refactor: move duration package out of internal (#202)

2021-07-21 11:52:21 -04:00
parent 90a47e33db
commit 68cfff003a
7 changed files with 6 additions and 6 deletions
--- a/pkg/duration/parser.go
+++ b/pkg/duration/parser.go
@ -0,0 +1,150 @@
+package duration
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"time"
+	"unicode"
+	"unicode/utf8"
+)
+
+const (
+	Day  = 24 * time.Hour
+	Week = 7 * Day
+)
+
+type durations []duration
+
+type duration struct {
+	magnitude int64
+	unit      string
+}
+
+var (
+	ErrInvalidUnit = errors.New("duration must be week(w), day(d), hour(h), min(m), sec(s), millisec(ms), microsec(us), or nanosec(ns)")
+	ErrInvalidRune = errors.New("invalid rune in declaration")
+)
+
+// RawDurationToTimeDuration extends the builtin duration-parser to support days(d) and weeks(w) as parseable units.
+// The core implementation is copied from InfluxDB OSS's task engine, which itself copied the logic from an
+// internal module in Flux.
+func RawDurationToTimeDuration(raw string) (time.Duration, error) {
+	if raw == "" {
+		return 0, nil
+	}
+
+	if dur, err := time.ParseDuration(raw); err == nil {
+		return dur, nil
+	}
+
+	parsed, err := parseSignedDuration(raw)
+	if err != nil {
+		return 0, err
+	}
+
+	var dur time.Duration
+	for _, d := range parsed {
+		if d.magnitude < 0 {
+			return 0, errors.New("must be greater than 0")
+		}
+		mag := time.Duration(d.magnitude)
+		switch d.unit {
+		case "w":
+			dur += mag * Week
+		case "d":
+			dur += mag * Day
+		case "h":
+			dur += mag * time.Hour
+		case "m":
+			dur += mag * time.Minute
+		case "s":
+			dur += mag * time.Second
+		case "ms":
+			dur += mag * time.Millisecond
+		case "us":
+			dur += mag * time.Microsecond
+		case "ns":
+			dur += mag * time.Nanosecond
+		default:
+			return 0, ErrInvalidUnit
+		}
+	}
+	return dur, nil
+}
+
+func parseSignedDuration(text string) (durations, error) {
+	if r, s := utf8.DecodeRuneInString(text); r == '-' {
+		d, err := parseDuration(text[s:])
+		if err != nil {
+			return nil, err
+		}
+		for i := range d {
+			d[i].magnitude = -d[i].magnitude
+		}
+		return d, nil
+	}
+
+	d, err := parseDuration(text)
+	if err != nil {
+		return nil, err
+	}
+	return d, nil
+}
+
+// parseDuration will convert a string into components of the duration.
+func parseDuration(lit string) (durations, error) {
+	var values durations
+	for len(lit) > 0 {
+		n := 0
+		for n < len(lit) {
+			ch, size := utf8.DecodeRuneInString(lit[n:])
+			if size == 0 {
+				return nil, ErrInvalidRune
+			}
+
+			if !unicode.IsDigit(ch) {
+				break
+			}
+			n += size
+		}
+
+		if n == 0 {
+			return nil, fmt.Errorf("invalid duration %s", lit)
+		}
+
+		magnitude, err := strconv.ParseInt(lit[:n], 10, 64)
+		if err != nil {
+			return nil, err
+		}
+		lit = lit[n:]
+
+		n = 0
+		for n < len(lit) {
+			ch, size := utf8.DecodeRuneInString(lit[n:])
+			if size == 0 {
+				return nil, ErrInvalidRune
+			}
+
+			if !unicode.IsLetter(ch) {
+				break
+			}
+			n += size
+		}
+
+		if n == 0 {
+			return nil, fmt.Errorf("duration is missing a unit: %s", lit)
+		}
+
+		unit := lit[:n]
+		if unit == "µs" {
+			unit = "us"
+		}
+		values = append(values, duration{
+			magnitude: magnitude,
+			unit:      unit,
+		})
+		lit = lit[n:]
+	}
+	return values, nil
+}