query

README

Hod Query

What to preserve from SPARQL:

• top level: basic, flexible graph pattern matching
• variables for linking records
• select, select distinct
• property paths (https://www.w3.org/TR/sparql11-query/#propertypaths)

Documentation

Index

• Constants
• func FlattenOrClauseList(oclist []OrClause) [][]Filter
• func TokenName(t Token) string
• type Definition
• type Filter
  • func (f Filter) Copy() Filter
  • func (f Filter) Equals(f2 Filter) bool
  • func (f Filter) NumVars() int
  • func (f Filter) String() string
• type Link
• type OrClause
  • func FilterListToOrClause(filters []Filter) OrClause
  • func (oc OrClause) Flatten() [][]Filter
• type PathPattern
  • func (pp PathPattern) String() string
• type Pattern
  • func (p Pattern) String() string
• type Query
  • func Parse(r io.Reader) (Query, error)
  • func (q Query) Copy() Query
  • func (q Query) Hash(orTerms [][]Filter) []byte
• type Result
• type Scanner
  • func NewScanner(defs []Definition) *Scanner
  • func (s *Scanner) Next() *Result
  • func (s *Scanner) ScanWords(data []byte, atEOF bool) (advance int, token []byte, err error)
  • func (s *Scanner) SetInput(input io.Reader)
  • func (s *Scanner) Tokenize() []*Result
• type SelectClause
• type SelectVar
  • func (v SelectVar) Copy() SelectVar
• type Token
• type WhereClause

Constants

const (
	PATTERN_SINGLE = iota + 1
	PATTERN_ZERO_ONE
	PATTERN_ONE_PLUS
	PATTERN_ZERO_PLUS
)

const ASTERISK = 57366

const BAR = 57367

const COMMA = 57356

const COUNT = 57347

const DISTINCT = 57348

const DOT = 57361

const FULLURI = 57371

const LBRACE = 57357

const LBRACK = 57372

const LIMIT = 57353

const LINK = 57368

const LITERAL = 57375

const LPAREN = 57359

const NAMESPACE = 57355

const NUMBER = 57374

const OR = 57350

const PARTIAL = 57352

const PLUS = 57364

const PREFIX = 57354

const QUESTION = 57365

const RBRACE = 57358

const RBRACK = 57373

const RPAREN = 57360

const SELECT = 57346

const SEMICOLON = 57362

const SLASH = 57363

const UNION = 57351

const URI = 57370

const VAR = 57369

const WHERE = 57349

Functions

func FlattenOrClauseList

func FlattenOrClauseList(oclist []OrClause) [][]Filter

func TokenName

func TokenName(t Token) string

Types

type Definition

type Definition struct {
	Token   Token
	Pattern string
	// contains filtered or unexported fields
}

type Filter

type Filter struct {
	Subject turtle.URI
	Path    []PathPattern
	Object  turtle.URI
}

func (Filter) Copy

func (f Filter) Copy() Filter

func (Filter) Equals

func (f Filter) Equals(f2 Filter) bool

func (Filter) NumVars

func (f Filter) NumVars() int

func (Filter) String

func (f Filter) String() string

type Link

type Link struct {
	Name string
}

type OrClause

type OrClause struct {
	// a component of an OR clause
	Terms []Filter
	// pointer to the left/right of OR clause
	// These are nestable
	LeftOr     []OrClause
	LeftTerms  []Filter
	RightOr    []OrClause
	RightTerms []Filter
}

func FilterListToOrClause

func FilterListToOrClause(filters []Filter) OrClause

func (OrClause) Flatten

func (oc OrClause) Flatten() [][]Filter

returns a flat list of triples that comes from expanding out the OrClause tree

type PathPattern

type PathPattern struct {
	Predicate turtle.URI
	Pattern   Pattern
}

func (PathPattern) String

func (pp PathPattern) String() string

type Pattern

type Pattern uint

func (Pattern) String

func (p Pattern) String() string

type Query

type Query struct {
	Select SelectClause
	Where  WhereClause
}

func Parse

func Parse(r io.Reader) (Query, error)

func (Query) Copy

func (q Query) Copy() Query

func (Query) Hash

func (q Query) Hash(orTerms [][]Filter) []byte

generate a unique hash for this query. To do this, we SORT the components (Select.Variables, Where.Filters, Where.Ors), and then append them together to create the hash

type Result

type Result struct {
	Token Token
	Value []byte
	Line  int
}

type Scanner

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

func NewScanner

func NewScanner(defs []Definition) *Scanner

func (*Scanner) Next

func (s *Scanner) Next() *Result

func (*Scanner) ScanWords

func (s *Scanner) ScanWords(data []byte, atEOF bool) (advance int, token []byte, err error)

slightly altered version of https://golang.org/src/bufio/scan.go?s=12794:12872 to keep track of line numbers

func (*Scanner) SetInput

func (s *Scanner) SetInput(input io.Reader)

func (*Scanner) Tokenize

func (s *Scanner) Tokenize() []*Result

type SelectClause

type SelectClause struct {
	Variables []SelectVar
	Distinct  bool
	Count     bool
	Partial   bool
	HasLinks  bool
	Limit     int
}

type SelectVar

type SelectVar struct {
	Var      turtle.URI
	AllLinks bool
	Links    []Link
}

func (SelectVar) Copy

func (v SelectVar) Copy() SelectVar

type Token

type Token uint32

const (
	EOF Token = 1<<32 - 1 - iota
	Error
)

type WhereClause

type WhereClause struct {
	Filters []Filter
	Ors     []OrClause
}