sketch out first steps of prettyprompt.go

1 files changed, 66 insertions, 0 deletions

diff --git a/pkg/prompt/buffer.go b/pkg/prompt/buffer.go
new file mode 100644
index 0000000..03aca43
--- /dev/null
+++ b/pkg/prompt/buffer.go
@@ -0,0 +1,66 @@
+/*******************************************************************************
+*
+* Copyright 2017 Stefan Majewsky <majewsky@gmx.net>
+*
+* This program is free software: you can redistribute it and/or modify it under
+* the terms of the GNU General Public License as published by the Free Software
+* Foundation, either version 3 of the License, or (at your option) any later
+* version.
+*
+* This program is distributed in the hope that it will be useful, but WITHOUT ANY
+* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License along with
+* this program. If not, see <http://www.gnu.org/licenses/>.
+*
+*******************************************************************************/
+
+package prompt
+
+import "bytes"
+
+//LineBuffer wraps bytes.Buffer that measures the length of the displayed text
+//(minus ANSI escape sequences).
+type LineBuffer struct {
+	buffer bytes.Buffer
+	length int
+}
+
+//Bytes returns the complete string (including non-printable characters) in the
+//buffer.
+func (b *LineBuffer) Bytes() []byte {
+	return b.buffer.Bytes()
+}
+
+//Length returns the number of printable characters in the buffer.
+func (b *LineBuffer) Length() int {
+	return b.length
+}
+
+//Write implements the io.Writer interface. Use this only for printable
+//characters.
+func (b *LineBuffer) Write(buf []byte) (n int, err error) {
+	n, err = b.buffer.Write(buf)
+	b.length += n
+	return
+}
+
+//WriteNonprintable works like Write, but bytes written do not count towards
+//Length().
+func (b *LineBuffer) WriteNonprintable(buf []byte) (int, error) {
+	return b.buffer.Write(buf)
+}
+
+//WriteWithColor writes a colored printable string. The color is given as the
+//semicolon-separated list of arguments to the ANSI escape sequence SGR, e.g.
+//"1;41" for bold with red background.
+func (b *LineBuffer) WriteWithColor(text, color string) {
+	if color == "0" {
+		b.Write([]byte(text))
+	} else {
+		b.WriteNonprintable([]byte("\x1B[" + color + "m"))
+		b.Write([]byte(text))
+		b.WriteNonprintable([]byte("\x1B[0m"))
+	}
+}