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+[![Go Report Card](https://goreportcard.com/badge/github.com/go-toolsmith/astcast)](https://goreportcard.com/report/github.com/go-toolsmith/astcast)
+[![GoDoc](https://godoc.org/github.com/go-toolsmith/astcast?status.svg)](https://godoc.org/github.com/go-toolsmith/astcast)
+
+# astcast
+
+Package astcast wraps type assertion operations in such way that you don't have
+to worry about nil pointer results anymore.
+
+## Installation
+
+```bash
+go get -v 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)
+}
+```