Tags: #go #iterator
// This code demonstrates how iterators work in Go.
// This particular example is contrived, but I wanted something simple enough to demonstrate the point.
package main
import (
"fmt"
"iter"
"strings"
)
// stringlines returns an iterator over lines in a string.
func stringlines(s string) iter.Seq[string] {
return func(yield func(string) bool) {
lines := strings.Split(s, "\n")
for _, line := range lines {
if !yield(line) { // Call yield with the current line
return // Stop if yield returns false
}
}
fmt.Println("yield() never returned false so the internal for loop kept going")
}
}
func main() {
data := "line one\nline two\nline three"
// function stringlines() returns an iterator:
for line := range stringlines(data) {
fmt.Println(line)
}
// Iterating with early exit:
// If the range 'block' returns/breaks, then that == false
// If the range 'block' completes, then that == true
for line := range stringlines(data) {
fmt.Println(line)
if line == "line two" {
break // exits the loop, signifying to yield() it should stop the loop inside of stringlines()
}
}
}