cuntdb/iterate.go

package buntdb

import "github.com/tidwall/match"

// AscendKeys allows for iterating through keys based on the specified pattern.
func (tx *Tx) AscendKeys(pattern string,
	iterator func(key, value string) bool) error {
	if pattern == "" {
		return nil
	}
	if pattern[0] == '*' {
		if pattern == "*" {
			return tx.Ascend("", iterator)
		}
		return tx.Ascend("", func(key, value string) bool {
			if match.Match(key, pattern) {
				if !iterator(key, value) {
					return false
				}
			}
			return true
		})
	}
	min, max := match.Allowable(pattern)
	return tx.AscendGreaterOrEqual("", min, func(key, value string) bool {
		if key > max {
			return false
		}
		if match.Match(key, pattern) {
			if !iterator(key, value) {
				return false
			}
		}
		return true
	})
}

// DescendKeys allows for iterating through keys based on the specified pattern.
func (tx *Tx) DescendKeys(pattern string,
	iterator func(key, value string) bool) error {
	if pattern == "" {
		return nil
	}
	if pattern[0] == '*' {
		if pattern == "*" {
			return tx.Descend("", iterator)
		}
		return tx.Descend("", func(key, value string) bool {
			if match.Match(key, pattern) {
				if !iterator(key, value) {
					return false
				}
			}
			return true
		})
	}
	min, max := match.Allowable(pattern)
	return tx.DescendLessOrEqual("", max, func(key, value string) bool {
		if key < min {
			return false
		}
		if match.Match(key, pattern) {
			if !iterator(key, value) {
				return false
			}
		}
		return true
	})
}

// Ascend calls the iterator for every item in the database within the range
// [first, last], until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) Ascend(index string,
	iterator func(key, value string) bool) error {
	return tx.scan(false, false, false, index, "", "", iterator)
}

// AscendGreaterOrEqual calls the iterator for every item in the database within
// the range [pivot, last], until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) AscendGreaterOrEqual(index, pivot string,
	iterator func(key, value string) bool) error {
	return tx.scan(false, true, false, index, pivot, "", iterator)
}

// AscendLessThan calls the iterator for every item in the database within the
// range [first, pivot), until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) AscendLessThan(index, pivot string,
	iterator func(key, value string) bool) error {
	return tx.scan(false, false, true, index, pivot, "", iterator)
}

// AscendRange calls the iterator for every item in the database within
// the range [greaterOrEqual, lessThan), until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) AscendRange(index, greaterOrEqual, lessThan string,
	iterator func(key, value string) bool) error {
	return tx.scan(
		false, true, true, index, greaterOrEqual, lessThan, iterator,
	)
}

// Descend calls the iterator for every item in the database within the range
// [last, first], until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) Descend(index string,
	iterator func(key, value string) bool) error {
	return tx.scan(true, false, false, index, "", "", iterator)
}

// DescendGreaterThan calls the iterator for every item in the database within
// the range [last, pivot), until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) DescendGreaterThan(index, pivot string,
	iterator func(key, value string) bool) error {
	return tx.scan(true, true, false, index, pivot, "", iterator)
}

// DescendLessOrEqual calls the iterator for every item in the database within
// the range [pivot, first], until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) DescendLessOrEqual(index, pivot string,
	iterator func(key, value string) bool) error {
	return tx.scan(true, false, true, index, pivot, "", iterator)
}

// DescendRange calls the iterator for every item in the database within
// the range [lessOrEqual, greaterThan), until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) DescendRange(index, lessOrEqual, greaterThan string,
	iterator func(key, value string) bool) error {
	return tx.scan(
		true, true, true, index, lessOrEqual, greaterThan, iterator,
	)
}

// AscendEqual calls the iterator for every item in the database that equals
// pivot, until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) AscendEqual(index, pivot string,
	iterator func(key, value string) bool) error {
	var err error
	var less func(a, b string) bool
	if index != "" {
		less, err = tx.GetLess(index)
		if err != nil {
			return err
		}
	}
	return tx.AscendGreaterOrEqual(index, pivot, func(key, value string) bool {
		if less == nil {
			if key != pivot {
				return false
			}
		} else if less(pivot, value) {
			return false
		}
		return iterator(key, value)
	})
}

// DescendEqual calls the iterator for every item in the database that equals
// pivot, until iterator returns false.
// When an index is provided, the results will be ordered by the item values
// as specified by the less() function of the defined index.
// When an index is not provided, the results will be ordered by the item key.
// An invalid index will return an error.
func (tx *Tx) DescendEqual(index, pivot string,
	iterator func(key, value string) bool) error {
	var err error
	var less func(a, b string) bool
	if index != "" {
		less, err = tx.GetLess(index)
		if err != nil {
			return err
		}
	}
	return tx.DescendLessOrEqual(index, pivot, func(key, value string) bool {
		if less == nil {
			if key != pivot {
				return false
			}
		} else if less(value, pivot) {
			return false
		}
		return iterator(key, value)
	})
}