/
types.go
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/
types.go
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// Copyright 2015 Matthew Collins
//
// 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.
package console
import (
"fmt"
"math"
"reflect"
"strconv"
"strings"
)
// TypeHandler handles defining and parsing dynamic arguments for
// command.
//
// DefineType is called during Register where arg is the string
// after %, the return value will be stored and passed to ParseType
//
// ParseType is called during execute where arg is the argument to
// parse. info is the value original returned from DefineType.
// This should return the parsed value.
//
// Equals is called on the value returned from DefineType to see if
// the type has been defined already
type TypeHandler interface {
DefineType(arg string) interface{}
ParseType(arg string, info interface{}) (interface{}, error)
Equals(a, b interface{}) bool
}
// RegisterType adds the passed type and handler to the the registry,
// any future calls to Register will be able use the type added
// here
func RegisterType(t reflect.Type, handler TypeHandler) {
defaultRegistry.RegisterType(t, handler)
}
func (r *registry) RegisterType(t reflect.Type, handler TypeHandler) {
if r.typeHandlers == nil {
r.initTypes()
}
_, ok := r.typeHandlers[t]
if ok {
panic("type already registered")
}
r.typeHandlers[t] = handler
}
func (r *registry) initTypes() {
r.typeHandlers = map[reflect.Type]TypeHandler{}
r.RegisterType(reflect.TypeOf(""), stringHandler{})
r.RegisterType(reflect.TypeOf(int(0)), intHandler{})
r.RegisterType(reflect.TypeOf(false), boolHandler{})
}
type stringHandler struct{}
func (stringHandler) DefineType(arg string) interface{} {
if len(arg) >= 1 {
i, err := strconv.ParseInt(arg, 10, 32)
if err != nil {
panic(err)
}
return int(i)
}
return -1
}
func (stringHandler) ParseType(arg string, info interface{}) (interface{}, error) {
limit := info.(int)
if limit != -1 && len(arg) > limit {
return nil, fmt.Errorf("string too long (%d > %d)", len(arg), limit)
}
return arg, nil
}
func (stringHandler) Equals(a, b interface{}) bool {
return a.(int) == b.(int)
}
type intHandler struct{}
type intDetails struct {
min, max int
}
func (intHandler) DefineType(arg string) interface{} {
if len(arg) >= 1 {
args := strings.SplitN(arg, ",", 2)
i, err := strconv.ParseInt(args[0], 10, 32)
if err != nil {
panic(err)
}
i2, err := strconv.ParseInt(args[1], 10, 32)
if err != nil {
panic(err)
}
return intDetails{min: int(i), max: int(i2)}
}
return intDetails{min: 0, max: math.MaxInt32}
}
func (intHandler) ParseType(arg string, info interface{}) (interface{}, error) {
i, err := strconv.ParseInt(arg, 10, 32)
if err != nil {
return nil, err
}
limit := info.(intDetails)
if int(i) < limit.min {
return nil, fmt.Errorf("int too small (%d < %d)", i, limit.min)
}
if int(i) > limit.max {
return nil, fmt.Errorf("int too big (%d > %d)", i, limit.max)
}
return int(i), nil
}
func (intHandler) Equals(a, b interface{}) bool {
return a.(intDetails) == b.(intDetails)
}
type boolHandler struct{}
func (boolHandler) DefineType(arg string) interface{} {
return nil
}
func (boolHandler) ParseType(arg string, info interface{}) (interface{}, error) {
return strconv.ParseBool(arg)
}
func (boolHandler) Equals(a, b interface{}) bool {
return true
}