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use std::sync::Arc;
use crate::{Span, Value, ast::Expression, ir::DataSlice};
/// Represents a fully evaluated argument to a call.
#[derive(Debug, Clone)]
pub enum Argument {
/// A positional argument
Positional {
span: Span,
val: Value,
ast: Option<Arc<Expression>>,
},
/// A spread argument, e.g. `...$args`
Spread {
span: Span,
vals: Value,
ast: Option<Arc<Expression>>,
},
/// A named argument with no value, e.g. `--flag`
Flag {
data: Arc<[u8]>,
name: DataSlice,
short: DataSlice,
span: Span,
},
/// A named argument with a value, e.g. `--flag value` or `--flag=`
Named {
data: Arc<[u8]>,
name: DataSlice,
short: DataSlice,
span: Span,
val: Value,
ast: Option<Arc<Expression>>,
},
/// Information generated by the parser for use by certain keyword commands
ParserInfo {
data: Arc<[u8]>,
name: DataSlice,
// TODO: rather than `Expression`, this would probably be best served by a specific enum
// type for this purpose.
info: Box<Expression>,
},
}
impl Argument {
/// The span encompassing the argument's usage within the call, distinct from the span of the
/// actual value of the argument.
pub fn span(&self) -> Option<Span> {
match self {
Argument::Positional { span, .. } => Some(*span),
Argument::Spread { span, .. } => Some(*span),
Argument::Flag { span, .. } => Some(*span),
Argument::Named { span, .. } => Some(*span),
// Because `ParserInfo` is generated, its span shouldn't be used
Argument::ParserInfo { .. } => None,
}
}
/// The original AST [`Expression`] for the argument's value. This is not usually available;
/// declarations have to opt-in if they require this.
pub fn ast_expression(&self) -> Option<&Arc<Expression>> {
match self {
Argument::Positional { ast, .. } => ast.as_ref(),
Argument::Spread { ast, .. } => ast.as_ref(),
Argument::Flag { .. } => None,
Argument::Named { ast, .. } => ast.as_ref(),
Argument::ParserInfo { .. } => None,
}
}
}
/// Stores the argument context for calls in IR evaluation.
#[derive(Debug, Clone, Default)]
pub struct ArgumentStack {
arguments: Vec<Argument>,
}
impl ArgumentStack {
/// Create a new, empty argument stack.
pub const fn new() -> Self {
ArgumentStack { arguments: vec![] }
}
/// Returns the index of the end of the argument stack. Call and save this before adding
/// arguments.
pub fn get_base(&self) -> usize {
self.arguments.len()
}
/// Calculates the number of arguments past the given [previously retrieved](.get_base) base
/// pointer.
pub fn get_len(&self, base: usize) -> usize {
self.arguments.len().checked_sub(base).unwrap_or_else(|| {
panic!(
"base ({}) is beyond the end of the arguments stack ({})",
base,
self.arguments.len()
);
})
}
/// Push an argument onto the end of the argument stack.
pub fn push(&mut self, argument: Argument) {
self.arguments.push(argument);
}
/// Clear all of the arguments after the given base index, to prepare for the next frame.
pub fn leave_frame(&mut self, base: usize) {
self.arguments.truncate(base);
}
/// Get arguments for the frame based on the given [`base`](`.get_base()`) and
/// [`len`](`.get_len()`) parameters.
pub fn get_args(&self, base: usize, len: usize) -> &[Argument] {
&self.arguments[base..(base + len)]
}
/// Move arguments for the frame based on the given [`base`](`.get_base()`) and
/// [`len`](`.get_len()`) parameters.
pub fn drain_args(&mut self, base: usize, len: usize) -> impl Iterator<Item = Argument> + '_ {
self.arguments.drain(base..(base + len))
}
}