func (rt *Runtime) startRepl(ctx context.Context, params *Params) {
banner := rt.getBanner()
repl := repl.New(rt.Store, params.HistoryPath, params.Output, params.OutputFormat, banner)
if params.Watch {
watcher, err := getWatcher(params.Paths)
if err != nil {
fmt.Fprintln(params.Output, "error opening watch:", err)
os.Exit(1)
}
go rt.readWatcher(ctx, watcher, params.Paths)
}
if params.Eval == "" {
repl.Loop(ctx)
} else {
repl.DisableUndefinedOutput(true)
repl.DisableMultiLineBuffering(true)
if err := repl.OneShot(ctx, params.Eval); err != nil {
fmt.Fprintln(params.Output, "error:", err)
os.Exit(1)
}
}
}
func ExampleREPL_OneShot() {
// Initialize context for the example. Normally the caller would obtain the
// context from an input parameter or instantiate their own.
ctx := context.Background()
// Instantiate the policy engine's storage layer.
store := storage.New(storage.InMemoryConfig())
// Create a buffer that will receive REPL output.
var buf bytes.Buffer
// Create a new REPL.
repl := repl.New(store, "", &buf, "json", "")
// Define a rule inside the REPL.
repl.OneShot(ctx, "p :- a = [1, 2, 3, 4], a[_] > 3")
// Query the rule defined above.
repl.OneShot(ctx, "p")
// Inspect the output. Defining rules does not produce output so we only expect
// output from the second line of input.
fmt.Println(buf.String())
// Output:
// true
}