refactor the grammar a bit

2 files changed, 21 insertions, 17 deletions

diff --git a/src/parse/ast.rs b/src/parse/ast.rs
index 9cf583a..053f07f 100644
--- a/src/parse/ast.rs
+++ b/src/parse/ast.rs
@@ -160,7 +160,7 @@ impl Word {
     fn build_ast(pair: pest::iterators::Pair<Rule>) -> Self {
         assert!(matches!(pair.as_rule(), Rule::word));
         Self {
-            parts: pair.into_inner().map(WordPart::build_ast).collect(),
+            parts: pair.into_inner().flat_map(WordPart::build_ast).collect(),
         }
     }
 
@@ -183,8 +183,11 @@ enum WordPart {
 
 impl WordPart {
     #[allow(clippy::needless_pass_by_value)]
-    fn build_ast(pair: pest::iterators::Pair<Rule>) -> Self {
-        match pair.as_rule() {
+    fn build_ast(
+        pair: pest::iterators::Pair<Rule>,
+    ) -> impl Iterator<Item = Self> + '_ {
+        assert!(matches!(pair.as_rule(), Rule::word_part));
+        pair.into_inner().map(|pair| match pair.as_rule() {
             Rule::var => {
                 let s = pair.as_str();
                 let inner = s.strip_prefix('$').unwrap();
@@ -205,7 +208,7 @@ impl WordPart {
                 Self::SingleQuoted(strip_basic_escape(pair.as_str()))
             }
             _ => unreachable!(),
-        }
+        })
     }
 
     fn eval(self, env: &Env) -> String {
@@ -282,7 +285,7 @@ enum WordOrRedirect {
 
 impl WordOrRedirect {
     fn build_ast(pair: pest::iterators::Pair<Rule>) -> Self {
-        assert!(matches!(pair.as_rule(), Rule::word));
+        assert!(matches!(pair.as_rule(), Rule::word_or_redirect));
         let mut inner = pair.into_inner().peekable();
         let prefix = if matches!(
             inner.peek().map(pest::iterators::Pair::as_rule),
@@ -292,9 +295,7 @@ impl WordOrRedirect {
         } else {
             None
         };
-        let word = Word {
-            parts: inner.map(WordPart::build_ast).collect(),
-        };
+        let word = Word::build_ast(inner.next().unwrap());
         if let Some(prefix) = prefix {
             Self::Redirect(Redirect::parse(&prefix, word))
         } else {
diff --git a/src/shell.pest b/src/shell.pest
index dc3f247..393e60e 100644
--- a/src/shell.pest
+++ b/src/shell.pest
@@ -8,27 +8,30 @@ bareword_char = @{
 single_string_char = @{ basic_escape_char | (!"'" ~ ANY) }
 double_string_char = @{ escape_char | (!"\"" ~ ANY) }
 
+redir_prefix = @{
+    ("in" | "out" | "err" | ASCII_DIGIT*) ~ (">>" | ">" | "<") ~ WHITESPACE*
+}
+
 var = @{
     ("$" ~ XID_START ~ XID_CONTINUE*) |
     ("$" ~ ("?" | "$" | "*" | ASCII_DIGIT)) |
     ("${" ~ (!"}" ~ ANY)+ ~ "}")
 }
-
-redir_prefix = @{
-    ("in" | "out" | "err" | ASCII_DIGIT*) ~ (">>" | ">" | "<") ~ WHITESPACE*
-}
 bareword      = @{ bareword_char+ }
 single_string = @{ single_string_char+ }
 double_string = @{ double_string_char+ }
 
-word     = ${
-    redir_prefix? ~
-    (var | bareword |
+word_part = ${
+    var |
+    bareword |
     "'" ~ single_string ~ "'" |
-    "\"" ~ (var | double_string)+ ~ "\"")+
+    "\"" ~ (var | double_string)+ ~ "\""
 }
+word = ${ word_part+ }
+
+word_or_redirect = ${ redir_prefix? ~ word }
 
-exe      = ${ word ~ (w ~ word)* }
+exe      = ${ word_or_redirect ~ (w ~ word_or_redirect)* }
 list     = ${ word ~ (w ~ word)* }
 pipeline = ${ exe ~ (w? ~ "|" ~ w? ~ exe)* }