vendor/github.com/google/go-cmp/cmp/internal/function/func.go

   1 // Copyright 2017, The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE.md file.
   4
   5 // Package function identifies function types.
   6 package function
   7
   8 import "reflect"
   9
  10 type funcType int
  11
  12 const (
  13         _ funcType = iota
  14
  15         ttbFunc // func(T, T) bool
  16         tibFunc // func(T, I) bool
  17         trFunc  // func(T) R
  18
  19         Equal           = ttbFunc // func(T, T) bool
  20         EqualAssignable = tibFunc // func(T, I) bool; encapsulates func(T, T) bool
  21         Transformer     = trFunc  // func(T) R
  22         ValueFilter     = ttbFunc // func(T, T) bool
  23         Less            = ttbFunc // func(T, T) bool
  24 )
  25
  26 var boolType = reflect.TypeOf(true)
  27
  28 // IsType reports whether the reflect.Type is of the specified function type.
  29 func IsType(t reflect.Type, ft funcType) bool {
  30         if t == nil || t.Kind() != reflect.Func || t.IsVariadic() {
  31                 return false
  32         }
  33         ni, no := t.NumIn(), t.NumOut()
  34         switch ft {
  35         case ttbFunc: // func(T, T) bool
  36                 if ni == 2 && no == 1 && t.In(0) == t.In(1) && t.Out(0) == boolType {
  37                         return true
  38                 }
  39         case tibFunc: // func(T, I) bool
  40                 if ni == 2 && no == 1 && t.In(0).AssignableTo(t.In(1)) && t.Out(0) == boolType {
  41                         return true
  42                 }
  43         case trFunc: // func(T) R
  44                 if ni == 1 && no == 1 {
  45                         return true
  46                 }
  47         }
  48         return false
  49 }