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go/internal/lsp/source/completion_snippet.go
Muir Manders dd2b5c81c5 internal/lsp: simplify snippet config/generation
I moved the "usePlaceholders" config field on to CompletionOptions.
This way the completion code generates a single snippet with a little
conditional logic based on the "WantPlaceholders" option instead of
juggling the generation of two almost identical "plain" and
"placeholder" snippets at the same time. It also reduces the work done
generating completion candidates a little.

I also made a minor tweak to the snippet builder where empty
placeholders are now always represented as e.g "${1:}" instead of
"${1}" or "${1:}", depending on if you passed a callback to
WritePlaceholder() or not.

Change-Id: Ib84cc0cd729a11b9e13ad3ac4b6fd2d82460acd5
Reviewed-on: https://go-review.googlesource.com/c/tools/+/193697
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-09-10 04:45:52 +00:00

98 lines
2.6 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 (
"go/ast"
"golang.org/x/tools/internal/lsp/snippet"
)
// structFieldSnippets calculates the snippet for struct literal field names.
func (c *completer) structFieldSnippet(label, detail string) *snippet.Builder {
if !c.wantStructFieldCompletions() {
return nil
}
// If we are in a deep completion then we can't be completing a field
// name (e.g. "Foo{f<>}" completing to "Foo{f.Bar}" should not generate
// a snippet).
if c.inDeepCompletion() {
return nil
}
clInfo := c.enclosingCompositeLiteral
// If we are already in a key-value expression, we don't want a snippet.
if clInfo.kv != nil {
return nil
}
snip := &snippet.Builder{}
// A plain snippet turns "Foo{Ba<>" into "Foo{Bar: <>".
snip.WriteText(label + ": ")
snip.WritePlaceholder(func(b *snippet.Builder) {
// A placeholder snippet turns "Foo{Ba<>" into "Foo{Bar: <*int*>".
if c.opts.Placeholders {
b.WriteText(detail)
}
})
// If the cursor position is on a different line from the literal's opening brace,
// we are in a multiline literal.
if c.view.Session().Cache().FileSet().Position(c.pos).Line != c.view.Session().Cache().FileSet().Position(clInfo.cl.Lbrace).Line {
snip.WriteText(",")
}
return snip
}
// functionCallSnippets calculates the snippet for function calls.
func (c *completer) functionCallSnippet(name string, params []string) *snippet.Builder {
// If we are the left side (i.e. "Fun") part of a call expression,
// we don't want a snippet since there are already parens present.
if len(c.path) > 1 {
switch n := c.path[1].(type) {
case *ast.CallExpr:
// The Lparen != Rparen check detects fudged CallExprs we
// inserted when fixing the AST. In this case, we do still need
// to insert the calling "()" parens.
if n.Fun == c.path[0] && n.Lparen != n.Rparen {
return nil
}
case *ast.SelectorExpr:
if len(c.path) > 2 {
if call, ok := c.path[2].(*ast.CallExpr); ok && call.Fun == c.path[1] && call.Lparen != call.Rparen {
return nil
}
}
}
}
snip := &snippet.Builder{}
snip.WriteText(name + "(")
if c.opts.Placeholders {
// A placeholder snippet turns "someFun<>" into "someFunc(<*i int*>, *s string*)".
for i, p := range params {
if i > 0 {
snip.WriteText(", ")
}
snip.WritePlaceholder(func(b *snippet.Builder) {
b.WriteText(p)
})
}
} else {
// A plain snippet turns "someFun<>" into "someFunc(<>)".
if len(params) > 0 {
snip.WritePlaceholder(nil)
}
}
snip.WriteText(")")
return snip
}