Add FileSystemCompleter and example

_tools/complete_file/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/c-bata/go-prompt"
+	"github.com/c-bata/go-prompt/completer"
+)
+
+func executor(in string) {
+	fmt.Println("Your input: " + in)
+}
+
+func main() {
+	c := completer.FilePathCompleter{
+		IgnoreCase: true,
+		Filter: func(fi os.FileInfo, filename string) bool {
+			return fi.IsDir() || strings.HasSuffix(fi.Name(), ".go")
+		},
+	}
+	p := prompt.New(
+		executor,
+		c.Complete,
+		prompt.OptionPrefix(">>> "),
+		prompt.OptionCompletionWordSeparator(completer.FilePathCompletionSeparator),
+	)
+	p.Run()
+}

completer/file.go

@@ -0,0 +1,56 @@
+package completer
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/c-bata/go-prompt"
+)
+
+var (
+	FilePathCompletionSeparator = string([]byte{' ', os.PathSeparator})
+)
+
+// FilePathCompleter is a completer for your local file system.
+type FilePathCompleter struct {
+	Filter        func(fi os.FileInfo, filename string) bool
+	IgnoreCase    bool
+	fileListCache map[string][]prompt.Suggest
+}
+
+// Complete returns suggestions from your local file system.
+func (c *FilePathCompleter) Complete(d prompt.Document) []prompt.Suggest {
+	if c.fileListCache == nil {
+		c.fileListCache = make(map[string][]prompt.Suggest, 4)
+	}
+	path := d.GetWordBeforeCursor()
+	base := filepath.Base(path)
+	if len(path) == 0 || path[len(path)-1] == os.PathSeparator {
+		base = ""
+	}
+
+	dir := filepath.Dir(path)
+	if cached, ok := c.fileListCache[dir]; ok {
+		return prompt.FilterHasPrefix(cached, base, c.IgnoreCase)
+	}
+
+	files, err := ioutil.ReadDir(dir)
+	if err != nil && os.IsNotExist(err) {
+		return nil
+	} else if err != nil {
+		log.Print("[ERROR] completer: cannot read directory items " + err.Error())
+		return nil
+	}
+
+	suggests := make([]prompt.Suggest, 0, len(files))
+	for _, f := range files {
+		if c.Filter != nil && !c.Filter(f, f.Name()) {
+			continue
+		}
+		suggests = append(suggests, prompt.Suggest{Text: f.Name()})
+	}
+	c.fileListCache[dir] = suggests
+	return prompt.FilterHasPrefix(suggests, base, c.IgnoreCase)
+}