terraform/vendor/github.com/mitchellh/hashstructure/README.md

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# hashstructure [![GoDoc](https://godoc.org/github.com/mitchellh/hashstructure?status.svg)](https://godoc.org/github.com/mitchellh/hashstructure)
hashstructure is a Go library for creating a unique hash value
for arbitrary values in Go.
This can be used to key values in a hash (for use in a map, set, etc.)
that are complex. The most common use case is comparing two values without
sending data across the network, caching values locally (de-dup), and so on.
## Features
* Hash any arbitrary Go value, including complex types.
* Tag a struct field to ignore it and not affect the hash value.
* Tag a slice type struct field to treat it as a set where ordering
doesn't affect the hash code but the field itself is still taken into
account to create the hash value.
* Optionally specify a custom hash function to optimize for speed, collision
avoidance for your data set, etc.
* Optionally hash the output of `.String()` on structs that implement fmt.Stringer,
allowing effective hashing of time.Time
## Installation
Standard `go get`:
```
$ go get github.com/mitchellh/hashstructure
```
## Usage & Example
For usage and examples see the [Godoc](http://godoc.org/github.com/mitchellh/hashstructure).
A quick code example is shown below:
```go
type ComplexStruct struct {
Name string
Age uint
Metadata map[string]interface{}
}
v := ComplexStruct{
Name: "mitchellh",
Age: 64,
Metadata: map[string]interface{}{
"car": true,
"location": "California",
"siblings": []string{"Bob", "John"},
},
}
hash, err := hashstructure.Hash(v, nil)
if err != nil {
panic(err)
}
fmt.Printf("%d", hash)
// Output:
// 2307517237273902113
```