session.go
// Copyright 2014 The Cayley Authors. All rights reserved.
//
// 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 sexp
// Defines a running session of the sexp query language.
import (
"errors"
"fmt"
"sort"
"golang.org/x/net/context"
"github.com/cayleygraph/cayley/clog"
"github.com/cayleygraph/cayley/graph"
"github.com/cayleygraph/cayley/query"
)
type Session struct {
qs graph.QuadStore
debug bool
}
func NewSession(qs graph.QuadStore) *Session {
var s Session
s.qs = qs
return &s
}
func (s *Session) Debug(ok bool) {
s.debug = ok
}
func (s *Session) Parse(input string) (query.ParseResult, error) {
var parenDepth int
for i, x := range input {
if x == '(' {
parenDepth++
}
if x == ')' {
parenDepth--
if parenDepth < 0 {
min := 0
if (i - 10) > min {
min = i - 10
}
return query.ParseFail, fmt.Errorf("too many close parentheses at char %d: %s", i, input[min:i])
}
}
}
if parenDepth > 0 {
return query.ParseMore, nil
}
if len(ParseString(input)) > 0 {
return query.Parsed, nil
}
return query.ParseFail, errors.New("invalid syntax")
}
func (s *Session) Execute(input string, out chan interface{}, limit int) {
defer close(out)
it := BuildIteratorTreeForQuery(s.qs, input)
err := graph.Iterate(context.TODO(), it).Paths(true).Limit(limit).TagEach(func(tags map[string]graph.Value) {
out <- &tags
})
if err != nil {
clog.Errorf("sexp: %v", err)
}
}
func (s *Session) Format(result interface{}) string {
out := fmt.Sprintln("****")
tags, ok := result.(map[string]graph.Value)
if !ok {
return ""
}
tagKeys := make([]string, len(tags))
i := 0
for k := range tags {
tagKeys[i] = k
i++
}
sort.Strings(tagKeys)
for _, k := range tagKeys {
if k == "$_" {
continue
}
out += fmt.Sprintf("%s : %s\n", k, s.qs.NameOf(tags[k]))
}
return out
}