// 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 (
	
	
	
)

// -----------------------------------------------------------------------------
// 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 ( *Position) () bool { return .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 ( Position) () string {
	 := .Filename
	if .IsValid() {
		if  != "" {
			 += ":"
		}
		 += fmt.Sprintf("%d", .Line)
		if .Column != 0 {
			 += fmt.Sprintf(":%d", .Column)
		}
	}
	if  == "" {
		 = "-"
	}
	return 
}

// 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 ( Pos) () bool {
	return  != 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 {
	set  *FileSet
	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 ( *File) () string {
	return .name
}

// Base returns the base offset of file f as registered with AddFile.
func ( *File) () int {
	return .base
}

// Size returns the size of file f as registered with AddFile.
func ( *File) () int {
	return .size
}

// LineCount returns the number of lines in file f.
func ( *File) () int {
	.mutex.Lock()
	 := len(.lines)
	.mutex.Unlock()
	return 
}

// 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 ( *File) ( int) {
	.mutex.Lock()
	if  := len(.lines); ( == 0 || .lines[-1] < ) &&  < .size {
		.lines = append(.lines, )
	}
	.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 ( *File) ( int) {
	if  < 1 {
		panic(fmt.Sprintf("invalid line number %d (should be >= 1)", ))
	}
	.mutex.Lock()
	defer .mutex.Unlock()
	if  >= len(.lines) {
		panic(fmt.Sprintf("invalid line number %d (should be < %d)", , len(.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(.lines[:], .lines[+1:])
	.lines = .lines[:len(.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 ( *File) ( []int) bool {
	// verify validity of lines table
	 := .size
	for ,  := range  {
		if  > 0 &&  <= [-1] ||  <=  {
			return false
		}
	}

	// set lines table
	.mutex.Lock()
	.lines = 
	.mutex.Unlock()
	return true
}

// SetLinesForContent sets the line offsets for the given file content.
// It ignores position-altering //line comments.
func ( *File) ( []byte) {
	var  []int
	 := 0
	for ,  := range  {
		if  >= 0 {
			 = append(, )
		}
		 = -1
		if  == '\n' {
			 =  + 1
		}
	}

	// set lines table
	.mutex.Lock()
	.lines = 
	.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 ( *File) ( int) Pos {
	if  < 1 {
		panic(fmt.Sprintf("invalid line number %d (should be >= 1)", ))
	}
	.mutex.Lock()
	defer .mutex.Unlock()
	if  > len(.lines) {
		panic(fmt.Sprintf("invalid line number %d (should be < %d)", , len(.lines)))
	}
	return Pos(.base + .lines[-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 ( *File) ( int,  string,  int) {
	.AddLineColumnInfo(, , , 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 ( *File) ( int,  string, ,  int) {
	.mutex.Lock()
	if  := len(.infos);  == 0 || .infos[-1].Offset <  &&  < .size {
		.infos = append(.infos, lineInfo{, , , })
	}
	.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 ( *File) ( int) Pos {
	if  > .size {
		panic(fmt.Sprintf("invalid file offset %d (should be <= %d)", , .size))
	}
	return Pos(.base + )
}

// 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 ( *File) ( Pos) int {
	if int() < .base || int() > .base+.size {
		panic(fmt.Sprintf("invalid Pos value %d (should be in [%d, %d])", , .base, .base+.size))
	}
	return int() - .base
}

// Line returns the line number for the given file position p;
// p must be a Pos value in that file or NoPos.
//
func ( *File) ( Pos) int {
	return .Position().Line
}

func searchLineInfos( []lineInfo,  int) int {
	return sort.Search(len(), func( int) bool { return [].Offset >  }) - 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 ( *File) ( int,  bool) ( string, ,  int) {
	.mutex.Lock()
	defer .mutex.Unlock()
	 = .name
	if  := searchInts(.lines, );  >= 0 {
		,  = +1, -.lines[]+1
	}
	if  && len(.infos) > 0 {
		// few files have extra line infos
		if  := searchLineInfos(.infos, );  >= 0 {
			 := &.infos[]
			 = .Filename
			if  := searchInts(.lines, .Offset);  >= 0 {
				// i+1 is the line at which the alternative position was recorded
				 :=  - ( + 1) // line distance from alternative position base
				 = .Line + 
				if .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)
					 = 0
				} else if  == 0 {
					// the alternative position base is on the current line
					// => column is relative to alternative column
					 = .Column + ( - .Offset)
				}
			}
		}
	}
	return
}

func ( *File) ( Pos,  bool) ( Position) {
	 := int() - .base
	.Offset = 
	.Filename, .Line, .Column = .unpack(, )
	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 ( *File) ( Pos,  bool) ( Position) {
	if  != NoPos {
		if int() < .base || int() > .base+.size {
			panic(fmt.Sprintf("invalid Pos value %d (should be in [%d, %d])", , .base, .base+.size))
		}
		 = .position(, )
	}
	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 ( *File) ( Pos) ( Position) {
	return .PositionFor(, 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  *File        // cache of last file looked up
}

// NewFileSet creates a new file set.
func () *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 ( *FileSet) () int {
	.mutex.RLock()
	 := .base
	.mutex.RUnlock()
	return 

}

// 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 ( *FileSet) ( string, ,  int) *File {
	.mutex.Lock()
	defer .mutex.Unlock()
	if  < 0 {
		 = .base
	}
	if  < .base {
		panic(fmt.Sprintf("invalid base %d (should be >= %d)", , .base))
	}
	if  < 0 {
		panic(fmt.Sprintf("invalid size %d (should be >= 0)", ))
	}
	// base >= s.base && size >= 0
	 := &File{set: , name: , base: , size: , lines: []int{0}}
	 +=  + 1 // +1 because EOF also has a position
	if  < 0 {
		panic("token.Pos offset overflow (> 2G of source code in file set)")
	}
	// add the file to the file set
	.base = 
	.files = append(.files, )
	.last = 
	return 
}

// Iterate calls f for the files in the file set in the order they were added
// until f returns false.
//
func ( *FileSet) ( func(*File) bool) {
	for  := 0; ; ++ {
		var  *File
		.mutex.RLock()
		if  < len(.files) {
			 = .files[]
		}
		.mutex.RUnlock()
		if  == nil || !() {
			break
		}
	}
}

func searchFiles( []*File,  int) int {
	return sort.Search(len(), func( int) bool { return [].base >  }) - 1
}

func ( *FileSet) ( Pos) *File {
	.mutex.RLock()
	// common case: p is in last file
	if  := .last;  != nil && .base <= int() && int() <= .base+.size {
		.mutex.RUnlock()
		return 
	}
	// p is not in last file - search all files
	if  := searchFiles(.files, int());  >= 0 {
		 := .files[]
		// f.base <= int(p) by definition of searchFiles
		if int() <= .base+.size {
			.mutex.RUnlock()
			.mutex.Lock()
			.last =  // race is ok - s.last is only a cache
			.mutex.Unlock()
			return 
		}
	}
	.mutex.RUnlock()
	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 ( *FileSet) ( Pos) ( *File) {
	if  != NoPos {
		 = .file()
	}
	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 ( *FileSet) ( Pos,  bool) ( Position) {
	if  != NoPos {
		if  := .file();  != nil {
			return .position(, )
		}
	}
	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 ( *FileSet) ( Pos) ( Position) {
	return .PositionFor(, true)
}

// -----------------------------------------------------------------------------
// Helper functions

func searchInts( []int,  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.
	,  := 0, len()
	for  <  {
		 :=  + (-)>>1 // avoid overflow when computing h
		// i ≤ h < j
		if [] <=  {
			 =  + 1
		} else {
			 = 
		}
	}
	return  - 1
}