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Merge pull request #149 from rogerlucena/filter-latest-grammar
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FILTER keyword for latest anchor queries (grammar/lexer/hooks)
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@thiagovas
thiagovas authored Oct 9, 2020
2 parents 915bd33 + 13e02b0 commit b515c3e
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Showing 9 changed files with 597 additions and 2 deletions.
36 changes: 36 additions & 0 deletions bql/grammar/grammar.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -327,6 +327,7 @@ func moreClauses() []*Clause {
Elements: []Element{
NewTokenType(lexer.ItemDot),
NewSymbol("CLAUSES"),
NewSymbol("FILTER_CLAUSES"),
},
},
{},
Expand Down Expand Up @@ -365,6 +366,33 @@ func clauses() []*Clause {
}
}

func moreFilterClauses() []*Clause {
return []*Clause{
{
Elements: []Element{
NewTokenType(lexer.ItemDot),
NewSymbol("FILTER_CLAUSES"),
},
},
{},
}
}
func filterClauses() []*Clause {
return []*Clause{
{
Elements: []Element{
NewTokenType(lexer.ItemFilter),
NewTokenType(lexer.ItemFilterFunction),
NewTokenType(lexer.ItemLPar),
NewTokenType(lexer.ItemBinding),
NewTokenType(lexer.ItemRPar),
NewSymbol("MORE_FILTER_CLAUSES"),
},
},
{},
}
}

func optionalClauses() []*Clause {
return []*Clause{
{
Expand Down Expand Up @@ -1266,6 +1294,8 @@ func BQL() *Grammar {
"MORE_CLAUSES": moreClauses(),
"CLAUSES": clauses(),
"OPTIONAL_CLAUSE": optionalClauses(),
"FILTER_CLAUSES": filterClauses(),
"MORE_FILTER_CLAUSES": moreFilterClauses(),
"SUBJECT_EXTRACT": subjectExtractClauses(),
"SUBJECT_TYPE": subjectTypeClauses(),
"SUBJECT_ID": subjectIDClauses(),
Expand Down Expand Up @@ -1400,6 +1430,12 @@ func SemanticBQL() *Grammar {
}
setElementHook(semanticBQL, objSymbols, semantic.WhereObjectClauseHook(), nil)

// Filter clause hook.
filterSymbols := []semantic.Symbol{
"FILTER_CLAUSES",
}
setElementHook(semanticBQL, filterSymbols, semantic.WhereFilterClauseHook(), nil)

// Collect binding variables variables.
varSymbols := []semantic.Symbol{
"VARS", "VARS_AS", "MORE_VARS", "COUNT_DISTINCT",
Expand Down
94 changes: 94 additions & 0 deletions bql/grammar/grammar_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -194,6 +194,20 @@ func TestAcceptByParse(t *testing.T) {
?n "_object"@[] ?o};`,
// Show the graphs.
`show graphs;`,
// Test FILTER clause inside WHERE.
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest(?p)
};`,
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest(?p) .
FILTER latest(?o)
};`,
// Test optional trailing dot after the last clause inside WHERE.
`select ?a
from ?b
Expand Down Expand Up @@ -229,6 +243,19 @@ func TestAcceptByParse(t *testing.T) {
?s ?p ?o .
/u<paul> ?p ?o
};`,
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest(?p) .
};`,
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest(?p) .
FILTER latest(?o) .
};`,
}
p, err := NewParser(BQL())
if err != nil {
Expand Down Expand Up @@ -386,6 +413,46 @@ func TestRejectByParse(t *testing.T) {
where {?n "_subject"@[] ?s.
?n "_predicate"@[] ?p.
?n "_object"@[] ?o};`,
// Test invalid FILTER clause inside WHERE.
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest ?p
};`,
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest (?p)
};`,
`select ?a
from ?b
where {
FILTER latest(?p) .
?s ?p ?o
};`,
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest(?p) .
/u<paul> ?p ?o
};`,
`select ?a
from ?b
where {
?s ?p ?o .
?s ?p ?o .
FILTER latest(?p) .
/u<paul> ?p ?o
};`,
`select ?a
from ?b
where {
?s ?p ?o .
FILTER late^st(?p)
};`,
// Test invalid trailing dot use inside WHERE.
`select ?a
from ?b
Expand All @@ -411,6 +478,19 @@ func TestRejectByParse(t *testing.T) {
?s ?p ?o
/u<paul> ?p ?o
};`,
`select ?a
from ?b
where {
?s ?p ?o
FILTER latest(?p)
};`,
`select ?a
from ?b
where {
?s ?p ?o .
FILTER latest(?p)
FILTER latest(?o)
};`,
}
p, err := NewParser(BQL())
if err != nil {
Expand Down Expand Up @@ -565,6 +645,13 @@ func TestAcceptQueryBySemanticParse(t *testing.T) {
`select ?s from ?g where{/_<foo> as ?s ?p "id"@[?foo, ?bar] as ?o} order by ?s;`,
`select ?s as ?a, ?o as ?b, ?o as ?c from ?g where{?s ?p ?o} order by ?a ASC, ?b DESC;`,
`select ?s as ?a, ?o as ?b, ?o as ?c from ?g where{?s ?p ?o} order by ?a ASC, ?b DESC, ?a ASC, ?b DESC, ?c;`,
// Test valid FILTER clause for grammar with hooks.
`select ?p
from ?b
where {
?s ?p ?o .
FILTER latest(?p)
};`,
}
p, err := NewParser(SemanticBQL())
if err != nil {
Expand Down Expand Up @@ -596,6 +683,13 @@ func TestRejectByParseAndSemantic(t *testing.T) {
`select ?s as ?a, ?o as ?b, ?o as ?c from ?g where{?s ?p ?o} order by ?a ASC, ?a DESC;`,
// Wrong limit literal.
`select ?s as ?a, ?o as ?b, ?o as ?c from ?g where{?s ?p ?o} LIMIT "true"^^type:bool;`,
// Reject not supported FILTER function.
`select ?p, ?o
from ?test
where {
/u<peter> ?p ?o .
FILTER notSupportedFilterFunction(?p)
};`,
}
p, err := NewParser(SemanticBQL())
if err != nil {
Expand Down
35 changes: 35 additions & 0 deletions bql/lexer/lexer.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -139,6 +139,10 @@ const (
ItemGraphs
// ItemOptional identifies optional graph pattern clauses.
ItemOptional
// ItemFilter represents the filter keyword in BQL.
ItemFilter
// ItemFilterFunction represents a filter function in BQL.
ItemFilterFunction
)

func (tt TokenType) String() string {
Expand Down Expand Up @@ -253,6 +257,10 @@ func (tt TokenType) String() string {
return "GRAPHS"
case ItemOptional:
return "OPTIONAL"
case ItemFilter:
return "FILTER"
case ItemFilterFunction:
return "FILTER_FUNCTION"
default:
return "UNKNOWN"
}
Expand Down Expand Up @@ -294,6 +302,7 @@ const (
from = "from"
where = "where"
optional = "optional"
filter = "filter"
as = "as"
before = "before"
after = "after"
Expand Down Expand Up @@ -402,6 +411,9 @@ func lexToken(l *lexer) stateFn {
return lexPredicateOrLiteral
}
if unicode.IsLetter(r) {
if l.lastTokenType == ItemFilter {
return lexFilterFunction
}
return lexKeyword
}
}
Expand Down Expand Up @@ -617,6 +629,10 @@ func lexKeyword(l *lexer) stateFn {
consumeKeyword(l, ItemOptional)
return lexSpace
}
if strings.EqualFold(input, filter) {
consumeKeyword(l, ItemFilter)
return lexSpace
}
if strings.EqualFold(input, typeKeyword) {
consumeKeyword(l, ItemType)
return lexSpace
Expand Down Expand Up @@ -648,6 +664,25 @@ func lexKeyword(l *lexer) stateFn {
return nil
}

// lexFilterFunction lexes a filter function out of the input (used in FILTER clauses).
func lexFilterFunction(l *lexer) stateFn {
l.next()
var nr rune
for {
nr = l.next()
if nr == leftPar {
l.backup()
break
}
if !unicode.IsLetter(nr) {
l.emitError(`invalid rune in filter function: "` + string(nr) + `"; filter functions should be formed only by letters`)
return nil
}
}
l.emit(ItemFilterFunction)
return lexSpace
}

func lexNode(l *lexer) stateFn {
ltID := false
for done := false; !done; {
Expand Down
55 changes: 55 additions & 0 deletions bql/lexer/lexer_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,8 @@ func TestTokenTypeString(t *testing.T) {
{ItemShow, "SHOW"},
{ItemGraphs, "GRAPHS"},
{ItemOptional, "OPTIONAL"},
{ItemFilter, "FILTER"},
{ItemFilterFunction, "FILTER_FUNCTION"},
{TokenType(-1), "UNKNOWN"},
}

Expand Down Expand Up @@ -388,6 +390,29 @@ func TestIndividualTokens(t *testing.T) {
{Type: ItemEOF},
},
},
{
`FILTER latest(?p)`,
[]Token{
{Type: ItemFilter, Text: "FILTER"},
{Type: ItemFilterFunction, Text: "latest"},
{Type: ItemLPar, Text: "("},
{Type: ItemBinding, Text: "?p"},
{Type: ItemRPar, Text: ")"},
{Type: ItemEOF},
},
},
{
`FILTER latest(?p) .`,
[]Token{
{Type: ItemFilter, Text: "FILTER"},
{Type: ItemFilterFunction, Text: "latest"},
{Type: ItemLPar, Text: "("},
{Type: ItemBinding, Text: "?p"},
{Type: ItemRPar, Text: ")"},
{Type: ItemDot, Text: "."},
{Type: ItemEOF},
},
},
}

for _, test := range table {
Expand Down Expand Up @@ -578,6 +603,36 @@ func TestValidTokenQuery(t *testing.T) {
ItemHaving, ItemBinding, ItemEQ, ItemTime, ItemSemicolon, ItemEOF,
},
},
{
`select ?s ?p ?o
from ?foo
where {
?s ?p ?o .
FILTER latest(?p)
};`,
[]TokenType{
ItemQuery, ItemBinding, ItemBinding, ItemBinding, ItemFrom, ItemBinding,
ItemWhere, ItemLBracket, ItemBinding, ItemBinding, ItemBinding, ItemDot,
ItemFilter, ItemFilterFunction, ItemLPar, ItemBinding, ItemRPar,
ItemRBracket, ItemSemicolon, ItemEOF,
},
},
{
`select ?s ?p ?o
from ?foo
where {
?s ?p ?o .
FILTER latest(?p) .
FILTER latest(?o)
};`,
[]TokenType{
ItemQuery, ItemBinding, ItemBinding, ItemBinding, ItemFrom, ItemBinding,
ItemWhere, ItemLBracket, ItemBinding, ItemBinding, ItemBinding, ItemDot,
ItemFilter, ItemFilterFunction, ItemLPar, ItemBinding, ItemRPar, ItemDot,
ItemFilter, ItemFilterFunction, ItemLPar, ItemBinding, ItemRPar,
ItemRBracket, ItemSemicolon, ItemEOF,
},
},
}

for _, test := range table {
Expand Down
5 changes: 5 additions & 0 deletions bql/semantic/convert.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,11 @@ func (c ConsumedElement) Token() *lexer.Token {
return c.token
}

// String returns a string representation of the ConsumedElement.
func (c ConsumedElement) String() string {
return fmt.Sprintf("{isSymbol=%v, symbol=%s, token=%s}", c.isSymbol, c.symbol, c.token)
}

// ToNode converts the node found by the lexer and converts it into a BadWolf
// node.
func ToNode(ce ConsumedElement) (*node.Node, error) {
Expand Down
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