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// Copyright 2021 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 typeparams
import (
"fmt"
"go/ast"
"go/token"
)
func PackIndexExpr(x ast.Expr, lbrack token.Pos, exprs []ast.Expr, rbrack token.Pos) ast.Expr {
switch len(exprs) {
case 0:
panic("internal error: PackIndexExpr with empty expr slice")
case 1:
return &ast.IndexExpr{
X: x,
Lbrack: lbrack,
Index: exprs[0],
Rbrack: rbrack,
}
default:
return &ast.MultiIndexExpr{
X: x,
Lbrack: lbrack,
Indices: exprs,
Rbrack: rbrack,
}
}
}
// IndexExpr wraps an ast.IndexExpr or ast.MultiIndexExpr into the
// MultiIndexExpr interface.
//
// Orig holds the original ast.Expr from which this IndexExpr was derived.
type IndexExpr struct {
Orig ast.Expr // the wrapped expr, which may be distinct from MultiIndexExpr below.
*ast.MultiIndexExpr
}
func UnpackIndexExpr(n ast.Node) *IndexExpr {
switch e := n.(type) {
case *ast.IndexExpr:
return &IndexExpr{e, &ast.MultiIndexExpr{
X: e.X,
Lbrack: e.Lbrack,
Indices: []ast.Expr{e.Index},
Rbrack: e.Rbrack,
}}
case *ast.MultiIndexExpr:
return &IndexExpr{e, e}
}
return nil
}
func Get(n ast.Node) *ast.FieldList {
switch n := n.(type) {
case *ast.TypeSpec:
return n.TParams
case *ast.FuncType:
return n.TParams
default:
panic(fmt.Sprintf("node type %T has no type parameters", n))
}
}
func Set(n ast.Node, params *ast.FieldList) {
switch n := n.(type) {
case *ast.TypeSpec:
n.TParams = params
case *ast.FuncType:
n.TParams = params
default:
panic(fmt.Sprintf("node type %T has no type parameters", n))
}
}
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