support reverse iteration & show RAM payer in get table (#6216 #6271)

[taokayan]

#6216 #6271

Change Description

• allow developers/users to reversely iterate rows in get_table_rows RPC call
• allow developers/users to get RAM payer information for each row
• allow developers/users to reversely iterate rows in get_table_by_scope RPC call

API Changes
RPC call: get_table_rows (cleos get table)
RPC call: get_table_by_scope (cleos get scope)

Documentation Additions
new parameters for get table rows:
-r,--reverse Iterate in reverse order (default: false)
--show-payer show RAM payer (default: false)

new parameter for get table by scope:
-r,--reverse Iterate in reverse order (default: false)

Command example
find the bid name with the lowest bid:

./cleos get table eosio eosio namebids --key-type i64 --index 2 -r -l 1
{
  "rows": [{
      "newname": "com",
      "high_bidder": "a123",
      "high_bid": 100000,
      "last_bid_time": "1541667021500000"
    }
  ],
  "more": true
}

to show all bid names from lowbid to highbid, with RAM payer information

./cleos get table eosio eosio namebids --key-type i64 --index 2 -r --show-payer
{
  "rows": [{
      "data": {
        "newname": "com",
        "high_bidder": "a123",
        "high_bid": 100000,
        "last_bid_time": "1541667021500000"
      },
      "payer": "a123"
    },{
      "data": {
        "newname": "abc",
        "high_bidder": "a123",
        "high_bid": 110000,
        "last_bid_time": "1541667021500000"
      },
      "payer": "a123"
    },{
      "data": {
        "newname": "ddd",
        "high_bidder": "a123",
        "high_bid": 120000,
        "last_bid_time": "1541667021500000"
      },
      "payer": "a123"
    },{
      "data": {
        "newname": "zoo",
        "high_bidder": "a123",
        "high_bid": 9990000,
        "last_bid_time": "1541667022000000"
      },
      "payer": "a123"
    }
  ],
  "more": false
}

[heifner]

Please add some tests to tests/get_table_tests.cpp for this new functionality.

[heifner]

This needs to be optional to support older clients.

[arhag]

I pushed some changes to account for the changed definition of upper_bound from PR #6285. I also added support for reverse iteration in get_table_by_scope.

[znebby]

Hey guys, I'm really looking forward to getting this merged in.