https://github.com/go-toolsmith/astcast
Package astcast wraps type assertion operations in such way that you don't have to worry about nil pointer results anymore.
https://github.com/go-toolsmith/astcast
ast cast coercion convert go golang
Last synced: 5 months ago
JSON representation
Package astcast wraps type assertion operations in such way that you don't have to worry about nil pointer results anymore.
- Host: GitHub
- URL: https://github.com/go-toolsmith/astcast
- Owner: go-toolsmith
- License: mit
- Created: 2018-10-28T20:14:46.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2025-08-17T10:22:41.000Z (10 months ago)
- Last Synced: 2025-08-17T12:17:24.961Z (10 months ago)
- Topics: ast, cast, coercion, convert, go, golang
- Language: Go
- Size: 18.6 KB
- Stars: 4
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# astcast
[![build-img]][build-url]
[![pkg-img]][pkg-url]
[![reportcard-img]][reportcard-url]
[![version-img]][version-url]
Package `astcast` wraps type assertion operations in such way that you don't have
to worry about nil pointer results anymore.
## Installation
Go version 1.16+
```bash
go get github.com/go-toolsmith/astcast
```
## Example
```go
package main
import (
"fmt"
"github.com/go-toolsmith/astcast"
"github.com/go-toolsmith/strparse"
)
func main() {
x := strparse.Expr(`(foo * bar) + 1`)
// x type is ast.Expr, we want to access bar operand
// that is a RHS of the LHS of the addition.
// Note that addition LHS (X field) is has parenthesis,
// so we have to remove them too.
add := astcast.ToBinaryExpr(x)
mul := astcast.ToBinaryExpr(astcast.ToParenExpr(add.X).X)
bar := astcast.ToIdent(mul.Y)
fmt.Printf("%T %s\n", bar, bar.Name) // => *ast.Ident bar
// If argument has different dynamic type,
// non-nil sentinel object of requested type is returned.
// Those sentinel objects are exported so if you need
// to know whether it was a nil interface value of
// failed type assertion, you can compare returned
// object with such a sentinel.
y := astcast.ToCallExpr(strparse.Expr(`x`))
if y == astcast.NilCallExpr {
fmt.Println("it is a sentinel, type assertion failed")
}
}
```
Without `astcast`, you would have to do a lots of type assertions:
```go
package main
import (
"fmt"
"github.com/go-toolsmith/strparse"
)
func main() {
x := strparse.Expr(`(foo * bar) + 1`)
add, ok := x.(*ast.BinaryExpr)
if !ok || add == nil {
return
}
additionLHS, ok := add.X.(*ast.ParenExpr)
if !ok || additionLHS == nil {
return
}
mul, ok := additionLHS.X.(*ast.BinaryExpr)
if !ok || mul == nil {
return
}
bar, ok := mul.Y.(*ast.Ident)
if !ok || bar == nil {
return
}
fmt.Printf("%T %s\n", bar, bar.Name)
}
```
## License
[MIT License](LICENSE).
[build-img]: https://github.com/go-toolsmith/astcast/workflows/build/badge.svg
[build-url]: https://github.com/go-toolsmith/astcast/actions
[pkg-img]: https://pkg.go.dev/badge/go-toolsmith/astcast
[pkg-url]: https://pkg.go.dev/github.com/go-toolsmith/astcast
[reportcard-img]: https://goreportcard.com/badge/go-toolsmith/astcast
[reportcard-url]: https://goreportcard.com/report/go-toolsmith/astcast
[version-img]: https://img.shields.io/github/v/release/go-toolsmith/astcast
[version-url]: https://github.com/go-toolsmith/astcast/releases