Manage errors

errors.go

@@ -0,0 +1,68 @@
+package gonfig
+
+import (
+	"errors"
+	"reflect"
+	"strings"
+)
+
+var (
+	// Can not handle specified type
+	ErrUnsupportedType = errors.New("unsupported type")
+
+	// Field is required but no value provided
+	ErrMissingValue = errors.New("missing value")
+
+	// Could not parse the string value
+	ErrParsing = errors.New("failed parsing")
+
+	// Value overflows type
+	ErrValueOverflow = errors.New("value overflow")
+)
+
+const (
+	missingValueErrFormat           = `%w: "%v" is required`
+	unsupportedTypeErrFormat        = `%w: cannot handle type "%v" at "%v"`
+	unsupportedElementTypeErrFormat = `%w: cannot handle slice/array of "%v" at "%v"`
+	parseErrFormat                  = `%w at "%v": %v`
+	overflowErrFormat               = `%w: "%v" overflows type "%v" at "%v"`
+)
+
+// An InvalidInputError describes an invalid argument passed to Into function
+// The argument must be a non-nil struct pointer
+type InvalidInputError struct {
+	Type  reflect.Type
+	Value reflect.Value
+}
+
+func (e *InvalidInputError) Error() string {
+	msg := "gonfig: invalid input: "
+
+	if e.Type == nil {
+		msg += "nil"
+	} else if e.Type.Kind() != reflect.Ptr {
+		msg += "non-pointer type"
+	} else if e.Value.IsNil() {
+		msg += "nil pointer"
+	} else {
+		msg += "non-struct type"
+	}
+
+	return msg
+}
+
+// Collection of errors during populating the input struct
+type ConfigErrors []error
+
+func (ce ConfigErrors) Error() string {
+	if len(ce) == 0 {
+		return ""
+	}
+
+	msg := "gonfig:\n"
+	for i := range ce {
+		msg += "  * " + ce[i].Error() + "\n"
+	}
+
+	return strings.TrimSpace(msg)
+}