func updateDict()

in starlark/library.go [2221:2283]

• 55 lines of code
• 16 McCabe index (conditional complexity)

func updateDict(dict *Dict, updates Tuple, kwargs []Tuple) error {
	if len(updates) == 1 {
		switch updates := updates[0].(type) {
		case IterableMapping:
			// Iterate over dict's key/value pairs, not just keys.
			for _, item := range updates.Items() {
				if err := dict.SetKey(item[0], item[1]); err != nil {
					return err // dict is frozen
				}
			}
		default:
			// all other sequences
			iter := Iterate(updates)
			if iter == nil {
				return fmt.Errorf("got %s, want iterable", updates.Type())
			}
			defer iter.Done()
			var pair Value
			for i := 0; iter.Next(&pair); i++ {
				iter2 := Iterate(pair)
				if iter2 == nil {
					return fmt.Errorf("dictionary update sequence element #%d is not iterable (%s)", i, pair.Type())

				}
				defer iter2.Done()
				len := Len(pair)
				if len < 0 {
					return fmt.Errorf("dictionary update sequence element #%d has unknown length (%s)", i, pair.Type())
				} else if len != 2 {
					return fmt.Errorf("dictionary update sequence element #%d has length %d, want 2", i, len)
				}
				var k, v Value
				iter2.Next(&k)
				iter2.Next(&v)
				if err := dict.SetKey(k, v); err != nil {
					return err
				}
			}
		}
	}

	// Then add the kwargs.
	before := dict.Len()
	for _, pair := range kwargs {
		if err := dict.SetKey(pair[0], pair[1]); err != nil {
			return err // dict is frozen
		}
	}
	// In the common case, each kwarg will add another dict entry.
	// If that's not so, check whether it is because there was a duplicate kwarg.
	if dict.Len() < before+len(kwargs) {
		keys := make(map[String]bool, len(kwargs))
		for _, kv := range kwargs {
			k := kv[0].(String)
			if keys[k] {
				return fmt.Errorf("duplicate keyword arg: %v", k)
			}
			keys[k] = true
		}
	}

	return nil
}