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go/cmd/guru/definition.go
Alan Donovan 2da0720e4f cmd/guru: support streaming plain and -json output
Visible changes:
- "referrers" queries now emit a stream of results,
  so they start appearing quickly even in large queries.
  We no longer report the total number of matches.
- packageReferrers now also uses AfterTypeCheck hook and streaming.
- XML support has been dropped.
- The -format flag has been replaced by -json.

JSON protocol changes:
- The enclosing Result struct has been removed.
- Likewise the 'mode' field (since the caller knows it already)
- "freevars" and "referrers" now emit a stream of objects
  In the case of referrers, the first object has a different from the rest.
- The "referrers" results include the text of the matching line
  (parity with -json=false)

Implementation details:
- the concurrency-safe q.Output function can be called
  many times, each with a queryResult to print.
- fset is no longer saved in Query (cleaner)
- queryResult methods renamed PrintPlain, JSON

Change-Id: I41a4e3f57f266fcf043ece4045bca82c6f6a356f
Reviewed-on: https://go-review.googlesource.com/21397
Reviewed-by: Michael Matloob <matloob@golang.org>
2016-04-11 19:51:55 +00:00

100 lines
2.2 KiB
Go

// Copyright 2013 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 main
import (
"fmt"
"go/ast"
"go/token"
"golang.org/x/tools/cmd/guru/serial"
"golang.org/x/tools/go/loader"
)
// definition reports the location of the definition of an identifier.
func definition(q *Query) error {
// First try the simple resolution done by parser.
// It only works for intra-file references but it is very fast.
// (Extending this approach to all the files of the package,
// resolved using ast.NewPackage, was not worth the effort.)
{
qpos, err := fastQueryPos(q.Build, q.Pos)
if err != nil {
return err
}
id, _ := qpos.path[0].(*ast.Ident)
if id == nil {
return fmt.Errorf("no identifier here")
}
if obj := id.Obj; obj != nil && obj.Pos().IsValid() {
q.Output(qpos.fset, &definitionResult{
pos: obj.Pos(),
descr: fmt.Sprintf("%s %s", obj.Kind, obj.Name),
})
return nil // success
}
}
// Run the type checker.
lconf := loader.Config{Build: q.Build}
allowErrors(&lconf)
if _, err := importQueryPackage(q.Pos, &lconf); err != nil {
return err
}
// Load/parse/type-check the program.
lprog, err := lconf.Load()
if err != nil {
return err
}
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
id, _ := qpos.path[0].(*ast.Ident)
if id == nil {
return fmt.Errorf("no identifier here")
}
obj := qpos.info.ObjectOf(id)
if obj == nil {
// Happens for y in "switch y := x.(type)",
// and the package declaration,
// but I think that's all.
return fmt.Errorf("no object for identifier")
}
if !obj.Pos().IsValid() {
return fmt.Errorf("%s is built in", obj.Name())
}
q.Output(lprog.Fset, &definitionResult{
pos: obj.Pos(),
descr: qpos.objectString(obj),
})
return nil
}
type definitionResult struct {
pos token.Pos // (nonzero) location of definition
descr string // description of object it denotes
}
func (r *definitionResult) PrintPlain(printf printfFunc) {
printf(r.pos, "defined here as %s", r.descr)
}
func (r *definitionResult) JSON(fset *token.FileSet) []byte {
return toJSON(&serial.Definition{
Desc: r.descr,
ObjPos: fset.Position(r.pos).String(),
})
}