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use crate::context::CaseTracker;
use crate::error::{RableError, Result};
use super::Lexer;
use super::word_builder::{QuotingContext, WordBuilder, WordSpanKind};
impl Lexer {
/// Reads a dollar expansion into the value string.
pub(super) fn read_dollar(&mut self, wb: &mut WordBuilder) -> Result<()> {
let span_start = wb.span_start();
self.advance_char(); // consume '$'
wb.push('$');
match self.peek_char() {
Some('(') => {
self.advance_char();
wb.push('(');
if self.peek_char() == Some('(') {
self.advance_char();
wb.push('(');
self.read_matched_parens(wb, 2)?;
wb.record(span_start, WordSpanKind::ArithmeticSub);
} else {
self.read_command_sub(wb)?;
wb.record(span_start, WordSpanKind::CommandSub);
}
}
Some('{') => {
self.advance_char();
wb.push('{');
self.read_param_expansion_braces(wb)?;
wb.record(span_start, WordSpanKind::ParamExpansion);
}
Some('\'') => {
self.advance_char();
wb.push('\'');
self.read_ansi_c_quoted(wb)?;
wb.record(span_start, WordSpanKind::AnsiCQuote);
}
Some('"') => {
self.advance_char();
wb.push('"');
self.read_double_quoted(wb)?;
wb.record(span_start, WordSpanKind::LocaleString);
}
Some('[') => {
self.advance_char();
wb.push('[');
self.read_deprecated_arith(wb)?;
wb.record(span_start, WordSpanKind::DeprecatedArith);
}
Some(c) if is_dollar_start(c) => {
self.read_variable_name(wb, c);
wb.record(span_start, WordSpanKind::SimpleVar);
}
_ => {} // Bare $ — no span
}
Ok(())
}
/// Reads `$(...)` command substitution content and validates it.
fn read_command_sub(&mut self, wb: &mut WordBuilder) -> Result<()> {
let content_start = wb.len();
self.read_matched_parens(wb, 1)?;
let content_end = wb.len().saturating_sub(1);
if content_start < content_end {
let content = &wb.value[content_start..content_end];
if !content.trim().is_empty() && crate::parse(content, self.extglob()).is_err() {
return Err(RableError::parse(
"invalid command substitution",
self.pos,
self.line,
));
}
}
Ok(())
}
/// Reads a variable name after `$` for simple expansions.
pub(super) fn read_variable_name(&mut self, wb: &mut WordBuilder, first: char) {
if first.is_ascii_alphabetic() || first == '_' {
while let Some(nc) = self.peek_char() {
if nc.is_ascii_alphanumeric() || nc == '_' {
self.advance_char();
wb.push(nc);
} else {
break;
}
}
} else {
self.advance_char();
wb.push(first);
}
}
/// Reads until matching closing parentheses.
#[allow(clippy::too_many_lines)]
pub(super) fn read_matched_parens(
&mut self,
wb: &mut WordBuilder,
close_count: usize,
) -> Result<()> {
wb.enter_context(QuotingContext::CommandSub);
let result = self.read_matched_parens_inner(wb, close_count);
wb.leave_context();
result
}
#[allow(clippy::too_many_lines)]
fn read_matched_parens_inner(
&mut self,
wb: &mut WordBuilder,
close_count: usize,
) -> Result<()> {
let mut depth = close_count;
let mut case = CaseTracker::default();
let mut word_buf = String::new();
loop {
match self.peek_char() {
Some(')') => {
// Check keyword before consuming `)`
case.check_word(&word_buf);
word_buf.clear();
self.advance_char();
wb.push(')');
if case.is_pattern_close() {
// This `)` terminates a case pattern — don't decrement depth
case.close_pattern();
} else {
depth -= 1;
if depth == 0 {
return Ok(());
}
}
}
Some('(') => {
case.check_word(&word_buf);
word_buf.clear();
self.advance_char();
wb.push('(');
// In case pattern mode, `(` is optional pattern prefix — don't increment
if !case.is_pattern_open() {
depth += 1;
}
}
Some('\'') => {
case.check_word(&word_buf);
word_buf.clear();
self.advance_char();
wb.push('\'');
self.read_single_quoted(wb)?;
}
Some('"') => {
case.check_word(&word_buf);
word_buf.clear();
self.advance_char();
wb.push('"');
self.read_double_quoted(wb)?;
}
Some('\\') => {
word_buf.clear();
self.advance_char();
if self.peek_char() == Some('\n') {
self.advance_char(); // line continuation
} else {
wb.push('\\');
if let Some(c) = self.advance_char() {
wb.push(c);
} else {
wb.push('\\');
}
}
}
Some('$') => {
word_buf.clear();
self.read_dollar(wb)?;
}
Some('`') => {
word_buf.clear();
self.advance_char();
wb.push('`');
self.read_backtick(wb)?;
}
Some('#') => {
case.check_word(&word_buf);
word_buf.clear();
// # is a comment when preceded by whitespace/newline
let prev = wb.value.chars().last().unwrap_or('\n');
if prev == '\n' || prev == ' ' || prev == '\t' {
// Comment — skip to end of line
while let Some(c) = self.peek_char() {
if c == '\n' {
break;
}
self.advance_char();
}
} else {
self.advance_char();
wb.push('#');
}
}
Some(';') => {
case.check_word(&word_buf);
word_buf.clear();
self.advance_char();
wb.push(';');
// Check for ;; ;& ;;& which resume case pattern mode
if self.peek_char() == Some(';') {
self.advance_char();
wb.push(';');
if self.peek_char() == Some('&') {
self.advance_char();
wb.push('&');
}
case.resume_pattern();
} else if self.peek_char() == Some('&') {
self.advance_char();
wb.push('&');
case.resume_pattern();
}
}
Some(' ' | '\t' | '\n') => {
case.check_word(&word_buf);
word_buf.clear();
let c = self.advance_char().unwrap_or(' ');
wb.push(c);
}
Some('|') => {
case.check_word(&word_buf);
word_buf.clear();
self.advance_char();
wb.push('|');
}
Some(c) => {
word_buf.push(c);
self.advance_char();
wb.push(c);
}
None => {
return Err(RableError::matched_pair(
"unterminated parenthesis",
self.pos,
self.line,
));
}
}
}
}
/// Reads a parameter expansion `${...}` allowing unbalanced inner `{`.
pub(super) fn read_param_expansion_braces(&mut self, wb: &mut WordBuilder) -> Result<()> {
wb.enter_context(QuotingContext::ParamExpansion);
let result = self.read_param_expansion_inner(wb);
wb.leave_context();
result
}
fn read_param_expansion_inner(&mut self, wb: &mut WordBuilder) -> Result<()> {
loop {
match self.peek_char() {
Some('}') => {
self.advance_char();
wb.push('}');
return Ok(());
}
Some('\'') => {
self.advance_char();
wb.push('\'');
self.read_single_quoted(wb)?;
}
Some('"') => {
self.advance_char();
wb.push('"');
self.read_double_quoted(wb)?;
}
Some('\\') => {
self.advance_char();
if self.peek_char() == Some('\n') {
self.advance_char(); // line continuation
} else {
wb.push('\\');
if let Some(c) = self.advance_char() {
wb.push(c);
} else {
wb.push('\\');
}
}
}
Some('$') => {
self.read_dollar(wb)?;
}
Some('`') => {
self.advance_char();
wb.push('`');
self.read_backtick(wb)?;
}
Some(c) => {
self.advance_char();
wb.push(c);
}
None => {
return Err(RableError::matched_pair(
"unterminated parameter expansion",
self.pos,
self.line,
));
}
}
}
}
/// Reads a backtick command substitution.
pub(super) fn read_backtick(&mut self, wb: &mut WordBuilder) -> Result<()> {
wb.enter_context(QuotingContext::Backtick);
let result = self.read_backtick_inner(wb);
wb.leave_context();
result
}
fn read_backtick_inner(&mut self, wb: &mut WordBuilder) -> Result<()> {
loop {
match self.peek_char() {
Some('`') => {
self.advance_char();
wb.push('`');
return Ok(());
}
Some('\\') => {
self.advance_char();
wb.push('\\');
if let Some(c) = self.advance_char() {
wb.push(c);
}
}
Some(c) => {
self.advance_char();
wb.push(c);
}
None => {
return Err(RableError::matched_pair(
"unterminated backtick",
self.pos,
self.line,
));
}
}
}
}
/// Reads deprecated `$[...]` arithmetic with bracket depth tracking.
fn read_deprecated_arith(&mut self, wb: &mut WordBuilder) -> Result<()> {
let mut depth = 1;
loop {
match self.advance_char() {
Some('[') => {
depth += 1;
wb.push('[');
}
Some(']') => {
depth -= 1;
wb.push(']');
if depth == 0 {
return Ok(());
}
}
Some(c) => wb.push(c),
None => {
return Err(RableError::matched_pair(
"unterminated '$['",
self.pos,
self.line,
));
}
}
}
}
}
/// Returns true if the character can follow `$` to start a variable expansion.
pub(super) const fn is_dollar_start(c: char) -> bool {
c.is_ascii_alphanumeric() || matches!(c, '_' | '@' | '*' | '#' | '?' | '-' | '$' | '!')
}