Start refactor how qemu-system commands are built

qemucli/str_arg.go

@@ -0,0 +1,54 @@
+package qemucli
+
+import (
+	"github.com/pkg/errors"
+)
+
+type StringArg struct {
+	key   string
+	value string
+}
+
+func MustNewStringArg(key string, value string) *StringArg {
+	a, err := NewStringArg(key, value)
+	if err != nil {
+		panic(err)
+	}
+
+	return a
+}
+
+func NewStringArg(key string, value string) (*StringArg, error) {
+	a := &StringArg{
+		key:   key,
+		value: value,
+	}
+
+	// Preflight arg key/type check.
+	err := validateArgKey(a.key, a.ValueType())
+	if err != nil {
+		return nil, errors.Wrap(err, "validate arg key")
+	}
+
+	err = validateArgStrValue(a.value)
+	if err != nil {
+		return nil, errors.Wrap(err, "validate str value")
+	}
+
+	return a, nil
+}
+
+func (a *StringArg) StringKey() string {
+	return a.key
+}
+
+func (a *StringArg) StringValue() string {
+	// We're not validating anything here because
+	// we expect that the string value was validated
+	// at the creation of the StringArg.
+	return a.value
+}
+
+func (a *StringArg) ValueType() ArgAcceptedValue {
+	return ArgAcceptedValueString
+}