shape

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 Go to latest Published: Nov 27, 2019 License: Apache-2.0 Imports: 10 Imported by: 0

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Index

Constants

This section is empty.

Variables

View Source 
var MaterializeThreshold = 100 // TODO: tune

Functions

func BuildIterator 

func BuildIterator(ctx context.Context, qs graph.QuadStore, s Shape) iterator.Shape

BuildIterator optimizes the shape and builds a corresponding iterator tree.

func IsNull 

func IsNull(s Shape) bool

IsNull safely checks if shape represents an empty set. It accounts for both Null and nil.

func Iterate 

func Iterate(ctx context.Context, qs graph.QuadStore, s Shape) *iterator.Chain

func One 

func One(s Shape) (refs.Ref, bool)

One checks if Shape represents a single fixed value and returns it.

func Walk 

func Walk(s Shape, fnc WalkFunc)

Walk calls provided function for each shape in the tree.

Types

type AllNodes 

type AllNodes struct{}

AllNodes represents all nodes in QuadStore.

func (AllNodes) BuildIterator 

func (s AllNodes) BuildIterator(qs graph.QuadStore) iterator.Shape

func (AllNodes) Optimize 

func (s AllNodes) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Comparison 

type Comparison struct {
	Op  iterator.Operator
	Val quad.Value
}

Comparison is a value filter that evaluates binary operation in reference to a fixed value.

func (Comparison) BuildIterator 

func (f Comparison) BuildIterator(qs graph.QuadStore, it iterator.Shape) iterator.Shape

type Composite 

type Composite interface {
	Simplify() Shape
}

Composite shape can be simplified to a tree of more basic shapes.

type Count 

type Count struct {
	Values Shape
}

Count returns a count of objects in source as a single value. It always returns exactly one value.

func (Count) BuildIterator 

func (s Count) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Count) Optimize 

func (s Count) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Except 

type Except struct {
	Exclude Shape // nodes to exclude
	From    Shape // a set of all nodes to exclude from; nil means AllNodes
}

Except excludes a set on nodes from a source. If source is nil, AllNodes is assumed.

func (Except) BuildIterator 

func (s Except) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Except) Optimize 

func (s Except) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Filter 

type Filter struct {
	From    Shape         // source that will be filtered
	Filters []ValueFilter // filters to apply
}

Filter filters all values from the source using a list of operations.

func (Filter) BuildIterator 

func (s Filter) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Filter) Optimize 

func (s Filter) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Fixed 

type Fixed []refs.Ref

Fixed is a static set of nodes. Defined only for a particular QuadStore.

func (*Fixed) Add 

func (s *Fixed) Add(v ...refs.Ref)

func (Fixed) BuildIterator 

func (s Fixed) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Fixed) Optimize 

func (s Fixed) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type FixedTags 

type FixedTags struct {
	Tags map[string]refs.Ref
	On   Shape
}

FixedTags adds a set of fixed tag values to query results. It does not affect query execution in any other way.

Shape implementations should try to push these objects up the tree during optimization process.

func (FixedTags) BuildIterator 

func (s FixedTags) BuildIterator(qs graph.QuadStore) iterator.Shape

func (FixedTags) Optimize 

func (s FixedTags) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type InternalQuad 

type InternalQuad struct {
	Subject   refs.Ref
	Predicate refs.Ref
	Object    refs.Ref
	Label     refs.Ref
}

InternalQuad is an internal representation of quad index in QuadStore.

func (InternalQuad) Get 

func (q InternalQuad) Get(d quad.Direction) refs.Ref

Get returns a specified direction of the quad.

func (InternalQuad) Set 

func (q InternalQuad) Set(d quad.Direction, v refs.Ref)

Set assigns a specified direction of the quad to a given value.

type Intersect 

type Intersect []Shape

Intersect computes an intersection of nodes between multiple queries. Similar to And iterator.

func (Intersect) BuildIterator 

func (s Intersect) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Intersect) Optimize 

func (s Intersect) Optimize(ctx context.Context, r Optimizer) (sout Shape, opt bool)

type IntersectOpt 

type IntersectOpt struct {
	Sub Intersect
	Opt []Shape
}

IntersectOpt is like Intersect but it also joins optional query shapes to the main query.

func (*IntersectOpt) Add 

func (s *IntersectOpt) Add(arr ...Shape)

func (*IntersectOpt) AddOptional 

func (s *IntersectOpt) AddOptional(arr ...Shape)

func (IntersectOpt) BuildIterator 

func (s IntersectOpt) BuildIterator(qs graph.QuadStore) iterator.Shape

func (IntersectOpt) Optimize 

func (s IntersectOpt) Optimize(ctx context.Context, r Optimizer) (_ Shape, opt bool)

type Lookup 

type Lookup []quad.Value

Lookup is a static set of values that must be resolved to nodes by QuadStore.

func (*Lookup) Add 

func (s *Lookup) Add(v ...quad.Value)

func (Lookup) BuildIterator 

func (s Lookup) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Lookup) Optimize 

func (s Lookup) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Materialize 

type Materialize struct {
	Size   int // approximate size; zero means undefined
	Values Shape
}

Materialize loads results of sub-query into memory during execution to speedup iteration.

func (Materialize) BuildIterator 

func (s Materialize) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Materialize) Optimize 

func (s Materialize) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type NodesFrom 

type NodesFrom struct {
	Dir   quad.Direction
	Quads Shape
}

NodesFrom extracts nodes on a given direction from source quads. Similar to HasA iterator.

func (NodesFrom) BuildIterator 

func (s NodesFrom) BuildIterator(qs graph.QuadStore) iterator.Shape

func (NodesFrom) Optimize 

func (s NodesFrom) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Null 

type Null struct{}

Null represent an empty set. Mostly used as a safe alias for nil shape.

func (Null) BuildIterator 

func (Null) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Null) Optimize 

func (s Null) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Optimizer 

type Optimizer interface {
	OptimizeShape(ctx context.Context, s Shape) (Shape, bool)
}

type Page 

type Page struct {
	From  Shape
	Skip  int64
	Limit int64 // zero means unlimited
}

Page provides a simple form of pagination. Can be used to skip or limit results.

func (Page) ApplyPage 

func (s Page) ApplyPage(p Page) *Page

func (Page) BuildIterator 

func (s Page) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Page) Optimize 

func (s Page) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type QuadFilter 

type QuadFilter struct {
	Dir    quad.Direction
	Values Shape
}

QuadFilter is a constraint used to filter quads that have a certain set of values on a given direction. Analog of LinksTo iterator.

type QuadIndexer 

type QuadIndexer interface {
	// SizeOfIndex returns a size of a quad index with given constraints.
	SizeOfIndex(c map[quad.Direction]refs.Ref) (int64, bool)
	// LookupQuadIndex finds a quad that matches a given constraint.
	// It returns false if quad was not found, or there are multiple quads matching constraint.
	LookupQuadIndex(c map[quad.Direction]refs.Ref) (InternalQuad, bool)
}

QuadIndexer is an optional interface for quad stores that keep an index of quad directions.

It is used to optimize shapes based on stats from these indexes.

type Quads 

type Quads []QuadFilter

Quads is a selector of quads with a given set of node constraints. Empty or nil Quads is equivalent to AllQuads. Equivalent to And(AllQuads,LinksTo*) iterator tree.

func (Quads) BuildIterator 

func (s Quads) BuildIterator(qs graph.QuadStore) iterator.Shape

func (*Quads) Intersect 

func (s *Quads) Intersect(q ...QuadFilter)

func (Quads) Optimize 

func (s Quads) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type QuadsAction 

type QuadsAction struct {
	Size   int64 // approximate size; zero means undefined
	Result quad.Direction
	Save   map[quad.Direction][]string
	Filter map[quad.Direction]refs.Ref
}

QuadsAction represents a set of actions that can be done to a set of quads in a single scan pass. It filters quads according to Filter constraints (equivalent of LinksTo), tags directions using tags in Save field and returns a specified quad direction as result of the iterator (equivalent of HasA). Optionally, Size field may be set to indicate an approximate number of quads that will be returned by this query.

func (QuadsAction) BuildIterator 

func (s QuadsAction) BuildIterator(qs graph.QuadStore) iterator.Shape

func (QuadsAction) Clone 

func (s QuadsAction) Clone() QuadsAction

func (QuadsAction) Optimize 

func (s QuadsAction) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

func (*QuadsAction) SetFilter 

func (s *QuadsAction) SetFilter(d quad.Direction, v refs.Ref)

func (QuadsAction) Simplify 

func (s QuadsAction) Simplify() Shape

func (QuadsAction) SimplifyFrom 

func (s QuadsAction) SimplifyFrom(quads Shape) Shape

type Regexp 

type Regexp struct {
	Re   *regexp.Regexp
	Refs bool // allow to match IRIs
}

Regexp filters values using regular expression.

Since regexp patterns can not be optimized in most cases, Wildcard should be used if possible.

func (Regexp) BuildIterator 

func (f Regexp) BuildIterator(qs graph.QuadStore, it iterator.Shape) iterator.Shape

type Save 

type Save struct {
	Tags []string
	From Shape
}

Save tags a results of query with provided tags.

func (Save) BuildIterator 

func (s Save) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Save) Optimize 

func (s Save) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Shape 

type Shape interface {
	// BuildIterator constructs an iterator tree from a given shapes and binds it to QuadStore.
	BuildIterator(qs graph.QuadStore) iterator.Shape
	// Optimize runs an optimization pass over a query shape.
	//
	// It returns a bool that indicates if shape was replaced and should always return a copy of shape in this case.
	// In case no optimizations were made, it returns the same unmodified shape.
	//
	// If Optimizer is specified, it will be used instead of default optimizations.
	Optimize(ctx context.Context, r Optimizer) (Shape, bool)
}

Shape represent a query tree shape.

func AddFilters 

func AddFilters(nodes Shape, filters ...ValueFilter) Shape

func Compare 

func Compare(nodes Shape, op iterator.Operator, v quad.Value) Shape

func FilterQuads 

func FilterQuads(subject, predicate, object, label []quad.Value) Shape

func Has 

func Has(from, via, nodes Shape, rev bool) Shape

func HasLabels 

func HasLabels(from, via, nodes, labels Shape, rev bool) Shape

func In 

func In(from, via, labels Shape, tags ...string) Shape

func IntersectOptional 

func IntersectOptional(s, opt Shape) Shape

func IntersectShapes 

func IntersectShapes(s1, s2 Shape) Shape

func Labels 

func Labels(from Shape) Shape

func Optimize 

func Optimize(ctx context.Context, s Shape, qs graph.QuadStore) (Shape, bool)

Optimize applies generic optimizations for the tree. If quad store is specified it will also resolve Lookups and apply any specific optimizations. Should not be used with Simplify - it will fold query to a compact form again.

func Out 

func Out(from, via, labels Shape, tags ...string) Shape

func Predicates 

func Predicates(from Shape, in bool) Shape

func SavePredicates 

func SavePredicates(from Shape, in bool, tag string) Shape

func SaveVia 

func SaveVia(from, via Shape, tag string, rev, opt bool) Shape

func SaveViaLabels 

func SaveViaLabels(from, via, labels Shape, tag string, rev, opt bool) Shape

type Sort 

type Sort struct {
	From Shape
}

func (Sort) BuildIterator 

func (s Sort) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Sort) Optimize 

func (s Sort) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Union 

type Union []Shape

Union joins results of multiple queries together. It does not make results unique.

func UnionShapes 

func UnionShapes(s1, s2 Shape) Union

func (Union) BuildIterator 

func (s Union) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Union) Optimize 

func (s Union) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type Unique 

type Unique struct {
	From Shape
}

Unique makes query results unique.

func (Unique) BuildIterator 

func (s Unique) BuildIterator(qs graph.QuadStore) iterator.Shape

func (Unique) Optimize 

func (s Unique) Optimize(ctx context.Context, r Optimizer) (Shape, bool)

type ValueFilter 

type ValueFilter interface {
	BuildIterator(qs graph.QuadStore, it iterator.Shape) iterator.Shape
}

ValueFilter is an interface for iterator wrappers that can filter node values.

type WalkFunc 

type WalkFunc func(Shape) bool

WalkFunc is used to visit all shapes in the tree. If false is returned, branch will not be traversed further.

type Wildcard 

type Wildcard struct {
	Pattern string // allowed wildcards are: % and ?
}

Wildcard is a filter for string patterns. 

% - zero or more characters
? - exactly one character

func (Wildcard) BuildIterator 

func (f Wildcard) BuildIterator(qs graph.QuadStore, it iterator.Shape) iterator.Shape

func (Wildcard) Regexp 

func (f Wildcard) Regexp() string

Regexp returns an analog regexp pattern in format accepted by Go stdlib (RE2).

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