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) Equals(f2 Filter) bool
• type Link
• type OrClause
  • func FilterListToOrClause(filters []Filter) OrClause
  • func (oc OrClause) Flatten() [][]Filter
• type PathPattern
• type Pattern
  • func (p Pattern) String() string
• type Query
  • func Parse(r io.Reader) (Query, error)
• 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
• type Token
• type WhereClause

Constants

const (
	PATTERN_SINGLE = iota + 1
	PATTERN_ZERO_ONE
	PATTERN_ONE_PLUS
	PATTERN_ZERO_PLUS
)

const ASTERISK = 57364

const BAR = 57365

const COMMA = 57354

const COUNT = 57347

const DISTINCT = 57348

const DOT = 57359

const LBRACE = 57355

const LBRACK = 57369

const LIMIT = 57353

const LINK = 57366

const LPAREN = 57357

const NUMBER = 57371

const OR = 57350

const PARTIAL = 57352

const PLUS = 57362

const QUESTION = 57363

const RBRACE = 57356

const RBRACK = 57370

const RPAREN = 57358

const SELECT = 57346

const SEMICOLON = 57360

const SLASH = 57361

const UNION = 57351

const URI = 57368

const VAR = 57367

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) Equals

func (f Filter) Equals(f2 Filter) bool

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
}

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)

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
}

type Token

type Token uint32

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

type WhereClause

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