forked from nytlabs/streamtools
/
filter.go
92 lines (78 loc) · 1.51 KB
/
filter.go
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package library
import (
"github.com/nytlabs/gojee"
"github.com/nytlabs/streamtools/st/blocks" // blocks
"github.com/nytlabs/streamtools/st/util"
)
type Filter struct {
blocks.Block
queryrule chan chan interface{}
inrule chan interface{}
in chan interface{}
out chan interface{}
quit chan interface{}
}
// a bit of boilerplate for streamtools
func NewFilter() blocks.BlockInterface {
return &Filter{}
}
func (b *Filter) Setup() {
b.Kind = "Filter"
b.in = b.InRoute("in")
b.inrule = b.InRoute("rule")
b.queryrule = b.QueryRoute("rule")
b.quit = b.Quit()
b.out = b.Broadcast()
}
func (b *Filter) Run() {
filter := ". != null"
lexed, _ := jee.Lexer(filter)
parsed, _ := jee.Parser(lexed)
for {
select {
case msg := <-b.in:
if parsed == nil {
b.Error("no filter set")
break
}
e, err := jee.Eval(parsed, msg)
if err != nil {
b.Error(err)
break
}
eval, ok := e.(bool)
if !ok {
break
}
if eval == true {
b.out <- msg
}
case ruleI := <-b.inrule:
filterS, err := util.ParseString(ruleI, "Filter")
if err != nil {
b.Error("bad filter")
break
}
lexed, err := jee.Lexer(filterS)
if err != nil {
b.Error(err)
break
}
tree, err := jee.Parser(lexed)
if err != nil {
b.Error(err)
break
}
parsed = tree
filter = filterS
case c := <-b.queryrule:
// deal with a query request
c <- map[string]interface{}{
"Filter": filter,
}
case <-b.quit:
// quit the block
return
}
}
}