/
literal.go
439 lines (386 loc) · 12.8 KB
/
literal.go
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
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
// 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 completion
import (
"context"
"fmt"
"go/ast"
"go/token"
"go/types"
"strings"
"unicode"
"github.com/kevinswiber/languageserver-go/event"
"github.com/kevinswiber/languageserver-go/lsp/diff"
"github.com/kevinswiber/languageserver-go/lsp/protocol"
"github.com/kevinswiber/languageserver-go/lsp/snippet"
"github.com/kevinswiber/languageserver-go/lsp/source"
)
// literal generates composite literal, function literal, and make()
// completion items.
func (c *completer) literal(ctx context.Context, literalType types.Type, imp *importInfo) {
if !c.opts.literal {
return
}
expType := c.inference.objType
if c.inference.matchesVariadic(literalType) {
// Don't offer literal slice candidates for variadic arguments.
// For example, don't offer "[]interface{}{}" in "fmt.Print(<>)".
return
}
// Avoid literal candidates if the expected type is an empty
// interface. It isn't very useful to suggest a literal candidate of
// every possible type.
if expType != nil && isEmptyInterface(expType) {
return
}
// We handle unnamed literal completions explicitly before searching
// for candidates. Avoid named-type literal completions for
// unnamed-type expected type since that results in duplicate
// candidates. For example, in
//
// type mySlice []int
// var []int = <>
//
// don't offer "mySlice{}" since we have already added a candidate
// of "[]int{}".
if _, named := literalType.(*types.Named); named && expType != nil {
if _, named := source.Deref(expType).(*types.Named); !named {
return
}
}
// Check if an object of type literalType would match our expected type.
cand := candidate{
obj: c.fakeObj(literalType),
}
switch literalType.Underlying().(type) {
// These literal types are addressable (e.g. "&[]int{}"), others are
// not (e.g. can't do "&(func(){})").
case *types.Struct, *types.Array, *types.Slice, *types.Map:
cand.addressable = true
}
if !c.matchingCandidate(&cand) {
return
}
var (
qf = c.qf
sel = enclosingSelector(c.path, c.pos)
)
// Don't qualify the type name if we are in a selector expression
// since the package name is already present.
if sel != nil {
qf = func(_ *types.Package) string { return "" }
}
typeName := types.TypeString(literalType, qf)
// A type name of "[]int" doesn't work very will with the matcher
// since "[" isn't a valid identifier prefix. Here we strip off the
// slice (and array) prefix yielding just "int".
matchName := typeName
switch t := literalType.(type) {
case *types.Slice:
matchName = types.TypeString(t.Elem(), qf)
case *types.Array:
matchName = types.TypeString(t.Elem(), qf)
}
addlEdits, err := c.importEdits(imp)
if err != nil {
event.Error(ctx, "error adding import for literal candidate", err)
return
}
// If prefix matches the type name, client may want a composite literal.
if score := c.matcher.Score(matchName); score > 0 {
if cand.takeAddress {
if sel != nil {
// If we are in a selector we must place the "&" before the selector.
// For example, "foo.B<>" must complete to "&foo.Bar{}", not
// "foo.&Bar{}".
edits, err := prependEdit(c.snapshot.FileSet(), c.mapper, sel, "&")
if err != nil {
event.Error(ctx, "error making edit for literal pointer completion", err)
return
}
addlEdits = append(addlEdits, edits...)
} else {
// Otherwise we can stick the "&" directly before the type name.
typeName = "&" + typeName
}
}
switch t := literalType.Underlying().(type) {
case *types.Struct, *types.Array, *types.Slice, *types.Map:
c.compositeLiteral(t, typeName, float64(score), addlEdits)
case *types.Signature:
// Add a literal completion for a signature type that implements
// an interface. For example, offer "http.HandlerFunc()" when
// expected type is "http.Handler".
if source.IsInterface(expType) {
c.basicLiteral(t, typeName, float64(score), addlEdits)
}
case *types.Basic:
// Add a literal completion for basic types that implement our
// expected interface (e.g. named string type http.Dir
// implements http.FileSystem), or are identical to our expected
// type (i.e. yielding a type conversion such as "float64()").
if source.IsInterface(expType) || types.Identical(expType, literalType) {
c.basicLiteral(t, typeName, float64(score), addlEdits)
}
}
}
// If prefix matches "make", client may want a "make()"
// invocation. We also include the type name to allow for more
// flexible fuzzy matching.
if score := c.matcher.Score("make." + matchName); !cand.takeAddress && score > 0 {
switch literalType.Underlying().(type) {
case *types.Slice:
// The second argument to "make()" for slices is required, so default to "0".
c.makeCall(typeName, "0", float64(score), addlEdits)
case *types.Map, *types.Chan:
// Maps and channels don't require the second argument, so omit
// to keep things simple for now.
c.makeCall(typeName, "", float64(score), addlEdits)
}
}
// If prefix matches "func", client may want a function literal.
if score := c.matcher.Score("func"); !cand.takeAddress && score > 0 && !source.IsInterface(expType) {
switch t := literalType.Underlying().(type) {
case *types.Signature:
c.functionLiteral(ctx, t, float64(score))
}
}
}
// prependEdit produces text edits that preprend the specified prefix
// to the specified node.
func prependEdit(fset *token.FileSet, m *protocol.ColumnMapper, node ast.Node, prefix string) ([]protocol.TextEdit, error) {
rng := source.NewMappedRange(fset, m, node.Pos(), node.Pos())
spn, err := rng.Span()
if err != nil {
return nil, err
}
return source.ToProtocolEdits(m, []diff.TextEdit{{
Span: spn,
NewText: prefix,
}})
}
// literalCandidateScore is the base score for literal candidates.
// Literal candidates match the expected type so they should be high
// scoring, but we want them ranked below lexical objects of the
// correct type, so scale down highScore.
const literalCandidateScore = highScore / 2
// functionLiteral adds a function literal completion item for the
// given signature.
func (c *completer) functionLiteral(ctx context.Context, sig *types.Signature, matchScore float64) {
snip := &snippet.Builder{}
snip.WriteText("func(")
// First we generate names for each param and keep a seen count so
// we know if we need to uniquify param names. For example,
// "func(int)" will become "func(i int)", but "func(int, int64)"
// will become "func(i1 int, i2 int64)".
var (
paramNames = make([]string, sig.Params().Len())
paramNameCount = make(map[string]int)
)
for i := 0; i < sig.Params().Len(); i++ {
var (
p = sig.Params().At(i)
name = p.Name()
)
if name == "" {
// If the param has no name in the signature, guess a name based
// on the type. Use an empty qualifier to ignore the package.
// For example, we want to name "http.Request" "r", not "hr".
name = source.FormatVarType(ctx, c.snapshot, c.pkg, p, func(p *types.Package) string {
return ""
})
name = abbreviateTypeName(name)
}
paramNames[i] = name
if name != "_" {
paramNameCount[name]++
}
}
for n, c := range paramNameCount {
// Any names we saw more than once will need a unique suffix added
// on. Reset the count to 1 to act as the suffix for the first
// name.
if c >= 2 {
paramNameCount[n] = 1
} else {
delete(paramNameCount, n)
}
}
for i := 0; i < sig.Params().Len(); i++ {
if i > 0 {
snip.WriteText(", ")
}
var (
p = sig.Params().At(i)
name = paramNames[i]
)
// Uniquify names by adding on an incrementing numeric suffix.
if idx, found := paramNameCount[name]; found {
paramNameCount[name]++
name = fmt.Sprintf("%s%d", name, idx)
}
if name != p.Name() && c.opts.placeholders {
// If we didn't use the signature's param name verbatim then we
// may have chosen a poor name. Give the user a placeholder so
// they can easily fix the name.
snip.WritePlaceholder(func(b *snippet.Builder) {
b.WriteText(name)
})
} else {
snip.WriteText(name)
}
// If the following param's type is identical to this one, omit
// this param's type string. For example, emit "i, j int" instead
// of "i int, j int".
if i == sig.Params().Len()-1 || !types.Identical(p.Type(), sig.Params().At(i+1).Type()) {
snip.WriteText(" ")
typeStr := source.FormatVarType(ctx, c.snapshot, c.pkg, p, c.qf)
if sig.Variadic() && i == sig.Params().Len()-1 {
typeStr = strings.Replace(typeStr, "[]", "...", 1)
}
snip.WriteText(typeStr)
}
}
snip.WriteText(")")
results := sig.Results()
if results.Len() > 0 {
snip.WriteText(" ")
}
resultsNeedParens := results.Len() > 1 ||
results.Len() == 1 && results.At(0).Name() != ""
if resultsNeedParens {
snip.WriteText("(")
}
for i := 0; i < results.Len(); i++ {
if i > 0 {
snip.WriteText(", ")
}
r := results.At(i)
if name := r.Name(); name != "" {
snip.WriteText(name + " ")
}
snip.WriteText(source.FormatVarType(ctx, c.snapshot, c.pkg, r, c.qf))
}
if resultsNeedParens {
snip.WriteText(")")
}
snip.WriteText(" {")
snip.WriteFinalTabstop()
snip.WriteText("}")
c.items = append(c.items, CompletionItem{
Label: "func(...) {}",
Score: matchScore * literalCandidateScore,
Kind: protocol.VariableCompletion,
snippet: snip,
})
}
// abbreviateTypeName abbreviates type names into acronyms. For
// example, "fooBar" is abbreviated "fb". Care is taken to ignore
// non-identifier runes. For example, "[]int" becomes "i", and
// "struct { i int }" becomes "s".
func abbreviateTypeName(s string) string {
var (
b strings.Builder
useNextUpper bool
)
// Trim off leading non-letters. We trim everything between "[" and
// "]" to handle array types like "[someConst]int".
var inBracket bool
s = strings.TrimFunc(s, func(r rune) bool {
if inBracket {
inBracket = r != ']'
return true
}
if r == '[' {
inBracket = true
}
return !unicode.IsLetter(r)
})
for i, r := range s {
// Stop if we encounter a non-identifier rune.
if !unicode.IsLetter(r) && !unicode.IsNumber(r) {
break
}
if i == 0 {
b.WriteRune(unicode.ToLower(r))
}
if unicode.IsUpper(r) {
if useNextUpper {
b.WriteRune(unicode.ToLower(r))
useNextUpper = false
}
} else {
useNextUpper = true
}
}
return b.String()
}
// compositeLiteral adds a composite literal completion item for the given typeName.
func (c *completer) compositeLiteral(T types.Type, typeName string, matchScore float64, edits []protocol.TextEdit) {
snip := &snippet.Builder{}
snip.WriteText(typeName + "{")
// Don't put the tab stop inside the composite literal curlies "{}"
// for structs that have no accessible fields.
if strct, ok := T.(*types.Struct); !ok || fieldsAccessible(strct, c.pkg.GetTypes()) {
snip.WriteFinalTabstop()
}
snip.WriteText("}")
nonSnippet := typeName + "{}"
c.items = append(c.items, CompletionItem{
Label: nonSnippet,
InsertText: nonSnippet,
Score: matchScore * literalCandidateScore,
Kind: protocol.VariableCompletion,
AdditionalTextEdits: edits,
snippet: snip,
})
}
// basicLiteral adds a literal completion item for the given basic
// type name typeName.
func (c *completer) basicLiteral(T types.Type, typeName string, matchScore float64, edits []protocol.TextEdit) {
snip := &snippet.Builder{}
snip.WriteText(typeName + "(")
snip.WriteFinalTabstop()
snip.WriteText(")")
nonSnippet := typeName + "()"
c.items = append(c.items, CompletionItem{
Label: nonSnippet,
InsertText: nonSnippet,
Detail: T.String(),
Score: matchScore * literalCandidateScore,
Kind: protocol.VariableCompletion,
AdditionalTextEdits: edits,
snippet: snip,
})
}
// makeCall adds a completion item for a "make()" call given a specific type.
func (c *completer) makeCall(typeName string, secondArg string, matchScore float64, edits []protocol.TextEdit) {
// Keep it simple and don't add any placeholders for optional "make()" arguments.
snip := &snippet.Builder{}
snip.WriteText("make(" + typeName)
if secondArg != "" {
snip.WriteText(", ")
snip.WritePlaceholder(func(b *snippet.Builder) {
if c.opts.placeholders {
b.WriteText(secondArg)
}
})
}
snip.WriteText(")")
var nonSnippet strings.Builder
nonSnippet.WriteString("make(" + typeName)
if secondArg != "" {
nonSnippet.WriteString(", ")
nonSnippet.WriteString(secondArg)
}
nonSnippet.WriteByte(')')
c.items = append(c.items, CompletionItem{
Label: nonSnippet.String(),
InsertText: nonSnippet.String(),
Score: matchScore * literalCandidateScore,
Kind: protocol.FunctionCompletion,
AdditionalTextEdits: edits,
snippet: snip,
})
}