base+f.size { |
| return f |
| } |
| |
| s.mutex.RLock() |
| defer s.mutex.RUnlock() |
| |
| // 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 { |
| // Update cache of last file. A race is ok, |
| // but an exclusive lock causes heavy contention. |
| s.last.Store(f) |
| return f |
| } |
| } |
| return nil |
| } |
| |
| // 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 |
| } |
| |
| // PositionFor converts a Pos p in the fileset into a Position value. |
| // If adjusted is set, the position may be adjusted by position-altering |
| // //line comments; otherwise those comments are ignored. |
| // p must be a Pos value in s or NoPos. |
| func (s *FileSet) PositionFor(p Pos, adjusted bool) (pos Position) { |
| if p != NoPos { |
| if f := s.file(p); f != nil { |
| return f.position(p, adjusted) |
| } |
| } |
| return |
| } |
| |
| // Position converts a Pos p in the fileset into a Position value. |
| // Calling s.Position(p) is equivalent to calling s.PositionFor(p, true). |
| func (s *FileSet) Position(p Pos) (pos Position) { |
| return s.PositionFor(p, true) |
| } |
| |
| // ----------------------------------------------------------------------------- |
| // Helper functions |
| |
| func searchInts(a []int, x int) int { |
| // This function body is a manually inlined version of: |
| // |
| // return sort.Search(len(a), func(i int) bool { return a[i] > x }) - 1 |
| // |
| // With better compiler optimizations, this may not be needed in the |
| // future, but at the moment this change improves the go/printer |
| // benchmark performance by ~30%. This has a direct impact on the |
| // speed of gofmt and thus seems worthwhile (2011-04-29). |
| // TODO(gri): Remove this when compilers have caught up. |
| i, j := 0, len(a) |
| for i < j { |
| h := int(uint(i+j) >> 1) // avoid overflow when computing h |
| // i ≤ h < j |
| if a[h] <= x { |
| i = h + 1 |
| } else { |
| j = h |
| } |
| } |
| return i - 1 |
| } |