repl.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.
// +build !appengine
package repl
import (
"context"
"fmt"
"io"
"os"
"os/signal"
"strconv"
"strings"
"time"
"github.com/peterh/liner"
"github.com/cayleygraph/cayley/clog"
"github.com/cayleygraph/cayley/graph"
"github.com/cayleygraph/cayley/query"
"github.com/cayleygraph/quad/nquads"
)
func trace(s string) (string, time.Time) {
return s, time.Now()
}
func un(s string, startTime time.Time) {
endTime := time.Now()
fmt.Printf(s, float64(endTime.UnixNano()-startTime.UnixNano())/float64(1e6))
}
func Run(ctx context.Context, qu string, ses query.REPLSession) error {
nResults := 0
startTrace, startTime := trace("Elapsed time: %g ms\n\n")
defer func() {
if nResults > 0 {
un(startTrace, startTime)
}
}()
fmt.Printf("\n")
it, err := ses.Execute(ctx, qu, query.Options{
Collation: query.REPL,
Limit: 100,
})
if err != nil {
return err
}
defer it.Close()
for it.Next(ctx) {
fmt.Print(it.Result())
nResults++
}
if err := it.Err(); err != nil {
return err
}
if nResults > 0 {
results := "Result"
if nResults > 1 {
results += "s"
}
fmt.Printf("-----------\n%d %s\n", nResults, results)
}
return nil
}
const (
defaultLanguage = "gizmo"
ps1 = "cayley> "
ps2 = "... "
history = ".cayley_history"
)
func Repl(ctx context.Context, h *graph.Handle, queryLanguage string, timeout time.Duration) error {
if queryLanguage == "" {
queryLanguage = defaultLanguage
}
l := query.GetLanguage(queryLanguage)
if l == nil || l.REPL == nil {
return fmt.Errorf("unsupported query language: %q", queryLanguage)
}
ses := l.REPL(h.QuadStore)
term, err := terminal(history)
if os.IsNotExist(err) {
fmt.Printf("creating new history file: %q\n", history)
}
defer persist(term, history)
var (
prompt = ps1
code string
)
newCtx := func() (context.Context, func()) { return ctx, func() {} }
if timeout > 0 {
newCtx = func() (context.Context, func()) { return context.WithTimeout(ctx, timeout) }
}
for {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
if len(code) == 0 {
prompt = ps1
} else {
prompt = ps2
}
line, err := term.Prompt(prompt)
if err != nil {
if err == io.EOF {
fmt.Println()
return nil
}
return err
}
term.AppendHistory(line)
line = strings.TrimSpace(line)
if len(line) == 0 || line[0] == '#' {
continue
}
if code == "" {
cmd, args := splitLine(line)
switch cmd {
case ":debug":
args = strings.TrimSpace(args)
var debug bool
switch args {
case "t":
debug = true
case "f":
// Do nothing.
default:
debug, err = strconv.ParseBool(args)
if err != nil {
fmt.Printf("Error: cannot parse %q as a valid boolean - acceptable values: 't'|'true' or 'f'|'false'\n", args)
continue
}
}
if debug {
clog.SetV(2)
} else {
clog.SetV(0)
}
fmt.Printf("Debug set to %t\n", debug)
continue
case ":a":
quad, err := nquads.Parse(args)
if err == nil {
err = h.QuadWriter.AddQuad(quad)
}
if err != nil {
fmt.Printf("Error: not a valid quad: %v\n", err)
continue
}
continue
case ":d":
quad, err := nquads.Parse(args)
if err != nil {
fmt.Printf("Error: not a valid quad: %v\n", err)
continue
}
err = h.QuadWriter.RemoveQuad(quad)
if err != nil {
fmt.Printf("error deleting: %v\n", err)
}
continue
case "help":
fmt.Printf("Help\n\texit // Exit\n\thelp // this help\n\td: <quad> // delete quad\n\ta: <quad> // add quad\n\t:debug [t|f]\n")
continue
case "exit":
term.Close()
os.Exit(0)
default:
if cmd[0] == ':' {
fmt.Printf("Unknown command: %q\n", cmd)
continue
}
}
}
code += line
nctx, cancel := newCtx()
err = Run(nctx, code, ses)
cancel()
if err == query.ErrParseMore {
// collect more input
} else if err != nil {
fmt.Println("Error: ", err)
code = ""
} else {
code = ""
}
}
}
// Splits a line into a command and its arguments
// e.g. ":a b c d ." will be split into ":a" and " b c d ."
func splitLine(line string) (string, string) {
var command, arguments string
line = strings.TrimSpace(line)
// An empty line/a line consisting of whitespace contains neither command nor arguments
if len(line) > 0 {
command = strings.Fields(line)[0]
// A line containing only a command has no arguments
if len(line) > len(command) {
arguments = line[len(command):]
}
}
return command, arguments
}
func terminal(path string) (*liner.State, error) {
term := liner.NewLiner()
go func() {
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, os.Kill)
<-c
err := persist(term, history)
if err != nil {
fmt.Fprintf(os.Stderr, "failed to properly clean up terminal: %v\n", err)
os.Exit(1)
}
os.Exit(0)
}()
f, err := os.Open(path)
if err != nil {
return term, err
}
defer f.Close()
_, err = term.ReadHistory(f)
return term, err
}
func persist(term *liner.State, path string) error {
f, err := os.OpenFile(path, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0666)
if err != nil {
return fmt.Errorf("could not open %q to append history: %v", path, err)
}
defer f.Close()
_, err = term.WriteHistory(f)
if err != nil {
return fmt.Errorf("could not write history to %q: %v", path, err)
}
return term.Close()
}