add other utils

utils/file.go

@@ -1,11 +1,79 @@
 package utils
 
 import (
+	"bufio"
+	"errors"
+	"io"
 	"os"
 	"path/filepath"
+	"regexp"
 )
 
 func SelfPath() string {
 	path, _ := filepath.Abs(os.Args[0])
 	return path
 }
+
+func SelfDir() string {
+	return filepath.Dir(SelfPath())
+}
+
+// FileExists reports whether the named file or directory exists.
+func FileExists(name string) bool {
+	if _, err := os.Stat(name); err != nil {
+		if os.IsNotExist(err) {
+			return false
+		}
+	}
+	return true
+}
+
+// search a file in paths.
+// this is offen used in search config file in /etc ~/
+func LookFile(filename string, paths ...string) (fullpath string, err error) {
+	for _, path := range paths {
+		if fullpath = filepath.Join(path, filename); FileExists(fullpath) {
+			return
+		}
+	}
+	err = errors.New(fullpath + " not found in paths")
+	return
+}
+
+// like command grep -E
+// for example: GrepE(`^hello`, "hello.txt")
+// \n is striped while read
+func GrepE(patten string, filename string) (lines []string, err error) {
+	re, err := regexp.Compile(patten)
+	if err != nil {
+		return
+	}
+
+	fd, err := os.Open(filename)
+	if err != nil {
+		return
+	}
+	lines = make([]string, 0)
+	reader := bufio.NewReader(fd)
+	prefix := ""
+	for {
+		byteLine, isPrefix, er := reader.ReadLine()
+		if er != nil && er != io.EOF {
+			return nil, er
+		}
+		line := string(byteLine)
+		if isPrefix {
+			prefix += line
+			continue
+		}
+
+		line = prefix + line
+		if re.MatchString(line) {
+			lines = append(lines, line)
+		}
+		if er == io.EOF {
+			break
+		}
+	}
+	return lines, nil
+}

utils/file_test.go

@@ -1,9 +1,13 @@
 package utils
 
 import (
+	"path/filepath"
+	"reflect"
 	"testing"
 )
 
+var noExistedFile = "/tmp/not_existed_file"
+
 func TestSelfPath(t *testing.T) {
 	path := SelfPath()
 	if path == "" {
@@ -11,3 +15,47 @@ func TestSelfPath(t *testing.T) {
 	}
 	t.Logf("SelfPath: %s", path)
 }
+
+func TestSelfDir(t *testing.T) {
+	dir := SelfDir()
+	t.Logf("SelfDir: %s", dir)
+}
+
+func TestFileExists(t *testing.T) {
+	if !FileExists("/bin/echo") {
+		t.Errorf("/bin/echo should exists, but it didn't")
+	}
+
+	if FileExists(noExistedFile) {
+		t.Errorf("Wierd, how could this file exists: %s", noExistedFile)
+	}
+}
+
+func TestLookFile(t *testing.T) {
+	path, err := LookFile(filepath.Base(SelfPath()), SelfDir())
+	if err != nil {
+		t.Error(err)
+	}
+	t.Log(path)
+
+	path, err = LookFile(noExistedFile, ".")
+	if err == nil {
+		t.Errorf("err shouldnot be nil, got path: %s", SelfDir())
+	}
+}
+
+func TestGrepE(t *testing.T) {
+	_, err := GrepE("", noExistedFile)
+	if err == nil {
+		t.Error("expect file-not-existed error, but got nothing")
+	}
+
+	path := filepath.Join(".", "testdata", "grepe.test")
+	lines, err := GrepE(`^\s*[^#]+`, path)
+	if err != nil {
+		t.Error(err)
+	}
+	if !reflect.DeepEqual(lines, []string{"hello", "world"}) {
+		t.Errorf("expect [hello world], but receive %v", lines)
+	}
+}

utils/testdata/grepe.test

@@ -0,0 +1,7 @@
+# empty lines
+
+
+
+hello
+# comment
+world