mirror of
https://github.com/tailscale/tailscale.git
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104 lines
2.7 KiB
Go
104 lines
2.7 KiB
Go
// Copyright (c) 2020 Tailscale Inc & 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 file.
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// Package deepprint walks a Go value recursively, in a predictable
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// order, without looping, and prints each value out to a given
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// Writer, which is assumed to be a hash.Hash, as this package doesn't
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// format things nicely.
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//
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// This is intended as a lighter version of go-spew, etc. We don't need its
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// features when our writer is just a hash.
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package deepprint
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import (
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"crypto/sha256"
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"fmt"
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"io"
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"reflect"
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)
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func Hash(v ...interface{}) string {
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h := sha256.New()
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Print(h, v)
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return fmt.Sprintf("%x", h.Sum(nil))
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}
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// UpdateHash sets last to the hash of v and reports whether its value changed.
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func UpdateHash(last *string, v ...interface{}) (changed bool) {
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sig := Hash(v)
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if *last != sig {
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*last = sig
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return true
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}
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return false
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}
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func Print(w io.Writer, v ...interface{}) {
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print(w, reflect.ValueOf(v), make(map[uintptr]bool))
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}
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func print(w io.Writer, v reflect.Value, visited map[uintptr]bool) {
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if !v.IsValid() {
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return
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}
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switch v.Kind() {
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default:
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panic(fmt.Sprintf("unhandled kind %v for type %v", v.Kind(), v.Type()))
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case reflect.Ptr:
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ptr := v.Pointer()
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if visited[ptr] {
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return
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}
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visited[ptr] = true
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print(w, v.Elem(), visited)
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return
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case reflect.Struct:
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fmt.Fprintf(w, "struct{\n")
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t := v.Type()
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for i, n := 0, v.NumField(); i < n; i++ {
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sf := t.Field(i)
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fmt.Fprintf(w, "%s: ", sf.Name)
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print(w, v.Field(i), visited)
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fmt.Fprintf(w, "\n")
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}
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case reflect.Slice, reflect.Array:
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if v.Type().Elem().Kind() == reflect.Uint8 && v.CanInterface() {
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fmt.Fprintf(w, "%q", v.Interface())
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return
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}
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fmt.Fprintf(w, "[%d]{\n", v.Len())
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for i, ln := 0, v.Len(); i < ln; i++ {
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fmt.Fprintf(w, " [%d]: ", i)
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print(w, v.Index(i), visited)
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fmt.Fprintf(w, "\n")
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}
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fmt.Fprintf(w, "}\n")
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case reflect.Interface:
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print(w, v.Elem(), visited)
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case reflect.Map:
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sm := newSortedMap(v)
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fmt.Fprintf(w, "map[%d]{\n", len(sm.Key))
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for i, k := range sm.Key {
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print(w, k, visited)
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fmt.Fprintf(w, ": ")
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print(w, sm.Value[i], visited)
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fmt.Fprintf(w, "\n")
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}
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fmt.Fprintf(w, "}\n")
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case reflect.String:
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fmt.Fprintf(w, "%s", v.String())
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case reflect.Bool:
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fmt.Fprintf(w, "%v", v.Bool())
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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fmt.Fprintf(w, "%v", v.Int())
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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fmt.Fprintf(w, "%v", v.Uint())
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case reflect.Float32, reflect.Float64:
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fmt.Fprintf(w, "%v", v.Float())
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case reflect.Complex64, reflect.Complex128:
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fmt.Fprintf(w, "%v", v.Complex())
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}
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}
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