escaped := false
	quoted := false
	quote := '\x00'
	i := 0
	for _, r := range s {
		switch {
		case escaped:
			escaped = false
		case r == '\\':
			escaped = true
			continue
		case quote != 0:
			if r == quote {
				quote = 0
				continue
			}
		case r == '"' || r == '\'':
			quoted = true
			quote = r
			continue
		case unicode.IsSpace(r):

\f   U+000C form feed
\n   U+000A line feed or newline
\r   U+000D carriage return
\t   U+0009 horizontal tab
\v   U+000B vertical tab
\\   U+005C backslash
\'   U+0027 single quote  (valid escape only within rune literals)
\"   U+0022 double quote  (valid escape only within string literals)
</pre>

<p>
All other sequences starting with a backslash are illegal inside rune literals.
</p>
<pre class="ebnf">

	os.Exit(1)
}

// expectText is like Error but adds "got XXX" where XXX is a quoted representation of the most recent token.
func (in *Input) expectText(args ...interface{}) {
	in.Error(append(args, "; got", strconv.Quote(in.Stack.Text()))...)
}

// enabled reports whether the input is enabled by an ifdef, or is at the top level.
func (in *Input) enabled() bool {
	return len(in.ifdefStack) == 0 || in.ifdefStack[len(in.ifdefStack)-1]
}

	{"TrimLeft", "abba", "b", "abba"},
	{"TrimRight", "abba", "a", "abb"},
	{"TrimRight", "abba", "b", "abba"},
	{"Trim", "<tag>", "<>", "tag"},
	{"Trim", "* listitem", " *", "listitem"},
	{"Trim", `"quote"`, `"`, "quote"},
	{"Trim", "\u2C6F\u2C6F\u0250\u0250\u2C6F\u2C6F", "\u2C6F", "\u0250\u0250"},
	{"Trim", "\x80test\xff", "\xff", "test"},
	{"Trim", " Ġ ", " ", "Ġ"},
	{"Trim", " Ġİ0", "0 ", "Ġİ"},
	//empty string tests

\f   U+000C form feed
\n   U+000A line feed or newline
\r   U+000D carriage return
\t   U+0009 horizontal tab
\v   U+000B vertical tab
\\   U+005C backslash
\'   U+0027 single quote  (valid escape only within rune literals)
\"   U+0022 double quote  (valid escape only within string literals)
</pre>

<p>
An unrecognized character following a backslash in a rune literal is illegal.
</p>

<pre class="ebnf">