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go/internal/lsp/source/highlight.go
Ian Cottrell 4457e4cfd4 internal/lsp: add some trace spans to important functions
This uses the new opencensus compatability layer to add telementry to some of
the functions in the lsp, in order to allow us to understand their costs and
call patterns.

Change-Id: I7df820cd4eace7a4840ac6397d5df402369bf0a7
Reviewed-on: https://go-review.googlesource.com/c/tools/+/183419
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
2019-07-03 19:14:57 +00:00

48 lines
1.2 KiB
Go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package source
import (
"context"
"fmt"
"go/ast"
"go/token"
"golang.org/x/tools/go/ast/astutil"
"golang.org/x/tools/internal/lsp/telemetry/trace"
"golang.org/x/tools/internal/span"
)
func Highlight(ctx context.Context, f GoFile, pos token.Pos) ([]span.Span, error) {
ctx, ts := trace.StartSpan(ctx, "source.Highlight")
defer ts.End()
file := f.GetAST(ctx)
if file == nil {
return nil, fmt.Errorf("no AST for %s", f.URI())
}
fset := f.FileSet()
path, _ := astutil.PathEnclosingInterval(file, pos, pos)
if len(path) == 0 {
return nil, fmt.Errorf("no enclosing position found for %s", fset.Position(pos))
}
id, ok := path[0].(*ast.Ident)
if !ok {
return nil, fmt.Errorf("%s is not an identifier", fset.Position(pos))
}
var result []span.Span
if id.Obj != nil {
ast.Inspect(path[len(path)-1], func(n ast.Node) bool {
if n, ok := n.(*ast.Ident); ok && n.Obj == id.Obj {
s, err := nodeSpan(n, fset)
if err == nil {
result = append(result, s)
}
}
return true
})
}
return result, nil
}