got/cli/options.go

package cli

import (
	"fmt"
	"math"
	"strconv"
	"strings"
)

// Options is the resolved configuration: a flat name->value map plus a record
// of which names were explicitly set (so callers can tell a default from a
// chosen value). Values are kept as strings end-to-end and converted only at
// the point of use by the typed getters below.
type Options struct {
	vals map[string]string
	set  map[string]bool
}

func newOptions() *Options {
	return &Options{vals: map[string]string{}, set: map[string]bool{}}
}

// IsSet reports whether name was given on the command line or in the config
// (as opposed to coming from the built-in default).
func (o *Options) IsSet(name string) bool { return o.set[name] }

// Str returns the raw string value (empty if unset and no default).
func (o *Options) Str(name string) string { return o.vals[name] }

// boolWords is the single accepted vocabulary for boolean options, mapping each
// recognised spelling to its truth value. The Bool reader, truthy, and
// validate() all consult it, so exactly the words that validate are honoured
// (no "accepted by the reader but rejected by validate" surprises like --x=on).
var boolWords = map[string]bool{
	"true": true, "yes": true, "1": true, "on": true,
	"false": false, "no": false, "0": false, "off": false,
}

// boolWord reports a value's truth and whether it is a recognised boolean word.
func boolWord(s string) (val, ok bool) {
	val, ok = boolWords[strings.ToLower(strings.TrimSpace(s))]
	return val, ok
}

// Bool reports whether the value is a truthy boolean word.
func (o *Options) Bool(name string) bool {
	val, _ := boolWord(o.vals[name])
	return val
}

// Int returns the value as an int, or 0 if empty/invalid.
func (o *Options) Int(name string) int { return int(o.Int64(name)) }

// Int64 returns the value as an int64, or 0 if empty/invalid.
func (o *Options) Int64(name string) int64 {
	n, _ := strconv.ParseInt(strings.TrimSpace(o.vals[name]), 10, 64)
	return n
}

// Float returns the value as a float64, or 0 if empty/invalid.
func (o *Options) Float(name string) float64 {
	f, _ := strconv.ParseFloat(strings.TrimSpace(o.vals[name]), 64)
	return f
}

// Size returns a byte count parsed from a value like "20M" or "512K".
func (o *Options) Size(name string) int64 {
	n, _ := parseSize(o.vals[name])
	return n
}

// List returns a repeatable option's accumulated values.
func (o *Options) List(name string) []string {
	v := o.vals[name]
	if v == "" {
		return nil
	}
	return strings.Split(v, "\n")
}

// parseSize converts a size string into a byte count: the first 'K'/'k' or
// 'M'/'m' in the string selects the multiplier (1024 or 1024*1024) and
// everything from that byte on is discarded; with no such unit the whole string
// is the byte count. There is no gigabyte unit, so "1G" is rejected; "1Mi" and
// "10MB" are 1M and 10M (the trailing bytes are dropped). An empty string is 0
// bytes; a negative value is rejected.
func parseSize(s string) (int64, error) {
	s = strings.TrimSpace(s)
	if s == "" {
		return 0, nil
	}
	mult := int64(1)
	if i := strings.IndexAny(s, "KkMm"); i >= 0 {
		if c := s[i]; c == 'M' || c == 'm' {
			mult = 1 << 20
		} else {
			mult = 1 << 10
		}
		s = s[:i]
	}
	n, err := strconv.ParseInt(strings.TrimSpace(s), 10, 64)
	if err != nil {
		return 0, fmt.Errorf("bad size %q", s)
	}
	// Size parsing rejects negative sizes outright.
	if n < 0 {
		return 0, fmt.Errorf("negative size %q", s)
	}
	// Reject a value whose unit multiply would overflow int64 and silently wrap to
	// a bogus (positive or negative) byte count.
	if mult > 1 && n > math.MaxInt64/mult {
		return 0, fmt.Errorf("size %q too large", s)
	}
	return n * mult, nil
}