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//! context.c - context save and restore
//!
//! Port of Src/context.c
//!
//! This short file provides a home for the stack of saved contexts.
//! The actions for saving and restoring are encapsulated within
//! individual modules. After P7-P8 dissolved the ZshLexer and ZshParser structs into
//! free fns + thread_locals, the save/restore signatures simplified —
//! the lexer/parser parameters went away. Callers just call zcontext_*
//! and the underlying thread_local state is what's saved/restored.
use crate::ported::zsh_h::hist_stack;
use crate::ported::zsh_h::{ZCONTEXT_HIST, ZCONTEXT_LEX, ZCONTEXT_PARSE};
use std::sync::Mutex;
use crate::zsh_h::lex_stack;
use super::parse::{ParseStack};
/// Port of `struct context_stack` from Src/context.c:38-44.
#[allow(non_camel_case_types)]
pub struct context_stack { // c:52
pub next: Option<Box<context_stack>>, // c:52
pub hist_stack: hist_stack, // c:52
pub lex_stack: lex_stack, // c:52
pub parse_stack: ParseStack, // c:52
}
/// Port of `void zcontext_save_partial(int parts)` from Src/context.c:52.
#[allow(non_snake_case)]
pub fn zcontext_save_partial(parts: i32) { // c:52
crate::ported::signals::queue_signals(); // c:52
let mut cs = Box::new(context_stack { // c:58
next: None,
hist_stack: hist_stack {
histactive: 0, histdone: 0, stophist: 0, hlinesz: 0, defev: 0,
hline: None, hptr: None, chwords: Vec::new(),
chwordlen: 0, chwordpos: 0, csp: 0, hist_keep_comment: 0,
},
lex_stack: lex_stack::default(),
parse_stack: ParseStack::default(),
});
let mut head = cstack.lock().unwrap();
let toplevel: i32 = if head.is_none() { 1 } else { 0 }; // !cstack
if (parts & ZCONTEXT_HIST) != 0 { // c:60
crate::ported::hist::hist_context_save(&mut cs.hist_stack, toplevel); // c:61
}
if (parts & ZCONTEXT_LEX) != 0 { // c:63
crate::ported::lex::lex_context_save(&mut cs.lex_stack);
}
if (parts & ZCONTEXT_PARSE) != 0 { // c:80
crate::ported::parse::parse_context_save(&mut cs.parse_stack);
}
cs.next = head.take(); // c:89
*head = Some(cs); // c:89
crate::ported::signals::unqueue_signals(); // c:89
}
/// Port of `void zcontext_save(void)` from Src/context.c:80.
pub fn zcontext_save() { // c:80
zcontext_save_partial(ZCONTEXT_HIST | ZCONTEXT_LEX | ZCONTEXT_PARSE);
}
/// Port of `void zcontext_restore_partial(int parts)` from Src/context.c:89.
pub fn zcontext_restore_partial(parts: i32) { // c:89
let mut head = cstack.lock().unwrap();
let mut cs = match head.take() { // c:91
Some(cs) => cs,
None => {
return;
}
};
crate::ported::signals::queue_signals(); // c:95
*head = cs.next.take(); // c:96
let toplevel: i32 = if head.is_none() { 1 } else { 0 };
if (parts & ZCONTEXT_HIST) != 0 { // c:98
crate::ported::hist::hist_context_restore(&cs.hist_stack, toplevel); // c:99
}
if (parts & ZCONTEXT_LEX) != 0 { // c:101
crate::ported::lex::lex_context_restore(&mut cs.lex_stack);
}
if (parts & ZCONTEXT_PARSE) != 0 { // c:117
crate::ported::parse::parse_context_restore(&cs.parse_stack);
}
drop(cs); // c:117
crate::ported::signals::unqueue_signals(); // c:117
}
/// Port of `void zcontext_restore(void)` from Src/context.c:117.
pub fn zcontext_restore() { // c:117
zcontext_restore_partial(ZCONTEXT_HIST | ZCONTEXT_LEX | ZCONTEXT_PARSE);
}
/// Port of `static struct context_stack *cstack` from Src/context.c:52.
static cstack: Mutex<Option<Box<context_stack>>> = Mutex::new(None); // c:52
#[cfg(test)]
mod tests {
use super::*;
fn reset_cstack() {
*cstack.lock().unwrap() = None;
}
#[test]
fn save_restore_balances_stack() {
reset_cstack();
crate::ported::lex::lex_init("");
zcontext_save();
assert!(cstack.lock().unwrap().is_some());
zcontext_restore();
assert!(cstack.lock().unwrap().is_none());
}
#[test]
fn nested_saves_pop_lifo() {
reset_cstack();
crate::ported::lex::lex_init("");
zcontext_save();
zcontext_save();
zcontext_restore();
assert!(cstack.lock().unwrap().is_some());
zcontext_restore();
assert!(cstack.lock().unwrap().is_none());
}
#[test]
fn restore_without_save_is_noop() {
reset_cstack();
crate::ported::lex::lex_init("");
zcontext_restore();
assert!(cstack.lock().unwrap().is_none());
}
#[test]
fn lex_save_restore_roundtrips_state() {
reset_cstack();
crate::ported::lex::lex_init("echo hello");
crate::ported::lex::LEX_DBPARENS.set(true);
crate::ported::lex::set_toklineno(42);
zcontext_save();
assert!(crate::ported::lex::LEX_DBPARENS.with(|c| c.get()));
assert_eq!(crate::ported::lex::toklineno(), 42);
zcontext_restore();
assert!(crate::ported::lex::LEX_DBPARENS.with(|c| c.get()));
assert_eq!(crate::ported::lex::toklineno(), 42);
}
/// `Src/zsh.h:491-495` — `ZCONTEXT_HIST = (1<<0)`,
/// `ZCONTEXT_LEX = (1<<1)`, `ZCONTEXT_PARSE = (1<<2)`. The three
/// bits must be distinct and non-overlapping; `zcontext_save_partial`
/// at c:60/63/66 AND-tests each independently and a flag collision
/// would silently double-save one substrate and skip another on
/// every nested context (heredoc-inside-eval, `read -E`, …).
#[test]
fn zcontext_flag_bits_are_distinct_and_nonzero() {
use crate::ported::zsh_h::{ZCONTEXT_HIST, ZCONTEXT_LEX, ZCONTEXT_PARSE};
// Pin the exact C constants from Src/zsh.h:491-495.
assert_eq!(ZCONTEXT_HIST, 1 << 0);
assert_eq!(ZCONTEXT_LEX, 1 << 1);
assert_eq!(ZCONTEXT_PARSE, 1 << 2);
// Bitfield discipline: no overlapping bits.
assert_eq!(ZCONTEXT_HIST & ZCONTEXT_LEX, 0);
assert_eq!(ZCONTEXT_HIST & ZCONTEXT_PARSE, 0);
assert_eq!(ZCONTEXT_LEX & ZCONTEXT_PARSE, 0);
}
/// `Src/context.c:52-72` — `zcontext_save_partial(parts)` allocates
/// the frame BEFORE the `parts &` gates at c:60/63/66, then pushes
/// at c:70-71 unconditionally (`cs->next = cstack; cstack = cs`).
/// `parts == 0` is a legitimate caller pattern (probe-save); the
/// push must still fire. Regression that early-exits on a zero
/// mask would mis-balance the stack for any such caller.
#[test]
fn zcontext_save_partial_with_zero_mask_still_pushes_frame() {
reset_cstack();
crate::ported::lex::lex_init("");
zcontext_save_partial(0);
assert!(cstack.lock().unwrap().is_some(),
"c:70-71 push must fire even when no parts requested");
zcontext_restore_partial(0);
assert!(cstack.lock().unwrap().is_none(),
"c:96 pop must mirror the push regardless of parts mask");
}
/// `Src/context.c:89-96` — `zcontext_restore_partial` reads
/// `cs = cstack` at c:91 and a `DPUTS(!cstack, ...)` at c:93 fires
/// in C debug builds. Release C dereferences a NULL `cs` — UB —
/// but the Rust port chose to silently no-op on empty stack
/// (`head.take()` returns None → early return). Pin the no-op so
/// a refactor doesn't suddenly start panicking on unbalanced
/// restore calls.
#[test]
fn zcontext_restore_partial_on_empty_stack_is_noop() {
reset_cstack();
zcontext_restore_partial(0);
zcontext_restore_partial(crate::ported::zsh_h::ZCONTEXT_HIST);
assert!(cstack.lock().unwrap().is_none());
}
/// `Src/context.c:52` — Deep LIFO check. 5 saves pushed; 5
/// restores must drain to empty. Pin the depth-handling so a
/// regression that uses a fixed-size buffer instead of the
/// linked stack would surface on the third+ push.
#[test]
fn deep_save_restore_lifo_drains_to_empty() {
reset_cstack();
crate::ported::lex::lex_init("");
for _ in 0..5 { zcontext_save(); }
// Stack now has 5 frames
for i in (0..5).rev() {
assert!(cstack.lock().unwrap().is_some(),
"stack must still have entries before restore #{}", 5 - i);
zcontext_restore();
}
assert!(cstack.lock().unwrap().is_none(),
"5 restores must drain the 5 saves to empty");
}
/// `Src/context.c:80` — `zcontext_save()` is a convenience
/// wrapper for `zcontext_save_partial(ALL)`. Pin the alias
/// contract: a full-mask partial-save followed by any restore
/// yields the same final state as save→restore.
#[test]
fn zcontext_save_equals_save_partial_full_mask() {
use crate::ported::zsh_h::{ZCONTEXT_HIST, ZCONTEXT_LEX, ZCONTEXT_PARSE};
let full = ZCONTEXT_HIST | ZCONTEXT_LEX | ZCONTEXT_PARSE;
reset_cstack();
crate::ported::lex::lex_init("");
zcontext_save();
zcontext_restore();
let after_full = cstack.lock().unwrap().is_none();
reset_cstack();
crate::ported::lex::lex_init("");
zcontext_save_partial(full);
zcontext_restore_partial(full);
let after_partial = cstack.lock().unwrap().is_none();
assert_eq!(after_full, after_partial,
"save/restore must equal save_partial(ALL)/restore_partial(ALL)");
}
/// `Src/context.c:52` — Many save calls with NO matching restores
/// must not corrupt or panic, just grow the stack. Pin defensive
/// behavior for shell-script abort paths where partial state
/// rewinds may skip restores.
#[test]
fn many_saves_without_restore_grow_stack_safely() {
reset_cstack();
crate::ported::lex::lex_init("");
for _ in 0..20 { zcontext_save(); }
// Stack should still be intact, top frame accessible
assert!(cstack.lock().unwrap().is_some());
// Now drain — must not panic
for _ in 0..20 { zcontext_restore(); }
assert!(cstack.lock().unwrap().is_none());
}
}