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3d643c64ae
Add support for literal completion candidates such as "[]int{}" or
"make([]int, 0)". We support both named and unnamed types. I used the
existing type matching logic, so, for example, if the expected type is
an interface, we will suggest literal candidates that implement the
interface.
The literal candidates have a lower score than normal matching
candidates, so they shouldn't be disruptive in cases where you don't
want a literal candidate.
This commit adds support for slice, array, struct, map, and channel
literal candidates since they are pretty similar. Functions will be
supported in a subsequent commit.
I also added support for setting a snippet's final tab stop. This is
useful if you want the cursor to end up somewhere other than the
character after the snippet.
Change-Id: Id3b74260fff4d61703989b422267021b00cec005
Reviewed-on: https://go-review.googlesource.com/c/tools/+/193698
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
94 lines
2.9 KiB
Go
94 lines
2.9 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package snippet implements the specification for the LSP snippet format.
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//
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// Snippets are "tab stop" templates returned as an optional attribute of LSP
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// completion candidates. As the user presses tab, they cycle through a series of
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// tab stops defined in the snippet. Each tab stop can optionally have placeholder
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// text, which can be pre-selected by editors. For a full description of syntax
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// and features, see "Snippet Syntax" at
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// https://microsoft.github.io/language-server-protocol/specification#textDocument_completion.
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//
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// A typical snippet looks like "foo(${1:i int}, ${2:s string})".
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package snippet
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import (
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"fmt"
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"strings"
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)
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// A Builder is used to build an LSP snippet piecemeal.
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// The zero value is ready to use. Do not copy a non-zero Builder.
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type Builder struct {
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// currentTabStop is the index of the previous tab stop. The
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// next tab stop will be currentTabStop+1.
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currentTabStop int
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sb strings.Builder
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}
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// Escape characters defined in https://microsoft.github.io/language-server-protocol/specification#textDocument_completion under "Grammar".
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var replacer = strings.NewReplacer(
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`\`, `\\`,
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`}`, `\}`,
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`$`, `\$`,
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)
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func (b *Builder) WriteText(s string) {
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replacer.WriteString(&b.sb, s)
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}
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// WritePlaceholder writes a tab stop and placeholder value to the Builder.
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// The callback style allows for creating nested placeholders. To write an
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// empty tab stop, provide a nil callback.
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func (b *Builder) WritePlaceholder(fn func(*Builder)) {
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fmt.Fprintf(&b.sb, "${%d:", b.nextTabStop())
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if fn != nil {
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fn(b)
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}
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b.sb.WriteByte('}')
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}
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// WriteFinalTabstop marks where cursor ends up after the user has
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// cycled through all the normal tab stops. It defaults to the
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// character after the snippet.
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func (b *Builder) WriteFinalTabstop() {
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fmt.Fprint(&b.sb, "$0")
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}
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// In addition to '\', '}', and '$', snippet choices also use '|' and ',' as
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// meta characters, so they must be escaped within the choices.
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var choiceReplacer = strings.NewReplacer(
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`\`, `\\`,
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`}`, `\}`,
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`$`, `\$`,
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`|`, `\|`,
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`,`, `\,`,
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)
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// WriteChoice writes a tab stop and list of text choices to the Builder.
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// The user's editor will prompt the user to choose one of the choices.
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func (b *Builder) WriteChoice(choices []string) {
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fmt.Fprintf(&b.sb, "${%d|", b.nextTabStop())
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for i, c := range choices {
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if i != 0 {
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b.sb.WriteByte(',')
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}
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choiceReplacer.WriteString(&b.sb, c)
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}
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b.sb.WriteString("|}")
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}
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// String returns the built snippet string.
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func (b *Builder) String() string {
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return b.sb.String()
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}
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// nextTabStop returns the next tab stop index for a new placeholder.
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func (b *Builder) nextTabStop() int {
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// Tab stops start from 1, so increment before returning.
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b.currentTabStop++
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return b.currentTabStop
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}
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