50 lines
1.2 KiB
Go
50 lines
1.2 KiB
Go
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// Copyright 2017, The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE.md file.
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// Package function identifies function types.
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package function
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import "reflect"
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type funcType int
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const (
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_ funcType = iota
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ttbFunc // func(T, T) bool
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tibFunc // func(T, I) bool
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trFunc // func(T) R
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Equal = ttbFunc // func(T, T) bool
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EqualAssignable = tibFunc // func(T, I) bool; encapsulates func(T, T) bool
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Transformer = trFunc // func(T) R
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ValueFilter = ttbFunc // func(T, T) bool
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Less = ttbFunc // func(T, T) bool
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)
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var boolType = reflect.TypeOf(true)
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// IsType reports whether the reflect.Type is of the specified function type.
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func IsType(t reflect.Type, ft funcType) bool {
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if t == nil || t.Kind() != reflect.Func || t.IsVariadic() {
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return false
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}
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ni, no := t.NumIn(), t.NumOut()
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switch ft {
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case ttbFunc: // func(T, T) bool
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if ni == 2 && no == 1 && t.In(0) == t.In(1) && t.Out(0) == boolType {
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return true
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}
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case tibFunc: // func(T, I) bool
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if ni == 2 && no == 1 && t.In(0).AssignableTo(t.In(1)) && t.Out(0) == boolType {
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return true
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}
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case trFunc: // func(T) R
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if ni == 1 && no == 1 {
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return true
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}
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}
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return false
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}
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