Don't interpret environment variables in single quoted stringscompose

Previously, if an environment variable was given in a string, such as:
'$PATH' or "$PATH", both would be replaced with the value of $PATH from
the environment. However, for single quotes strings, any values inside
should be taken at face value. In other words, echo '$PATH' should
simply write out: $PATH, and not whatever environment value $PATH
happens to be. This patch replaced '$' in single quoted strings with
the ASCII shift out (x0e) character. Any ASCII SO placeholder is
replaced with a '$' in recite(), after the environment variables have
been accounted for.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/poem/read/parse.rs b/src/poem/read/parse.rs
index c1dec44..0836eea 100644
--- a/src/poem/read/parse.rs
+++ b/src/poem/read/parse.rs
@@ -31,6 +31,10 @@ macro_rules! string {
             match $chars.next() {
                 None => return Err(Mishap::PartialMishap($j, $i, $c)),
                 Some(c) if c == token => break,
+                Some(c) if token == '\'' && c == '$' => {
+                    $word.push('\x0e');
+                    $i += 1;
+                }
                 Some(c) => {
                     $word.push(c);
                     $i += 1;