From 278a4952b91a4a28bbe25e4dc96e68fe203a9dc1 Mon Sep 17 00:00:00 2001
From: Arpad Ryszka <arpad.ryszka@gmail.com>
Date: Sun, 29 Oct 2017 16:38:32 +0100
Subject: [PATCH] cleanup boot

---
 unescape.go | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 unescape.go

diff --git a/unescape.go b/unescape.go
new file mode 100644
index 0000000..f6bb163
--- /dev/null
+++ b/unescape.go
@@ -0,0 +1,64 @@
+package treerack
+
+func runesContain(rs []rune, r rune) bool {
+	for _, ri := range rs {
+		if ri == r {
+			return true
+		}
+	}
+
+	return false
+}
+
+func unescapeChar(c rune) rune {
+	switch c {
+	case 'n':
+		return '\n'
+	case 't':
+		return '\t'
+	case 'b':
+		return '\b'
+	case 'f':
+		return '\f'
+	case 'r':
+		return '\r'
+	case 'v':
+		return '\v'
+	default:
+		return c
+	}
+}
+
+func unescape(escape rune, banned []rune, chars []rune) ([]rune, error) {
+	var (
+		unescaped []rune
+		escaped   bool
+	)
+
+	for _, ci := range chars {
+		if escaped {
+			unescaped = append(unescaped, unescapeChar(ci))
+			escaped = false
+			continue
+		}
+
+		switch {
+		case ci == escape:
+			escaped = true
+		case runesContain(banned, ci):
+			return nil, ErrInvalidEscapeCharacter
+		default:
+			unescaped = append(unescaped, ci)
+		}
+	}
+
+	if escaped {
+		return nil, ErrInvalidEscapeCharacter
+	}
+
+	return unescaped, nil
+}
+
+func unescapeCharSequence(s string) ([]rune, error) {
+	return unescape('\\', []rune{'"', '\\'}, []rune(s))
+}