Generate Solidity style full descriptions of functions/events/structs

[peterbroadhurst]

In PR chain with #70

firefly-signer/pkg/abi/abi_test.go

Lines 1002 to 1017 in 97939c6

	solDef, childStructs, err := abi.Functions()["invoice"].SolidityDef()
	assert.NoError(t, err)
	assert.Equal(t, "function invoice(Invoice memory _invoice) external payable { }", solDef)
	assert.Equal(t, []string{
	"struct Customer { address owner; bytes32 locator; }",
	"struct Widget { string description; uint256 price; string[] attributes; }",
	"struct Invoice { Customer customer; Widget[] widgets; }",
	}, childStructs)
	solDef, childStructs, err = abi.Events()["Invoiced"].SolidityDef()
	assert.NoError(t, err)
	assert.Equal(t, "event Invoiced(Customer customer, Widget[] widgets)", solDef)
	assert.Equal(t, []string{
	"struct Customer { address owner; bytes32 locator; }",
	"struct Widget { string description; uint256 price; string[] attributes; }",
	}, childStructs)

There are cases where we need to build descriptors of functions/events (and their containing structures) that preserve the full information of how they will be parsed/serialized.

For example when determining if the list of event definitions, including containing type names, is identical to another list.

This PR provides that feature, and does it uses Solidity as the inspiration for the formatting, which makes it human readable.

The solidity strings have the characteristic that they uniquely identify each function, including where overrides are used.

[awrichar]

Why include "external" in the descriptor if it's the same for all functions? Is it just to make it read more like a proper Solidity function definition?

[peterbroadhurst]

Exactly that.
It allows you to paste it into a code editor in an interface or actual .sol file and it work as-is

[awrichar]

I asked some questions inline, but I think this looks good.