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session.go
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session.go
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// 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 (
"context"
"errors"
"fmt"
"sort"
"github.com/cayleygraph/cayley/graph"
"github.com/cayleygraph/cayley/query"
)
const Name = "sexp"
func init() {
query.RegisterLanguage(query.Language{
Name: Name,
Session: func(qs graph.QuadStore) query.Session {
return NewSession(qs)
},
REPL: func(qs graph.QuadStore) query.REPLSession {
return NewSession(qs)
},
})
}
type Session struct {
qs graph.QuadStore
}
func NewSession(qs graph.QuadStore) *Session {
return &Session{qs: qs}
}
func (s *Session) Parse(input string) 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 fmt.Errorf("too many close parentheses at char %d: %s", i, input[min:i])
}
}
}
if parenDepth > 0 {
return query.ErrParseMore
}
if len(ParseString(input)) > 0 {
return nil
}
return errors.New("invalid syntax")
}
func (s *Session) Execute(ctx context.Context, input string, out chan query.Result, limit int) {
defer close(out)
it := BuildIteratorTreeForQuery(s.qs, input)
err := graph.Iterate(ctx, it).Paths(true).Limit(limit).TagEach(func(tags map[string]graph.Value) {
select {
case out <- query.TagMapResult(tags):
case <-ctx.Done():
}
})
if err != nil {
select {
case out <- query.ErrorResult(err):
case <-ctx.Done():
}
}
}
func (s *Session) FormatREPL(result query.Result) string {
out := fmt.Sprintln("****")
tags, ok := result.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
}