Added WHERE expressions

It's now possible to do:

   SCAN fleet WHERE "properties.speed < 25 || properties.speed > 50"

Uses javascript-like syntax using the https://github.com/tidwall/expr package.

Automatically reference fields and GeoJSON properties:

   SET fleet truck1 FIELD speed 65 POINT -112 33

Can be queried:

   SCAN fleet WHERE "speed > 50"
   SCAN fleet WHERE "id == 'truck1'"
   SCAN fleet WHERE "speed > 50 && id == 'truck1'"

go.mod

@@ -91,6 +91,7 @@ require (
 	github.com/prometheus/common v0.32.1 // indirect
 	github.com/prometheus/procfs v0.7.3 // indirect
 	github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 // indirect
+	github.com/tidwall/expr v0.8.3 // indirect
 	github.com/tidwall/geoindex v1.7.0 // indirect
 	github.com/tidwall/grect v0.1.4 // indirect
 	github.com/tidwall/rtred v0.1.2 // indirect

go.sum

@@ -356,6 +356,8 @@ github.com/tidwall/buntdb v1.2.9 h1:XVz684P7X6HCTrdr385yDZWB1zt/n20ZNG3M1iGyFm4=
 github.com/tidwall/buntdb v1.2.9/go.mod h1:IwyGSvvDg6hnKSIhtdZ0AqhCZGH8ukdtCAzaP8fI1X4=
 github.com/tidwall/cities v0.1.0 h1:CVNkmMf7NEC9Bvokf5GoSsArHCKRMTgLuubRTHnH0mE=
 github.com/tidwall/cities v0.1.0/go.mod h1:lV/HDp2gCcRcHJWqgt6Di54GiDrTZwh1aG2ZUPNbqa4=
+github.com/tidwall/expr v0.8.3 h1:hLaz3DmuXsat+LAO904UxjD1WHrHEbRYZgzzzcn7JB4=
+github.com/tidwall/expr v0.8.3/go.mod h1:GnVpaS2R9wWV9Ft2u5TPDypJ+iQNxhAt9ISTUaUTlto=
 github.com/tidwall/geoindex v1.4.4/go.mod h1:rvVVNEFfkJVWGUdEfU8QaoOg/9zFX0h9ofWzA60mz1I=
 github.com/tidwall/geoindex v1.7.0 h1:jtk41sfgwIt8MEDyC3xyKSj75iXXf6rjReJGDNPtR5o=
 github.com/tidwall/geoindex v1.7.0/go.mod h1:rvVVNEFfkJVWGUdEfU8QaoOg/9zFX0h9ofWzA60mz1I=

internal/server/expr.go

@@ -0,0 +1,140 @@
+package server
+
+import (
+	"sync"
+
+	"github.com/tidwall/expr"
+	"github.com/tidwall/geojson"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/tile38/internal/field"
+	"github.com/tidwall/tile38/internal/object"
+)
+
+type exprPool struct {
+	pool *sync.Pool
+}
+
+func typeForObject(o *object.Object) expr.Value {
+	switch o.Geo().(type) {
+	case *geojson.Point, *geojson.SimplePoint:
+		return expr.String("Point")
+	case *geojson.LineString:
+		return expr.String("LineString")
+	case *geojson.Polygon, *geojson.Circle, *geojson.Rect:
+		return expr.String("Polygon")
+	case *geojson.MultiPoint:
+		return expr.String("MultiPoint")
+	case *geojson.MultiLineString:
+		return expr.String("MultiLineString")
+	case *geojson.MultiPolygon:
+		return expr.String("MultiPolygon")
+	case *geojson.GeometryCollection:
+		return expr.String("GeometryCollection")
+	case *geojson.Feature:
+		return expr.String("Feature")
+	case *geojson.FeatureCollection:
+		return expr.String("FeatureCollection")
+	default:
+		return expr.Undefined
+	}
+}
+
+func resultToValue(r gjson.Result) expr.Value {
+	if !r.Exists() {
+		return expr.Undefined
+	}
+	switch r.Type {
+	case gjson.String:
+		return expr.String(r.String())
+	case gjson.False:
+		return expr.Bool(false)
+	case gjson.True:
+		return expr.Bool(true)
+	case gjson.Number:
+		return expr.Number(r.Float())
+	case gjson.JSON:
+		return expr.String(r.String())
+	default:
+		return expr.Null
+	}
+}
+
+func newExprPool(s *Server) *exprPool {
+	ext := expr.NewExtender(
+		// ref
+		func(info expr.RefInfo, ctx *expr.Context) (expr.Value, error) {
+			o := ctx.UserData.(*object.Object)
+			if !info.Chain {
+				// root
+				if r := gjson.Get(o.Geo().Members(), info.Ident); r.Exists() {
+					return resultToValue(r), nil
+				}
+				switch info.Ident {
+				case "id":
+					return expr.String(o.ID()), nil
+				case "type":
+					return typeForObject(o), nil
+				default:
+					var rf field.Field
+					var ok bool
+					o.Fields().Scan(func(f field.Field) bool {
+						if f.Name() == info.Ident {
+							rf = f
+							ok = true
+							return false
+						}
+						return true
+					})
+					if ok {
+						r := gjson.Parse(rf.Value().JSON())
+						return resultToValue(r), nil
+					}
+				}
+			} else {
+				switch info.Value.Value().(type) {
+				case string:
+					r := gjson.Get(info.Value.String(), info.Ident)
+					return resultToValue(r), nil
+				}
+			}
+			return expr.Undefined, nil
+		},
+		// call
+		func(info expr.CallInfo, ctx *expr.Context) (expr.Value, error) {
+			// No custom calls
+			return expr.Undefined, nil
+		},
+		// op
+		func(info expr.OpInfo, ctx *expr.Context) (expr.Value, error) {
+			// No custom operations
+			return expr.Undefined, nil
+		},
+	)
+	return &exprPool{
+		pool: &sync.Pool{
+			New: func() any {
+				ctx := &expr.Context{
+					Extender: ext,
+				}
+				return ctx
+			},
+		},
+	}
+}
+
+func (p *exprPool) Get(o *object.Object) *expr.Context {
+	ctx := p.pool.Get().(*expr.Context)
+	ctx.UserData = o
+	return ctx
+}
+
+func (p *exprPool) Put(ctx *expr.Context) {
+	p.pool.Put(ctx)
+}
+
+func (where whereT) matchExpr(s *Server, o *object.Object) bool {
+	ctx := s.epool.Get(o)
+	res, _ := expr.Eval(where.name, ctx)
+	s.epool.Put(ctx)
+	return res.Bool()
+}

internal/server/scanner.go

@@ -229,9 +229,15 @@ func getFieldValue(o *object.Object, name string) field.Value {
 
 func (sw *scanWriter) fieldMatch(o *object.Object) (bool, error) {
 	for _, where := range sw.wheres {
-		if !where.match(getFieldValue(o, where.name)) {
+		if where.expr {
+			if !where.matchExpr(sw.s, o) {
 				return false, nil
 			}
+		} else {
+			if !where.matchField(getFieldValue(o, where.name)) {
+				return false, nil
+			}
+		}
 	}
 	for _, wherein := range sw.whereins {
 		if !wherein.match(getFieldValue(o, wherein.name)) {

internal/server/scanner_test.go

@@ -36,8 +36,8 @@ func BenchmarkFieldMatch(t *testing.B) {
 	}
 	sw := &scanWriter{
 		wheres: []whereT{
-			{"foo", false, field.ValueOf("1"), false, field.ValueOf("3")},
+			{false, "foo", false, field.ValueOf("1"), false, field.ValueOf("3")},
-			{"bar", false, field.ValueOf("10"), false, field.ValueOf("30")},
+			{false, "bar", false, field.ValueOf("10"), false, field.ValueOf("30")},
 		},
 		whereins: []whereinT{
 			{"foo", []field.Value{field.ValueOf("1"), field.ValueOf("2")}},

internal/server/server.go

@@ -79,6 +79,7 @@ type Server struct {
 	started time.Time
 	config  *Config
 	epc     *endpoint.Manager
+	epool   *exprPool
 
 	lnmu sync.Mutex
 	ln   net.Listener // server listener
@@ -222,7 +223,7 @@ func Serve(opts Options) error {
 		hookExpires:  btree.NewNonConcurrent(byHookExpires),
 		opts:         opts,
 	}
-
+	s.epool = newExprPool(s)
 	s.epc = endpoint.NewManager(s)
 	defer s.epc.Shutdown()
 	s.luascripts = s.newScriptMap()

internal/server/token.go

@@ -63,6 +63,7 @@ func lc(s1, s2 string) bool {
 }
 
 type whereT struct {
+	expr bool
 	name string
 	minx bool
 	min  field.Value
@@ -76,7 +77,7 @@ func mGT(a, b field.Value) bool  { return mLT(b, a) }
 func mGTE(a, b field.Value) bool { return !mLT(a, b) }
 func mEQ(a, b field.Value) bool  { return a.Equals(b) }
 
-func (where whereT) match(value field.Value) bool {
+func (where whereT) matchField(value field.Value) bool {
 	switch where.min.Data() {
 	case "<":
 		return mLT(value, where.max)
@@ -275,6 +276,19 @@ func (s *Server) parseSearchScanBaseTokens(
 				continue
 			case "where":
 				vs = nvs
+				if detectExprToken(vs) {
+					// using expressions
+					// WHERE expr
+					var expr string
+					if vs, expr, ok = tokenval(vs); !ok {
+						err = errInvalidNumberOfArguments
+						return
+					}
+					t.wheres = append(t.wheres, whereT{name: expr, expr: true})
+					continue
+				} else {
+					// using field filter
+					// WHERE min max
 					var name, smin, smax string
 					if vs, name, ok = tokenval(vs); !ok {
 						err = errInvalidNumberOfArguments
@@ -314,6 +328,7 @@ func (s *Server) parseSearchScanBaseTokens(
 						max:  field.ValueOf(smax),
 					})
 					continue
+				}
 			case "wherein":
 				vs = nvs
 				var name, nvalsStr, valStr string
@@ -675,6 +690,25 @@ func (s *Server) parseSearchScanBaseTokens(
 	return
 }
 
+func detectExprToken(vs []string) bool {
+	// Detect the kind of where, either:
+	// - expr
+	// - name min max
+	if len(vs) == 0 {
+		return false
+	} else if len(vs) == 1 || (len(vs) == 2 && len(vs[1]) == 0) {
+		return true
+	}
+	v := vs[1]
+	if (v[0] >= 'a' && v[0] <= 'z') || (v[0] >= 'A' && v[0] <= 'Z') {
+		if (v[0] == 'i' || v[0] == 'I') && strings.ToLower(v) == "inf" {
+			return false
+		}
+		return true
+	}
+	return false
+}
+
 type parentStack []*areaExpression
 
 func (ps *parentStack) isEmpty() bool {

tests/keys_test.go

@@ -463,7 +463,7 @@ func keys_FIELDS_test(mc *mockServer) error {
 		// Do some GJSON queries.
 		Do("SET", "fleet", "truck2", "FIELD", "hello", `{"world":"tom"}`, "POINT", "-112", "33").JSON().OK(),
 		Do("SCAN", "fleet", "WHERE", "hello", `{"world":"tom"}`, `{"world":"tom"}`, "COUNT").JSON().Str(`{"ok":true,"count":1,"cursor":0}`),
-		Do("SCAN", "fleet", "WHERE", "hello.world", `tom`, `tom`, "COUNT").JSON().Str(`{"ok":true,"count":1,"cursor":0}`),
+		Do("SCAN", "fleet", "WHERE", "hello.world == 'tom'", "COUNT").JSON().Str(`{"ok":true,"count":1,"cursor":0}`),
 		// The next scan does not match on anything, but since we're matching
 		// on zeros, which is the default, then all (two) objects are returned.
 		Do("SCAN", "fleet", "WHERE", "hello.world.1", `0`, `0`, "IDS").JSON().Str(`{"ok":true,"ids":["truck1","truck2"],"count":2,"cursor":0}`),