l3kernel (4dec20)

git-svn-id: svn://tug.org/texlive/trunk@57066 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 769 insertions, 237 deletions

diff --git a/Master/texmf-dist/tex/latex/l3kernel/expl3-code.tex b/Master/texmf-dist/tex/latex/l3kernel/expl3-code.tex
index ef1d0a3732c..616bc6dddff 100644
--- a/Master/texmf-dist/tex/latex/l3kernel/expl3-code.tex
+++ b/Master/texmf-dist/tex/latex/l3kernel/expl3-code.tex
@@ -69,7 +69,7 @@
 %% and all files in that bundle must be distributed together.
 %% 
 %% File: expl3.dtx
-\def\ExplFileDate{2020-10-27}%
+\def\ExplFileDate{2020-12-03}%
 \begingroup
   \def\next{\endgroup}%
   \expandafter\ifx\csname PackageError\endcsname\relax
@@ -8682,6 +8682,7 @@
       { \tl_to_str:n {#2} }
   }
 \tl_const:Nx \c_catcode_other_space_tl { \char_generate:nn { `\  } { 12 } }
+\scan_new:N \s__token_mark
 \scan_new:N \s__token_stop
 \group_begin:
   \__kernel_chk_if_free_cs:N \c_group_begin_token
@@ -8951,6 +8952,45 @@
         \fi:
       }
   }
+\cs_new:Npn \token_case_catcode:Nn #1#2
+  { \exp:w \__token_case:NNnTF \token_if_eq_catcode:NNTF #1 {#2} { } { } }
+\cs_new:Npn \token_case_catcode:NnT #1#2#3
+  { \exp:w \__token_case:NNnTF \token_if_eq_catcode:NNTF #1 {#2} {#3} { } }
+\cs_new:Npn \token_case_catcode:NnF #1#2
+  { \exp:w \__token_case:NNnTF \token_if_eq_catcode:NNTF #1 {#2} { } }
+\cs_new:Npn \token_case_catcode:NnTF
+  { \exp:w \__token_case:NNnTF \token_if_eq_catcode:NNTF }
+\cs_new:Npn \token_case_charcode:Nn #1#2
+  { \exp:w \__token_case:NNnTF \token_if_eq_charcode:NNTF #1 {#2} { } { } }
+\cs_new:Npn \token_case_charcode:NnT #1#2#3
+  { \exp:w \__token_case:NNnTF \token_if_eq_charcode:NNTF #1 {#2} {#3} { } }
+\cs_new:Npn \token_case_charcode:NnF #1#2
+  { \exp:w \__token_case:NNnTF \token_if_eq_charcode:NNTF #1 {#2} { } }
+\cs_new:Npn \token_case_charcode:NnTF
+  { \exp:w \__token_case:NNnTF \token_if_eq_charcode:NNTF }
+\cs_new:Npn \token_case_meaning:Nn #1#2
+  { \exp:w \__token_case:NNnTF \token_if_eq_meaning:NNTF #1 {#2} { } { } }
+\cs_new:Npn \token_case_meaning:NnT #1#2#3
+  { \exp:w \__token_case:NNnTF \token_if_eq_meaning:NNTF #1 {#2} {#3} { } }
+\cs_new:Npn \token_case_meaning:NnF #1#2
+  { \exp:w \__token_case:NNnTF \token_if_eq_meaning:NNTF #1 {#2} { } }
+\cs_new:Npn \token_case_meaning:NnTF
+  { \exp:w \__token_case:NNnTF \token_if_eq_meaning:NNTF }
+\cs_new:Npn \__token_case:NNnTF #1#2#3#4#5
+  {
+    \__token_case:NNw #1 #2 #3 #2 { }
+    \s__token_mark {#4}
+    \s__token_mark {#5}
+    \s__token_stop
+  }
+\cs_new:Npn \__token_case:NNw #1#2#3#4
+  {
+    #1 #2 #3
+      { \__token_case_end:nw {#4} }
+      { \__token_case:NNw #1 #2 }
+  }
+\cs_new:Npn \__token_case_end:nw #1#2#3 \s__token_mark #4#5 \s__token_stop
+  { \exp_end: #1 #4 }
 \cs_new_eq:NN \l_peek_token ?
 \cs_new_eq:NN \g_peek_token ?
 \cs_new_eq:NN \l__peek_search_token ?
@@ -13830,6 +13870,39 @@
     \exp_after:wN \__intarray_to_clist:w
     \int_value:w \int_eval:w #1 + \c_one_int ; #2 {#3}
   }
+\cs_new:Npn \__kernel_intarray_range_to_clist:Nnn #1#2#3
+  {
+    \exp_last_unbraced:Nf \use_none:n
+      {
+        \exp_after:wN \__intarray_range_to_clist:ww
+        \int_value:w \int_eval:w #2 \exp_after:wN ;
+        \int_value:w \int_eval:w #3 ;
+        #1 \prg_break_point:
+      }
+  }
+\cs_new:Npn \__intarray_range_to_clist:ww #1 ; #2 ; #3
+  {
+    \if_int_compare:w #1 > #2 \exp_stop_f:
+      \prg_break:n
+    \fi:
+    , \__kernel_intarray_item:Nn #3 {#1}
+    \exp_after:wN \__intarray_range_to_clist:ww
+    \int_value:w \int_eval:w #1 + \c_one_int ; #2 ; #3
+  }
+\cs_new_protected:Npn \__kernel_intarray_gset_range_from_clist:Nnn #1#2#3
+  {
+    \int_set:Nn \l__intarray_loop_int {#2}
+    \__intarray_gset_range:Nw #1 #3 , , \prg_break_point:
+  }
+\cs_new_protected:Npn \__intarray_gset_range:Nw #1 #2 ,
+  {
+    \if_catcode:w \scan_stop: \tl_to_str:n {#2} \scan_stop:
+      \prg_break:n
+    \fi:
+    \__kernel_intarray_gset:Nnn #1 \l__intarray_loop_int {#2}
+    \int_incr:N \l__intarray_loop_int
+    \__intarray_gset_range:Nw #1
+  }
 \cs_new_protected:Npn \intarray_show:N { \__intarray_show:NN \msg_show:nnxxxx }
 \cs_generate_variant:Nn \intarray_show:N { c }
 \cs_new_protected:Npn \intarray_log:N { \__intarray_show:NN \msg_log:nnxxxx }
@@ -22376,6 +22449,23 @@
 \scan_new:N \s__tl
 \cs_new_eq:NN \l__tl_analysis_token ?
 \cs_new_eq:NN \l__tl_analysis_char_token ?
+\cs_new_eq:NN \l__tl_analysis_next_token ?
+\tl_new:N \l__tl_peek_code_tl
+\group_begin:
+\char_set_active_eq:NN \  \scan_stop:
+\tl_const:Nx \c__tl_peek_catcodes_tl
+  {
+    \char_generate:nn { 32 } { 3 }   3
+    \char_generate:nn { 32 } { 4 }   4
+    # \char_generate:nn { 32 } { 6 } 6
+    \char_generate:nn { 32 } { 7 }   7
+    \char_generate:nn { 32 } { 8 }   8
+    \c_space_tl                     \token_to_str:N A
+    \char_generate:nn { 32 } { 11 } \token_to_str:N B
+    \char_generate:nn { 32 } { 12 } \token_to_str:N C
+    \char_generate:nn { 32 } { 13 } \token_to_str:N D
+  }
+\group_end:
 \int_new:N \l__tl_analysis_normal_int
 \int_new:N \l__tl_analysis_index_int
 \int_new:N \l__tl_analysis_nesting_int
@@ -22794,6 +22884,216 @@
       { #1 ~ ( #4 #2 #3 ) }
   }
 \cs_generate_variant:Nn \__tl_analysis_show_long_aux:nnnn { oof }
+\cs_new:Npn \peek_analysis_map_break:
+  { \prg_map_break:Nn \peek_analysis_map_break: { } }
+\cs_new:Npn \peek_analysis_map_break:n
+  { \prg_map_break:Nn \peek_analysis_map_break: }
+\int_new:N \l__tl_peek_charcode_int
+\cs_new:Npn \__tl_analysis_char_arg:Nw
+  {
+    \if_meaning:w \l__tl_analysis_token \c_space_token
+      \exp_after:wN \__tl_analysis_char_arg_aux:Nw
+    \fi:
+  }
+\cs_new:Npn \__tl_analysis_char_arg_aux:Nw #1 ~ { #1 { ~ } }
+\cs_new_protected:Npn \peek_analysis_map_inline:n #1
+  {
+    \int_gincr:N \g__kernel_prg_map_int
+    \cs_set_protected:cpn
+      { __tl_analysis_map_ \int_use:N \g__kernel_prg_map_int :nnN }
+      ##1##2##3
+      {
+        \group_end:
+        #1
+        \__tl_peek_analysis_loop:NNn
+          \prg_break_point:Nn \peek_analysis_map_break: { }
+      }
+    \__tl_peek_analysis_loop:NNn ? ? ?
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_loop:NNn #1#2#3
+  {
+    \group_begin:
+    \tl_set:Nx \l__tl_peek_code_tl
+      {
+        \exp_not:c
+          { __tl_analysis_map_ \int_use:N \g__kernel_prg_map_int :nnN }
+      }
+    \int_set:Nn \tex_escapechar:D { `\\ }
+    \peek_after:Nw \__tl_peek_analysis_test:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_test:
+  {
+    \if_int_odd:w
+      \if_catcode:w \exp_not:N \l_peek_token {   1 \exp_stop_f: \fi:
+      \if_catcode:w \exp_not:N \l_peek_token }   1 \exp_stop_f: \fi:
+      \if_meaning:w \l_peek_token \c_space_token 1 \exp_stop_f: \fi:
+      0 \exp_stop_f:
+      \exp_after:wN \__tl_peek_analysis_special:
+    \else:
+      \exp_after:wN \exp_after:wN
+      \exp_after:wN \__tl_peek_analysis_normal:N
+      \exp_after:wN \exp_not:N
+    \fi:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_normal:N #1
+  {
+    \exp_after:wN \reverse_if:N \exp_after:wN \if_meaning:w
+        \exp_not:N #1 #1
+      \tex_let:D #1 \scan_stop:
+      \tl_put_right:Nn \l__tl_peek_code_tl { { \exp_not:N #1 } }
+    \else:
+      \tl_put_right:Nn \l__tl_peek_code_tl { { \exp_not:n {#1} } }
+    \fi:
+    \if_charcode:w
+        \scan_stop:
+        \exp_after:wN \use_none:n \token_to_str:N #1 \prg_do_nothing:
+        \scan_stop:
+      \exp_after:wN \__tl_peek_analysis_char:N
+      \exp_after:wN #1
+    \else:
+      \exp_after:wN \__tl_peek_analysis_cs:
+    \fi:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_cs:
+  { \l__tl_peek_code_tl { -1 } 0 }
+\cs_new_protected:Npn \__tl_peek_analysis_char:N #1
+  {
+    \char_set_lccode:nn { `#1 } { 32 }
+    \tex_lowercase:D { \__tl_peek_analysis_char:nN {#1} } #1
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_char:nN #1#2
+  {
+    \cs_set_protected:Npn \__tl_tmp:w ##1 #1 ##2 ##3 \scan_stop:
+      { \exp_args:No \l__tl_peek_code_tl { \int_value:w `#2 } ##2 }
+    \exp_after:wN \__tl_tmp:w \c__tl_peek_catcodes_tl \scan_stop:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_special:
+  {
+    \tex_let:D \l__tl_analysis_token = ~ \l_peek_token
+    \int_set:Nn \l__tl_peek_charcode_int
+      { \__tl_analysis_extract_charcode: }
+    \if_int_compare:w \l__tl_peek_charcode_int = \tex_escapechar:D
+      \int_set:Nn \tex_escapechar:D { `\/ }
+    \fi:
+    \char_set_active_eq:nN { \l__tl_peek_charcode_int } \scan_stop:
+    \char_set_active_eq:nN { \tex_escapechar:D } \scan_stop:
+    \cs_set_eq:cN { } \scan_stop:
+    \tex_futurelet:D \l__tl_analysis_token
+    \__tl_peek_analysis_retest:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_retest:
+  {
+    \if_meaning:w \l__tl_analysis_token \scan_stop:
+      \exp_after:wN \__tl_peek_analysis_normal:N
+    \else:
+      \exp_after:wN \__tl_peek_analysis_next:
+    \fi:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_next:
+  {
+    \tl_if_empty:oT { \tex_the:D \tex_everyeof:D }
+      { \tex_everyeof:D { \scan_stop: } }
+    \tex_afterassignment:D \__tl_peek_analysis_str:
+    \tex_futurelet:D \l__tl_analysis_next_token
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_str:
+  {
+    \exp_after:wN \tex_futurelet:D
+    \exp_after:wN \l__tl_analysis_token
+    \exp_after:wN \__tl_peek_analysis_str:w
+    \token_to_str:N
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_str:w
+  { \__tl_analysis_char_arg:Nw \__tl_peek_analysis_str:n }
+\cs_new_protected:Npn \__tl_peek_analysis_str:n #1
+  {
+    \int_case:nnF { `#1 }
+      {
+        { \l__tl_peek_charcode_int }
+          { \__tl_peek_analysis_explicit:n {#1} }
+        { \tex_escapechar:D } { \__tl_peek_analysis_escape: }
+      }
+      { \__tl_peek_analysis_active_str:n {#1} }
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_active_str:n #1
+  {
+    \tl_put_right:Nx \l__tl_peek_code_tl
+      {
+        { \char_generate:nn { `#1 } { 13 } }
+        { \int_value:w `#1 }
+        \token_to_str:N D
+      }
+    \l__tl_peek_code_tl
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_explicit:n #1
+  {
+    \tl_put_right:Nx \l__tl_peek_code_tl
+      {
+        \if_meaning:w \l_peek_token \c_space_token
+          { ~ } { 32 } \token_to_str:N A
+        \else:
+          \if_catcode:w \l_peek_token \c_group_begin_token
+            {
+              \exp_not:N \exp_after:wN
+              \char_generate:nn { `#1 } { 1 }
+              \exp_not:N \if_false:
+              \if_false: { \fi: }
+              \exp_not:N \fi:
+            }
+            { \int_value:w `#1 }
+            1
+          \else:
+            {
+              \exp_not:N \if_false:
+              { \if_false: } \fi:
+              \exp_not:N \fi:
+              \char_generate:nn { `#1 } { 2 }
+            }
+            { \int_value:w `#1 }
+            2
+          \fi:
+        \fi:
+      }
+    \l__tl_peek_code_tl
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_escape:
+  {
+    \tl_clear:N \l__tl_internal_a_tl
+    \tex_futurelet:D \l__tl_analysis_token
+      \__tl_peek_analysis_collect:w
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_collect:w
+  { \__tl_analysis_char_arg:Nw \__tl_peek_analysis_collect:n }
+\cs_new_protected:Npn \__tl_peek_analysis_collect:n #1
+  {
+    \tl_put_right:Nn \l__tl_internal_a_tl {#1}
+    \__tl_peek_analysis_collect_loop:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_collect_loop:
+  {
+    \tex_futurelet:D \l__tl_analysis_token
+      \__tl_peek_analysis_collect_test:
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_collect_test:
+  {
+    \if_meaning:w \l__tl_analysis_token \l__tl_analysis_next_token
+      \exp_after:wN \if_meaning:w \cs:w \l__tl_internal_a_tl \cs_end: \l_peek_token
+        \__tl_peek_analysis_collect_end:NNN
+      \fi:
+    \fi:
+    \__tl_peek_analysis_collect:w
+  }
+\cs_new_protected:Npn \__tl_peek_analysis_collect_end:NNN #1#2#3
+  {
+    #1 #2
+    \tl_put_right:Nx \l__tl_peek_code_tl
+      {
+        { \exp_not:N \exp_not:n { \exp_not:c { \l__tl_internal_a_tl } } }
+        { -1 }
+        0
+      }
+    \l__tl_peek_code_tl
+  }
 \tl_const:Nx \c__tl_analysis_show_etc_str % (
   { \token_to_str:N \ETC.) }
 \__kernel_msg_new:nnn { kernel } { show-tl-analysis }
@@ -22812,7 +23112,7 @@
   { \__regex_toks_set:Nn #1 { } }
 \cs_new_eq:NN \__regex_toks_set:Nn \tex_toks:D
 \cs_new_protected:Npn \__regex_toks_set:No #1
-  { \__regex_toks_set:Nn #1 \exp_after:wN }
+  { \tex_toks:D #1 \exp_after:wN }
 \cs_new_protected:Npn \__regex_toks_memcpy:NNn #1#2#3
   {
     \prg_replicate:nn {#3}
@@ -22824,13 +23124,13 @@
   }
 \cs_new_protected:Npn \__regex_toks_put_left:Nx #1#2
   {
-    \cs_set:Npx \__regex_tmp:w { #2 }
+    \cs_set_nopar:Npx \__regex_tmp:w { #2 }
     \tex_toks:D #1 \exp_after:wN \exp_after:wN \exp_after:wN
       { \exp_after:wN \__regex_tmp:w \tex_the:D \tex_toks:D #1 }
   }
 \cs_new_protected:Npn \__regex_toks_put_right:Nx #1#2
   {
-    \cs_set:Npx \__regex_tmp:w {#2}
+    \cs_set_nopar:Npx \__regex_tmp:w {#2}
     \tex_toks:D #1 \exp_after:wN
       { \tex_the:D \tex_toks:D \exp_after:wN #1 \__regex_tmp:w }
   }
@@ -22839,8 +23139,21 @@
 \cs_new:Npn \__regex_curr_cs_to_str:
   {
     \exp_after:wN \exp_after:wN \exp_after:wN \cs_to_str:N
-    \tex_the:D \tex_toks:D \l__regex_curr_pos_int
+    \l__regex_curr_token_tl
   }
+\cs_new:Npn \__regex_intarray_item:NnF #1#2
+  { \exp_args:Nf \__regex_intarray_item_aux:nNF { \int_eval:n {#2} } #1 }
+\cs_new:Npn \__regex_intarray_item_aux:nNF #1#2
+  {
+    \if_int_compare:w #1 > \c_zero_int
+      \exp_after:wN \use_i:nn
+    \else:
+      \exp_after:wN \use_ii:nn
+    \fi:
+    { \__kernel_intarray_item:Nn #2 {#1} }
+  }
+\cs_new:Npn \__regex_maplike_break:
+  { \prg_map_break:Nn \__regex_maplike_break: { } }
 \cs_new:Npn \__regex_tmp:w { }
 \tl_new:N   \l__regex_internal_a_tl
 \tl_new:N   \l__regex_internal_b_tl
@@ -22856,11 +23169,7 @@
     \__regex_branch:n
       { \__regex_class:NnnnN \c_true_bool { } { 1 } { 0 } \c_true_bool }
   }
-\intarray_new:Nn \g__regex_charcode_intarray { 65536 }
-\intarray_new:Nn \g__regex_catcode_intarray { 65536 }
-\intarray_new:Nn \g__regex_balance_intarray { 65536 }
 \int_new:N \l__regex_balance_int
-\tl_new:N \l__regex_cs_name_tl
 \int_const:Nn \c__regex_ascii_min_int { 0 }
 \int_const:Nn \c__regex_ascii_max_control_int { 31 }
 \int_const:Nn \c__regex_ascii_max_int { 127 }
@@ -22986,13 +23295,12 @@
     \int_compare:nNnT \l__regex_curr_catcode_int = 0
       {
         \group_begin:
-          \__kernel_tl_set:Nx \l__regex_cs_name_tl { \__regex_curr_cs_to_str: }
           \__regex_single_match:
           \__regex_disable_submatches:
           \__regex_build_for_cs:n {#1}
           \bool_set_eq:NN \l__regex_saved_success_bool
             \g__regex_success_bool
-          \exp_args:NV \__regex_match_cs:n \l__regex_cs_name_tl
+          \exp_args:Nx \__regex_match_cs:n { \__regex_curr_cs_to_str: }
           \if_meaning:w \c_true_bool \g__regex_success_bool
             \group_insert_after:N \__regex_break_true:w
           \fi:
@@ -23711,48 +24019,39 @@
 \__regex_tmp:w w W
 \cs_new_protected:cpn { __regex_compile_/N: }
   { \__regex_compile_one:n \__regex_prop_N: }
-\cs_new_protected:Npn \__regex_compile_anchor:NF #1#2
+\cs_new_protected:Npn \__regex_compile_anchor_letter:NNN #1#2#3
   {
-    \__regex_if_in_class_or_catcode:TF {#2}
+    \__regex_if_in_class_or_catcode:TF { \__regex_compile_raw_error:N #1 }
       {
         \tl_build_put_right:Nn \l__regex_build_tl
-          { \__regex_assertion:Nn \c_true_bool { \__regex_anchor:N #1 } }
+          { \__regex_assertion:Nn #2 {#3} }
       }
   }
-\cs_set_protected:Npn \__regex_tmp:w #1#2
-  {
-    \cs_new_protected:cpn { __regex_compile_/#1: }
-      { \__regex_compile_anchor:NF #2 { \__regex_compile_raw_error:N #1 } }
-  }
-\__regex_tmp:w A \l__regex_min_pos_int
-\__regex_tmp:w G \l__regex_start_pos_int
-\__regex_tmp:w Z \l__regex_max_pos_int
-\__regex_tmp:w z \l__regex_max_pos_int
-\cs_set_protected:Npn \__regex_tmp:w #1#2
-  {
-    \cs_new_protected:cpn { __regex_compile_#1: }
-      { \__regex_compile_anchor:NF #2 { \__regex_compile_raw:N #1 } }
-  }
-\exp_args:Nx \__regex_tmp:w { \iow_char:N \^ } \l__regex_min_pos_int
-\exp_args:Nx \__regex_tmp:w { \iow_char:N \$ } \l__regex_max_pos_int
+\cs_new_protected:cpn { __regex_compile_/A: }
+  { \__regex_compile_anchor_letter:NNN A \c_true_bool \__regex_A_test: }
+\cs_new_protected:cpn { __regex_compile_/G: }
+  { \__regex_compile_anchor_letter:NNN G \c_true_bool \__regex_G_test: }
+\cs_new_protected:cpn { __regex_compile_/Z: }
+  { \__regex_compile_anchor_letter:NNN Z \c_true_bool \__regex_Z_test: }
+\cs_new_protected:cpn { __regex_compile_/z: }
+  { \__regex_compile_anchor_letter:NNN z \c_true_bool \__regex_Z_test: }
 \cs_new_protected:cpn { __regex_compile_/b: }
-  {
-    \__regex_if_in_class_or_catcode:TF
-      { \__regex_compile_raw_error:N b }
-      {
-        \tl_build_put_right:Nn \l__regex_build_tl
-          { \__regex_assertion:Nn \c_true_bool { \__regex_b_test: } }
-      }
-  }
+  { \__regex_compile_anchor_letter:NNN b \c_true_bool \__regex_b_test: }
 \cs_new_protected:cpn { __regex_compile_/B: }
+  { \__regex_compile_anchor_letter:NNN B \c_false_bool \__regex_b_test: }
+\cs_set_protected:Npn \__regex_tmp:w #1#2
   {
-    \__regex_if_in_class_or_catcode:TF
-      { \__regex_compile_raw_error:N B }
+    \cs_new_protected:cpn { __regex_compile_#1: }
       {
-        \tl_build_put_right:Nn \l__regex_build_tl
-          { \__regex_assertion:Nn \c_false_bool { \__regex_b_test: } }
+        \__regex_if_in_class_or_catcode:TF { \__regex_compile_raw:N #1 }
+          {
+            \tl_build_put_right:Nn \l__regex_build_tl
+              { \__regex_assertion:Nn \c_true_bool {#2} }
+          }
       }
   }
+\exp_args:Nx \__regex_tmp:w { \iow_char:N \^ } { \__regex_A_test: }
+\exp_args:Nx \__regex_tmp:w { \iow_char:N \$ } { \__regex_Z_test: }
 \cs_new_protected:cpn { __regex_compile_]: }
   {
     \__regex_if_in_class:TF
@@ -24282,7 +24581,9 @@
             { \bool_if:NF ##1 { negative~ } assertion:~##2 }
         }
       \cs_set:Npn \__regex_b_test: { word~boundary }
-      \cs_set_eq:NN \__regex_anchor:N \__regex_show_anchor_to_str:N
+      \cs_set:Npn \__regex_Z_test: { anchor~at~end~(\iow_char:N\\Z) }
+      \cs_set:Npn \__regex_A_test: { anchor~at~start~(\iow_char:N\\A) }
+      \cs_set:Npn \__regex_G_test: { anchor~at~start~of~match~(\iow_char:N\\G) }
       \cs_set_protected:Npn \__regex_item_caseful_equal:n ##1
         { \__regex_show_one:n { char~code~\int_eval:n{##1} } }
       \cs_set_protected:Npn \__regex_item_caseful_range:nn ##1##2
@@ -24383,17 +24684,6 @@
           }
       }
   }
-\cs_new:Npn \__regex_show_anchor_to_str:N #1
-  {
-    anchor~at~
-    \str_case:nnF { #1 }
-      {
-        { \l__regex_min_pos_int   } { start~(\iow_char:N\\A) }
-        { \l__regex_start_pos_int } { start~of~match~(\iow_char:N\\G) }
-        { \l__regex_max_pos_int   } { end~(\iow_char:N\\Z) }
-      }
-      { <error:~'#1'~not~recognized> }
-  }
 \cs_new_protected:Npn \__regex_show_item_catcode:NnT #1#2
   {
     \seq_set_split:Nnn \l__regex_internal_seq { } { CBEMTPUDSLOA }
@@ -24423,12 +24713,16 @@
 \seq_new:N  \l__regex_left_state_seq
 \seq_new:N  \l__regex_right_state_seq
 \int_new:N  \l__regex_capturing_group_int
-\cs_new_protected:Npn \__regex_build:n #1
+\cs_new_protected:Npn \__regex_build:n
+  { \__regex_build_aux:Nn \c_true_bool }
+\cs_new_protected:Npn \__regex_build:N
+  { \__regex_build_aux:NN \c_true_bool }
+\cs_new_protected:Npn \__regex_build_aux:Nn #1#2
   {
-    \__regex_compile:n {#1}
-    \__regex_build:N \l__regex_internal_regex
+    \__regex_compile:n {#2}
+    \__regex_build_aux:NN #1 \l__regex_internal_regex
   }
-\cs_new_protected:Npn \__regex_build:N #1
+\cs_new_protected:Npn \__regex_build_aux:NN #1#2
   {
     \__regex_standard_escapechar:
     \int_zero:N \l__regex_capturing_group_int
@@ -24436,15 +24730,14 @@
     \__regex_build_new_state:
     \__regex_build_new_state:
     \__regex_toks_put_right:Nn \l__regex_left_state_int
-      { \__regex_action_start_wildcard: }
-    \__regex_group:nnnN {#1} { 1 } { 0 } \c_false_bool
+      { \__regex_action_start_wildcard:N #1 }
+    \__regex_group:nnnN {#2} { 1 } { 0 } \c_false_bool
     \__regex_toks_put_right:Nn \l__regex_right_state_int
       { \__regex_action_success: }
   }
 \cs_new_protected:Npn \__regex_build_for_cs:n #1
   {
-    \int_set_eq:NN \l__regex_min_state_int \l__regex_max_active_int
-    \int_set_eq:NN \l__regex_max_state_int \l__regex_min_state_int
+    \int_set_eq:NN \l__regex_min_state_int \l__regex_max_state_int
     \__regex_build_new_state:
     \__regex_build_new_state:
     \__regex_push_lr_states:
@@ -24452,7 +24745,7 @@
     \__regex_pop_lr_states:
     \__regex_toks_put_right:Nn \l__regex_right_state_int
       {
-        \if_int_compare:w \l__regex_curr_pos_int = \l__regex_max_pos_int
+        \if_int_compare:w -2 = \l__regex_curr_char_int
           \exp_after:wN \__regex_action_success:
         \fi:
       }
@@ -24624,8 +24917,8 @@
 \cs_new_protected:Npn \__regex_group_submatches:nNN #1#2#3
   {
     \if_int_compare:w #1 > - 1 \exp_stop_f:
-      \__regex_toks_put_left:Nx #2 { \__regex_action_submatch:n { #1 < } }
-      \__regex_toks_put_left:Nx #3 { \__regex_action_submatch:n { #1 > } }
+      \__regex_toks_put_left:Nx #2 { \__regex_action_submatch:nN {#1} < }
+      \__regex_toks_put_left:Nx #3 { \__regex_action_submatch:nN {#1} > }
     \fi:
   }
 \cs_new_protected:Npn \__regex_group_repeat_aux:n #1
@@ -24731,12 +25024,6 @@
           \bool_if:NT #1 { { } }
       }
   }
-\cs_new_protected:Npn \__regex_anchor:N #1
-  {
-    \if_int_compare:w #1 = \l__regex_curr_pos_int
-      \exp_after:wN \__regex_break_true:w
-    \fi:
-  }
 \cs_new_protected:Npn \__regex_b_test:
   {
     \group_begin:
@@ -24746,12 +25033,30 @@
         { \group_end: \__regex_item_reverse:n \__regex_prop_w: }
         { \group_end: \__regex_prop_w: }
   }
+\cs_new_protected:Npn \__regex_Z_test:
+  {
+    \if_int_compare:w -2 = \l__regex_curr_char_int
+      \exp_after:wN \__regex_break_true:w
+    \fi:
+  }
+\cs_new_protected:Npn \__regex_A_test:
+  {
+    \if_int_compare:w -2 = \l__regex_last_char_int
+      \exp_after:wN \__regex_break_true:w
+    \fi:
+  }
+\cs_new_protected:Npn \__regex_G_test:
+  {
+    \if_int_compare:w \l__regex_curr_pos_int = \l__regex_start_pos_int
+      \exp_after:wN \__regex_break_true:w
+    \fi:
+  }
 \cs_new_protected:Npn \__regex_command_K:
   {
     \__regex_build_new_state:
     \__regex_toks_put_right:Nx \l__regex_left_state_int
       {
-        \__regex_action_submatch:n { 0< }
+        \__regex_action_submatch:nN { 0 } <
         \bool_set_true:N \l__regex_fresh_thread_bool
         \__regex_action_free:n
           {
@@ -24768,16 +25073,20 @@
 \int_new:N \l__regex_success_pos_int
 \int_new:N \l__regex_curr_char_int
 \int_new:N \l__regex_curr_catcode_int
+\tl_new:N \l__regex_curr_token_tl
 \int_new:N \l__regex_last_char_int
+\int_new:N \l__regex_last_char_success_int
 \int_new:N \l__regex_case_changed_char_int
 \int_new:N \l__regex_curr_state_int
-\prop_new:N \l__regex_curr_submatches_prop
-\prop_new:N \l__regex_success_submatches_prop
+\tl_new:N \l__regex_curr_submatches_tl
+\tl_new:N \l__regex_success_submatches_tl
 \int_new:N \l__regex_step_int
-\int_new:N \l__regex_min_active_int
-\int_new:N \l__regex_max_active_int
+\int_new:N \l__regex_min_thread_int
+\int_new:N \l__regex_max_thread_int
 \intarray_new:Nn \g__regex_state_active_intarray { 65536 }
-\intarray_new:Nn \g__regex_thread_state_intarray { 65536 }
+\intarray_new:Nn \g__regex_thread_info_intarray { 65536 }
+\tl_new:N \l__regex_matched_analysis_tl
+\tl_new:N \l__regex_curr_analysis_tl
 \tl_new:N \l__regex_every_match_tl
 \bool_new:N \l__regex_fresh_thread_bool
 \bool_new:N \l__regex_empty_success_bool
@@ -24787,38 +25096,26 @@
 \bool_new:N \l__regex_match_success_bool
 \cs_new_protected:Npn \__regex_match:n #1
   {
-    \int_zero:N \l__regex_balance_int
-    \int_set:Nn \l__regex_curr_pos_int { 2 * \l__regex_max_state_int }
-    \__regex_query_set:nnn { } { -1 } { -2 }
-    \int_set_eq:NN \l__regex_min_pos_int \l__regex_curr_pos_int
-    \tl_analysis_map_inline:nn {#1}
-      { \__regex_query_set:nnn {##1} {"##3} {##2} }
-    \int_set_eq:NN \l__regex_max_pos_int \l__regex_curr_pos_int
-    \__regex_query_set:nnn { } { -1 } { -2 }
     \__regex_match_init:
-    \__regex_match_once:
+    \__regex_match_once_init:
+    \tl_analysis_map_inline:nn {#1}
+      { \__regex_match_one_token:nnN {##1} {##2} ##3 }
+    \__regex_match_one_token:nnN { } { -2 } F
+    \prg_break_point:Nn \__regex_maplike_break: { }
   }
 \cs_new_protected:Npn \__regex_match_cs:n #1
   {
-    \int_zero:N \l__regex_balance_int
-    \int_set:Nn \l__regex_curr_pos_int
-      {
-        \int_max:nn { 2 * \l__regex_max_state_int - \l__regex_min_state_int }
-        { \l__regex_max_pos_int }
-        + 1
-      }
-    \__regex_query_set:nnn { } { -1 } { -2 }
-    \int_set_eq:NN \l__regex_min_pos_int \l__regex_curr_pos_int
+    \int_set_eq:NN \l__regex_min_thread_int \l__regex_max_thread_int
+    \__regex_match_init:
+    \__regex_match_once_init:
     \str_map_inline:nn {#1}
       {
-        \__regex_query_set:nnn { \exp_not:n {##1} }
-          { \tl_if_blank:nTF {##1} { 10 } { 12 } }
-          { `##1 }
+        \tl_if_blank:nTF {##1}
+          { \__regex_match_one_token:nnN {##1} {`##1} A }
+          { \__regex_match_one_token:nnN {##1} {`##1} C }
       }
-    \int_set_eq:NN \l__regex_max_pos_int \l__regex_curr_pos_int
-    \__regex_query_set:nnn { } { -1 } { -2 }
-    \__regex_match_init:
-    \__regex_match_once:
+    \__regex_match_one_token:nnN { } { -2 } F
+    \prg_break_point:Nn \__regex_maplike_break: { }
   }
 \cs_new_protected:Npn \__regex_match_init:
   {
@@ -24829,15 +25126,17 @@
         \__kernel_intarray_gset:Nnn
           \g__regex_state_active_intarray {##1} { 1 }
       }
-    \int_set_eq:NN \l__regex_min_active_int \l__regex_max_state_int
     \int_zero:N \l__regex_step_int
+    \int_set:Nn \l__regex_min_pos_int { 2 }
     \int_set_eq:NN \l__regex_success_pos_int \l__regex_min_pos_int
-    \int_set:Nn \l__regex_min_submatch_int
-      { 2 * \l__regex_max_state_int }
+    \int_set:Nn \l__regex_last_char_success_int { -2 }
+    \tl_build_begin:N \l__regex_matched_analysis_tl
+    \tl_clear:N \l__regex_curr_analysis_tl
+    \int_set:Nn \l__regex_min_submatch_int { 1 }
     \int_set_eq:NN \l__regex_submatch_int \l__regex_min_submatch_int
     \bool_set_false:N \l__regex_empty_success_bool
   }
-\cs_new_protected:Npn \__regex_match_once:
+\cs_new_protected:Npn \__regex_match_once_init:
   {
     \if_meaning:w \c_true_bool \l__regex_empty_success_bool
       \cs_set:Npn \__regex_if_two_empty_matches:F
@@ -24850,14 +25149,24 @@
     \fi:
     \int_set_eq:NN \l__regex_start_pos_int \l__regex_success_pos_int
     \bool_set_false:N \l__regex_match_success_bool
-    \prop_clear:N \l__regex_curr_submatches_prop
-    \int_set_eq:NN \l__regex_max_active_int \l__regex_min_active_int
+    \tl_set:Nx \l__regex_curr_submatches_tl
+      { \prg_replicate:nn { 2 * \l__regex_capturing_group_int } { 0 , } }
+    \int_set_eq:NN \l__regex_max_thread_int \l__regex_min_thread_int
     \__regex_store_state:n { \l__regex_min_state_int }
     \int_set:Nn \l__regex_curr_pos_int
       { \l__regex_start_pos_int - 1 }
-    \__regex_query_get:
-    \__regex_match_loop:
-    \l__regex_every_match_tl
+    \int_set_eq:NN \l__regex_curr_char_int \l__regex_last_char_success_int
+    \tl_build_get:NN \l__regex_matched_analysis_tl \l__regex_internal_a_tl
+    \exp_args:NNf \__regex_match_once_init_aux:
+    \tl_map_inline:nn
+      { \exp_after:wN \l__regex_internal_a_tl \l__regex_curr_analysis_tl }
+      { \__regex_match_one_token:nnN ##1 }
+    \prg_break_point:Nn \__regex_maplike_break: { }
+  }
+\cs_new_protected:Npn \__regex_match_once_init_aux:
+  {
+    \tl_build_clear:N \l__regex_matched_analysis_tl
+    \tl_clear:N \l__regex_curr_analysis_tl
   }
 \cs_new_protected:Npn \__regex_single_match:
   {
@@ -24866,71 +25175,58 @@
         \bool_gset_eq:NN
           \g__regex_success_bool
           \l__regex_match_success_bool
+        \__regex_maplike_break:
       }
   }
 \cs_new_protected:Npn \__regex_multi_match:n #1
   {
     \tl_set:Nn \l__regex_every_match_tl
       {
-        \if_meaning:w \c_true_bool \l__regex_match_success_bool
-          \bool_gset_true:N \g__regex_success_bool
-          #1
-          \exp_after:wN \__regex_match_once:
+        \if_meaning:w \c_false_bool \l__regex_match_success_bool
+          \exp_after:wN \__regex_maplike_break:
         \fi:
+        \bool_gset_true:N \g__regex_success_bool
+        #1
+        \__regex_match_once_init:
       }
   }
-\cs_new_protected:Npn \__regex_match_loop:
+\cs_new_protected:Npn \__regex_match_one_token:nnN #1#2#3
   {
     \int_add:Nn \l__regex_step_int { 2 }
     \int_incr:N \l__regex_curr_pos_int
     \int_set_eq:NN \l__regex_last_char_int \l__regex_curr_char_int
     \int_set_eq:NN \l__regex_case_changed_char_int \c_max_int
-    \__regex_query_get:
+    \tl_set:Nn \l__regex_curr_token_tl {#1}
+    \int_set:Nn \l__regex_curr_char_int {#2}
+    \int_set:Nn \l__regex_curr_catcode_int { "#3 }
+    \tl_build_put_right:Nx \l__regex_matched_analysis_tl
+      { \exp_not:o \l__regex_curr_analysis_tl }
+    \tl_set:Nn \l__regex_curr_analysis_tl { { {#1} {#2} #3 } }
     \use:x
       {
-        \int_set_eq:NN \l__regex_max_active_int \l__regex_min_active_int
+        \int_set_eq:NN \l__regex_max_thread_int \l__regex_min_thread_int
         \int_step_function:nnN
-          { \l__regex_min_active_int }
-          { \l__regex_max_active_int - 1 }
+          { \l__regex_min_thread_int }
+          { \l__regex_max_thread_int - 1 }
           \__regex_match_one_active:n
       }
     \prg_break_point:
     \bool_set_false:N \l__regex_fresh_thread_bool
-    \if_int_compare:w \l__regex_max_active_int > \l__regex_min_active_int
-      \if_int_compare:w \l__regex_curr_pos_int < \l__regex_max_pos_int
-        \exp_after:wN \exp_after:wN \exp_after:wN \__regex_match_loop:
+    \if_int_compare:w \l__regex_max_thread_int > \l__regex_min_thread_int
+      \if_int_compare:w -2 < \l__regex_curr_char_int
+        \exp_after:wN \exp_after:wN \exp_after:wN \use_none:n
       \fi:
     \fi:
+    \l__regex_every_match_tl
   }
 \cs_new:Npn \__regex_match_one_active:n #1
   {
-    \__regex_use_state_and_submatches:nn
-      { \__kernel_intarray_item:Nn \g__regex_thread_state_intarray {#1} }
-      { \__regex_toks_use:w #1 }
-  }
-\cs_new_protected:Npn \__regex_query_set:nnn #1#2#3
-  {
-    \__kernel_intarray_gset:Nnn \g__regex_charcode_intarray
-      { \l__regex_curr_pos_int } {#3}
-    \__kernel_intarray_gset:Nnn \g__regex_catcode_intarray
-      { \l__regex_curr_pos_int } {#2}
-    \__kernel_intarray_gset:Nnn \g__regex_balance_intarray
-      { \l__regex_curr_pos_int } { \l__regex_balance_int }
-    \__regex_toks_set:Nn \l__regex_curr_pos_int {#1}
-    \int_incr:N \l__regex_curr_pos_int
-    \if_case:w #2 \exp_stop_f:
-    \or: \int_incr:N \l__regex_balance_int
-    \or: \int_decr:N \l__regex_balance_int
-    \fi:
-  }
-\cs_new_protected:Npn \__regex_query_get:
-  {
-    \l__regex_curr_char_int
-      = \__kernel_intarray_item:Nn \g__regex_charcode_intarray
-          { \l__regex_curr_pos_int } \scan_stop:
-    \l__regex_curr_catcode_int
-      = \__kernel_intarray_item:Nn \g__regex_catcode_intarray
-          { \l__regex_curr_pos_int } \scan_stop:
+    \__regex_use_state_and_submatches:w
+    \__kernel_intarray_range_to_clist:Nnn
+      \g__regex_thread_info_intarray
+      { 1 + #1 * (\l__regex_capturing_group_int * 2 + 1) }
+      { (1 + #1) * (\l__regex_capturing_group_int * 2 + 1) }
+    ;
   }
 \cs_new_protected:Npn \__regex_use_state:
   {
@@ -24941,24 +25237,24 @@
       { \l__regex_curr_state_int }
       { \int_eval:n { \l__regex_step_int + 1 } }
   }
-\cs_new_protected:Npn \__regex_use_state_and_submatches:nn #1 #2
+\cs_new_protected:Npn \__regex_use_state_and_submatches:w #1 , #2 ;
   {
     \int_set:Nn \l__regex_curr_state_int {#1}
     \if_int_compare:w
         \__kernel_intarray_item:Nn \g__regex_state_active_intarray
           { \l__regex_curr_state_int }
                       < \l__regex_step_int
-      \tl_set:Nn \l__regex_curr_submatches_prop {#2}
+      \tl_set:Nn \l__regex_curr_submatches_tl { #2 , }
       \exp_after:wN \__regex_use_state:
     \fi:
     \scan_stop:
   }
-\cs_new_protected:Npn \__regex_action_start_wildcard:
+\cs_new_protected:Npn \__regex_action_start_wildcard:N #1
   {
     \bool_set_true:N \l__regex_fresh_thread_bool
     \__regex_action_free:n {1}
     \bool_set_false:N \l__regex_fresh_thread_bool
-    \__regex_action_cost:n {0}
+    \bool_if:NT #1 { \__regex_action_cost:n {0} }
   }
 \cs_new_protected:Npn \__regex_action_free:n
   { \__regex_action_free_aux:nn { > \l__regex_step_int \else: } }
@@ -24980,8 +25276,8 @@
           }
         \int_set:Nn \l__regex_curr_state_int
           { \int_use:N \l__regex_curr_state_int }
-        \tl_set:Nn \exp_not:N \l__regex_curr_submatches_prop
-          { \exp_not:o \l__regex_curr_submatches_prop }
+        \tl_set:Nn \exp_not:N \l__regex_curr_submatches_tl
+          { \exp_not:o \l__regex_curr_submatches_tl }
       }
   }
 \cs_new_protected:Npn \__regex_action_cost:n #1
@@ -24991,26 +25287,47 @@
   }
 \cs_new_protected:Npn \__regex_store_state:n #1
   {
-    \__regex_store_submatches:
-    \__kernel_intarray_gset:Nnn \g__regex_thread_state_intarray
-      { \l__regex_max_active_int } {#1}
-    \int_incr:N \l__regex_max_active_int
+    \exp_args:No \__regex_store_submatches:nn
+      \l__regex_curr_submatches_tl {#1}
+    \int_incr:N \l__regex_max_thread_int
   }
-\cs_new_protected:Npn \__regex_store_submatches:
+\cs_new_protected:Npn \__regex_store_submatches:nn #1#2
   {
-    \__regex_toks_set:No \l__regex_max_active_int
-      { \l__regex_curr_submatches_prop }
+    \__kernel_intarray_gset_range_from_clist:Nnn
+      \g__regex_thread_info_intarray
+      {
+        \__regex_int_eval:w
+        1 + \l__regex_max_thread_int *
+        (\l__regex_capturing_group_int * 2 + 1)
+      }
+      { #2 , #1 }
   }
 \cs_new_protected:Npn \__regex_disable_submatches:
   {
-    \cs_set_protected:Npn \__regex_store_submatches: { }
-    \cs_set_protected:Npn \__regex_action_submatch:n ##1 { }
+    \cs_set_protected:Npn \__regex_store_submatches:n ##1 { }
+    \cs_set_protected:Npn \__regex_action_submatch:nN ##1##2 { }
   }
-\cs_new_protected:Npn \__regex_action_submatch:n #1
+\cs_new_protected:Npn \__regex_action_submatch:nN #1#2
   {
-    \prop_put:Nno \l__regex_curr_submatches_prop {#1}
-      { \int_use:N \l__regex_curr_pos_int }
+    \exp_after:wN \__regex_action_submatch_aux:w
+    \l__regex_curr_submatches_tl ; {#1} #2
   }
+\cs_new_protected:Npn \__regex_action_submatch_aux:w #1 ; #2#3
+  {
+    \tl_set:Nx \l__regex_curr_submatches_tl
+      {
+        \prg_replicate:nn
+          { #2 \if_meaning:w > #3 + \l__regex_capturing_group_int \fi: }
+          { \__regex_action_submatch_auxii:w }
+        \__regex_action_submatch_auxiii:w
+        #1
+      }
+  }
+\cs_new:Npn \__regex_action_submatch_auxii:w
+    #1 \__regex_action_submatch_auxiii:w #2 ,
+  { #2 , #1 \__regex_action_submatch_auxiii:w }
+\cs_new:Npn \__regex_action_submatch_auxiii:w #1 ,
+  { \int_use:N \l__regex_curr_pos_int , }
 \cs_new_protected:Npn \__regex_action_success:
   {
     \__regex_if_two_empty_matches:F
@@ -25019,8 +25336,10 @@
         \bool_set_eq:NN \l__regex_empty_success_bool
           \l__regex_fresh_thread_bool
         \int_set_eq:NN \l__regex_success_pos_int \l__regex_curr_pos_int
-        \prop_set_eq:NN \l__regex_success_submatches_prop
-          \l__regex_curr_submatches_prop
+        \int_set_eq:NN \l__regex_last_char_success_int \l__regex_last_char_int
+        \tl_build_clear:N \l__regex_matched_analysis_tl
+        \tl_set_eq:NN \l__regex_success_submatches_tl
+          \l__regex_curr_submatches_tl
         \prg_break:
       }
   }
@@ -25037,6 +25356,7 @@
       { \__kernel_intarray_item:Nn \g__regex_submatch_begin_intarray {#1} }
   }
 \cs_new:Npn \__regex_replacement_exp_not:N #1 { \exp_not:n {#1} }
+\cs_new_eq:NN \__regex_replacement_exp_not:V \exp_not:V
 \cs_new:Npn \__regex_query_range:nn #1#2
   {
     \exp_after:wN \__regex_query_range_loop:ww
@@ -25063,37 +25383,21 @@
 \cs_new_protected:Npn \__regex_submatch_balance:n #1
   {
     \int_eval:n
-     {
-      \int_compare:nNnTF
-        {
-          \__kernel_intarray_item:Nn
-            \g__regex_submatch_end_intarray {#1}
-        }
-          = 0
-        { 0 }
-        {
-          \__kernel_intarray_item:Nn \g__regex_balance_intarray
-            {
-              \__kernel_intarray_item:Nn
-                \g__regex_submatch_end_intarray {#1}
-            }
-        }
-      -
-      \int_compare:nNnTF
-        {
-          \__kernel_intarray_item:Nn
-            \g__regex_submatch_begin_intarray {#1}
-        }
-          = 0
-        { 0 }
-        {
-          \__kernel_intarray_item:Nn \g__regex_balance_intarray
-            {
-              \__kernel_intarray_item:Nn
-                \g__regex_submatch_begin_intarray {#1}
-            }
-        }
-     }
+      {
+        \__regex_intarray_item:NnF \g__regex_balance_intarray
+          {
+            \__kernel_intarray_item:Nn
+              \g__regex_submatch_end_intarray {#1}
+          }
+          { 0 }
+        -
+        \__regex_intarray_item:NnF \g__regex_balance_intarray
+          {
+            \__kernel_intarray_item:Nn
+              \g__regex_submatch_begin_intarray {#1}
+          }
+          { 0 }
+      }
   }
 \cs_new_protected:Npn \__regex_replacement:n #1
   {
@@ -25153,10 +25457,12 @@
         #1
       }
   }
+\cs_new_protected:Npn \__regex_replacement_put:n
+  { \tl_build_put_right:Nn \l__regex_build_tl }
 \cs_new_protected:Npn \__regex_replacement_normal:n #1
   {
     \tl_if_empty:NTF \l__regex_replacement_category_tl
-      { \tl_build_put_right:Nn \l__regex_build_tl {#1} }
+      { \__regex_replacement_put:n {#1} }
       { % (
         \token_if_eq_charcode:NNTF #1 )
           {
@@ -25188,15 +25494,19 @@
 \cs_new_protected:Npn \__regex_replacement_put_submatch:n #1
   {
     \if_int_compare:w #1 < \l__regex_capturing_group_int
-      \tl_build_put_right:Nn \l__regex_build_tl
-        { \__regex_query_submatch:n { \int_eval:n { #1 + ##1 } } }
-      \if_int_compare:w \l__regex_replacement_csnames_int = 0 \exp_stop_f:
-        \tl_put_right:Nn \l__regex_balance_tl
-          {
-            + \__regex_submatch_balance:n
-              { \exp_not:N \int_eval:n { #1 + ##1 } }
-          }
-      \fi:
+      \__regex_replacement_put_submatch_aux:n {#1}
+    \fi:
+  }
+\cs_new_protected:Npn \__regex_replacement_put_submatch_aux:n #1
+  {
+    \tl_build_put_right:Nn \l__regex_build_tl
+      { \__regex_query_submatch:n { \int_eval:n { #1 + ##1 } } }
+    \if_int_compare:w \l__regex_replacement_csnames_int = 0 \exp_stop_f:
+      \tl_put_right:Nn \l__regex_balance_tl
+        {
+          + \__regex_submatch_balance:n
+            { \exp_not:N \int_eval:n { #1 + ##1 } }
+        }
     \fi:
   }
 \cs_new_protected:Npn \__regex_replacement_g:w #1#2
@@ -25262,7 +25572,7 @@
   {
     \__regex_two_if_eq:NNNNTF
       #1 #2 \__regex_replacement_normal:n \c_left_brace_str
-      { \__regex_replacement_cu_aux:Nw \exp_not:V }
+      { \__regex_replacement_cu_aux:Nw \__regex_replacement_exp_not:V }
       { \__regex_replacement_error:NNN u #1#2 }
   }
 \cs_new_protected:Npn \__regex_replacement_rbrace:N #1
@@ -25312,7 +25622,7 @@
   \cs_new_protected:Npn \__regex_replacement_char:nNN #1#2#3
     {
       \tex_lccode:D 0 = `#3 \scan_stop:
-      \tex_lowercase:D { \tl_build_put_right:Nn \l__regex_build_tl {#1} }
+      \tex_lowercase:D { \__regex_replacement_put:n {#1} }
     }
   \char_set_catcode_active:N \^^@
   \cs_new_protected:Npn \__regex_replacement_c_A:w
@@ -25329,7 +25639,7 @@
   \cs_new_protected:Npn \__regex_replacement_c_C:w #1#2
     {
       \tl_build_put_right:Nn \l__regex_build_tl
-        { \exp_not:N \exp_not:N \exp_not:c {#2} }
+        { \exp_not:N \__regex_replacement_exp_not:N \exp_not:c {#2} }
     }
   \char_set_catcode_math_subscript:N \^^@
   \cs_new_protected:Npn \__regex_replacement_c_D:w
@@ -25364,7 +25674,7 @@
         \__kernel_msg_error:nn { kernel } { replacement-null-space }
       \fi:
       \tex_lccode:D `\ = `#2 \scan_stop:
-      \tex_lowercase:D { \tl_build_put_right:Nn \l__regex_build_tl {~} }
+      \tex_lowercase:D { \__regex_replacement_put:n {~} }
     }
   \char_set_catcode_alignment:N \^^@
   \cs_new_protected:Npn \__regex_replacement_c_T:w
@@ -25458,6 +25768,7 @@
 \intarray_new:Nn \g__regex_submatch_prev_intarray { 65536 }
 \intarray_new:Nn \g__regex_submatch_begin_intarray { 65536 }
 \intarray_new:Nn \g__regex_submatch_end_intarray { 65536 }
+\intarray_new:Nn \g__regex_balance_intarray { 65536 }
 \cs_new_protected:Npn \__regex_return:
   {
     \if_meaning:w \c_true_bool \g__regex_success_bool
@@ -25466,6 +25777,27 @@
       \prg_return_false:
     \fi:
   }
+\cs_new_protected:Npn \__regex_query_set:n #1
+  {
+    \int_zero:N \l__regex_balance_int
+    \int_zero:N \l__regex_curr_pos_int
+    \__regex_query_set_aux:nN { } F
+    \tl_analysis_map_inline:nn {#1}
+      { \__regex_query_set_aux:nN {##1} ##3 }
+    \__regex_query_set_aux:nN { } F
+    \int_set_eq:NN \l__regex_max_pos_int \l__regex_curr_pos_int
+  }
+\cs_new_protected:Npn \__regex_query_set_aux:nN #1#2
+  {
+    \int_incr:N \l__regex_curr_pos_int
+    \__regex_toks_set:Nn \l__regex_curr_pos_int {#1}
+    \__kernel_intarray_gset:Nnn \g__regex_balance_intarray
+      { \l__regex_curr_pos_int } { \l__regex_balance_int }
+    \if_case:w "#2 \exp_stop_f:
+    \or: \int_incr:N \l__regex_balance_int
+    \or: \int_decr:N \l__regex_balance_int
+    \fi:
+  }
 \cs_new_protected:Npn \__regex_if_match:nn #1#2
   {
     \group_begin:
@@ -25494,6 +25826,7 @@
       #1
       \__regex_match:n {#2}
       \__regex_extract:
+      \__regex_query_set:n {#2}
     \__regex_group_end_extract_seq:N #3
   }
 \cs_new_protected:Npn \__regex_extract_all:nnN #1#2#3
@@ -25502,6 +25835,7 @@
       \__regex_multi_match:n { \__regex_extract: }
       #1
       \__regex_match:n {#2}
+      \__regex_query_set:n {#2}
     \__regex_group_end_extract_seq:N #3
   }
 \cs_new_protected:Npn \__regex_split:nnN #1#2#3
@@ -25527,6 +25861,7 @@
         }
       #1
       \__regex_match:n {#2}
+      \__regex_query_set:n {#2}
       \__kernel_intarray_gset:Nnn \g__regex_submatch_prev_intarray
         { \l__regex_submatch_int } { 0 }
       \__kernel_intarray_gset:Nnn \g__regex_submatch_end_intarray
@@ -25593,45 +25928,38 @@
       \int_set_eq:NN \l__regex_zeroth_submatch_int \l__regex_submatch_int
       \prg_replicate:nn \l__regex_capturing_group_int
         {
-          \__kernel_intarray_gset:Nnn \g__regex_submatch_begin_intarray
-            { \l__regex_submatch_int } { 0 }
-          \__kernel_intarray_gset:Nnn \g__regex_submatch_end_intarray
-            { \l__regex_submatch_int } { 0 }
           \__kernel_intarray_gset:Nnn \g__regex_submatch_prev_intarray
             { \l__regex_submatch_int } { 0 }
           \int_incr:N \l__regex_submatch_int
         }
-      \prop_map_inline:Nn \l__regex_success_submatches_prop
+      \__kernel_intarray_gset:Nnn \g__regex_submatch_prev_intarray
+        { \l__regex_zeroth_submatch_int } { \l__regex_start_pos_int }
+      \int_zero:N \l__regex_internal_a_int
+      \clist_map_inline:Nn \l__regex_success_submatches_tl
         {
-          \if_int_compare:w ##1 - 1 \exp_stop_f:
-            \exp_after:wN \__regex_extract_e:wn \int_value:w
+          \if_int_compare:w \l__regex_internal_a_int < \l__regex_capturing_group_int
+            \__kernel_intarray_gset:Nnn \g__regex_submatch_begin_intarray
+              { \__regex_int_eval:w \l__regex_zeroth_submatch_int + \l__regex_internal_a_int } {##1}
           \else:
-            \exp_after:wN \__regex_extract_b:wn \int_value:w
+            \__kernel_intarray_gset:Nnn \g__regex_submatch_end_intarray
+              { \__regex_int_eval:w \l__regex_zeroth_submatch_int + \l__regex_internal_a_int - \l__regex_capturing_group_int } {##1}
           \fi:
-          \__regex_int_eval:w \l__regex_zeroth_submatch_int + ##1 {##2}
+          \int_incr:N \l__regex_internal_a_int
         }
-      \__kernel_intarray_gset:Nnn \g__regex_submatch_prev_intarray
-        { \l__regex_zeroth_submatch_int } { \l__regex_start_pos_int }
     \fi:
   }
-\cs_new_protected:Npn \__regex_extract_b:wn #1 < #2
-  {
-    \__kernel_intarray_gset:Nnn
-      \g__regex_submatch_begin_intarray {#1} {#2}
-  }
-\cs_new_protected:Npn \__regex_extract_e:wn #1 > #2
-  { \__kernel_intarray_gset:Nnn \g__regex_submatch_end_intarray {#1} {#2} }
 \cs_new_protected:Npn \__regex_replace_once:nnN #1#2#3
   {
     \group_begin:
       \__regex_single_match:
       #1
-      \__regex_replacement:n {#2}
-      \exp_args:No \__regex_match:n { #3 }
+      \exp_args:No \__regex_match:n {#3}
       \if_meaning:w \c_false_bool \g__regex_success_bool
         \group_end:
       \else:
         \__regex_extract:
+        \exp_args:No \__regex_query_set:n {#3}
+        \__regex_replacement:n {#2}
         \int_set:Nn \l__regex_balance_int
           {
             \__regex_replacement_balance_one_match:n
@@ -25656,8 +25984,9 @@
     \group_begin:
       \__regex_multi_match:n { \__regex_extract: }
       #1
-      \__regex_replacement:n {#2}
       \exp_args:No \__regex_match:n {#3}
+      \exp_args:No \__regex_query_set:n {#3}
+      \__regex_replacement:n {#2}
       \int_set:Nn \l__regex_balance_int
         {
           0
@@ -25705,6 +26034,196 @@
           }
       }
   }
+\tl_new:N \l__regex_peek_true_tl
+\tl_new:N \l__regex_peek_false_tl
+\tl_new:N \l__regex_replacement_tl
+\tl_new:N \l__regex_input_tl
+\cs_new_eq:NN \__regex_input_item:n ?
+\cs_new_protected:Npn \peek_regex:nTF #1
+  {
+    \__regex_peek:nnTF
+      { \__regex_build_aux:Nn \c_false_bool {#1} }
+      { \__regex_peek_end: }
+  }
+\cs_new_protected:Npn \peek_regex:nT #1#2
+  { \peek_regex:nTF {#1} {#2} { } }
+\cs_new_protected:Npn \peek_regex:nF #1 { \peek_regex:nTF {#1} { } }
+\cs_new_protected:Npn \peek_regex:NTF #1
+  {
+    \__regex_peek:nnTF
+      { \__regex_build_aux:NN \c_false_bool #1 }
+      { \__regex_peek_end: }
+  }
+\cs_new_protected:Npn \peek_regex:NT #1#2
+  { \peek_regex:NTF #1 {#2} { } }
+\cs_new_protected:Npn \peek_regex:NF #1 { \peek_regex:NTF {#1} { } }
+\cs_new_protected:Npn \peek_regex_remove_once:nTF #1
+  {
+    \__regex_peek:nnTF
+      { \__regex_build_aux:Nn \c_false_bool {#1} }
+      { \__regex_peek_remove_end:n {##1} }
+  }
+\cs_new_protected:Npn \peek_regex_remove_once:nT #1#2
+  { \peek_regex_remove_once:nTF {#1} {#2} { } }
+\cs_new_protected:Npn \peek_regex_remove_once:nF #1
+  { \peek_regex_remove_once:nTF {#1} { } }
+\cs_new_protected:Npn \peek_regex_remove_once:NTF #1
+  {
+    \__regex_peek:nnTF
+      { \__regex_build_aux:NN \c_false_bool #1 }
+      { \__regex_peek_remove_end:n {##1} }
+  }
+\cs_new_protected:Npn \peek_regex_remove_once:NT #1#2
+  { \peek_regex_remove_once:NTF #1 {#2} { } }
+\cs_new_protected:Npn \peek_regex_remove_once:NF #1
+  { \peek_regex_remove_once:NTF #1 { } }
+\cs_new_protected:Npn \__regex_peek:nnTF #1
+  {
+    \__regex_peek_aux:nnTF
+      {
+        \__regex_disable_submatches:
+        #1
+      }
+  }
+\cs_new_protected:Npn \__regex_peek_aux:nnTF #1#2#3#4
+  {
+    \group_begin:
+      \tl_set:Nn \l__regex_peek_true_tl { \group_end: #3 }
+      \tl_set:Nn \l__regex_peek_false_tl { \group_end: #4 }
+      \__regex_single_match:
+      #1
+      \__regex_match_init:
+      \tl_build_clear:N \l__regex_input_tl
+      \__regex_match_once_init:
+      \peek_analysis_map_inline:n
+        {
+          \tl_build_put_right:Nn \l__regex_input_tl
+            { \__regex_input_item:n {##1} }
+          \__regex_match_one_token:nnN {##1} {##2} ##3
+          \use_none:nnn
+          \prg_break_point:Nn \__regex_maplike_break:
+            { \peek_analysis_map_break:n {#2} }
+        }
+  }
+\cs_new_protected:Npn \__regex_peek_end:
+  {
+    \bool_if:NTF \g__regex_success_bool
+      { \__regex_peek_reinsert:N \l__regex_peek_true_tl }
+      { \__regex_peek_reinsert:N \l__regex_peek_false_tl }
+  }
+\cs_new_protected:Npn \__regex_peek_remove_end:n #1
+  {
+    \bool_if:NTF \g__regex_success_bool
+      { \exp_after:wN \l__regex_peek_true_tl #1 }
+      { \__regex_peek_reinsert:N \l__regex_peek_false_tl }
+  }
+\cs_new_protected:Npn \__regex_peek_reinsert:N #1
+  {
+    \tl_build_end:N \l__regex_input_tl
+    \cs_set_eq:NN \__regex_input_item:n \__regex_reinsert_item:n
+    \exp_after:wN #1 \exp:w \l__regex_input_tl \exp_end:
+  }
+\cs_new_protected:Npn \__regex_reinsert_item:n #1
+  {
+    \exp_after:wN \exp_after:wN
+    \exp_after:wN \exp_end:
+    \exp_after:wN \exp_after:wN
+    #1
+    \exp:w
+  }
+\cs_new_protected:Npn \peek_regex_replace_once:nnTF #1
+  { \__regex_peek_replace:nnTF { \__regex_build_aux:Nn \c_false_bool {#1} } }
+\cs_new_protected:Npn \peek_regex_replace_once:nnT #1#2#3
+  { \peek_regex_replace_once:nnTF {#1} {#2} {#3} { } }
+\cs_new_protected:Npn \peek_regex_replace_once:nnF #1#2
+  { \peek_regex_replace_once:nnTF {#1} {#2} { } }
+\cs_new_protected:Npn \peek_regex_replace_once:nn #1#2
+  { \peek_regex_replace_once:nnTF {#1} {#2} { } { } }
+\cs_new_protected:Npn \peek_regex_replace_once:NnTF #1
+  { \__regex_peek_replace:nnTF { \__regex_build_aux:NN \c_false_bool #1 } }
+\cs_new_protected:Npn \peek_regex_replace_once:NnT #1#2#3
+  { \peek_regex_replace_once:NnTF #1 {#2} {#3} { } }
+\cs_new_protected:Npn \peek_regex_replace_once:NnF #1#2
+  { \peek_regex_replace_once:NnTF #1 {#2} { } }
+\cs_new_protected:Npn \peek_regex_replace_once:Nn #1#2
+  { \peek_regex_replace_once:NnTF #1 {#2} { } { } }
+\cs_new_protected:Npn \__regex_peek_replace:nnTF #1#2
+  {
+    \tl_set:Nn \l__regex_replacement_tl {#2}
+    \__regex_peek_aux:nnTF {#1} { \__regex_peek_replace_end: }
+  }
+\cs_new_protected:Npn \__regex_peek_replace_end:
+  {
+    \bool_if:NTF \g__regex_success_bool
+      {
+        \__regex_extract:
+        \__regex_query_set_from_input_tl:
+        \cs_set_eq:NN \__regex_replacement_put:n \__regex_peek_replacement_put:n
+        \cs_set_eq:NN \__regex_replacement_put_submatch_aux:n
+          \__regex_peek_replacement_put_submatch_aux:n
+        \cs_set_eq:NN \__regex_input_item:n \__regex_reinsert_item:n
+        \cs_set_eq:NN \__regex_replacement_exp_not:N \__regex_peek_replacement_token:n
+        \cs_set_eq:NN \__regex_replacement_exp_not:V \__regex_peek_replacement_var:N
+        \exp_args:No \__regex_replacement:n { \l__regex_replacement_tl }
+        \use:x
+          {
+            \exp_not:n { \exp_after:wN \l__regex_peek_true_tl \exp:w }
+            \__regex_replacement_do_one_match:n
+              { \l__regex_zeroth_submatch_int }
+            \__regex_query_range:nn
+              {
+                \__kernel_intarray_item:Nn \g__regex_submatch_end_intarray
+                  { \l__regex_zeroth_submatch_int }
+              }
+              { \l__regex_max_pos_int }
+            \exp_end:
+          }
+      }
+      { \__regex_peek_reinsert:N \l__regex_peek_false_tl }
+  }
+\cs_new_protected:Npn \__regex_query_set_from_input_tl:
+  {
+    \tl_build_end:N \l__regex_input_tl
+    \int_zero:N \l__regex_curr_pos_int
+    \cs_set_eq:NN \__regex_input_item:n \__regex_query_set_item:n
+    \__regex_query_set_item:n { }
+    \l__regex_input_tl
+    \__regex_query_set_item:n { }
+    \int_set_eq:NN \l__regex_max_pos_int \l__regex_curr_pos_int
+  }
+\cs_new_protected:Npn \__regex_query_set_item:n #1
+  {
+    \int_incr:N \l__regex_curr_pos_int
+    \__regex_toks_set:Nn \l__regex_curr_pos_int { \__regex_input_item:n {#1} }
+  }
+\cs_new_protected:Npn \__regex_peek_replacement_put:n #1
+  {
+    \if_case:w \l__regex_replacement_csnames_int
+      \tl_build_put_right:Nn \l__regex_build_tl
+        { \exp_not:N \__regex_reinsert_item:n {#1} }
+    \else:
+      \tl_build_put_right:Nn \l__regex_build_tl {#1}
+    \fi:
+  }
+\cs_new_protected:Npn \__regex_peek_replacement_token:n #1
+  { \exp_after:wN \exp_end: \exp_after:wN #1 \exp:w }
+\cs_new_protected:Npn \__regex_peek_replacement_put_submatch_aux:n #1
+  {
+    \if_case:w \l__regex_replacement_csnames_int
+      \tl_build_put_right:Nn \l__regex_build_tl
+        { \__regex_query_submatch:n { \int_eval:n { #1 + ##1 } } }
+    \else:
+      \tl_build_put_right:Nn \l__regex_build_tl
+        { \exp:w \__regex_query_submatch:n { \int_eval:n { #1 + ##1 } } \exp_end: }
+    \fi:
+  }
+\cs_new_protected:Npn \__regex_peek_replacement_var:N #1
+  {
+    \exp_after:wN \exp_last_unbraced:NV
+    \exp_after:wN \exp_end:
+    \exp_after:wN #1
+    \exp:w
+  }
 \use:x
   {
     \__kernel_msg_new:nnn { kernel } { trailing-backslash }
@@ -28555,7 +29074,7 @@
         \bool_lazy_and:nnTF
           { \cs_if_exist_p:N \fmtname }
           { \str_if_eq_p:Vn \fmtname { LaTeX2e } }
-          { \exp_not:N \__text_expand_encoding:N #1 }
+          { \exp_not:N \__text_expand_testopt:N #1 }
           { \exp_not:N \__text_expand_replace:N #1 }
       }
   }
@@ -28577,6 +29096,17 @@
       { \__text_expand_store:n { \protect #1 } }
     \__text_expand_loop:w
   }
+\cs_new:Npn \__text_expand_testopt:N #1
+  {
+    \str_if_eq:nnTF {#1} { \@protected@testopt }
+      { \__text_expand_testopt:NNn }
+      { \__text_expand_encoding:N #1 }
+  }
+\cs_new:Npn \__text_expand_testopt:NNn #1#2#3
+  {
+    \__text_expand_store:n {#1}
+    \__text_expand_loop:w
+  }
 \cs_new:Npn \__text_expand_encoding:N #1
   {
     \bool_lazy_or:nnTF
@@ -30414,6 +30944,8 @@
     \tiny
   }
   { \text_declare_purify_equivalent:Nn #1 { } }
+\exp_args:Nc \text_declare_purify_equivalent:Nn
+  { @protected@testopt } { \use_none:nnn }
 \text_declare_purify_equivalent:Nn \begin { \use:c }
 \text_declare_purify_equivalent:Nn \end { \__text_end_env:n }
 \cs_new:Npn \__text_end_env:n #1 { \cs:w end #1 \cs_end: }