index.gno

  1package datastore
  2
  3import (
  4	"gno.land/p/moul/collection"
  5)
  6
  7// DefaultIndexOptions defines the default options for new indexes.
  8const DefaultIndexOptions = collection.DefaultIndex | collection.SparseIndex
  9
 10type (
 11	// IndexFn defines a type for single value indexing functions.
 12	// This type of function extracts a single string value from
 13	// a record that is then used to index it.
 14	IndexFn func(Record) string
 15
 16	// IndexMultiValueFn defines a type for multi value indexing functions.
 17	// This type of function extracts multiple string values from a
 18	// record that are then used to index it.
 19	IndexMultiValueFn func(Record) []string
 20
 21	// Index defines a type for custom user defined storage indexes.
 22	// Storages are by default indexed by the auto geneated record ID
 23	// but can additionally be indexed by other custom record fields.
 24	Index struct {
 25		name    string
 26		options collection.IndexOption
 27		fn      interface{}
 28	}
 29)
 30
 31// NewIndex creates a new single value index.
 32//
 33// Usage example:
 34//
 35//	// Index a User record by email
 36//	idx := NewIndex("email", func(r Record) string {
 37//	  return r.MustGet("email").(string)
 38//	})
 39func NewIndex(name string, fn IndexFn) Index {
 40	return Index{
 41		name:    name,
 42		options: DefaultIndexOptions,
 43		fn: func(v interface{}) string {
 44			return fn(v.(Record))
 45		},
 46	}
 47}
 48
 49// NewMultiValueIndex creates a new multi value index.
 50//
 51// Usage example:
 52//
 53//	// Index a Post record by tag
 54//	idx := NewMultiValueIndex("tag", func(r Record) []string {
 55//	  return r.MustGet("tags").([]string)
 56//	})
 57func NewMultiValueIndex(name string, fn IndexMultiValueFn) Index {
 58	return Index{
 59		name:    name,
 60		options: DefaultIndexOptions,
 61		fn: func(v interface{}) []string {
 62			return fn(v.(Record))
 63		},
 64	}
 65}
 66
 67// Name returns index's name.
 68func (idx Index) Name() string {
 69	return idx.name
 70}
 71
 72// Options returns current index options.
 73// These options define the index behavior regarding case sensitivity and uniquenes.
 74func (idx Index) Options() collection.IndexOption {
 75	return idx.options
 76}
 77
 78// Func returns the function that storage collections apply
 79// to each record to get the value to use for indexing it.
 80func (idx Index) Func() interface{} {
 81	return idx.fn
 82}
 83
 84// Unique returns a copy of the index that indexes record values as unique values.
 85// Returned index contains previous options plus the unique one.
 86func (idx Index) Unique() Index {
 87	if idx.options&collection.UniqueIndex == 0 {
 88		idx.options |= collection.UniqueIndex
 89	}
 90	return idx
 91}
 92
 93// CaseInsensitive returns a copy of the index that indexes record values ignoring casing.
 94// Returned index contains previous options plus the case insensitivity one.
 95func (idx Index) CaseInsensitive() Index {
 96	if idx.options&collection.CaseInsensitiveIndex == 0 {
 97		idx.options |= collection.CaseInsensitiveIndex
 98	}
 99	return idx
100}