This change includes some progress on actual compilation (albeit with several
TODOs remaining before we can actually spit out a useful artifact). There are
also some general cleanups sprinkled throughout. In a nutshell:
* Add a compiler.Context object that will be available during template expansion.
* Introduce a diag.Document abstraction. This is better than passing raw filenames
around, and lets us embellish diagnostics as we go. In particular, we will be
in a better position to provide line/column error information.
* Move IO out of the Parser and into the Compiler, where it can cache and reuse
Documents. This will become important as we start to load up dependencies.
* Rename PosRange to Location. This reads nicer with the new Document terminology.
* Rename the mu/api package to mu/schema. It's likely we will need to introduce a
true AST that is decoupled from the serialization format and contains bound nodes.
As a result, treating the existing types as "schema" is more honest.
* Add in a big section of TODOs at the end of the compiler.Compiler.Build function.
This adds a bunch of general scaffolding and the beginning of a `build` command.
The general engineering scaffolding includes:
* Glide for dependency management.
* A Makefile that runs govet and golint during builds.
* Google's Glog library for logging.
* Cobra for command line functionality.
The Mu-specific scaffolding includes some packages:
* mu/pkg/diag: A package for compiler-like diagnostics. It's fairly barebones
at the moment, however we can embellish this over time.
* mu/pkg/errors: A package containing Mu's predefined set of errors.
* mu/pkg/workspace: A package containing workspace-related convenience helpers.
in addition to a main entrypoint that simply wires up and invokes the CLI. From
there, the mu/cmd package takes over, with the Cobra-defined CLI commands.
Finally, the mu/pkg/compiler package actually implements the compiler behavior.
Or, it will. For now, it simply parses a JSON or YAML Mufile into the core
mu/pkg/api types, and prints out the result.
