query

README

query

SQL-like query executor

Query language

It's like SQL, but not SQL. See below.

Supported features

• SELECT * without a GROUP BY.
• Basic WHERE clause
• LIMIT

Unsupported features

These are unsupported at the moment.

• GROUP BY
• JOIN
• ORDER BY

License

BSD (see LICENSE).

Documentation

Index

• Variables
• type ColumnDesc
• type Cursor
• type Executor
  • func NewExecutor(table Table) *Executor
  • func (e *Executor) Execute(query *Query) (*Result, error)
• type Filter
  • func EqualsFilter(column string, value interface{}) Filter
  • func GreaterThanFilter(column string, value interface{}) Filter
  • func GreaterThanOrEqualFilter(column string, value interface{}) Filter
  • func LessThanFilter(column string, value interface{}) Filter
  • func LessThanOrEqualFilter(column string, value interface{}) Filter
  • func MatchesFilter(column string, r *regexp.Regexp) Filter
  • func NotEqualsFilter(column string, value interface{}) Filter
  • func (f Filter) Filter(r Row) bool
• type FilterDesc
• type FilterType
  • func (f FilterType) String() string
• type Query
  • func Parse(query string) (*Query, error)
  • func (q Query) String() string
• type Result
  • func (res *Result) Rows() []Row
• type Row
• type Table

Variables

var (
	ErrUnsupported = errors.New("query: unsupported query")
)

Types

type ColumnDesc

type ColumnDesc struct {
	Name      string `json:"name"`
	Aggregate string `json:"aggregate,omitempty"`
}

ColumnDesc describes a column.

type Cursor

type Cursor interface {
	Row() Row
	Next() bool
	Err() error
}

type Executor

type Executor struct {
	// contains filtered or unexported fields
}

Executor is a query executor.

func NewExecutor

func NewExecutor(table Table) *Executor

func (*Executor) Execute

func (e *Executor) Execute(query *Query) (*Result, error)

Execute executes a query and returns a set of rows for the result.

type Filter

type Filter struct {
	// contains filtered or unexported fields
}

func EqualsFilter

func EqualsFilter(column string, value interface{}) Filter

func GreaterThanFilter

func GreaterThanFilter(column string, value interface{}) Filter

func GreaterThanOrEqualFilter

func GreaterThanOrEqualFilter(column string, value interface{}) Filter

func LessThanFilter

func LessThanFilter(column string, value interface{}) Filter

func LessThanOrEqualFilter

func LessThanOrEqualFilter(column string, value interface{}) Filter

func MatchesFilter

func MatchesFilter(column string, r *regexp.Regexp) Filter

func NotEqualsFilter

func NotEqualsFilter(column string, value interface{}) Filter

func (Filter) Filter

func (f Filter) Filter(r Row) bool

type FilterDesc

type FilterDesc struct {
	Column   string      `json:"column"`
	Operator string      `json:"operator"`
	Value    interface{} `json:"value"`
}

FilterDesc represents a filter expression.

type FilterType

type FilterType int

const (
	FilterUnknown FilterType = iota
	FilterEquals
	FilterNotEquals
	FilterLessThan
	FilterLessThanOrEqual
	FilterGreaterThan
	FilterGreaterThanOrEqual
	FilterMatches
)

func (FilterType) String

func (f FilterType) String() string

type Query

type Query struct {
	Columns    []ColumnDesc `json:"columns,omitempty"`
	GroupBy    []ColumnDesc `json:"group_by,omitempty"`
	Filters    []FilterDesc `json:"filters,omitempty"`
	OrderBy    []ColumnDesc `json:"order_by,omitempty"`
	Descending bool         `json:"descending"`
	Limit      int          `json:"limit,omitempty"`
}

Query describes a query.

func Parse

func Parse(query string) (*Query, error)

func (Query) String

func (q Query) String() string

type Result

type Result struct {
	// contains filtered or unexported fields
}

func (*Result) Rows

func (res *Result) Rows() []Row

type Row

type Row interface {
	Fields() []string
	Get(field string) (interface{}, bool)
}

type Table

type Table interface {
	NewCursor() (Cursor, error)
}