New data structure —— Hash

[qishenonly]

We need a new data structure, Hash, to extend the database's key-value storage structure.
We need to build some instructions into Hash to make it more complete.
If you are interested in extending the Hashdata structure, you can comment below on the issue id you would like to try and we will assign it to you.

id	issue	method	describtion	people	process
1	Hash method HSet	HSet key field value	Sets the value of the specified field in the specified hash key to the specified value.	@qishenonly	finished
2	Hash method HGet	HGet key field	Gets the value of the specified field in the specified hash key.	@qishenonly	finished
3	Hash method HMSet	HMSet key field1 value1 [field2 value2 ...]	Sets values for multiple fields in the specified hash key at the same time.
4	Hash method HMGet	HMGet key field1 [field2 ...]	Gets the values of multiple fields in the specified hash key at the same time.	@saeid-a	finished
5	Hash method HDel	HDel key field1 [field2 ...]	Removes one or more fields from the specified hash key.	@qishenonly	finished
6	Hash method HExists	HExists key field	Checks whether the specified field exists in the specified hash key.	@qishenonly	finished
7	Hash method HKeys	HKeys key	Gets all field names in the specified hash key.
8	Hash method HVals	HVals key	Gets all field values in the specified hash key.
9	Hash method HLen	HLen key	Gets the number of fields in the specified hash key	@qishenonly	finished
10	Hash method HGetAll	HGetAll key	Gets all fields and their values in the specified hash key.

[saeid-a]

#184

[saeid-a]

I've noticed the function decodeHashField in hash.go does not work; I mean, the way function encodeHashField encodes the HashField structure is impossible to decode since there are no delimiters; as a result, implementing the functions HKeys and HVals become very hard if not impossible. We can, however, rewrite the decode/encode functions using Golang's gob. Let me know what you think.

[qishenonly]

Unfortunately, due to my personal development habits, I usually write the corresponding decodeHashField method after writing the encodeHashField method. However, when I wrote various methods of hash, I actually did not use the decoding method, which may have some problems.

For your consideration, perhaps you can try to use gob to rewrite the codec function part, it may not affect the functional implementation of other functions, but still have to actually run the test.

Thank you very much for your valuable comments.

[saeid-a]

#184

[qishenonly]

#184

thanks