Golang Formalizer.Map方法代码示例

/*
This method qualifies identifiers for all the constituent clauses,
namely the by, letting and having expressions by mapping them.
*/
func (this *Group) Formalize(f *expression.Formalizer) (*expression.Formalizer, error) {
	var err error

	if this.by != nil {
		for i, b := range this.by {
			this.by[i], err = f.Map(b)
			if err != nil {
				return nil, err
			}
		}
	}

	if this.letting != nil {
		_, err = f.PushBindings(this.letting)
		if err != nil {
			return nil, err
		}
	}

	if this.having != nil {
		this.having, err = f.Map(this.having)
		if err != nil {
			return nil, err
		}
	}

	return f, nil
}

func sargableIndexes(indexes []datastore.Index, pred expression.Expression,
	primaryKey expression.Expressions, dnf *DNF, formalizer *expression.Formalizer) (
	map[datastore.Index]*indexEntry, error) {
	var err error
	var keys expression.Expressions
	sargables := make(map[datastore.Index]*indexEntry, len(indexes))

	for _, index := range indexes {
		if index.IsPrimary() {
			keys = primaryKey
		} else {
			keys = index.RangeKey()
			keys = keys.Copy()

			for i, key := range keys {
				key = key.Copy()

				key, err = formalizer.Map(key)
				if err != nil {
					return nil, err
				}

				key, err = dnf.Map(key)
				if err != nil {
					return nil, err
				}

				keys[i] = key
			}
		}

		cond := index.Condition()
		if cond != nil {
			cond = cond.Copy()

			cond, err = formalizer.Map(cond)
			if err != nil {
				return nil, err
			}

			cond, err = dnf.Map(cond)
			if err != nil {
				return nil, err
			}

			if !SubsetOf(pred, cond) {
				continue
			}
		}

		n := SargableFor(pred, keys)
		if n > 0 {
			sargables[index] = &indexEntry{keys, keys[0:n], cond, nil}
		}
	}

	return sargables, nil
}

/*
Fully qualify identifiers for the update-for clause and the path
expression in the unset clause.
*/
func (this *UnsetTerm) Formalize(f *expression.Formalizer) (err error) {
	if this.updateFor != nil {
		sv, err := f.PushBindings(this.updateFor.bindings)
		if err != nil {
			return err
		}

		defer f.PopBindings(sv)
	}

	path, err := f.Map(this.path)
	if err != nil {
		return err
	}

	this.path = path.(expression.Path)
	return
}

/*
Qualify all identifiers for the parent expression. Checks is
a nest alias exists and if it is a duplicate alias.
*/
func (this *IndexNest) Formalize(parent *expression.Formalizer) (f *expression.Formalizer, err error) {
	f, err = this.left.Formalize(parent)
	if err != nil {
		return
	}

	_, ok := f.Allowed.Field(this.keyFor)
	if !ok {
		err = errors.NewUnknownForError("NEST", this.keyFor, "plan.nest.unknown_for")
		return nil, err
	}

	alias := this.Alias()
	if alias == "" {
		err = errors.NewNoTermNameError("NEST", "plan.nest.requires_name_or_alias")
		return nil, err
	}

	_, ok = f.Allowed.Field(alias)
	if ok {
		err = errors.NewDuplicateAliasError("NEST", alias, "plan.nest.duplicate_alias")
		return nil, err
	}

	f.Allowed.SetField(alias, alias)
	f.Keyspace = ""

	var p *expression.Formalizer
	if parent != nil {
		p = parent.Copy()
	} else {
		p = expression.NewFormalizer()
	}

	p.Allowed.SetField(alias, alias)
	this.right.keys, err = p.Map(this.right.keys)
	return
}