Implemented scoping for expansions

src/expand/vars.rs

@@ -1,5 +1,7 @@
 use crate::{parse::lex::Token, prelude::*};
 
+use super::cmdsub::expand_cmdsub_string;
+
 pub fn expand_var(var_sub: Token, shenv: &mut ShEnv) -> Vec<Token> {
 	let var_name = var_sub.as_raw(shenv);
 	let var_name = var_name.trim_start_matches('$').trim_matches(['{','}']);
@@ -8,7 +10,7 @@ pub fn expand_var(var_sub: Token, shenv: &mut ShEnv) -> Vec<Token> {
 	shenv.expand_input(&value, var_sub.span())
 }
 
-pub fn expand_string(s: &str, shenv: &mut ShEnv) -> String {
+pub fn expand_string(s: &str, shenv: &mut ShEnv) -> ShResult<String> {
 	let mut result = String::new();
 	let mut var_name = String::new();
 	let mut chars = s.chars().peekable();
@@ -38,6 +40,30 @@ pub fn expand_string(s: &str, shenv: &mut ShEnv) -> String {
 							expanded = true;
 							break
 						}
+						'(' if var_name.is_empty() => {
+							let mut paren_count = 1;
+							var_name.push_str("$(");
+							while let Some(ch) = chars.next() {
+								match ch {
+									'(' => {
+										paren_count += 1;
+										var_name.push(ch);
+									}
+									')' => {
+										paren_count -= 1;
+										var_name.push(ch);
+										if paren_count == 0 {
+											break
+										}
+									}
+									_ => var_name.push(ch)
+								}
+							}
+							let value = expand_cmdsub_string(&var_name, shenv)?;
+							result.push_str(&value);
+							expanded = true;
+							break
+						}
 						_ if ch.is_ascii_digit() && var_name.is_empty() && !in_brace => {
 							var_name.push(ch);
 							let value = shenv.vars().get_var(&var_name);
@@ -72,5 +98,5 @@ pub fn expand_string(s: &str, shenv: &mut ShEnv) -> String {
 			_ => result.push(ch)
 		}
 	}
-	result
+	Ok(result)
 }