Add partial config implementation

Progress on #3

config/escape.go

@@ -0,0 +1,97 @@
+package config
+
+import "fmt"
+import "strings"
+// import "unicode"
+
+var escapeCodeToRune = map[rune] rune {
+	'\\': '\\',
+	'a':  '\a',
+	'b':  '\b',
+	't':  '\t',
+	'n':  '\n',
+	'v':  '\v',
+	'f':  '\f',
+	'r':  '\r',
+	'"':  '"',
+}
+
+var runeToEscapeCode = map[rune] rune { }
+func init () {
+	for code, char := range escapeCodeToRune {
+		runeToEscapeCode[char] = code
+	}
+}
+
+func escape (str string) string {
+	builder := strings.Builder { }
+	for _, char := range str {
+		code, escaped := runeToEscapeCode[char]
+		switch {
+		case escaped:
+			fmt.Fprintf(&builder, "\\%c", code)
+		// case !unicode.IsPrint(char):
+			// fmt.Fprintf(&builder, "\\%o", char)
+		default:
+			builder.WriteRune(char)
+		}
+	}
+	return builder.String()
+}
+
+func unescape (str string) (string, bool) {
+	runes := []rune(str)
+	builder := strings.Builder { }
+
+	end := func () bool {
+		return len(runes) < 1
+	}
+	next := func () {
+		if !end() { runes = runes[1:] }
+	}
+	
+	for !end() {
+		if runes[0] == '\\' {
+			if end() { return "", false }
+			next()
+			char, isEscape := escapeCodeToRune[runes[0]]
+			switch {
+			case isEscape:
+				builder.WriteRune(char)
+				next()
+			// case isOctalDigit(runes[0]):
+				// char = 0
+				// for !end() && isOctalDigit(runes[0]) {
+					// char *= 8
+					// char += runes[0] - '0'
+					// next()
+				// }
+				// builder.WriteRune(char)
+			default:
+				return "", false
+			}
+		} else {
+			builder.WriteRune(runes[0])
+			next()
+		}
+	}
+	return builder.String(), true
+}
+
+func unquote (str string) (string, bool) {
+	if len(str) < 2             { return "", false }
+	if firstRune(str)    != '"' { return "", false }
+	if str[len(str) - 1] != '"' { return "", false }
+	return str[1:len(str) - 1], true
+}
+
+func isOctalDigit (char rune) bool {
+	return char >= '0' && char <= '7'
+}
+
+func firstRune (str string) rune {
+	for _, char := range str {
+		return char
+	}
+	return 0
+}