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reading_time.go
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reading_time.go
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package readingtime
import (
"fmt"
"math"
"time"
)
const (
// defaultWordsPerMinute is the default number of words per minute an average reader can read.
defaultWordsPerMinute = 200
)
var (
// defaultWordBoundFunc is the default WordBoundFunc implementation.
defaultWordBoundFunc WordBoundFunc = func(b byte) bool {
return b == ' ' || b == '\n' || b == '\r' || b == '\t'
}
)
// WordBoundFunc is a function that returns a boolean value depending on if a character is considered as a word bound
type WordBoundFunc func(b byte) bool
// Option is the function that modifies the given options.
type Option func(opts *Options)
// WordsPerMinute is the function that modifies the number of words per minute.
func WordsPerMinute(wordsPerMinute int) Option {
return func(opts *Options) {
opts.WordsPerMinute = wordsPerMinute
}
}
// Options contains options to configure time reading estimation logic.
type Options struct {
// WordsPerMinute is the number of words per minute an average reader can read
// Default: 200.
WordsPerMinute int
// WordBound is a WordBoundFunc representation.
// Default: spaces, new lines and tabulations.
WordBound WordBoundFunc
}
// Result contains result of an estimated time to read an article.
type Result struct {
Text string
Duration time.Duration
Words int
}
// Estimate estimates how long the given text will take to read using the given configuration.
func Estimate(text string, opts ...Option) *Result {
if len(text) == 0 {
return &Result{
Text: "0 min read",
Duration: 0,
Words: 0,
}
}
// Init options with default values.
op := Options{
WordsPerMinute: defaultWordsPerMinute,
WordBound: defaultWordBoundFunc,
}
// Apply custom configuration.
for _, opt := range opts {
opt(&op)
}
words := 0
start := 0
end := len(text) - 1
// Fetch bounds.
for op.WordBound(text[start]) {
start++
}
for op.WordBound(text[end]) {
end--
}
// Calculate the number of words.
for i := start; i <= end; {
for i <= end && !op.WordBound(text[i]) {
i++
}
words++
for i <= end && op.WordBound(text[i]) {
i++
}
}
// Reading time stats.
minutes := math.Ceil(float64(words) / float64(op.WordsPerMinute))
duration := time.Duration(math.Ceil(minutes) * float64(time.Minute))
return &Result{
Text: fmt.Sprintf("%d min read", int(minutes)),
Duration: duration,
Words: words,
}
}