import "github.com/jmervine/filetrav"Package filetrav: Travel around files easily.
This may exist elsewhere, there's probably an easier way to do this. But it was a fun bit of code to write and I find it useful.
Warning: This is not fully tested as of yet.
// Example:
if traveler, err := ReadFileTraveler("_support/test.txt"); err == nil {
// Overly complex for example purposes.
if traveler.IsTop() {
fmt.Println("starting at the top")
}
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
if traveler.Next() {
fmt.Println("moving to the next line")
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
}
if traveler.Move(1) {
fmt.Println("moving down a line")
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
}
if traveler.Move(-1) {
fmt.Println("moving back up a line")
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
}
if traveler.Bottom() {
fmt.Println("moving to the bottom line")
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
}
if traveler.IsBottom() {
fmt.Println("finishing at the bottom")
}
}
for traveler.Top(); traveler.HasNext(); traveler.Next() {
}
// Output:
//
// starting at the top
// 0: "foo"
// moving to the next line
// 1: "bar"
// moving down a line
// 2: "bah"
// moving back up a line
// 1: "bar"
// moving to the bottom line
// 4: ""
// finishing at the bottomtype FileTraveler struct {
// contains filtered or unexported fields
}func NewFileTraveler(data []byte) (traveler FileTraveler, err error)NewFileTraveler creates a new FileTraveler from a []byte, like the one that would be read in from ioutil.ReadFile.
func ReadFileTraveler(file string) (traveler FileTraveler, err error)ReadFileTraveler creates a new FileTraveler from a path to a file on disk.
func (traveler *FileTraveler) Bottom() (moved bool)Bottom makes the bottom line in the file the current line.
func (traveler *FileTraveler) Current() (current []byte)Current returns the current line
func (traveler *FileTraveler) CurrentLength() (length int)CurrentLength returns the number of bytes in the current line.
func (traveler *FileTraveler) Find(rx *regexp.Regexp) (matches []int)Find takes a compiled regexp and starting at the top of the file returns the line number of all lines that match.
func (traveler *FileTraveler) FindString(pattern string) (matches []int)FindString takes a regexp as a string and starting at the top of the file returns the line number of all lines that match.
// Example:
traveler, err := ReadFileTraveler("_support/test.txt")
if err != nil {
panic(err)
}
for _, i := range traveler.FindString("^b.+$") {
if traveler.GoTo(i) {
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
}
}
// Output:
//
// 1: "bar"
// 2: "bah"
// 3: "bin"func (traveler *FileTraveler) ForEach(act func(position int, line []byte))ForEach iterates over the file from top to bottom, calling the passed method on each line. It leaves the current line unchanged when complete.
// Example:
traveler, err := ReadFileTraveler("_support/test.txt")
if err != nil {
panic(err)
}
traveler.ForEach(func(pos int, line []byte) {
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
})
// Output:
//
// 0: "foo"
// 1: "bar"
// 2: "bah"
// 3: "bin"
// 4: ""func (traveler *FileTraveler) ForRange(start int, end int, act func(position int, line []byte))ForRange iterates over the file from 'start' to 'end', calling the passed method on each line. It leaves the current line unchanged when complete.
// Example:
traveler, err := ReadFileTraveler("_support/test.txt")
if err != nil {
panic(err)
}
traveler.ForRange(1, 3, func(pos int, line []byte) {
fmt.Printf("%d: %q\n", traveler.Position(), traveler.Current())
})
// Output:
//
// 1: "bar"
// 2: "bah"
// 3: "bin"func (traveler *FileTraveler) Get(n int) (current []byte)Get line 'n' in file and return it.
func (traveler *FileTraveler) GetBottom() (bottom []byte)GetBottom makes the bottom line in the file the current line and then returns it.
func (traveler *FileTraveler) GetNext() (next []byte)GetNext makes the next line in the file the current line and then returns it.
func (traveler *FileTraveler) GetPrev() (prev []byte)GetPrev makes the previous line in the file the current line and then returns it.
func (traveler *FileTraveler) GetTop() (top []byte)GetTop makes the top line in the file the current line and then returns it.
func (traveler *FileTraveler) GoTo(n int) (moved bool)GoTo 'n' line in file.
func (traveler *FileTraveler) HasNext() (hasNext bool)HasNext checks to see if there is a line after the current line.
func (traveler *FileTraveler) HasPrev() (hasPrev bool)HasPrev checks to see if there is a line before the current line.
func (traveler *FileTraveler) IsBottom() (isBottom bool)IsBottom checks to see if this current line is the last line.
func (traveler *FileTraveler) IsTop() (isTop bool)IsTop checks to see if this current line is the first line.
func (traveler *FileTraveler) Length() (length int)Length returns the number of lines in the file.
func (traveler *FileTraveler) Move(n int) (moved bool)Move +/- 'n' lines in file.
// Example:
traveler, _ := ReadFileTraveler("_support/test.txt")
if traveler.Move(1) {
fmt.Printf("%q\n", traveler.Current())
}
if traveler.Move(-1) {
fmt.Printf("%q\n", traveler.Current())
}
if traveler.Bottom() {
fmt.Printf("%q\n", traveler.Current())
}
if traveler.Move(-1) {
fmt.Printf("%q\n", traveler.Current())
}
// Output:
// "bar"
// "foo"
// ""
// "bin"func (traveler *FileTraveler) Next() (next bool)Next makes the next line in file the current line.
func (traveler *FileTraveler) Position() (position int)Position within the current file.
func (traveler *FileTraveler) Prev() (prev bool)Prev makes the previous line in file the current line.
func (traveler *FileTraveler) Top() (moved bool)Top makes the top line in the file the current line.
// Example:
traveler, _ := ReadFileTraveler("_support/test.txt")
traveler.Top()
if traveler.IsTop() {
fmt.Println("top")
}
// Output: top