spf13--cobra/cobra.go

// Copyright © 2013 Steve Francia <spf@spf13.com>.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Commands similar to git, go tools and other modern CLI tools
// inspired by go, go-Commander, gh and subcommand

package cobra

import (
	"fmt"
	"io"
	"reflect"
	"strconv"
	"strings"
	"text/template"
)

var templateFuncs template.FuncMap = template.FuncMap{
	"trim": strings.TrimSpace,
	"rpad": rpad,
	"gt":   Gt,
	"eq":   Eq,
}

var initializers []func()

// automatic prefix matching can be a dangerous thing to automatically enable in CLI tools.
// Set this to true to enable it
var EnablePrefixMatching bool = false

// enables an information splash screen on Windows if the CLI is started from explorer.exe.
var EnableWindowsMouseTrap bool = true

var MousetrapHelpText string = `This is a command line tool

You need to open cmd.exe and run it from there.
`

//AddTemplateFunc adds a template function that's available to Usage and Help
//template generation.
func AddTemplateFunc(name string, tmplFunc interface{}) {
	templateFuncs[name] = tmplFunc
}

//AddTemplateFuncs adds multiple template functions availalble to Usage and
//Help template generation.
func AddTemplateFuncs(tmplFuncs template.FuncMap) {
	for k, v := range tmplFuncs {
		templateFuncs[k] = v
	}
}

//OnInitialize takes a series of func() arguments and appends them to a slice of func().
func OnInitialize(y ...func()) {
	for _, x := range y {
		initializers = append(initializers, x)
	}
}

//Gt takes two types and checks whether the first type is greater than the second. In case of types Arrays, Chans,
//Maps and Slices, Gt will compare their lengths. Ints are compared directly while strings are first parsed as
//ints and then compared.
func Gt(a interface{}, b interface{}) bool {
	var left, right int64
	av := reflect.ValueOf(a)

	switch av.Kind() {
	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
		left = int64(av.Len())
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		left = av.Int()
	case reflect.String:
		left, _ = strconv.ParseInt(av.String(), 10, 64)
	}

	bv := reflect.ValueOf(b)

	switch bv.Kind() {
	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
		right = int64(bv.Len())
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		right = bv.Int()
	case reflect.String:
		right, _ = strconv.ParseInt(bv.String(), 10, 64)
	}

	return left > right
}

//Eq takes two types and checks whether they are equal. Supported types are int and string. Unsupported types will panic.
func Eq(a interface{}, b interface{}) bool {
	av := reflect.ValueOf(a)
	bv := reflect.ValueOf(b)

	switch av.Kind() {
	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
		panic("Eq called on unsupported type")
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return av.Int() == bv.Int()
	case reflect.String:
		return av.String() == bv.String()
	}
	return false
}

//rpad adds padding to the right of a string
func rpad(s string, padding int) string {
	template := fmt.Sprintf("%%-%ds", padding)
	return fmt.Sprintf(template, s)
}

// tmpl executes the given template text on data, writing the result to w.
func tmpl(w io.Writer, text string, data interface{}) error {
	t := template.New("top")
	t.Funcs(templateFuncs)
	template.Must(t.Parse(text))
	return t.Execute(w, data)
}