initial import

core/iox/read.go

@@ -0,0 +1,103 @@
+package iox
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"io/ioutil"
+	"os"
+	"strings"
+)
+
+type (
+	textReadOptions struct {
+		keepSpace     bool
+		withoutBlanks bool
+		omitPrefix    string
+	}
+
+	TextReadOption func(*textReadOptions)
+)
+
+// The first returned reader needs to be read first, because the content
+// read from it will be written to the underlying buffer of the second reader.
+func DupReadCloser(reader io.ReadCloser) (io.ReadCloser, io.ReadCloser) {
+	var buf bytes.Buffer
+	tee := io.TeeReader(reader, &buf)
+	return ioutil.NopCloser(tee), ioutil.NopCloser(&buf)
+}
+
+func KeepSpace() TextReadOption {
+	return func(o *textReadOptions) {
+		o.keepSpace = true
+	}
+}
+
+// ReadBytes reads exactly the bytes with the length of len(buf)
+func ReadBytes(reader io.Reader, buf []byte) error {
+	var got int
+
+	for got < len(buf) {
+		n, err := reader.Read(buf[got:])
+		if err != nil {
+			return err
+		}
+
+		got += n
+	}
+
+	return nil
+}
+
+func ReadText(filename string) (string, error) {
+	content, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimSpace(string(content)), nil
+}
+
+func ReadTextLines(filename string, opts ...TextReadOption) ([]string, error) {
+	var readOpts textReadOptions
+	for _, opt := range opts {
+		opt(&readOpts)
+	}
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	var lines []string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if !readOpts.keepSpace {
+			line = strings.TrimSpace(line)
+		}
+		if readOpts.withoutBlanks && len(line) == 0 {
+			continue
+		}
+		if len(readOpts.omitPrefix) > 0 && strings.HasPrefix(line, readOpts.omitPrefix) {
+			continue
+		}
+
+		lines = append(lines, line)
+	}
+
+	return lines, scanner.Err()
+}
+
+func WithoutBlank() TextReadOption {
+	return func(o *textReadOptions) {
+		o.withoutBlanks = true
+	}
+}
+
+func OmitWithPrefix(prefix string) TextReadOption {
+	return func(o *textReadOptions) {
+		o.omitPrefix = prefix
+	}
+}