Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 565 insertions, 0 deletions

diff --git a/src/go/token/position.go b/src/go/token/position.go
new file mode 100644
index 0000000..a644382
--- /dev/null
+++ b/src/go/token/position.go
@@ -0,0 +1,565 @@
+// 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"
+	"strconv"
+	"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 += strconv.Itoa(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]
+}
+
+// Lines returns the effective line offset table of the form described by SetLines.
+// Callers must not mutate the result.
+func (f *File) Lines() []int {
+	f.mutex.Lock()
+	lines := f.lines
+	f.mutex.Unlock()
+	return lines
+}
+
+// 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()
+	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)
+				}
+			}
+		}
+	}
+	// TODO(mvdan): move Unlock back under Lock with a defer statement once
+	// https://go.dev/issue/38471 is fixed to remove the performance penalty.
+	f.mutex.Unlock()
+	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.
+//
+// A File may be removed from a FileSet when it is no longer needed.
+// This may reduce memory usage in a long-running application.
+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
+}
+
+// RemoveFile removes a file from the FileSet so that subsequent
+// queries for its Pos interval yield a negative result.
+// This reduces the memory usage of a long-lived FileSet that
+// encounters an unbounded stream of files.
+//
+// Removing a file that does not belong to the set has no effect.
+func (s *FileSet) RemoveFile(file *File) {
+	s.last.CompareAndSwap(file, nil) // clear last file cache
+
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+
+	if i := searchFiles(s.files, file.base); i >= 0 && s.files[i] == file {
+		last := &s.files[len(s.files)-1]
+		s.files = append(s.files[:i], s.files[i+1:]...)
+		*last = nil // don't prolong lifetime when popping last element
+	}
+}
+
+// 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
+}