1 files changed, 172 insertions, 0 deletions
diff --git a/source/luametatex/source/tex/texdirections.c b/source/luametatex/source/tex/texdirections.c
new file mode 100644
index 000000000..400b4c00d
--- /dev/null
+++ b/source/luametatex/source/tex/texdirections.c
@@ -0,0 +1,172 @@
+/*
+    See license.txt in the root of this project.
+*/
+
+/*tex
+
+    In \LUATEX\ we started with the \OMEGA\ direction model, although only a handful of directions
+    is supported there (four to be precise). For l2r and r2l typesetting the frontend can basically
+    ignore directions. Only the font handler needs to be direction aware. The vertical directions in
+    \LUATEX\ demand swapping height and width occasionally when doing calculations. In the end it is
+    the backend code that does the hard work.
+
+    In the end, in \LUAMETATEX\ we only kept the horizontal directions. The vertical ones were not
+    really useful and didn't even work well. It's up to the macro package to cook up proper
+    solutions. The simplification (and rewrite) of the code also resulted in a more advanced box
+    model (with rotation and offsets) that can help implementing vertical rendering, but that code
+    is not here.
+
+*/
+
+# include "luametatex.h"
+
+dir_state_info lmt_dir_state = {
+    .text_dir_ptr = null,
+    .padding      = 0,
+};
+
+/*tex The next two are used by the linebreak routine; they could be macros. */
+
+inline static halfword tex_aux_push_dir_node(halfword p, halfword d)
+{
+    halfword n = tex_copy_node(d);
+    node_next(n) = p;
+    return n;
+}
+
+inline static halfword tex_aux_pop_dir_node(halfword p)
+{
+    halfword n = node_next(p);
+    tex_flush_node(p);
+    return n;
+}
+
+halfword tex_update_dir_state(halfword p, halfword initial)
+{
+    if (node_subtype(p) == normal_dir_subtype) {
+        lmt_linebreak_state.dir_ptr = tex_aux_push_dir_node(lmt_linebreak_state.dir_ptr, p);
+        return dir_direction(p);
+    } else {
+        lmt_linebreak_state.dir_ptr = tex_aux_pop_dir_node(lmt_linebreak_state.dir_ptr);
+        if (lmt_linebreak_state.dir_ptr) {
+            return dir_direction(lmt_linebreak_state.dir_ptr);
+        } else {
+            return initial;
+        }
+    }
+}
+
+halfword tex_sanitize_dir_state(halfword first, halfword last, halfword initial)
+{
+    for (halfword e = first; e && e != last; e = node_next(e)) {
+        if (node_type(e) == dir_node) {
+            if (node_subtype(e) == normal_dir_subtype) {
+                lmt_linebreak_state.dir_ptr = tex_aux_push_dir_node(lmt_linebreak_state.dir_ptr, e);
+            } else if (lmt_linebreak_state.dir_ptr && dir_direction(lmt_linebreak_state.dir_ptr) == dir_direction(e)) {
+                /*tex A bit strange test. */
+                lmt_linebreak_state.dir_ptr = tex_aux_pop_dir_node(lmt_linebreak_state.dir_ptr);
+            }
+        }
+    }
+    if (lmt_linebreak_state.dir_ptr) {
+        return dir_direction(lmt_linebreak_state.dir_ptr);
+    } else {
+        return initial;
+    }
+}
+
+halfword tex_complement_dir_state(halfword tail)
+{
+    halfword e = node_next(tail);
+    for (halfword p = lmt_linebreak_state.dir_ptr; p ; p = node_next(p)) {
+        halfword s = tex_new_dir(cancel_dir_subtype, dir_direction(p));
+        tex_attach_attribute_list_copy(s, tail);
+        tex_couple_nodes(tail, s);
+        tex_try_couple_nodes(s, e);
+        tail = s;
+    }
+    return tail;
+}
+
+void tex_initialize_directions(void)
+{
+    lmt_dir_state.text_dir_ptr = tex_new_dir(normal_dir_subtype, direction_def_value);
+}
+
+void tex_cleanup_directions(void)
+{
+    tex_flush_node(lmt_dir_state.text_dir_ptr); /* tex_free_node(lmt_dir_state.text_dir_ptr, dir_node_size) */
+}
+
+halfword tex_new_dir(quarterword subtype, halfword direction)
+{
+    halfword p = tex_new_node(dir_node, subtype);
+    dir_direction(p) = direction;
+    dir_level(p) = cur_level;
+    return p;
+}
+
+/* todo: |\tracingdirections| */
+
+void tex_push_text_dir_ptr(halfword val)
+{
+    if (dir_level(lmt_dir_state.text_dir_ptr) == cur_level) {
+        /*tex update */
+        dir_direction(lmt_dir_state.text_dir_ptr) = val;
+    } else {
+        /*tex add */
+        halfword text_dir_tmp = tex_new_dir(normal_dir_subtype, val);
+        node_next(text_dir_tmp) = lmt_dir_state.text_dir_ptr;
+        lmt_dir_state.text_dir_ptr = text_dir_tmp;
+    }
+}
+
+void tex_pop_text_dir_ptr(void)
+{
+    halfword text_dir_ptr = lmt_dir_state.text_dir_ptr;
+    if (dir_level(text_dir_ptr) == cur_level) {
+        /*tex remove */
+        halfword text_dir_tmp = node_next(text_dir_ptr);
+        tex_flush_node(text_dir_ptr);
+        lmt_dir_state.text_dir_ptr = text_dir_tmp;
+    }
+}
+
+void tex_set_math_dir(halfword d)
+{
+    if (valid_direction(d)) {
+        update_tex_math_direction(d);
+    }
+}
+
+void tex_set_par_dir(halfword d)
+{
+    if (valid_direction(d)) {
+        update_tex_par_direction(d);
+    }
+}
+
+void tex_set_text_dir(halfword d)
+{
+    if (valid_direction(d)) {
+        tex_inject_text_or_line_dir(d, 0);
+        update_tex_text_direction(d);
+        update_tex_internal_dir_state(internal_dir_state_par + 1);
+    }
+}
+
+void tex_set_line_dir(halfword d)
+{
+    if (valid_direction(d)) {
+        tex_inject_text_or_line_dir(d, 1);
+        update_tex_text_direction(d);
+        update_tex_internal_dir_state(internal_dir_state_par + 1);
+    }
+}
+
+void tex_set_box_dir(halfword b, singleword d)
+{
+    if (valid_direction(d)) {
+        box_dir(box_register(b)) = (singleword) d;
+    }
+}