First draft of SQLite shell in Go.

shell.go

+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"os/signal"
+	"os/user"
+	"path"
+	"syscall"
+	"text/tabwriter"
+	"unicode"
+
+	"github.com/gwenn/gosqlite"
+	"github.com/gwenn/liner"
+)
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+func trace(err error) bool {
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err.Error())
+	}
+	return err != nil
+}
+
+const (
+	mainPrompt      = "sqlite> "
+	continuePrompt  = "   ...> "
+	historyFileName = ".gosqlite_history"
+)
+
+func loadHistory(state *liner.State, historyFileName string) error {
+	//liner.HistoryLimit = 100 // to limit memory usage
+	user, err := user.Current()
+	if err != nil {
+		return err
+	}
+	path := path.Join(user.HomeDir, historyFileName)
+	f, err := os.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	defer f.Close()
+
+	r := bufio.NewReader(f)
+	_, err = state.ReadHistory(r)
+	return err
+}
+
+func isBlank(line string) bool {
+	for _, r := range line {
+		if unicode.IsSpace(r) {
+			continue
+		}
+		return false
+	}
+	return true
+}
+func isCommand(line string) bool {
+	return len(line) > 0 && line[0] == '.'
+}
+
+func appendHistory(state *liner.State, item string) {
+	state.AppendHistory(item) // ignore consecutive dups, blank line, space
+}
+
+func saveHistory(state *liner.State, historyFileName string) error {
+	user, err := user.Current()
+	if err != nil {
+		return err
+	}
+	path := path.Join(user.HomeDir, historyFileName)
+	// append for multi-sessions handling
+	f, err := os.OpenFile(path, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0600) // os.O_TRUNC
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	w := bufio.NewWriter(f)
+	_, err = state.WriteHistory(w)
+	if err != nil {
+		return err
+	}
+	err = w.Flush()
+	return err
+}
+
+// Ctl-C
+func catchInterrupt() {
+	ch := make(chan os.Signal)
+	go func() {
+		for _ = range ch {
+			/*db.Interrupt()
+			if !interactive {
+				os.Exit(0)
+			}*/
+			fmt.Fprintln(os.Stderr, "^C")
+		}
+	}()
+	signal.Notify(ch, syscall.SIGINT)
+}
+
+func main() {
+	if !liner.IsTerminal() {
+		return // TODO non-interactive mode
+	}
+	state, err := liner.NewLiner()
+	check(err)
+	defer func() {
+		err := saveHistory(state, historyFileName)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err.Error())
+		}
+		state.Close()
+	}()
+	// TODO state.SetCompleter(completion)
+	err = loadHistory(state, historyFileName)
+	check(err)
+
+	db, err := sqlite.Open(":memory:") // TODO command-line flag
+	check(err)
+	defer db.Close()
+
+	catchInterrupt()
+
+	// TODO .mode MODE ?TABLE?     Set output mode where MODE is one of:
+	// TODO .separator STRING      Change separator used by output mode and .import
+	tw := tabwriter.NewWriter(os.Stdout, 0, 8, 0, '\t', 0)
+	prompt := mainPrompt
+	var b bytes.Buffer
+	for {
+		line, err := state.Prompt(prompt)
+		if err != nil {
+			if err != io.EOF {
+				fmt.Fprintf(os.Stderr, "%#v\n", err)
+			}
+			println() /* End of input */
+			break
+		}
+
+		if isBlank(line) {
+			continue
+		} else if isCommand(line) {
+			fmt.Println("TBD")
+			continue
+		}
+
+		b.WriteString(line)
+		cmd := b.String()
+		if !sqlite.Complete(cmd) {
+			b.WriteByte(' ') // TODO Validate ' ' versus '\n'
+			prompt = continuePrompt
+			continue
+		}
+		prompt = mainPrompt
+		// TODO .echo ON|OFF           Turn command echo on or off
+		//fmt.Println(cmd)
+		appendHistory(state, cmd)
+		for len(cmd) > 0 {
+			s, err := db.Prepare(cmd)
+			if trace(err) {
+				break
+			} else if s.Empty() {
+				cmd = s.Tail()
+				continue
+			}
+			columnCount := s.ColumnCount()
+			if columnCount > 0 {
+				headers := s.ColumnNames() // TODO .header(s) ON|OFF      Turn display of headers on or off
+				for _, header := range headers {
+					io.WriteString(tw, header)
+					io.WriteString(tw, "\t")
+				}
+				io.WriteString(tw, "\n")
+				err = s.Select(func(s *sqlite.Stmt) error {
+					for i := 0; i < columnCount; i++ {
+						blob, _ := s.ScanRawBytes(i)
+						// TODO .nullvalue STRING      Use STRING in place of NULL values
+						tw.Write(blob)
+						io.WriteString(tw, "\t") // https://github.com/kr/text
+					}
+					io.WriteString(tw, "\n")
+					return nil
+				})
+				tw.Flush()
+			} else {
+				err = s.Exec()
+			}
+			if trace(err) {
+				s.Finalize()
+				break
+			}
+			if trace(s.Finalize()) {
+				break
+			}
+			cmd = s.Tail()
+		} // exec
+		b.Reset()
+	}
+}