Add parser to generate SubGraph. Should be a joyous moment, don't feel it though :-).

gql/lexer.go

+/*
+ * Copyright 2015 Manish R Jain <manishrjain@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 		http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package gql
 
 import (

gql/lexer_test.go

+/*
+ * Copyright 2015 Manish R Jain <manishrjain@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 		http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package gql
 
 import (

gql/parser.go

+/*
+ * Copyright 2015 Manish R Jain <manishrjain@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 		http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package gql
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+
+	"github.com/manishrjain/dgraph/query"
+	"github.com/manishrjain/dgraph/x"
+)
+
+func Parse(input string) (sg *query.SubGraph, rerr error) {
+	l := newLexer(input)
+	sg = nil
+	for item := range l.items {
+		if item.typ == itemText {
+			continue
+		}
+		if item.typ == itemOpType {
+			if item.val == "mutation" {
+				return nil, errors.New("Mutations not supported")
+			}
+		}
+		if item.typ == itemLeftCurl {
+			if sg == nil {
+				sg, rerr = getRoot(l)
+				if rerr != nil {
+					x.Err(glog, rerr).Error("While retrieving subgraph root")
+					return nil, rerr
+				}
+			} else {
+				godeep(l, sg)
+			}
+		}
+	}
+	return sg, nil
+}
+
+func getRoot(l *lexer) (sg *query.SubGraph, rerr error) {
+	item := <-l.items
+	if item.typ != itemName {
+		return nil, fmt.Errorf("Expected some name. Got: %v", item)
+	}
+	// ignore itemName for now.
+	item = <-l.items
+	if item.typ != itemLeftRound {
+		return nil, fmt.Errorf("Expected variable start. Got: %v", item)
+	}
+
+	var uid uint64
+	var xid string
+	for {
+		var key, val string
+		// Get key or close bracket
+		item = <-l.items
+		if item.typ == itemArgName {
+			key = item.val
+		} else if item.typ == itemRightRound {
+			break
+		} else {
+			return nil, fmt.Errorf("Expecting argument name. Got: %v", item)
+		}
+
+		// Get corresponding value.
+		item = <-l.items
+		if item.typ == itemArgVal {
+			val = item.val
+		} else {
+			return nil, fmt.Errorf("Expecting argument val. Got: %v", item)
+		}
+
+		if key == "uid" {
+			uid, rerr = strconv.ParseUint(val, 0, 64)
+			if rerr != nil {
+				return nil, rerr
+			}
+		} else if key == "xid" {
+			xid = val
+		} else {
+			return nil, fmt.Errorf("Expecting uid or xid. Got: %v", item)
+		}
+	}
+	if item.typ != itemRightRound {
+		return nil, fmt.Errorf("Unexpected token. Got: %v", item)
+	}
+	return query.NewGraph(uid, xid)
+}
+
+func godeep(l *lexer, sg *query.SubGraph) {
+	curp := sg // stores current pointer.
+	for {
+		switch item := <-l.items; {
+		case item.typ == itemName:
+			child := new(query.SubGraph)
+			child.Attr = item.val
+			sg.Children = append(sg.Children, child)
+			curp = child
+		case item.typ == itemLeftCurl:
+			godeep(l, curp) // recursive iteration
+		case item.typ == itemRightCurl:
+			return
+		case item.typ == itemLeftRound:
+			// absorb all these, we don't care right now.
+			for {
+				item = <-l.items
+				if item.typ == itemRightRound || item.typ == itemEOF {
+					break
+				}
+			}
+		default:
+			// continue
+		}
+	}
+
+}

gql/parser_test.go

+/*
+ * Copyright 2015 Manish R Jain <manishrjain@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 		http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package gql
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/manishrjain/dgraph/query"
+)
+
+func checkAttr(g *query.SubGraph, attr string) error {
+	if g.Attr != attr {
+		return fmt.Errorf("Expected: %v. Got: %v", attr, g.Attr)
+	}
+	return nil
+}
+
+func TestParse(t *testing.T) {
+	query := `
+	query {
+		me(uid:0x0a) {
+			friends {
+				name
+			}
+			gender
+			age
+			hometown
+		}
+	}
+`
+
+	sg, err := Parse(query)
+	if err != nil {
+		t.Error(err)
+	}
+	if len(sg.Children) != 4 {
+		t.Errorf("Expected 4 children. Got: %v", len(sg.Children))
+	}
+	if err := checkAttr(sg.Children[0], "friends"); err != nil {
+		t.Error(err)
+	}
+	if err := checkAttr(sg.Children[1], "gender"); err != nil {
+		t.Error(err)
+	}
+	if err := checkAttr(sg.Children[2], "age"); err != nil {
+		t.Error(err)
+	}
+	if err := checkAttr(sg.Children[3], "hometown"); err != nil {
+		t.Error(err)
+	}
+	child := sg.Children[0]
+	if len(child.Children) != 1 {
+		t.Errorf("Expected 1 child of friends. Got: %v", len(child.Children))
+	}
+	if err := checkAttr(child.Children[0], "name"); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestParse_error1(t *testing.T) {
+	query := `
+		mutation {
+			me(uid:0x0a) {
+				name
+			}
+		}
+	`
+	var err error
+	_, err = Parse(query)
+	t.Log(err)
+	if err == nil {
+		t.Error("Expected error")
+	}
+}
+
+func TestParse_error2(t *testing.T) {
+	query := `
+		query {
+			me {
+				name
+			}
+		}
+	`
+	var err error
+	_, err = Parse(query)
+	t.Log(err)
+	if err == nil {
+		t.Error("Expected error")
+	}
+}
+
+func TestParse_pass1(t *testing.T) {
+	query := `
+		{
+			me(uid:0x0a) {
+				name,
+				friends(xid:what) {  # xid would be ignored.
+				}
+			}
+		}
+	`
+	sg, err := Parse(query)
+	if err != nil {
+		t.Error(err)
+	}
+	if len(sg.Children) != 2 {
+		t.Errorf("Expected 2. Got: %v", len(sg.Children))
+	}
+	if err := checkAttr(sg.Children[0], "name"); err != nil {
+		t.Error(err)
+	}
+	if err := checkAttr(sg.Children[1], "friends"); err != nil {
+		t.Error(err)
+	}
+	f := sg.Children[1]
+	if len(f.Children) != 0 {
+		t.Errorf("Expected 0. Got: %v", len(sg.Children))
+	}
+}

gql/state.go

+/*
+ * Copyright 2015 Manish R Jain <manishrjain@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 		http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package gql
 
 const (