mirror of https://github.com/prometheus/prometheus
100 lines
2.5 KiB
Go
100 lines
2.5 KiB
Go
// 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 provides functionality for identifying function types.
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package function
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import (
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"reflect"
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"regexp"
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"runtime"
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"strings"
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)
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type funcType int
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const (
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_ funcType = iota
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tbFunc // func(T) bool
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ttbFunc // func(T, T) bool
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trbFunc // func(T, R) 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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ValuePredicate = tbFunc // func(T) bool
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KeyValuePredicate = trbFunc // func(T, R) 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 tbFunc: // func(T) bool
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if ni == 1 && no == 1 && t.Out(0) == boolType {
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return true
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}
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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 trbFunc: // func(T, R) bool
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if ni == 2 && no == 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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var lastIdentRx = regexp.MustCompile(`[_\p{L}][_\p{L}\p{N}]*$`)
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// NameOf returns the name of the function value.
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func NameOf(v reflect.Value) string {
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fnc := runtime.FuncForPC(v.Pointer())
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if fnc == nil {
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return "<unknown>"
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}
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fullName := fnc.Name() // e.g., "long/path/name/mypkg.(*MyType).(long/path/name/mypkg.myMethod)-fm"
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// Method closures have a "-fm" suffix.
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fullName = strings.TrimSuffix(fullName, "-fm")
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var name string
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for len(fullName) > 0 {
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inParen := strings.HasSuffix(fullName, ")")
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fullName = strings.TrimSuffix(fullName, ")")
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s := lastIdentRx.FindString(fullName)
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if s == "" {
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break
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}
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name = s + "." + name
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fullName = strings.TrimSuffix(fullName, s)
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if i := strings.LastIndexByte(fullName, '('); inParen && i >= 0 {
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fullName = fullName[:i]
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}
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fullName = strings.TrimSuffix(fullName, ".")
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}
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return strings.TrimSuffix(name, ".")
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}
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