1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
|
// Copyright 2024 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 golang
// This file implements the "Browse free symbols" code action.
import (
"bytes"
"fmt"
"go/ast"
"go/token"
"go/types"
"html"
"sort"
"strings"
"golang.org/x/tools/go/ast/astutil"
"golang.org/x/tools/gopls/internal/cache"
"golang.org/x/tools/gopls/internal/cache/metadata"
"golang.org/x/tools/gopls/internal/cache/parsego"
"golang.org/x/tools/gopls/internal/util/maps"
"golang.org/x/tools/gopls/internal/util/safetoken"
"golang.org/x/tools/gopls/internal/util/slices"
"golang.org/x/tools/internal/typesinternal"
)
// FreeSymbolsHTML returns an HTML document containing the report of
// free symbols referenced by the selection.
func FreeSymbolsHTML(viewID string, pkg *cache.Package, pgf *parsego.File, start, end token.Pos, web Web) []byte {
// Compute free references.
refs := freeRefs(pkg.Types(), pkg.TypesInfo(), pgf.File, start, end)
// -- model --
type Import struct {
Path metadata.PackagePath
Symbols []string
}
type Symbol struct {
Kind string
Type string
Refs []types.Object
}
var model struct {
Imported []Import
PkgLevel []Symbol
Local []Symbol
}
qualifier := typesinternal.NameRelativeTo(pkg.Types())
// Populate model.
{
// List the refs in order of dotted paths.
sort.Slice(refs, func(i, j int) bool {
return refs[i].dotted < refs[j].dotted
})
// Inspect the references.
imported := make(map[string][]*freeRef) // refs to imported symbols, by package path
seen := make(map[string]bool) // to de-dup dotted paths
for _, ref := range refs {
if seen[ref.dotted] {
continue // de-dup
}
seen[ref.dotted] = true
var symbols *[]Symbol
switch ref.scope {
case "file":
// imported symbol: group by package
if pkgname, ok := ref.objects[0].(*types.PkgName); ok {
path := pkgname.Imported().Path()
imported[path] = append(imported[path], ref)
}
continue
case "pkg":
symbols = &model.PkgLevel
case "local":
symbols = &model.Local
default:
panic(ref.scope)
}
// Package and local symbols are presented the same way.
// We treat each dotted path x.y.z as a separate entity.
// Compute kind and type of last object (y in obj.x.y).
typestr := " " + types.TypeString(ref.typ, qualifier)
var kind string
switch obj := ref.objects[len(ref.objects)-1].(type) {
case *types.Var:
kind = "var"
case *types.Func:
kind = "func"
case *types.TypeName:
if is[*types.TypeParam](obj.Type()) {
kind = "type parameter"
} else {
kind = "type"
}
typestr = "" // avoid "type T T"
case *types.Const:
kind = "const"
case *types.Label:
kind = "label"
typestr = "" // avoid "label L L"
}
*symbols = append(*symbols, Symbol{
Kind: kind,
Type: typestr,
Refs: ref.objects,
})
}
// Imported symbols.
// Produce one record per package, with a list of symbols.
pkgPaths := maps.Keys(imported)
sort.Strings(pkgPaths)
for _, pkgPath := range pkgPaths {
refs := imported[pkgPath]
var syms []string
for _, ref := range refs {
// strip package name (bytes.Buffer.Len -> Buffer.Len)
syms = append(syms, ref.dotted[len(ref.objects[0].Name())+len("."):])
}
sort.Strings(syms)
const max = 4
if len(syms) > max {
syms[max-1] = fmt.Sprintf("... (%d)", len(syms))
syms = syms[:max]
}
model.Imported = append(model.Imported, Import{
Path: PackagePath(pkgPath),
Symbols: syms,
})
}
}
// -- presentation --
var buf bytes.Buffer
buf.WriteString(`<!DOCTYPE html>
<html>
<head>
<style>
.col-pkg { color: #2eb007 }
.col-file { color: #a10b15 }
.col-local { color: #0cb7c9 }
li { font-family: monospace; }
p { max-width: 6in; }
</style>
<script src="/assets/common.js"></script>
<link rel="stylesheet" href="/assets/common.css">
</head>
<body>
<h1>Free symbols</h1>
<p>
The selected code contains references to these free* symbols:
</p>
`)
// Present the refs in three sections: imported, same package, local.
// -- imported symbols --
// Show one item per package, with a list of symbols.
fmt.Fprintf(&buf, "<h2><span class='col-file'>⬤</span> Imported symbols</h2>\n")
fmt.Fprintf(&buf, "<ul>\n")
for _, imp := range model.Imported {
fmt.Fprintf(&buf, "<li>import \"<a href='%s'>%s</a>\" // for %s</li>\n",
web.PkgURL(viewID, imp.Path, ""),
html.EscapeString(string(imp.Path)),
strings.Join(imp.Symbols, ", "))
}
if len(model.Imported) == 0 {
fmt.Fprintf(&buf, "<li>(none)</li>\n")
}
buf.WriteString("</ul>\n")
// -- package and local symbols --
showSymbols := func(scope, title string, symbols []Symbol) {
fmt.Fprintf(&buf, "<h2><span class='col-%s'>⬤</span> %s</h2>\n", scope, title)
fmt.Fprintf(&buf, "<ul>\n")
pre := buf.Len()
for _, sym := range symbols {
fmt.Fprintf(&buf, "<li>%s ", sym.Kind) // of rightmost symbol in dotted path
for i, obj := range sym.Refs {
if i > 0 {
buf.WriteByte('.')
}
buf.WriteString(objHTML(pkg.FileSet(), web, obj))
}
fmt.Fprintf(&buf, " %s</li>\n", html.EscapeString(sym.Type))
}
if buf.Len() == pre {
fmt.Fprintf(&buf, "<li>(none)</li>\n")
}
buf.WriteString("</ul>\n")
}
showSymbols("pkg", "Package-level symbols", model.PkgLevel)
showSymbols("local", "Local symbols", model.Local)
// -- code selection --
// Print the selection, highlighting references to free symbols.
buf.WriteString("<hr/>\n")
sort.Slice(refs, func(i, j int) bool {
return refs[i].expr.Pos() < refs[j].expr.Pos()
})
pos := start
emitTo := func(end token.Pos) {
if pos < end {
fileStart := pgf.Tok.Pos(0) // TODO(adonovan): use go1.20 pgf.File.FileStart
text := pgf.Mapper.Content[pos-fileStart : end-fileStart]
buf.WriteString(html.EscapeString(string(text)))
pos = end
}
}
buf.WriteString(`<pre>`)
for _, ref := range refs {
emitTo(ref.expr.Pos())
fmt.Fprintf(&buf, `<b class='col-%s'>`, ref.scope)
emitTo(ref.expr.End())
buf.WriteString(`</b>`)
}
emitTo(end)
buf.WriteString(`</pre>
<hr>
<p>
*A symbol is "free" if it is referenced within the selection but declared
outside of it.
The free variables are approximately the set of parameters that
would be needed if the block were extracted into its own function in
the same package.
Free identifiers may include local types and control labels as well.
Even when you don't intend to extract a block into a new function,
this information can help you to tell at a glance what names a block
of code depends on.
</p>
<p>
Each dotted path of identifiers (such as file.Name.Pos) is reported
as a separate item, so that you can see which parts of a complex
type are actually needed.
The free symbols referenced by the body of a function may
reveal that only a small part (a single field of a struct, say) of
one of the function's parameters is used, allowing you to simplify
and generalize the function by choosing a different type for that
parameter.
</p>
`)
return buf.Bytes()
}
// A freeRef records a reference to a dotted path obj.x.y,
// where obj (=objects[0]) is a free symbol.
type freeRef struct {
objects []types.Object // [obj x y]
dotted string // "obj.x.y" (used as sort key)
scope string // scope of obj: pkg|file|local
expr ast.Expr // =*Ident|*SelectorExpr
typ types.Type // type of obj.x.y
}
// freeRefs returns the list of references to free symbols (from
// within the selection to a symbol declared outside of it).
// It uses only info.{Scopes,Types,Uses}.
func freeRefs(pkg *types.Package, info *types.Info, file *ast.File, start, end token.Pos) []*freeRef {
// Keep us honest about which fields we access.
info = &types.Info{
Scopes: info.Scopes,
Types: info.Types,
Uses: info.Uses,
}
fileScope := info.Scopes[file]
pkgScope := fileScope.Parent()
// id is called for the leftmost id x in each dotted chain such as (x.y).z.
// suffix is the reversed suffix of selections (e.g. [z y]).
id := func(n *ast.Ident, suffix []types.Object) *freeRef {
obj := info.Uses[n]
if obj == nil {
return nil // not a reference
}
if start <= obj.Pos() && obj.Pos() < end {
return nil // defined within selection => not free
}
parent := obj.Parent()
// Compute dotted path.
objects := append(suffix, obj)
if obj.Pkg() != nil && obj.Pkg() != pkg && isPackageLevel(obj) { // dot import
// Synthesize the implicit PkgName.
pkgName := types.NewPkgName(token.NoPos, pkg, obj.Pkg().Name(), obj.Pkg())
parent = fileScope
objects = append(objects, pkgName)
}
slices.Reverse(objects)
var dotted strings.Builder
for i, obj := range objects {
if obj == nil {
return nil // type error
}
if i > 0 {
dotted.WriteByte('.')
}
dotted.WriteString(obj.Name())
}
// Compute scope of base object.
var scope string
switch parent {
case nil:
return nil // interface method or struct field
case types.Universe:
return nil // built-in (not interesting)
case fileScope:
scope = "file" // defined at file scope (imported package)
case pkgScope:
scope = "pkg" // defined at package level
default:
scope = "local" // defined within current function
}
return &freeRef{
objects: objects,
dotted: dotted.String(),
scope: scope,
}
}
// sel(x.y.z, []) calls sel(x.y, [z]) calls id(x, [z, y]).
sel := func(sel *ast.SelectorExpr, suffix []types.Object) *freeRef {
for {
suffix = append(suffix, info.Uses[sel.Sel])
switch x := astutil.Unparen(sel.X).(type) {
case *ast.Ident:
return id(x, suffix)
default:
return nil
case *ast.SelectorExpr:
sel = x
}
}
}
// Visit all the identifiers in the selected ASTs.
var free []*freeRef
path, _ := astutil.PathEnclosingInterval(file, start, end)
var visit func(n ast.Node) bool
visit = func(n ast.Node) bool {
// Is this node contained within the selection?
// (freesymbols permits inexact selections,
// like two stmts in a block.)
if n != nil && start <= n.Pos() && n.End() <= end {
var ref *freeRef
switch n := n.(type) {
case *ast.Ident:
ref = id(n, nil)
case *ast.SelectorExpr:
ref = sel(n, nil)
}
if ref != nil {
ref.expr = n.(ast.Expr)
ref.typ = info.Types[n.(ast.Expr)].Type
free = append(free, ref)
}
// After visiting x.sel, don't descend into sel.
// Descend into x only if we didn't get a ref for x.sel.
if sel, ok := n.(*ast.SelectorExpr); ok {
if ref == nil {
ast.Inspect(sel.X, visit)
}
return false
}
}
return true // descend
}
ast.Inspect(path[0], visit)
return free
}
// objHTML returns HTML for obj.Name(), possibly marked up as a link
// to the web server that, when visited, opens the declaration in the
// client editor.
func objHTML(fset *token.FileSet, web Web, obj types.Object) string {
text := obj.Name()
if posn := safetoken.StartPosition(fset, obj.Pos()); posn.IsValid() {
url := web.SrcURL(posn.Filename, posn.Line, posn.Column)
return sourceLink(text, url)
}
return text
}
// sourceLink returns HTML for a link to open a file in the client editor.
func sourceLink(text, url string) string {
// The /src URL returns nothing but has the side effect
// of causing the LSP client to open the requested file.
// So we use onclick to prevent the browser from navigating.
// We keep the href attribute as it causes the <a> to render
// as a link: blue, underlined, with URL hover information.
return fmt.Sprintf(`<a href="%[1]s" onclick='return httpGET("%[1]s")'>%[2]s</a>`,
html.EscapeString(url), text)
}
|
