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command.go
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command.go
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package clif
import (
"fmt"
"reflect"
"regexp"
"strings"
"os"
)
var (
rxFlag = regexp.MustCompile(`^(?:true|false|yes|no)$`)
)
// CallMethod is the interface for functions used as command callbacks.
// `interface{}` is used so that those functions can have arbitrary input and output signatures.
// However, they still must be functions.
type CallMethod interface{}
// Command represents a named callback with a set of arguments and options
type Command struct {
// Cli back-references the Cli in which the command is registered
Cli *Cli
// Name is the unique (within Cli scope) call-name of the command
Name string
// Usage is a shorthand description of what the command does. Used in help output.
Usage string
// Description is a long elaboration on what the command does. Used in help output.
Description string
// Options contain all the registered options of the command.
Options []*Option
// Arguments contain all the registered arguments of the command.
Arguments []*Argument
// Call holds reflections of the callback.
Call reflect.Value
}
// DefaultHelpOption is the "--help" option, which is (per default) added to any command.
var DefaultHelpOption = &Option{
parameter: parameter{
Name: "help",
Usage: "Display this help message",
Description: "Display this help message",
},
Alias: "h",
Flag: true,
}
// DefaultOptions are prepended to any newly created command. Will be added
// immediately in the `NewCommand` call. See also `cli.NewDefaultOption()` and
// `cli.AddDefaultOptions()`.
var DefaultOptions = []*Option{DefaultHelpOption}
// NewCommand constructs a new command
func NewCommand(name, usage string, call CallMethod) *Command {
ref := reflect.ValueOf(call)
if ref.Kind() != reflect.Func {
panic(fmt.Sprintf("Call must be method, but is %s", ref.Kind()))
}
return &Command{
Name: name,
Usage: usage,
Options: DefaultOptions,
Arguments: make([]*Argument, 0),
Call: ref,
}
}
// SetCli is builder method and sets the Cli back-reference
func (this *Command) SetCli(c *Cli) *Command {
this.Cli = c
return this
}
// SetDescription is builder method setting description
func (this *Command) SetDescription(desc string) *Command {
this.Description = desc
return this
}
// Parse extracts options and arguments from command line arguments
func (this *Command) Parse(args []string) error {
argNum := 0
var lastArg *Argument
argc := len(args)
la := len(this.Arguments)
for i := 0; i < argc; i++ {
a := args[i]
//l := len(a)
if a[0:1] == "-" {
n := strings.TrimLeft(a, "-")
v := ""
vv := false
// is --opt=foo format
if p := strings.Index(n, "="); p > -1 {
vv = true
if p == 0 {
return fmt.Errorf("Malformed option \"%s\"", a)
}
pp := strings.SplitN(n, "=", 2)
n = pp[0]
if len(pp) == 2 {
v = pp[1]
}
}
o := this.Option(n)
if o == nil {
return fmt.Errorf("Unrecognized option \"%s\"", a)
}
// not a flag: must have value
// is a flag: must not have non-flag value
if !o.Flag && !vv {
if i+1 == argc || args[i+1][0:1] == "-" {
return fmt.Errorf("Missing value for option \"%s\"", a)
} else {
i++
v = args[i]
}
} else if o.Flag && vv && !rxFlag.MatchString(v) {
return fmt.Errorf("Flag \"%s\" cannot have value", a)
} else if o.Flag {
v = "true"
}
if err := o.Assign(v); err != nil {
return err
}
} else {
if lastArg == nil || !lastArg.Multiple {
if argNum+1 > la {
return fmt.Errorf("Too many arguments. Expected (at most) %d, got %d", la, argNum+1)
} else {
lastArg = this.Arguments[argNum]
}
}
if err := lastArg.Assign(a); err != nil {
return err
}
argNum++
}
}
for _, a := range this.Arguments {
if err := this.postSetupParam(a, "Argument"); err != nil {
return err
}
}
for _, o := range this.Options {
if err := this.postSetupParam(o, "Option"); err != nil {
return err
}
}
return nil
}
func (this *Command) postSetupParam(x interface{}, t string) error {
var p *parameter
if a, ok := x.(*Argument); ok {
p = &(a.parameter)
} else {
p = &(x.(*Option).parameter)
}
if len(p.Values) == 0 {
v := ""
if p.Env != "" {
v = os.Getenv(p.Env)
}
if v == "" && p.Default != "" {
v = p.Default
}
if v != "" {
if err := p.Assign(v); err != nil {
return err
}
}
}
if p.Required && p.Count() == 0 {
return fmt.Errorf("%s \"%s\" is required but missing", t, p.Name)
} else {
return nil
}
}
// NewArgument is builder method to construct and add a new argument
func (this *Command) NewArgument(name, usage, _default string, required, multiple bool) *Command {
return this.AddArgument(NewArgument(name, usage, _default, required, multiple))
}
// AddArgument is builder method to add a new argument
func (this *Command) AddArgument(v *Argument) *Command {
var prev *Argument
if l := len(this.Arguments); l > 0 {
prev = this.Arguments[l-1]
}
if prev != nil {
if v.Required && !prev.Required {
panic("Cannot add required argument after optional argument")
} else if prev.Multiple {
panic("Cannot add argument after multiple style argument")
}
}
if this.Argument(v.Name) != nil {
panic(fmt.Sprintf("Argument with name \"%s\" already existing", v.Name))
} else if this.Option(v.Name) != nil {
panic(fmt.Sprintf("Option with name or alias \"%s\" already existing", v.Name))
}
this.Arguments = append(this.Arguments, v)
return this
}
// NewOption is builder method to construct and add a new option
func (this *Command) NewOption(name, alias, usage, _default string, required, multiple bool) *Command {
return this.AddOption(NewOption(name, alias, usage, _default, required, multiple))
}
// AddOption is builder method to add a new option
func (this *Command) AddOption(v *Option) *Command {
if this.Option(v.Name) != nil {
panic(fmt.Sprintf("Option with name or alias \"%s\" already existing", v.Name))
} else if this.Argument(v.Name) != nil {
panic(fmt.Sprintf("Argument with name \"%s\" already existing", v.Name))
} else if v.Alias != "" {
if this.Option(v.Alias) != nil {
panic(fmt.Sprintf("Option with name or alias \"%s\" already existing", v.Alias))
} else if this.Argument(v.Alias) != nil {
panic(fmt.Sprintf("Cannot use alias: Argument with name \"%s\" already existing", v.Alias))
}
}
this.Options = append(this.Options, v)
return this
}
// Argument provides access to registered, named arguments.
func (this *Command) Argument(name string) *Argument {
for _, a := range this.Arguments {
if a.Name == name {
return a
}
}
return nil
}
// Option provides access to registered, named options.
func (this *Command) Option(name string) *Option {
for _, o := range this.Options {
if o.Name == name || o.Alias == name {
return o
}
}
return nil
}
// Input returns map containing whole input values (of all options, all arguments)
func (this *Command) Input() map[string][]string {
res := make(map[string][]string)
for _, o := range this.Options {
if len(o.Values) > 0 {
res[o.Name] = o.Values
}
}
for _, a := range this.Arguments {
if len(a.Values) > 0 {
res[a.Name] = a.Values
}
}
return res
}