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go/internal/lsp/mod/format.go
Heschi Kreinick 72051f7961 internal/lsp: pass snapshot/view to memoize.Functions
Due to the runtime's inability to collect cycles involving finalizers,
we can't close over handles in memoize.Functions without causing memory
leaks. Up until now we've dealt with that by closing over all the bits
of the snapshot that we want, but it distorts the design of all the code
used in the Functions.

We can solve the problem another way: instead of closing over the
snapshot/view, we can force the caller to pass it in. This is somewhat
scary: there is no requirement that the argument matches the data that
we're working with. But the reality is that this is not a new problem:
the Function used to calculate a cache value is not necessarily the one
that the caller expects. As long as the cache key fully identifies all
the inputs to the Function, the output should be correct. And since the
caller used the snapshot/view to calculate that cache key, it should
always be safe to pass in that snapshot/view. If it's not, then we
already had a bug.

The Arg type in memoize is clumsy, but I thought it would be nice to
have at least a little bit of type safety. I'm open to suggestions.

Change-Id: I23f546638b0c66a4698620a986949087211f4762
Reviewed-on: https://go-review.googlesource.com/c/tools/+/244019
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
2020-07-28 17:34:46 +00:00

31 lines
762 B
Go

package mod
import (
"context"
"golang.org/x/tools/internal/event"
"golang.org/x/tools/internal/lsp/protocol"
"golang.org/x/tools/internal/lsp/source"
)
func Format(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle) ([]protocol.TextEdit, error) {
ctx, done := event.Start(ctx, "mod.Format")
defer done()
pmh, err := snapshot.ParseModHandle(ctx, fh)
if err != nil {
return nil, err
}
file, m, _, err := pmh.Parse(ctx, snapshot)
if err != nil {
return nil, err
}
formatted, err := file.Format()
if err != nil {
return nil, err
}
// Calculate the edits to be made due to the change.
diff := snapshot.View().Options().ComputeEdits(fh.URI(), string(m.Content), string(formatted))
return source.ToProtocolEdits(m, diff)
}