Module local_assignments 

Perl-style local assignments (dynamic scope)

This module provides stack-based dynamic scoping for global state, matching Perl’s local mechanism. Each “localized” field uses a Vec<T> as a stack: push to shadow, pop to restore.

RAII Guards

Each localized variable has a corresponding Guard type that pushes on creation and pops on Drop. This prevents leaked state on early returns or panics:

let _guard = local_current_token_guard(token);
// ... do work ...
// guard auto-pops when _guard goes out of scope

The explicit set_*/expire_* pairs still exist for cases where RAII doesn’t fit (e.g., cross-function push/pop with different lifetimes).

Structs

LocalGuard

Generic RAII guard that calls an expire function on drop. Zero-cost when the expire function is a simple fn pointer.

Localized

These are fields realized via Perl’s “local” mechanism in LaTeXML, but (for now) require explicit “expire” calls in Rust. Ideally their ergonomics gets improved, or we gradually phase them out.

SuppressedTabMarks

Disables tab marks for the lifetime of the guard, restoring the previous count on drop — tex.web §394 macro_call:

Functions

align_group_count

decrement_align_group_count

expire_align_group_count

expire_current_token

expires the most recent (localized) current token.

expire_dual_branch

expire (localized) flag for “dual branch”

expire_ifframe

expires the most recent (originally Perl-local) IfFrame

expire_reading_alignment

expire_state_unlocked

get_current_token

gets the (localized) current token

get_dual_branch

get the current value for “dual branch”

get_ifframe

retrieves the most recent (originally Perl-local) IfFrame

get_reading_alignment

has_reading_alignment

increment_align_group_count

initialize_localized

Reset all localized variables to their default state. Must be called between conversion runs to prevent state pollution.

local_align_group_count

local_align_group_count_guard

Push a localized align group count; returns guard that pops on drop.

local_build_template

local_current_token

localizes a new current token. see Stomach::invoke_token

local_current_token_guard

Push a localized current token; returns guard that pops on drop.

local_dual_branch_guard

Push a localized dual branch; returns guard that pops on drop.

local_ifframe_guard

Push a localized if-frame; returns guard that pops on drop.

local_reading_alignment

local_reading_alignment_guard

Push a localized reading alignment; returns guard that pops on drop.

local_state_unlocked

local_state_unlocked_guard

Push a localized state unlocked flag; returns guard that pops on drop.

open_conditional_count

Number of currently open conditional frames (\if… whose \fi has not been digested yet). Zero at any clean point between top-level constructs — the fragment-yield seam predicate requires exactly that.

set_align_group_count

set_build_template

set_dual_branch

sets the (localized) flag for “dual branch”

set_ifframe

sets a (originally Perl-local) IfFrame that needs to be manually expired.

state_is_unlocked

take_build_template

with_current_build_template