Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 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 | |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 5 | // Package function provides functionality for identifying function types. |
Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 6 | package function |
| 7 | |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 8 | import ( |
| 9 | "reflect" |
| 10 | "regexp" |
| 11 | "runtime" |
| 12 | "strings" |
| 13 | ) |
Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 14 | |
| 15 | type funcType int |
| 16 | |
| 17 | const ( |
| 18 | _ funcType = iota |
| 19 | |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 20 | tbFunc // func(T) bool |
Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 21 | ttbFunc // func(T, T) bool |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 22 | trbFunc // func(T, R) bool |
Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 23 | tibFunc // func(T, I) bool |
| 24 | trFunc // func(T) R |
| 25 | |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 26 | Equal = ttbFunc // func(T, T) bool |
| 27 | EqualAssignable = tibFunc // func(T, I) bool; encapsulates func(T, T) bool |
| 28 | Transformer = trFunc // func(T) R |
| 29 | ValueFilter = ttbFunc // func(T, T) bool |
| 30 | Less = ttbFunc // func(T, T) bool |
| 31 | ValuePredicate = tbFunc // func(T) bool |
| 32 | KeyValuePredicate = trbFunc // func(T, R) bool |
Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 33 | ) |
| 34 | |
| 35 | var boolType = reflect.TypeOf(true) |
| 36 | |
| 37 | // IsType reports whether the reflect.Type is of the specified function type. |
| 38 | func IsType(t reflect.Type, ft funcType) bool { |
| 39 | if t == nil || t.Kind() != reflect.Func || t.IsVariadic() { |
| 40 | return false |
| 41 | } |
| 42 | ni, no := t.NumIn(), t.NumOut() |
| 43 | switch ft { |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 44 | case tbFunc: // func(T) bool |
| 45 | if ni == 1 && no == 1 && t.Out(0) == boolType { |
| 46 | return true |
| 47 | } |
Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 48 | case ttbFunc: // func(T, T) bool |
| 49 | if ni == 2 && no == 1 && t.In(0) == t.In(1) && t.Out(0) == boolType { |
| 50 | return true |
| 51 | } |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 52 | case trbFunc: // func(T, R) bool |
| 53 | if ni == 2 && no == 1 && t.Out(0) == boolType { |
| 54 | return true |
| 55 | } |
Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 56 | case tibFunc: // func(T, I) bool |
| 57 | if ni == 2 && no == 1 && t.In(0).AssignableTo(t.In(1)) && t.Out(0) == boolType { |
| 58 | return true |
| 59 | } |
| 60 | case trFunc: // func(T) R |
| 61 | if ni == 1 && no == 1 { |
| 62 | return true |
| 63 | } |
| 64 | } |
| 65 | return false |
| 66 | } |
Pragya Arya | 324337e | 2020-02-20 14:35:08 +0530 | [diff] [blame] | 67 | |
| 68 | var lastIdentRx = regexp.MustCompile(`[_\p{L}][_\p{L}\p{N}]*$`) |
| 69 | |
| 70 | // NameOf returns the name of the function value. |
| 71 | func NameOf(v reflect.Value) string { |
| 72 | fnc := runtime.FuncForPC(v.Pointer()) |
| 73 | if fnc == nil { |
| 74 | return "<unknown>" |
| 75 | } |
| 76 | fullName := fnc.Name() // e.g., "long/path/name/mypkg.(*MyType).(long/path/name/mypkg.myMethod)-fm" |
| 77 | |
| 78 | // Method closures have a "-fm" suffix. |
| 79 | fullName = strings.TrimSuffix(fullName, "-fm") |
| 80 | |
| 81 | var name string |
| 82 | for len(fullName) > 0 { |
| 83 | inParen := strings.HasSuffix(fullName, ")") |
| 84 | fullName = strings.TrimSuffix(fullName, ")") |
| 85 | |
| 86 | s := lastIdentRx.FindString(fullName) |
| 87 | if s == "" { |
| 88 | break |
| 89 | } |
| 90 | name = s + "." + name |
| 91 | fullName = strings.TrimSuffix(fullName, s) |
| 92 | |
| 93 | if i := strings.LastIndexByte(fullName, '('); inParen && i >= 0 { |
| 94 | fullName = fullName[:i] |
| 95 | } |
| 96 | fullName = strings.TrimSuffix(fullName, ".") |
| 97 | } |
| 98 | return strings.TrimSuffix(name, ".") |
| 99 | } |