feat: support tilde expansion (#146)

Author: dsherret

Cargo.lock

@@ -25,7 +25,7 @@ monch = "0.5.0"
 thiserror = "2.0.9"
 tokio = { version = "1", features = ["fs", "io-std", "io-util", "macros", "process", "rt-multi-thread", "sync", "time"], optional = true }
 deno_path_util = "0.3.2"
-sys_traits = { version = "0.1.8", features = ["real"] }
+sys_traits = { version = "0.1.9", features = ["real", "winapi", "libc"] }
 
 [target.'cfg(unix)'.dependencies]
 nix = { version = "0.29.0", features = ["signal"], optional = true }

Cargo.toml

@@ -248,6 +248,8 @@ pub enum WordPart {
   Text(String),
   /// Variable substitution (ex. `$MY_VAR`)
   Variable(String),
+  /// Tilde expansion (ex. `~`)
+  Tilde,
   /// Command substitution (ex. `$(command)`)
   Command(SequentialList),
   /// Quoted string (ex. `"hello"` or `'test'`)
@@ -751,30 +753,44 @@ fn parse_word_parts(
     or7(
       parse_special_shell_var,
       parse_escaped_dollar_sign,
+      parse_escaped_char('~'),
       parse_escaped_char('`'),
       parse_escaped_char('"'),
       parse_escaped_char('('),
-      parse_escaped_char(')'),
-      if_true(parse_escaped_char('\''), move |_| {
-        mode == ParseWordPartsMode::DoubleQuotes
-      }),
+      or(
+        parse_escaped_char(')'),
+        if_true(parse_escaped_char('\''), move |_| {
+          mode == ParseWordPartsMode::DoubleQuotes
+        }),
+      ),
     )
   }
 
+  fn append_char(result: &mut Vec<WordPart>, c: char) {
+    if let Some(WordPart::Text(text)) = result.last_mut() {
+      text.push(c);
+    } else {
+      result.push(WordPart::Text(c.to_string()));
+    }
+  }
+
   move |input| {
     enum PendingPart<'a> {
       Char(char),
       Variable(&'a str),
+      Tilde,
       Command(SequentialList),
       Parts(Vec<WordPart>),
     }
 
+    let original_input = input;
     let (input, parts) = many0(or7(
-      or(
+      or3(
         map(tag("$?"), |_| PendingPart::Variable("?")),
         map(first_escaped_char(mode), PendingPart::Char),
+        map(parse_command_substitution, PendingPart::Command),
       ),
-      map(parse_command_substitution, PendingPart::Command),
+      map(ch('~'), |_| PendingPart::Tilde),
       map(preceded(ch('$'), parse_env_var_name), PendingPart::Variable),
       |input| {
         let (_, _) = ch('`')(input)?;
@@ -812,22 +828,32 @@ fn parse_word_parts(
     ))(input)?;
 
     let mut result = Vec::new();
-    for part in parts {
+    let mut parts = parts.into_iter().enumerate().peekable();
+    while let Some((i, part)) = parts.next() {
       match part {
         PendingPart::Char(c) => {
-          if let Some(WordPart::Text(text)) = result.last_mut() {
-            text.push(c);
+          append_char(&mut result, c);
+        }
+        PendingPart::Tilde => {
+          if i == 0 {
+            if matches!(parts.peek(), None | Some((_, PendingPart::Char('/'))))
+            {
+              result.push(WordPart::Tilde);
+            } else {
+              return ParseError::fail(
+                original_input,
+                "Unsupported tilde expansion.",
+              );
+            }
           } else {
-            result.push(WordPart::Text(c.to_string()));
+            append_char(&mut result, '~');
           }
         }
         PendingPart::Command(s) => result.push(WordPart::Command(s)),
         PendingPart::Variable(v) => {
-          result.push(WordPart::Variable(v.to_string()))
-        }
-        PendingPart::Parts(parts) => {
-          result.extend(parts);
+          result.push(WordPart::Variable(v.to_string()));
         }
+        PendingPart::Parts(parts) => result.extend(parts),
       }
     }
 
@@ -1427,6 +1453,25 @@ mod test {
     );
   }
 
+  #[test]
+  fn tilde_expansion() {
+    run_test(
+      parse_word_parts(ParseWordPartsMode::Unquoted),
+      r#"~test"#,
+      Err("Unsupported tilde expansion."),
+    );
+    run_test(
+      parse_word_parts(ParseWordPartsMode::Unquoted),
+      r#"~+/test"#,
+      Err("Unsupported tilde expansion."),
+    );
+    run_test(
+      parse_word_parts(ParseWordPartsMode::Unquoted),
+      r#"~/test"#,
+      Ok(vec![WordPart::Tilde, WordPart::Text("/test".to_string())]),
+    );
+  }
+
   #[test]
   fn test_parse_word() {
     run_test(parse_unquoted_word, "if", Err("Unsupported reserved word."));

src/parser.rs

@@ -750,11 +750,13 @@ pub enum EvaluateWordTextError {
   NotUtf8Pattern { part: OsString },
   #[error("glob: no matches found '{}'", pattern)]
   NoFilesMatched { pattern: String },
-  #[error("Invalid utf-8: {}", err)]
+  #[error("invalid utf-8: {}", err)]
   InvalidUtf8 {
     #[from]
     err: FromUtf8Error,
   },
+  #[error("failed resolving home directory for tilde expansion")]
+  NoHomeDirectory,
 }
 
 impl EvaluateWordTextError {
@@ -904,6 +906,11 @@ fn evaluate_word_parts(
             None
           }
           WordPart::Variable(name) => state.get_var(OsStr::new(&name)).cloned(),
+          WordPart::Tilde => Some(
+            sys_traits::impls::real_home_dir_with_env(state)
+              .map(|s| s.into_os_string())
+              .ok_or(EvaluateWordTextError::NoHomeDirectory)?,
+          ),
           WordPart::Command(list) => Some(
             evaluate_command_substitution(
               list,

src/shell/execute.rs

@@ -206,6 +206,12 @@ impl ShellState {
   }
 }
 
+impl sys_traits::BaseEnvVar for ShellState {
+  fn base_env_var_os(&self, key: &OsStr) -> Option<OsString> {
+    self.env_vars.get(key).cloned()
+  }
+}
+
 #[derive(Debug, PartialEq, Eq)]
 pub enum EnvChange {
   // `export ENV_VAR=VALUE`

src/shell/types.rs

@@ -1429,6 +1429,30 @@ async fn paren_escapes() {
     .await;
 }
 
+#[tokio::test]
+async fn tilde_expansion() {
+  let text = concat!(
+    r"export HOME=/home/dir && echo ~/test && echo ~ && ",
+    r"echo \~ && export HOME=/test && echo ~ && ",
+    r"HOME=/nope echo ~ && ",
+    r"HOME=/nope $(echo echo ~) && ",
+    r"echo ~/sub/~/sub"
+  );
+  let text = if cfg!(windows) {
+    // windows uses a different env var
+    text.replace("HOME", "USERPROFILE")
+  } else {
+    text.to_string()
+  };
+  TestBuilder::new()
+    .command(&text)
+    .assert_stdout(
+      "/home/dir/test\n/home/dir\n~\n/test\n/test\n/test\n/test/sub/~/sub\n",
+    )
+    .run()
+    .await;
+}
+
 #[tokio::test]
 async fn cross_platform_shebang() {
   // with -S