Minor fixes along with partial support for variable default to anothe…

…r expression

crates/deno_task_shell/src/grammar.pest

@@ -38,7 +38,7 @@ VARIABLE_EXPANSION = ${
     )
 }
 
-VARIABLE_MODIFIER = ${
+VARIABLE_MODIFIER = _{
     VAR_DEFAULT_VALUE |
     VAR_ASSIGN_DEFAULT |
     VAR_ALTERNATE_VALUE |
@@ -50,8 +50,6 @@ VAR_ASSIGN_DEFAULT = { ":=" ~ UNQUOTED_PENDING_WORD }
 VAR_ALTERNATE_VALUE = { ":+" ~ UNQUOTED_PENDING_WORD }
 VAR_SUBSTRING = { ":" ~ NUMBER ~ (":" ~ NUMBER)? }
 
-NUMBER = @{ "-"? ~ ASCII_DIGIT+ }
-
 TILDE_PREFIX = ${
     "~" ~ (!(OPERATOR | WHITESPACE | NEWLINE | "/") ~ (
         (!("\"" | "'" | "$" | "\\" | "/") ~ ANY)

crates/deno_task_shell/src/parser.rs

@@ -121,16 +121,6 @@ pub struct PipeSequence {
   pub next: PipelineInner,
 }
 
-#[cfg_attr(feature = "serialization", derive(serde::Serialize))]
-#[cfg_attr(feature = "serialization", serde(rename_all = "camelCase"))]
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Error)]
-pub enum PipeSequenceOperator {
-  #[error("Stdout pipe operator")]
-  Stdout,
-  #[error("Stdout and stderr pipe operator")]
-  StdoutStderr,
-}
-
 impl From<PipeSequence> for Sequence {
   fn from(p: PipeSequence) -> Self {
     Sequence::Pipeline(Pipeline {
@@ -385,12 +375,12 @@ impl Word {
 pub enum VariableModifier {
   #[error("Invalid substring")]
   Substring {
-    begin: i64,
-    length: Option<i64>,
+    begin: WordPart,
+    length: Option<WordPart>,
   },
-  DefaultValue(String),
-  AssignDefault(String),
-  AlternateValue(String),
+  DefaultValue(WordPart),
+  AssignDefault(WordPart),
+  AlternateValue(WordPart),
 }
 
 #[cfg_attr(feature = "serialization", derive(serde::Serialize))]
@@ -403,7 +393,7 @@ pub enum WordPart {
   #[error("Invalid text")]
   Text(String),
   #[error("Invalid variable")]
-  Variable(String, Option<VariableModifier>),
+  Variable(String, Option<Box<VariableModifier>>),
   #[error("Invalid command")]
   Command(SequentialList),
   #[error("Invalid quoted string")]
@@ -1258,9 +1248,6 @@ fn parse_word(pair: Pair<Rule>) -> Result<Word> {
               parse_complete_command(part.into_inner().next().unwrap())?;
             parts.push(WordPart::Command(command));
           }
-          Rule::VARIABLE => {
-            parts.push(WordPart::Variable(part.as_str().to_string(), None))
-          }
           Rule::VARIABLE_EXPANSION => {
             let variable_expansion = parse_variable_expansion(part)?;
             parts.push(variable_expansion);
@@ -1513,16 +1500,16 @@ fn parse_variable_expansion(part: Pair<Rule>) -> Result<WordPart> {
     .ok_or_else(|| miette!("Expected variable name"))?;
   let variable_name = variable.as_str().to_string();
 
-  let modifier = inner.next().unwrap().into_inner().next();
+  let modifier = inner.next();
 
   let parsed_modifier = if let Some(modifier) = modifier {
     match modifier.as_rule() {
       Rule::VAR_SUBSTRING => {
         let mut numbers = modifier.into_inner();
         let begin = numbers
           .next()
-          .and_then(|n| n.as_str().parse::<i64>().ok())
-          .unwrap_or(0);
+          .and_then(|n| n.as_str())
+          .unwrap_or("0");
         let length =
           numbers.next().and_then(|n| n.as_str().parse::<i64>().ok());
         Some(VariableModifier::Substring { begin, length })
@@ -2020,7 +2007,7 @@ mod test {
           env_vars: vec![],
           args: vec![
             Word::new_word("echo"),
-            Word(vec![WordPart::Variable("MY_ENV".to_string())]),
+            Word(vec![WordPart::Variable("MY_ENV".to_string(), None)]),
           ],
         }
         .into(),

crates/deno_task_shell/src/shell/execute.rs

@@ -1120,13 +1120,16 @@ impl From<anyhow::Error> for EvaluateWordTextError {
 }
 
 impl VariableModifier {
-  pub fn apply(&self, variable: Option<&String>) -> Option<String> {
+  pub fn apply(&self, variable: Option<&String>) -> Result<Option<String>, anyhow::Error> {
     match self {
       VariableModifier::DefaultValue(default_value) => match variable {
-        Some(v) => Some(v.to_string()),
-        None => Some(default_value.clone()),
+        Some(v) => Ok(Some(v.to_string())),
+        None => Ok(Some(default_value.clone())),
       },
       VariableModifier::Substring { begin, length } => {
+        if variable.is_none() {
+          return Err(anyhow::anyhow!("Variable not found"));
+        }
         let variable = variable.unwrap();
         let chars: Vec<char> = variable.chars().collect();
         let start = usize::try_from(*begin).unwrap();
@@ -1136,9 +1139,9 @@ impl VariableModifier {
           }
           None => chars.len(),
         };
-        Some(chars[start..end].iter().collect())
-      }
-      _ => unreachable!("Should not reach"),
+        Ok(Some(chars[start..end].iter().collect()))
+      },
+      _ => Err(anyhow::anyhow!("Unsupported variable modifier")),
     }
   }
 }
@@ -1282,7 +1285,7 @@ fn evaluate_word_parts(
           WordPart::Variable(name, modifier) => {
             let value = state.get_var(&name).map(|v| v.to_string());
             if let Some(modifier) = modifier {
-              modifier.apply(value.as_ref())
+              modifier.apply(value.as_ref())?
             } else {
               value
             }