func squashDict()

in rule/merge.go [372:437]
62 lines of code
15 McCabe index (conditional complexity)

func squashDict(x, y *bzl.DictExpr) (*bzl.DictExpr, error) {
	if x == nil {
		return y, nil
	}
	if y == nil {
		return x, nil
	}

	cases := make(map[string]*bzl.KeyValueExpr)
	addCase := func(e bzl.Expr) error {
		kv := e.(*bzl.KeyValueExpr)
		key, ok := kv.Key.(*bzl.StringExpr)
		if !ok {
			return errors.New("could not squash non-string dict key")
		}
		if _, ok := kv.Value.(*bzl.ListExpr); !ok {
			return errors.New("could not squash non-list dict value")
		}
		if c, ok := cases[key.Value]; ok {
			if sq, err := squashList(kv.Value.(*bzl.ListExpr), c.Value.(*bzl.ListExpr)); err != nil {
				return err
			} else {
				c.Value = sq
			}
		} else {
			kvCopy := *kv
			cases[key.Value] = &kvCopy
		}
		return nil
	}

	for _, e := range x.List {
		if err := addCase(e); err != nil {
			return nil, err
		}
	}
	for _, e := range y.List {
		if err := addCase(e); err != nil {
			return nil, err
		}
	}

	keys := make([]string, 0, len(cases))
	haveDefault := false
	for k := range cases {
		if k == "//conditions:default" {
			haveDefault = true
			continue
		}
		keys = append(keys, k)
	}
	sort.Strings(keys)
	if haveDefault {
		keys = append(keys, "//conditions:default") // must be last
	}

	squashed := *x
	squashed.Comments.Before = append(x.Comments.Before, y.Comments.Before...)
	squashed.Comments.Suffix = append(x.Comments.Suffix, y.Comments.Suffix...)
	squashed.Comments.After = append(x.Comments.After, y.Comments.After...)
	squashed.List = make([]*bzl.KeyValueExpr, 0, len(cases))
	for _, k := range keys {
		squashed.List = append(squashed.List, cases[k])
	}
	return &squashed, nil
}