tree e31082ab406f86ff14f3d4e4a19f6ace7fd8bb05
parent a4455febdef318395153612ab0489e96418ec51b
author Alan Donovan <adonovan@google.com> 1672876374 -0500
committer Alan Donovan <adonovan@google.com> 1672944868 +0000

gopls/internal/lsp/protocol: simplify ColumnMapper

This change decouples ColumnMapper from go/token.
Its TokFile field is now unexported and fully
encapsulated and will be removed in a follow-up;
it serves only as a line-number table.
ColumnMapper now provides only mapping between
byte offsets and columns, in three different
units (UTF-8, UTF-16, and runes).

Three operations that require both a Mapper and
a token.File--and require then to be consistent with
each other--have been moved to ParsedGoFile:
(Pos, PosRange, and RangeToSpanRange).
This is another step to keeping the use of token.Pos
close to its token.File or FileSet, and using
byte offsets and ColumnMappers more broadly.

MappedRange now holds a ParsedGoFile and (internally)
a start/end Pos pair, making it self-contained for all
conversions. (The File field is unfortunately public
for now due to one tricky use; fixing it would have
expanded this already large CL.)
I'm not sure whether MappedRange carries its weight;
I think it might be clearer for all users to simply
expand it out (i.e. hold a ColumnMapper and two byte
offsets), making one less creature in the zoo.
Numerous calls to NewMappedRange followed by .Range()
have been reduced to pgf.PosRange().

Also:
- New ColumnMapper methods:
    OffsetSpan
    OffsetPoint
- safetoken.Offsets(start, end) is the plural of Offset(pos).
- span.ToPosition renamed span.OffsetToLineCol8.
- span.NewTokenFile inlined into sole caller.
- avoid embedding of MappedRange, as it makes the references
  hard to see. (Embedded fields are both a def and a ref but
  gopls cross-references is confused by that.)
- findLinksInString uses offsets now.

Change-Id: I2c775e181e456604e2ce977d618b0f1ec8e76903
Reviewed-on: https://go-review.googlesource.com/c/tools/+/460615
Run-TryBot: Alan Donovan <adonovan@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>