Documentation ¶
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Hash ¶
func Hash(v interface{}, opts *HashOptions) (uint64, error)
Hash returns the hash value of an arbitrary value.
If opts is nil, then default options will be used. See HashOptions for the default values. The same *HashOptions value cannot be used concurrently. None of the values within a *HashOptions struct are safe to read/write while hashing is being done.
Notes on the value:
Unexported fields on structs are ignored and do not affect the hash value.
Adding an exported field to a struct with the zero value will change the hash value.
For structs, the hashing can be controlled using tags. For example:
struct { Name string UUID string `hash:"ignore"` }
The available tag values are:
"ignore" or "-" - The field will be ignored and not affect the hash code.
"set" - The field will be treated as a set, where ordering doesn't affect the hash code. This only works for slices.
"string" - The field will be hashed as a string, only works when the field implements fmt.Stringer
Example ¶
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 := Hash(v, nil) if err != nil { panic(err) } fmt.Printf("%d", hash)
Output: 6691276962590150517
Types ¶
type ErrNotStringer ¶
type ErrNotStringer struct {
Field string
}
ErrNotStringer is returned when there's an error with hash:"string"
func (*ErrNotStringer) Error ¶
func (ens *ErrNotStringer) Error() string
Error implements error for ErrNotStringer
type HashOptions ¶
type HashOptions struct { // Hasher is the hash function to use. If this isn't set, it will // default to FNV. Hasher hash.Hash64 // TagName is the struct tag to look at when hashing the structure. // By default this is "hash". TagName string // ZeroNil is flag determining if nil pointer should be treated equal // to a zero value of pointed type. By default this is false. ZeroNil bool // IgnoreZeroValue is determining if zero value fields should be // ignored for hash calculation. IgnoreZeroValue bool // SlicesAsSets assumes that a `set` tag is always present for slices. // Default is false (in which case the tag is used instead) SlicesAsSets bool // UseStringer will attempt to use fmt.Stringer aways. If the struct // doesn't implement fmt.Stringer, it'll fall back to trying usual tricks. // If this is true, and the "string" tag is also set, the tag takes // precedense (meaning that if the type doesn't implement fmt.Stringer, we // panic) UseStringer bool }
HashOptions are options that are available for hashing.
type Hashable ¶ added in v1.1.0
Hashable is an interface that can optionally be implemented by a struct to override the hash value. This value will override the hash value for the entire struct. Entries in the struct will not be hashed.
type Includable ¶
Includable is an interface that can optionally be implemented by a struct. It will be called for each field in the struct to check whether it should be included in the hash.
type IncludableMap ¶
IncludableMap is an interface that can optionally be implemented by a struct. It will be called when a map-type field is found to ask the struct if the map item should be included in the hash.