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use crate::error::{RableError, Result};
use super::Lexer;
/// Checks if a completed word is a case-related keyword and updates tracking state.
fn check_case_keyword(word: &str, case_depth: &mut usize, in_pattern: &mut bool) {
match word {
"case" => {
*case_depth += 1;
}
"in" if *case_depth > 0 => {
*in_pattern = true;
}
"esac" if *case_depth > 0 => {
*case_depth -= 1;
if *case_depth == 0 {
*in_pattern = false;
}
}
_ => {}
}
}
impl Lexer {
/// Reads a dollar expansion into the value string.
pub(super) fn read_dollar(&mut self, value: &mut String) -> Result<()> {
self.advance_char(); // consume '$'
value.push('$');
match self.peek_char() {
Some('(') => {
self.advance_char();
value.push('(');
if self.peek_char() == Some('(') {
// $(( ... )) arithmetic expansion
self.advance_char();
value.push('(');
self.read_matched_parens(value, 2)?;
} else {
// $( ... ) command substitution
let content_start = value.len();
self.read_matched_parens(value, 1)?;
// Validate content is parseable bash
let content_end = value.len().saturating_sub(1);
if content_start < content_end {
let content: String = value[content_start..content_end].to_string();
if !content.trim().is_empty()
&& crate::parse(&content, self.extglob()).is_err()
{
return Err(RableError::parse(
"invalid command substitution",
self.pos,
self.line,
));
}
}
}
}
Some('{') => {
self.advance_char();
value.push('{');
// Parameter expansion: don't count unquoted { as depth increase
self.read_param_expansion_braces(value)?;
}
Some('\'') => {
// $'...' ANSI-C quoting — handles \ escapes unlike regular ''
self.advance_char();
value.push('\'');
self.read_ansi_c_quoted(value)?;
}
Some('"') => {
// $"..." locale string
self.advance_char();
value.push('"');
self.read_double_quoted(value)?;
}
Some('[') => {
// $[...] deprecated arithmetic
self.advance_char();
value.push('[');
self.read_until_char(value, ']')?;
}
Some(c) if is_dollar_start(c) => self.read_variable_name(value, c),
_ => {} // Bare $ at end of word — just leave it
}
Ok(())
}
/// Reads a variable name after `$` for simple expansions.
pub(super) fn read_variable_name(&mut self, value: &mut String, first: char) {
if first.is_ascii_alphabetic() || first == '_' {
while let Some(nc) = self.peek_char() {
if nc.is_ascii_alphanumeric() || nc == '_' {
self.advance_char();
value.push(nc);
} else {
break;
}
}
} else {
self.advance_char();
value.push(first);
}
}
/// Reads until matching closing parentheses.
#[allow(clippy::too_many_lines)]
#[allow(clippy::too_many_lines)]
pub(super) fn read_matched_parens(
&mut self,
value: &mut String,
close_count: usize,
) -> Result<()> {
let mut depth = close_count;
// Case-awareness: track case/esac nesting so `)` in case patterns
// doesn't close the command substitution prematurely.
let mut case_depth = 0usize;
let mut in_case_pattern = false;
let mut word_buf = String::new();
loop {
match self.peek_char() {
Some(')') => {
// Check keyword before consuming `)`
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
self.advance_char();
value.push(')');
if case_depth > 0 && in_case_pattern {
// This `)` terminates a case pattern — don't decrement depth
in_case_pattern = false; // now in pattern body
} else {
depth -= 1;
if depth == 0 {
return Ok(());
}
}
}
Some('(') => {
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
self.advance_char();
value.push('(');
// In case pattern mode, `(` is optional pattern prefix — don't increment
if !(case_depth > 0 && in_case_pattern) {
depth += 1;
}
}
Some('\'') => {
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
self.advance_char();
value.push('\'');
self.read_single_quoted(value)?;
}
Some('"') => {
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
self.advance_char();
value.push('"');
self.read_double_quoted(value)?;
}
Some('\\') => {
word_buf.clear();
self.advance_char();
if self.peek_char() == Some('\n') {
self.advance_char(); // line continuation
} else {
value.push('\\');
if let Some(c) = self.advance_char() {
value.push(c);
}
}
}
Some('$') => {
word_buf.clear();
self.read_dollar(value)?;
}
Some('`') => {
word_buf.clear();
self.advance_char();
value.push('`');
self.read_backtick(value)?;
}
Some('#') => {
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
// # is a comment when preceded by whitespace/newline
let prev = 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();
value.push('#');
}
}
Some(';') => {
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
self.advance_char();
value.push(';');
// Check for ;; ;& ;;& which resume case pattern mode
if case_depth > 0 {
if self.peek_char() == Some(';') {
self.advance_char();
value.push(';');
// ;;&
if self.peek_char() == Some('&') {
self.advance_char();
value.push('&');
}
in_case_pattern = true;
} else if self.peek_char() == Some('&') {
self.advance_char();
value.push('&');
in_case_pattern = true;
}
}
}
Some(' ' | '\t' | '\n') => {
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
let c = self.advance_char().unwrap_or(' ');
value.push(c);
}
Some('|') => {
check_case_keyword(&word_buf, &mut case_depth, &mut in_case_pattern);
word_buf.clear();
self.advance_char();
value.push('|');
}
Some(c) => {
word_buf.push(c);
self.advance_char();
value.push(c);
}
None => {
return Err(RableError::matched_pair(
"unterminated parenthesis",
self.pos,
self.line,
));
}
}
}
}
/// Reads a parameter expansion `${...}` allowing unbalanced inner `{`.
pub(super) fn read_param_expansion_braces(&mut self, value: &mut String) -> Result<()> {
loop {
match self.peek_char() {
Some('}') => {
self.advance_char();
value.push('}');
return Ok(());
}
Some('\'') => {
self.advance_char();
value.push('\'');
self.read_single_quoted(value)?;
}
Some('"') => {
self.advance_char();
value.push('"');
self.read_double_quoted(value)?;
}
Some('\\') => {
self.advance_char();
if self.peek_char() == Some('\n') {
self.advance_char(); // line continuation
} else {
value.push('\\');
if let Some(c) = self.advance_char() {
value.push(c);
}
}
}
Some('$') => {
self.read_dollar(value)?;
}
Some('`') => {
self.advance_char();
value.push('`');
self.read_backtick(value)?;
}
Some(c) => {
self.advance_char();
value.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, value: &mut String) -> Result<()> {
loop {
match self.peek_char() {
Some('`') => {
self.advance_char();
value.push('`');
return Ok(());
}
Some('\\') => {
self.advance_char();
value.push('\\');
if let Some(c) = self.advance_char() {
value.push(c);
}
}
Some(c) => {
self.advance_char();
value.push(c);
}
None => {
return Err(RableError::matched_pair(
"unterminated backtick",
self.pos,
self.line,
));
}
}
}
}
/// Reads until the given closing character.
pub(super) fn read_until_char(&mut self, value: &mut String, close: char) -> Result<()> {
loop {
match self.advance_char() {
Some(c) if c == close => {
value.push(c);
return Ok(());
}
Some(c) => value.push(c),
None => {
return Err(RableError::matched_pair(
format!("unterminated '{close}'"),
self.pos,
self.line,
));
}
}
}
}
}
/// Returns true if the character can follow `$` to start a variable expansion.
pub(super) const fn is_dollar_start(c: char) -> bool {
c.is_ascii_alphanumeric() || matches!(c, '_' | '@' | '*' | '#' | '?' | '-' | '$' | '!')
}