AST end offsets and compressed source map

[iamdefinitelyahuman]

What I did

• Add end offsets to Vyper AST nodes and pc_pos_map
• Add jump map and compressed source map to compiler source map output

How I did it

• Add tokens to the python AST nodes using the asttokens library
• Use the tokens to add end_lineno and end_col_offset attributes to the final Vyper AST. (Attributes with these names are included in the standard ast library as of Python 3.8)
• include these new attributes when generating the LLLnode objects, and add their values to pc_pos_map as returned by vyper.compile_lll.assembly_to_evm
• add pc_jump_map to assembly_to_evm output, in the format {'program counter': [io-]} - i indicates a jump instruction going into a private function, o coming out of a private function, - is an internal instruction such as a for loop or if / else statement.
• added vyper.compiler.compress_source_map: given source code, pc_pos_map and pc_jump_map, generates a compressed source map in the same format used by solc
• added vyper.compiler.expand_source_map: given a compressed source map string, expands it into a list of 4 item lists as [start, length, contract_id, jump]
• include pc_jump_map and pc_pos_map_compressed to compiler output given by vyper.compiler.get_source_map

How to verify it

Run the tests. I have added several new test cases around the jump map and compressed source map.

Description for the changelog

• Add end offsets to source map

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[jacqueswww]

LGTM 🎇

[jacqueswww]

@iamdefinitelyahuman I think the CLI switch is missing?

[iamdefinitelyahuman]

@jacqueswww For now I've just included it as part of the output for source_map - my next target is #1520 where I plan to separate it all out a bit more.

If you'd like I can add another flag, compressed_source_map maybe?

[jacqueswww]

I reckon that's fine for now, especially because of #1520 👍