internal/lsp: provide deep completion candidates

Deep completion refers to searching through an object's fields and
methods for more completion candidates. For example:

func wantsInt(int) { }
var s struct { i int }
wantsInt(<>)

Will now give a candidate for "s.i" since its type matches the
expected type.

We limit to three deep completion results. In some cases there are
many useless deep completion matches. Showing too many options defeats
the purpose of "smart" completions. We also lower a completion item's
score according to its depth so that we favor shallower options. For
now we do not continue searching past function calls to limit our
search scope. In other words, we are not able to suggest results with
any chained fields/methods after the first method call.

Deep completions are behind the "useDeepCompletions" LSP config flag
for now.

Change-Id: I1b888c82e5c4b882f9718177ce07811e2bccbf22
GitHub-Last-Rev: 26522363730036e0b382a7bcd10aa1ed825f6866
GitHub-Pull-Request: golang/tools#100
Reviewed-on: https://go-review.googlesource.com/c/tools/+/177622
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
12 files changed
tree: d989ce82199f4d40c2ad4bc832312cbe3457e8c9
  1. benchmark/
  2. blog/
  3. cmd/
  4. container/
  5. cover/
  6. go/
  7. godoc/
  8. gopls/
  9. imports/
  10. internal/
  11. playground/
  12. present/
  13. refactor/
  14. .gitattributes
  15. .gitignore
  16. AUTHORS
  17. codereview.cfg
  18. CONTRIBUTING.md
  19. CONTRIBUTORS
  20. go.mod
  21. go.sum
  22. LICENSE
  23. PATENTS
  24. README.md
README.md

Go Tools

This subrepository holds the source for various packages and tools that support the Go programming language.

Some of the tools, godoc and vet for example, are included in binary Go distributions.

Others, including the Go guru and the test coverage tool, can be fetched with go get.

Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.

Download/Install

The easiest way to install is to run go get -u golang.org/x/tools/.... You can also manually git clone the repository to $GOPATH/src/golang.org/x/tools.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.

The main issue tracker for the tools repository is located at https://github.com/golang/go/issues. Prefix your issue with “x/tools/(your subdir):” in the subject line, so it is easy to find.