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//! Operator precedence chain: lists (`;`/`\n`), background (`&`),
//! and/or (`&&`/`||`), and pipelines (`|`/`|&`, plus `!` and `time`).
use crate::ast::{ListItem, ListOperator, Node, NodeKind, PipeSep, Span};
use crate::error::Result;
use crate::token::TokenType;
use super::Parser;
use super::helpers::{add_stderr_redirect, make_stderr_redirect, word_node_from_token};
/// Creates a binary list node: `left op right`.
fn make_list(left: Node, op: ListOperator, right: Node) -> Node {
let span = Span::new(left.span.start, right.span.end);
Node::new(
NodeKind::List {
items: vec![
ListItem {
command: left,
operator: Some(op),
},
ListItem {
command: right,
operator: None,
},
],
},
span,
)
}
/// Creates a trailing-operator list node: `left op` (no RHS).
fn make_trailing(left: Node, op: ListOperator, end: usize) -> Node {
let span = Span::new(left.span.start, end);
Node::new(
NodeKind::List {
items: vec![ListItem {
command: left,
operator: Some(op),
}],
},
span,
)
}
impl Parser {
/// Like `parse_list` but stops at newlines — used only at the top level so
/// that newline-separated commands become separate nodes.
pub(super) fn parse_top_level_list(&mut self) -> Result<Node> {
self.enter()?;
let mut left = self.parse_top_level_background()?;
loop {
if self.at_end()? {
break;
}
let prev_pos = self.lexer.pos();
if self.lexer.peek_token()?.kind != TokenType::Semi {
break;
}
self.lexer.next_token()?;
self.skip_newlines()?;
if self.at_end()? || self.is_list_terminator()? {
break;
}
let right = self.parse_background()?;
left = make_list(left, ListOperator::Semi, right);
if self.lexer.pos() == prev_pos {
break;
}
}
self.leave();
Ok(left)
}
/// Parses a command list. Precedence: `;`/`\n` < `&` < `&&`/`||` < `|`.
///
/// # Errors
///
/// Returns `RableError` on syntax errors or unclosed delimiters.
pub fn parse_list(&mut self) -> Result<Node> {
self.enter()?;
let mut left = self.parse_background()?;
loop {
if self.at_end()? {
break;
}
let prev_pos = self.lexer.pos();
let kind = self.lexer.peek_token()?.kind;
if !matches!(kind, TokenType::Semi | TokenType::Newline) {
break;
}
self.lexer.next_token()?;
self.skip_newlines()?;
if self.at_end()? || self.is_list_terminator()? {
break;
}
let right = self.parse_background()?;
left = make_list(left, ListOperator::Semi, right);
if self.lexer.pos() == prev_pos {
break;
}
}
self.leave();
Ok(left)
}
/// Top-level variant: does not swallow newlines after `&`, so a `&\n`
/// leaves the newline for `parse_all` to start the next top-level node.
fn parse_top_level_background(&mut self) -> Result<Node> {
self.parse_background_inner(true)
}
fn parse_background(&mut self) -> Result<Node> {
self.parse_background_inner(false)
}
/// Shared background-operator loop. `top_level = true` preserves post-`&`
/// newlines; `false` skips them so `&\n` is treated like `&` followed by
/// the next command.
fn parse_background_inner(&mut self, top_level: bool) -> Result<Node> {
let mut left = self.parse_and_or()?;
loop {
if self.at_end()? {
break;
}
if self.lexer.peek_token()?.kind != TokenType::Ampersand {
break;
}
self.lexer.next_token()?;
if !top_level {
self.skip_newlines()?;
}
if self.at_end()? || self.is_list_terminator()? {
left = make_trailing(left, ListOperator::Background, self.lexer.pos());
break;
}
// At top level a raw newline after `&` ends the current node;
// in nested contexts newlines have already been skipped, so only
// a Semi is left as a "trailing" marker. Matching both is harmless.
let peek_kind = self.lexer.peek_token()?.kind;
if matches!(peek_kind, TokenType::Semi | TokenType::Newline) {
left = make_trailing(left, ListOperator::Background, self.lexer.pos());
break;
}
let right = self.parse_and_or()?;
left = make_list(left, ListOperator::Background, right);
}
Ok(left)
}
fn parse_and_or(&mut self) -> Result<Node> {
let mut left = self.parse_pipeline()?;
loop {
if self.at_end()? {
break;
}
let tok = self.lexer.peek_token()?;
match tok.kind {
TokenType::And => {
self.lexer.next_token()?;
self.skip_newlines()?;
let right = self.parse_pipeline()?;
left = make_list(left, ListOperator::And, right);
}
TokenType::Or => {
self.lexer.next_token()?;
self.skip_newlines()?;
let right = self.parse_pipeline()?;
left = make_list(left, ListOperator::Or, right);
}
_ => break,
}
}
Ok(left)
}
fn parse_pipeline(&mut self) -> Result<Node> {
let start = self.peek_pos()?;
if self.lexer.peek_token()?.kind == TokenType::Bang {
self.lexer.next_token()?;
if self.lexer.peek_token()?.kind == TokenType::Bang {
self.lexer.next_token()?;
return self.parse_pipeline_inner();
}
let inner = self.parse_pipeline()?;
return Ok(self.spanned(
start,
NodeKind::Negation {
pipeline: Box::new(inner),
},
));
}
if self.lexer.peek_token()?.kind == TokenType::Time {
self.lexer.next_token()?;
let posix = if self.check_word("-p")? {
self.lexer.next_token()?;
true
} else {
false
};
if self.lexer.peek_token()?.kind == TokenType::Bang {
self.lexer.next_token()?;
let p = self.parse_pipeline_inner()?;
return Ok(self.spanned(
start,
NodeKind::Negation {
pipeline: Box::new(self.spanned(
start,
NodeKind::Time {
pipeline: Box::new(p),
posix,
},
)),
},
));
}
let inner = self.parse_pipeline_inner()?;
return Ok(self.spanned(
start,
NodeKind::Time {
pipeline: Box::new(inner),
posix,
},
));
}
self.parse_pipeline_inner()
}
fn parse_pipeline_inner(&mut self) -> Result<Node> {
let mut commands = vec![self.parse_command()?];
let mut separators = Vec::new();
loop {
if self.at_end()? {
break;
}
let tok = self.lexer.peek_token()?;
match tok.kind {
TokenType::Pipe => {
self.lexer.next_token()?;
self.skip_newlines()?;
separators.push(PipeSep::Pipe);
commands.push(self.parse_pipeline_command()?);
}
TokenType::PipeBoth => {
self.lexer.next_token()?;
self.skip_newlines()?;
separators.push(PipeSep::PipeBoth);
if !add_stderr_redirect(commands.last_mut()) {
commands.push(make_stderr_redirect());
}
commands.push(self.parse_pipeline_command()?);
}
_ => break,
}
}
if commands.len() == 1 {
Ok(commands.remove(0))
} else {
let span = Span::new(
commands.first().map_or(0, |c| c.span.start),
commands.last().map_or(0, |c| c.span.end),
);
Ok(Node::new(
NodeKind::Pipeline {
commands,
separators,
},
span,
))
}
}
fn check_word(&mut self, expected: &str) -> Result<bool> {
let tok = self.lexer.peek_token()?;
Ok(tok.kind == TokenType::Word && tok.value == expected)
}
/// Parse a command after `|` in a pipeline — `time` is a regular word here.
fn parse_pipeline_command(&mut self) -> Result<Node> {
self.enter()?;
let start = self.peek_pos()?;
let tok = self.lexer.peek_token()?;
let is_time = tok.kind == TokenType::Time;
let result = if is_time {
// After |, time is a regular word, not a keyword.
// Temporarily demote it and all following reserved words to words.
let time_tok = self.lexer.next_token()?;
let mut words = vec![word_node_from_token(time_tok)];
// Check for -p flag (also a word in this context)
if self.check_word("-p")? {
let p_tok = self.lexer.next_token()?;
words.push(word_node_from_token(p_tok));
}
// Consume all remaining words (including reserved words as plain words)
let mut redirects = Vec::new();
loop {
if self.at_end()? {
break;
}
let t = self.lexer.peek_token()?;
if matches!(
t.kind,
TokenType::Pipe
| TokenType::PipeBoth
| TokenType::Semi
| TokenType::Newline
| TokenType::Ampersand
| TokenType::And
| TokenType::Or
| TokenType::Eof
| TokenType::RightParen
) {
break;
}
if self.is_redirect_operator()? {
redirects.push(self.parse_redirect()?);
continue;
}
let t = self.lexer.next_token()?;
words.push(word_node_from_token(t));
}
Ok(self.spanned(
start,
NodeKind::Command {
assignments: Vec::new(),
words,
redirects,
},
))
} else {
self.parse_command_inner()
};
self.leave();
result
}
}