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repl.go
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repl.go
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package command
import (
"errors"
"fmt"
"io"
"regexp"
"strings"
"time"
"github.com/chzyer/readline"
"github.com/erizocosmico/csvquery"
"github.com/olekukonko/tablewriter"
sqle "gopkg.in/src-d/go-mysql-server.v0"
"gopkg.in/src-d/go-mysql-server.v0/sql"
)
// REPL will start a REPL to query CSV files.
type REPL struct {
baseCmd
Stdin io.Reader
Stdout, Stderr io.Writer
}
const initMsg = `
____ ______ _____
/ ___/ ___\ \ / / _ \ _ _ ___ _ __ _ _
| | \___ \\ \ / / | | | | | |/ _ \ '__| | | |
| |___ ___) |\ V /| |_| | |_| | __/ | | |_| |
\____|____/ \_/ \__\_\\__,_|\___|_| \__, |
|___/
Query CSV files with SQL.
Enter "help" to see more details about the usage, or "quit" to exit.
`
const replHelp = `Help:
help Show this message.
quit,exit Exit the REPL.
load <path>[ <name>] Load a new CSV file as a table. If name is not
provided, the file name will be used as table
name removing all characters that are not alpha
numeric or underscores and removing the extension.
<SQL query> Execute a SQL query.
`
var errHelp = errors.New(replHelp)
var loadRegex = regexp.MustCompile(`^\s?load\s+([^\s]+)\s?(.*)`)
// Execute the command
func (c *REPL) Execute([]string) error {
engine, db, err := c.engine()
if err != nil {
return err
}
rl, err := readline.NewEx(&readline.Config{
Prompt: "csvquery> ",
Stdin: c.Stdin,
Stderr: c.Stderr,
Stdout: c.Stdout,
})
if err != nil {
return err
}
defer rl.Close()
fmt.Fprintln(c.Stdout, initMsg)
for {
line, err := rl.Readline()
if err != nil {
return nil
}
switch strings.ToLower(strings.TrimSpace(line)) {
case "exit", "quit":
fmt.Fprintln(c.Stdout, "Bye, have a nice day!")
return nil
case "help":
fmt.Fprintln(c.Stdout, replHelp)
default:
if strings.HasPrefix(strings.TrimSpace(strings.ToLower(line)), "load ") {
if err := loadFile(line, db); err != nil {
fmt.Fprintln(c.Stderr, err)
} else {
fmt.Fprintln(c.Stdout, "Table loaded successfully.")
}
continue
}
c.runQuery(engine, line)
}
}
}
func loadFile(line string, db *csvquery.Database) error {
if loadRegex.MatchString(line) {
matches := loadRegex.FindStringSubmatch(line)
var path, name string
switch len(matches) {
case 2:
path = matches[1]
case 3:
path = matches[1]
name = matches[2]
default:
return errHelp
}
if name == "" {
name = nameFromPath(path)
}
return db.AddTable(name, path)
}
return errHelp
}
func (c *REPL) runQuery(engine *sqle.Engine, query string) {
start := time.Now()
schema, iter, err := engine.Query(sql.NewEmptyContext(), query)
if err != nil {
fmt.Fprintln(c.Stderr, err)
return
}
var columns = make([]string, len(schema))
for i, col := range schema {
columns[i] = col.Name
}
writer := tablewriter.NewWriter(c.Stdout)
writer.SetHeader(columns)
var errors []string
var rows int
for {
row, err := iter.Next()
if err == io.EOF {
break
}
if err != nil {
errors = append(errors, err.Error())
break
}
var values = make([]string, len(row))
for i, v := range row {
values[i] = fmt.Sprint(v)
}
rows++
writer.Append(values)
}
if err := iter.Close(); err != nil {
errors = append(errors, err.Error())
}
if len(errors) > 0 {
fmt.Fprintln(c.Stderr, "Error:")
fmt.Fprintf(c.Stderr, "%s\n", strings.Join(errors, "\n"))
} else {
writer.Render()
fmt.Fprintf(c.Stdout, "%d row(s) in %v\n", rows, time.Since(start))
}
}