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// 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 (
"fmt"
"go/ast"
"golang.org/x/tools/internal/lsp/snippet"
)
// structFieldSnippets calculates the plain and placeholder snippets for struct literal field names.
func (c *completer) structFieldSnippets(label, detail string) (*snippet.Builder, *snippet.Builder) {
if !c.inCompositeLiteralField {
return nil, nil
}
lit := c.enclosingCompositeLiteral
kv := c.enclosingKeyValue
// If we aren't in a composite literal or are already in a key-value expression,
// we don't want a snippet.
if lit == nil || kv != nil {
return nil, nil
}
// First, confirm that we are actually completing a struct field.
if len(lit.Elts) > 0 {
i := indexExprAtPos(c.pos, lit.Elts)
if i >= len(lit.Elts) {
return nil, nil
}
// If the expression is not an identifer, it is not a struct field name.
if _, ok := lit.Elts[i].(*ast.Ident); !ok {
return nil, nil
}
}
plain, placeholder := &snippet.Builder{}, &snippet.Builder{}
label = fmt.Sprintf("%s: ", label)
// A plain snippet turns "Foo{Ba<>" into "Foo{Bar: <>".
plain.WriteText(label)
plain.WritePlaceholder(nil)
// A placeholder snippet turns "Foo{Ba<>" into "Foo{Bar: <*int*>".
placeholder.WriteText(label)
placeholder.WritePlaceholder(func(b *snippet.Builder) {
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.FileSet().Position(c.pos).Line != c.view.FileSet().Position(lit.Lbrace).Line {
plain.WriteText(",")
placeholder.WriteText(",")
}
return plain, placeholder
}
// functionCallSnippets calculates the plain and placeholder snippets for function calls.
func (c *completer) functionCallSnippets(name string, params []string) (*snippet.Builder, *snippet.Builder) {
for i := 1; i <= 2 && i < len(c.path); i++ {
call, ok := c.path[i].(*ast.CallExpr)
// 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 ok && call.Fun == c.path[i-1] {
return nil, nil
}
}
plain, placeholder := &snippet.Builder{}, &snippet.Builder{}
label := fmt.Sprintf("%s(", name)
// A plain snippet turns "someFun<>" into "someFunc(<>)".
plain.WriteText(label)
if len(params) > 0 {
plain.WritePlaceholder(nil)
}
plain.WriteText(")")
// A placeholder snippet turns "someFun<>" into "someFunc(<*i int*>, *s string*)".
placeholder.WriteText(label)
for i, p := range params {
if i > 0 {
placeholder.WriteText(", ")
}
placeholder.WritePlaceholder(func(b *snippet.Builder) {
b.WriteText(p)
})
}
placeholder.WriteText(")")
return plain, placeholder
}