From 17f5b660e0ce0c5c1b1dc095df8213e078963809 Mon Sep 17 00:00:00 2001
From: Norbert Preining <norbert@preining.info>
Date: Mon, 24 Jan 2022 03:02:10 +0000
Subject: CTAN sync 202201240302

---
 macros/latex/contrib/chemformula/chemformula.sty | 598 ++++++++++-------------
 1 file changed, 268 insertions(+), 330 deletions(-)

(limited to 'macros/latex/contrib/chemformula/chemformula.sty')

diff --git a/macros/latex/contrib/chemformula/chemformula.sty b/macros/latex/contrib/chemformula/chemformula.sty
index 4ba76f16b5..3a7b1d94a1 100644
--- a/macros/latex/contrib/chemformula/chemformula.sty
+++ b/macros/latex/contrib/chemformula/chemformula.sty
@@ -12,7 +12,7 @@
 % If you have any ideas, questions, suggestions or bugs to report, please
 % feel free to contact me.
 % --------------------------------------------------------------------------
-% Copyright 2011--2020 Clemens Niederberger
+% Copyright 2011--2022 Clemens Niederberger
 %
 % This work may be distributed and/or modified under the
 % conditions of the LaTeX Project Public License, either version 1.3
@@ -30,8 +30,8 @@
 \usetikzlibrary{arrows.meta}
 
 \ExplSyntaxOn
-\tl_const:Nn \c_chemformula_date_tl {2020/12/22}
-\tl_const:Nn \c_chemformula_version_number_tl {4.16}
+\tl_const:Nn \c_chemformula_date_tl {2022/01/23}
+\tl_const:Nn \c_chemformula_version_number_tl {4.17}
 \tl_const:Nn \c_chemformula_version_suffix_tl {}
 \tl_const:Nx \c_chemformula_version_tl
   { \c_chemformula_version_number_tl \c_chemformula_version_suffix_tl }
@@ -128,14 +128,50 @@
     \NewChemSymbol \c_space_tl but~ a~ symbol~ `#1'~ doesn't~ exist.
   }
 
+\msg_new:nnn {chemformula} {deprecated}
+  {
+    On~ line~ \msg_line_number: : \\
+    The~ #1~ `#2'~ is~ deprecated.~ Use~ #1~ `#3'~ instead .
+  }
+
+\msg_new:nnn {chemformula} {deprecated-function}
+  { The~ command~ #1~ is~ deprecated.~ Use~ #2 instead . }
+
+\msg_new:nnn {chemformula} {removed-function}
+  { The~ command~ #1~ has~ been~ removed. }
+
+\msg_new:nnn {chemformula} {removed}
+  {
+    On~ line~ \msg_line_number: : \\
+    The~ #1~ `#2'~ has~ been~ removed~ from~ chemformula. \\
+    If~ you~ need~ it~ back~ please~ open~ an~ issue~ on~ \\
+    https://github.com/cgnieder/chemformula/issues
+    \tl_if_blank:nF {#3} { \\ #3 }
+  }
+
+\msg_new:nnn {chemformula} {load-time-option}
+  {
+    `#1'~ is~ a~ load-time~ option! \\
+    You~ cannot~ set~ it~ with~ \token_to_str:N \setchemformula ! \\
+    You~ need~ to~ use~ \token_to_str:N \usepackage [#1] {chemformula} .
+  }
+
+\msg_new:nnn {chemformula} {unknown-option}
+  {
+    Unknown~ option~ `#1' \\
+    I~ dont'~ know~ the~ option~ `#1'.~ Please~ make~ sure~ there~ is~ no~
+    typo.~ Check~ the~ manual~ for~ help.
+  }
+  
 % --------------------------------------------------------------------------
 % variants of kernel functions:
 \cs_generate_variant:Nn \keys_set:nn         {nV}
 \cs_generate_variant:Nn \tl_if_blank:nF      {V}
 \cs_generate_variant:Nn \tl_if_in:nnT        {x,nV}
 \cs_generate_variant:Nn \tl_if_eq:nnT        {V,x}
-\cs_generate_variant:Nn \tl_if_eq:nnTF       {o}
-\cs_generate_variant:Nn \tl_set:Nn           {cV}
+\cs_generate_variant:Nn \tl_if_eq:nnTF       {o,V}
+\cs_generate_variant:Nn \tl_set:Nn           {cV,Ne}
+\cs_generate_variant:Nn \tl_put_right:Nn     {Ne}
 \cs_generate_variant:Nn \tl_replace_all:Nnn  {NV,Nnx}
 \cs_generate_variant:Nn \tl_replace_once:Nnn {Nxx}
 \cs_generate_variant:Nn \tl_set_rescan:Nnn   {NnV}
@@ -168,6 +204,7 @@
 \bool_new:N \l__chemformula_tmpa_bool
 
 % booleans
+\bool_new:N \l__chemformula_debug_bool
 \bool_new:N \l_chemformula_inside_ch_bool
 \bool_new:N \l_chemformula_formal_charges_bool
 \bool_new:N \l_chemformula_formal_chem_bool
@@ -178,6 +215,7 @@
 \bool_new:N \l__chemformula_is_addition_symbol_bool
 \bool_new:N \l__chemformula_is_symbol_bool
 \bool_new:N \l__chemformula_is_arrow_bool
+\bool_new:N \l__chemformula_arrow_has_options_bool
 \bool_new:N \l__chemformula_is_name_bool
 \bool_new:N \l__chemformula_stoich_is_iupac_bool
 \bool_new:N \l__chemformula_stoich_parse_iupac_bool
@@ -265,6 +303,7 @@
 \tl_new:N \g__chemformula_output_tl
 \tl_new:N \l__chemformula_input_tl
 \tl_new:N \l__chemformula_stoich_tl
+\tl_new:N \l__chemformula_stoich_format_tl
 \tl_new:N \l__chemformula_decimal_output_tl
 \tl_new:N \l__chemformula_font_family_tl
 \tl_new:N \l__chemformula_font_series_tl
@@ -365,6 +404,89 @@
 \skip_set:Nn \l__chemformula_stoich_space_skip { .1667em plus .0333em minus .0117em }
 \skip_set:Nn \l__chemformula_math_space_skip { .1667em plus .0333em minus .0117em }
 
+% ----------------------------------------------------------------------------
+% debugging
+\prg_new_conditional:Npnn \__chemformula_if_debug: {T,F,TF}
+  {
+    \bool_if:NTF \l__chemformula_debug_bool
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
+  
+% ----------------------------------------------------------------------------
+% deprecation & removal:
+% #1: type
+% #2: old
+% #3: new
+\cs_new_protected:Npn \__chemformula_deprecation_warning:nnn #1#2#3
+  { \msg_warning:nnnnn {chemformula} {deprecated} {#1} {#2} {#3} }
+\cs_generate_variant:Nn \__chemformula_deprecation_warning:nnn {nne,nV}
+
+% #1: type
+% #2: old
+% #3: additional text
+\cs_new_protected:Npn \chemformula_removal_warning:nnn #1#2#3
+  { \msg_warning:nnnnn {chemformula} {removed} {#1} {#2} {#3} }
+\cs_generate_variant:Nn \chemformula_removal_warning:nnn {nV}
+
+% #1: type
+% #2: old
+\cs_new_protected:Npn \chemformula_removal_warning:nn #1#2
+  { \msg_warning:nnnn {chemformula} {removed} {#1} {#2} }
+\cs_generate_variant:Nn \chemformula_removal_warning:nn {nV}
+
+% #1: new
+\cs_new_protected:Npn \chemformula_deprecate_option:n #1
+  { \__chemformula_deprecation_warning:nVn {option} \l_keys_key_str {#1} }
+
+% #1: additional text
+\cs_new_protected:Npn \chemformula_remove_option:n #1
+  { \chemformula_removal_warning:nVn {option} \l_keys_key_str {#1} }
+
+\cs_new_protected:Npn \chemformula_remove_option:
+  { \chemformula_removal_warning:nV {option} \l_keys_key_str }
+
+% #1: old
+% #2: new
+\cs_new_protected:Npn \chemformula_deprecate_function:NN #1#2
+  {
+    \cs_set_protected:Npn #1
+      {
+        \msg_error:nnnn {chemformula} {deprecated-function} {#1} {#2}
+        #2
+      }
+  }
+
+% #1: old
+\cs_new_protected:Npn \chemformula_remove_function:N #1
+  {
+    \cs_set_protected:Npn #1
+      { \msg_error:nnn {chemformula} {removed-function} {#1} }
+  }
+
+% --------------------------------------------------------------------------
+% load-time options:
+\cs_new_protected:Npn \__chemformula_loadtime_error:n #1
+   { \msg_error:nnV {chemformula} {#1} \l_keys_key_str }
+
+\cs_new_protected:Npn \__chemformula_loadtime_warning:n #1
+  { \msg_warning:nnV {chemformula} {#1} \l_keys_key_str }
+
+\keys_define:nn {chemformula/load-time}
+  {
+    debug .bool_set:N = \l__chemformula_debug_bool ,
+    debug .initial:n  = false
+  }
+
+\ProcessKeysPackageOptions {chemformula/load-time}
+
+\keys_define:nn {chemformula}
+  {
+    debug   .code:n = \__chemformula_loadtime_error:n {load-time-option} ,
+    unknown .code:n = \__chemformula_loadtime_warning:n {unknown-option} ,
+    load-time / debug .meta:nn = {chemformula} {debug}
+  }
+
 % --------------------------------------------------------------------------
 % catcode stuff
 \cs_new_protected:Npn \__chemformula_save_catcodes:
@@ -413,8 +535,8 @@
       {
         \__chemformula_basic_catcodes:
         % disable some of the specials (needed for sub- and superscripts):
-        \char_set_catcode_letter:N \{
-        \char_set_catcode_letter:N \}
+        \char_set_catcode_other:N \{
+        \char_set_catcode_other:N \}
       }
       {#2}
   }
@@ -891,9 +1013,17 @@
       { \__chemformula_basic_catcodes: } {#1}
     % determine length of the arrow
     \hbox_set:Nn \l__chemformula_arrow_arg_i_box
-      { \tl_use:N \l__chemformula_arrow_label_style_tl #2 }
+      {
+        \tl_use:N \l__chemformula_arrow_label_style_tl
+        \cs_set:Npn \newline { \tabularnewline }
+        \begin {tabular} {c} #2 \end {tabular}
+      }
     \hbox_set:Nn \l__chemformula_arrow_arg_ii_box
-      { \tl_use:N \l__chemformula_arrow_label_style_tl #3 }
+      {
+        \tl_use:N \l__chemformula_arrow_label_style_tl
+        \cs_set:Npn \newline { \tabularnewline }
+        \begin {tabular} {c} #3 \end {tabular}
+      }
     \__chemformula_determine_arrow_length:NN
       \l__chemformula_arrow_arg_i_box
       \l__chemformula_arrow_arg_ii_box
@@ -1124,37 +1254,42 @@
 
 % --------------------------------------------------------------------------
 % MAIN COMMAND
-\cs_new_protected:Npn \__chemformula_ch_main:n #1
+\cs_set_protected:Npn \__chemformula_ch_main:n #1
   {
     \group_begin:
       % abort if `#1' is blank:
       \tl_if_blank:nF {#1}
         {
-          \tl_set:Nn \l__chemmacros_tmpa_tl {#1}
-          \tl_trim_spaces:N \l__chemmacros_tmpa_tl
-          \seq_set_split:NnV \l__chemformula_input_seq {~} \l__chemmacros_tmpa_tl
-          % remove empty items in order to avoid unnecessary processing:
-          \seq_remove_all:Nn \l__chemformula_input_seq {}
           % disable \xspace:
           \cs_set_eq:NN \xspace \scan_stop:
           \bool_set_true:N \l_chemformula_inside_ch_bool
           \tl_if_blank:VF \g__chemformula_options_tl
-            {
-              \keys_set:nV
-                {chemformula}
-                \g__chemformula_options_tl
-            }
-          \seq_map_function:NN
-            \l__chemformula_input_seq
-            \__chemformula_input:n
+            { \keys_set:nV {chemformula} \g__chemformula_options_tl }
+          \__chemformula_read_input:n {#1}
           \__chemformula_prepare_output:NV
             \l__chemformula_input_tl
             \l__chemformula_catcodes_tl
           \chemformula_write:V \l__chemformula_input_tl
+          \__chemformula_if_debug:T { \tl_show:N \l__chemformula_input_tl }
         }
     \group_end:
   }
 
+\cs_new_protected:Npn \__chemformula_read_input:n #1
+  { \__chemformula_read_input:w #1 ~ \q_stop }
+\cs_generate_variant:Nn \__chemformula_read_input:n {V}
+
+\cs_new_protected:Npn \__chemformula_read_input:w #1 ~ #2 \q_stop
+  {
+    \__chemformula_input:n {#1}
+    \tl_set:Nn \l__chemformula_tmpa_tl {#2}
+    \tl_if_blank:VF \l__chemformula_tmpa_tl
+      {
+        \tl_trim_spaces:N \l__chemformula_tmpa_tl
+        \__chemformula_read_input:V \l__chemformula_tmpa_tl
+      }
+  }
+
 \cs_new_protected:Npn \chemformula_write:n #1
   {
     \mode_if_math:TF
@@ -1171,7 +1306,7 @@
       \tl_if_blank:nTF {#1}
         { \tl_gclear:N \g__chemformula_options_tl }
         { \tl_gset:Nn  \g__chemformula_options_tl {#1} }
-      \__chemformula_ch_newline:w #2 \\ \q_no_value \q_stop
+      \__chemformula_ch_newline:w #2 \\ \q_nil \q_stop
     \group_align_safe_end:
     \tl_use:N    \g__chemformula_output_tl
     \tl_gclear:N \g__chemformula_output_tl
@@ -1182,8 +1317,8 @@
 % bypass \\:
 \cs_new_protected:Npn \__chemformula_ch_newline:w #1 \\ #2 \q_stop
   {
-    \__chemformula_ch_align:w #1 & \q_no_value \q_stop
-    \quark_if_no_value:nF {#2}
+    \__chemformula_ch_align:w #1 & \q_nil \q_stop
+    \quark_if_nil:nF {#2}
       {
         \tl_gput_right:Nn \g__chemformula_output_tl { \\ }
         % look for optional argument:
@@ -1203,8 +1338,8 @@
 % bypass &:
 \cs_new_protected:Npn \__chemformula_ch_align:w #1 & #2 \q_stop
   {
-    \__chemformula_ch_intertext:w #1 \intertext{} \q_no_value \q_stop
-    \quark_if_no_value:nF {#2}
+    \__chemformula_ch_intertext:w #1 \intertext{} \q_nil \q_stop
+    \quark_if_nil:nF {#2}
       {
         \tl_gput_right:Nn \g__chemformula_output_tl {&}
         \__chemformula_ch_align:w #2 \q_stop
@@ -1214,8 +1349,8 @@
 % bypass \intertext:
 \cs_new_protected:Npn \__chemformula_ch_intertext:w #1 \intertext#2 #3 \q_stop
   {
-    \__chemformula_ch_shortintertext:w #1 \shortintertext{} \q_no_value \q_stop
-    \quark_if_no_value:nF {#3}
+    \__chemformula_ch_shortintertext:w #1 \shortintertext{} \q_nil \q_stop
+    \quark_if_nil:nF {#3}
       {
         \tl_gput_right:Nn \g__chemformula_output_tl { \intertext {#2} }
         \__chemformula_ch_intertext:w #3 \q_stop
@@ -1227,7 +1362,7 @@
   {
     \tl_gput_right:Nn \g__chemformula_output_tl
       { \__chemformula_ch_main:n {#1} }
-    \quark_if_no_value:nF {#3}
+    \quark_if_nil:nF {#3}
       {
         \tl_gput_right:Nn \g__chemformula_output_tl { \shortintertext {#2} }
         \__chemformula_ch_shortintertext:w #3 \q_stop
@@ -1330,6 +1465,11 @@
             \prop_map_break:
           }
       }
+    \bool_if:NT \l__chemformula_is_arrow_bool
+      {
+        \tl_if_in:nnT {#1} {[}
+          { \bool_set_true:N \l__chemformula_arrow_has_options_bool }
+      }
   }
 
 % --------------------------------------------------------------------------
@@ -1348,19 +1488,11 @@
           \bool_if:NF \l__chemformula_name_width_bool
             {
               \chemformula_dim_to_width:Nn \l__chemformula_name_dim
-                {
-                  \group_begin:
-                  \l__chemformula_name_format_tl {#1}
-                  \group_end:
-                }
+                { \chemformula_name_write:n {#1} }
             }
           \parbox
             { \dim_use:N \l__chemformula_name_dim }
-            {
-              \group_begin:
-              \l__chemformula_name_format_tl {#1}
-              \group_end:
-            }
+            { \chemformula_name_write:n {#1} }
         }
         {
           \text
@@ -1373,6 +1505,13 @@
     \c_math_toggle_token
   }
 
+\cs_new_protected:Npn \chemformula_name_write:n #1
+  {
+    \group_begin:
+      \l__chemformula_name_format_tl {#1}
+    \group_end:
+  }
+
 \cs_new_protected:Npn \__chemformula_generate_name:Nn #1#2
   {
     \__chemformula_sanitize:Nn \l__chemformula_tmpa_tl {#2}
@@ -1716,7 +1855,7 @@
   {
     \bool_if:NTF \l__chemformula_number_style_math_bool
       { \ensuremath {#1} }
-      { \ensuremath { \text {#1} } }
+      { \ensuremath { \text { { \chemformula_atom: #1 } } } }
   }
 \cs_generate_variant:Nn \__chemformula_number_style:n {V}
 
@@ -1724,7 +1863,7 @@
   {
     \bool_if:NTF \l__chemformula_charge_style_math_bool
       { \ensuremath {#1} }
-      { \ensuremath { \text {#1} } }
+      { \ensuremath { \text { { \chemformula_atom: #1 } } } }
   }
 \cs_generate_variant:Nn \chemformula_charge_style:n {V}
 
@@ -1769,6 +1908,7 @@
   }
 \cs_generate_variant:Nn \__chemformula_subscript:n {V}
 
+
 \cs_new_protected:Npn \chemformula_add_subscript_cleanup:nn #1#2
   {
     \seq_put_right:Nn \l__chemformula_clean_subscript_seq {#1}
@@ -2121,7 +2261,7 @@
     \__chemformula_input_escape_text:V \l__chemformula_chemformula_tmpa_tl
     \__chemformula_input_escape_math:n {#1}
     \__chemformula_input_stoich:n {#1}
-    \__chemformula_clean_chemmacros:V \l__chemformula_chemformula_tmpa_tl
+    \__chemformula_clean_chemformula:V \l__chemformula_chemformula_tmpa_tl
     \__chemformula_input_compound:NV
       \l__chemformula_input_tl
       \l__chemformula_chemformula_tmpa_tl
@@ -2135,19 +2275,15 @@
 % set options for next compound:
 \cs_new_protected:Npn \__chemformula_input_options:n #1
   {
-    % \makeatother
-    \char_set_catcode_other:N \@
-    \tl_set_rescan:Nnn \l__chemformula_tmpa_tl
-      { \char_set_catcode_letter:N \@ }
-      {#1}
-    \tl_if_in:VnTF \l__chemformula_tmpa_tl { @ }
+    \tl_set_rescan:Nnn \l__chemformula_tmpa_tl {} {#1}
+    \tl_set:Ne \l__chemformula_tmpb_tl { \tl_tail:V \l__chemformula_tmpa_tl }
+    \tl_set:Ne \l__chemformula_tmpa_tl { \tl_head:V \l__chemformula_tmpa_tl }
+    \str_if_eq:VnTF \l__chemformula_tmpa_tl {@}
       {
         \bool_set_false:N \l__chemformula_options_bool
         \bool_set_true:N \l__chemformula_is_option_bool
-        \tl_remove_all:Nn \l__chemformula_tmpa_tl { @ }
         \exp_last_unbraced:Nno
-        \tl_set:Nn \l__chemformula_internal_options_tl
-          { \l__chemformula_tmpa_tl }
+        \tl_set:Nn \l__chemformula_internal_options_tl { \l__chemformula_tmpb_tl }
       }
       { \bool_set_false:N \l__chemformula_is_option_bool }
   }
@@ -2164,7 +2300,10 @@
     \tl_map_inline:nn {#1}
       {
         \prop_if_in:NnF \l__chemformula_no_stoich_prop {##1}
-          { \bool_set_false:N \l__chemformula_no_stoich_bool }
+          {
+            \bool_set_false:N \l__chemformula_no_stoich_bool
+            \tl_map_break:
+          }
       }
     \bool_if:NF \l__chemformula_no_stoich_bool
       {
@@ -2175,7 +2314,10 @@
                 \bool_if:NT \l__chemformula_stoich_bool
                   { \tl_put_right:NV \l__chemformula_stoich_tl \l__chemformula_tmpa_tl }
               }
-              { \bool_set_false:N \l__chemformula_stoich_bool }
+              {
+                \bool_set_false:N \l__chemformula_stoich_bool
+                \tl_map_break:
+              }
            }
       }
     \bool_if:NTF \l__chemformula_stoich_bool
@@ -2186,7 +2328,7 @@
             \__chemformula_sanitize:NV
               \l__chemformula_stoich_tl
               \l__chemformula_stoich_tl
-            \__chemformula_print_stoich:V
+            \chemformula_print_stoich:V
               \l__chemformula_stoich_tl
           }
       }
@@ -2195,15 +2337,23 @@
 
 \cs_new_protected:Npn \chemformula_bm:n #1 {#1}
 
-\cs_new_protected:Npn \__chemformula_print_stoich:n #1
+\cs_new_protected:Npn \chemformula_print_stoich:n #1
   { \chemformula_parse_stoich:n {#1} }
-\cs_generate_variant:Nn \__chemformula_print_stoich:n {V}
+\cs_generate_variant:Nn \chemformula_print_stoich:n {V}
+
+\cs_new_protected:Npn \__chemformula_print_stoich:n #1
+  { { \l__chemformula_stoich_format_tl {#1} } }
 
 \cs_new_protected:Npn \chemformula_parse_stoich:n #1
   { \__chemformula_parse_stoich:w #1 \q_nil }
 
 \NewDocumentCommand \chstoich {m}
-  { \chemformula_parse_stoich:n {#1} }
+  {
+    \group_begin:
+      \__chemformula_input_stoich:n {#1}
+      \l__chemformula_input_tl
+    \group_end:
+  }
 
 \cs_new_protected:Npn \__chemformula_parse_stoich:w \q_mark #1 \q_nil
   {
@@ -2235,8 +2385,14 @@
     \tl_set:Nn \l__chemformula_tmpb_tl { \chemformula_decimal: }
     % check if stoich starts with decimal-marker and add leading 0 if so:
     \tl_if_eq:NNTF \l__chemformula_tmpa_tl \l__chemformula_tmpb_tl
-      { \tl_put_right:Nn \l__chemformula_input_tl { 0#1 } }
-      { \tl_put_right:Nn \l__chemformula_input_tl {#1} }
+      {
+        \tl_put_right:Nn \l__chemformula_input_tl
+          { \__chemformula_print_stoich:n {0#1} }
+      }
+      {
+        \tl_put_right:Nn \l__chemformula_input_tl
+          { \__chemformula_print_stoich:n {#1} }
+      }
   }
 
 \cs_new_protected:Npn \__chemformula_parse_stoich_frac:n #1
@@ -2249,20 +2405,20 @@
 \cs_new_protected:Npn \__chemformula_parse_stoich_frac:w #1/#2 \q_nil
   {
     \tl_put_right:Nn \l__chemformula_input_tl
-      { \__chemformula_frac:nn {#1} {#2} }
+      { \__chemformula_print_stoich:n { \__chemformula_frac:nn {#1} {#2} } }
   }
 
 \cs_new_protected:Npn \__chemformula_parse_stoich_misc_frac:w #1_#2/#3 \q_nil
   {
     \tl_put_right:Nn \l__chemformula_input_tl
-      { \__chemformula_misc_frac:nnn {#1} {#2} {#3} }
+      { \__chemformula_print_stoich:n { \__chemformula_misc_frac:nnn {#1} {#2} {#3} } }
   }
 
 \cs_new_protected:Npn \__chemformula_parse_stoich_iupac:n #1
   {
     \bool_if:NTF \l__chemformula_stoich_parse_iupac_bool
       { \__chemformula_parse_stoich_iupac:w #1 \q_nil }
-      { \tl_put_right:Nn \l__chemformula_input_tl {#1} }
+      { \tl_put_right:Nn \l__chemformula_input_tl { \__chemformula_print_stoich:n {#1} } }
   }
 
 \cs_new_protected:Npn \__chemformula_parse_stoich_iupac:w (#1) \q_nil
@@ -2304,6 +2460,9 @@
   }
 
 % --------------------------------------------------------------------------
+\cs_new_protected:Npn \chemformula_atom:
+  { \mode_if_math:F { \l__chemformula_atom_format_tl } }
+
 % input compounds
 \cs_new_protected:Npn \__chemformula_input_compound:Nn #1#2
   {
@@ -2317,26 +2476,29 @@
         \bool_if:NT \l__chemformula_is_option_bool
           {
             \bool_set_true:N \l__chemformula_options_bool
-            \tl_put_right:Nx #1
+            \tl_put_right:Ne #1
               {
                 \group_begin:
                   % open group
                   \keys_set:nn
                     {chemformula}
                     { \exp_not:V \l__chemformula_internal_options_tl }
+                  \chemformula_atom:
               }
+            \tl_clear:N \l__chemformula_internal_options_tl
           }
-        \bool_if:nT
+        \bool_lazy_any:nF
           {
-            !\l__chemformula_is_option_bool &&
-            !\l__chemformula_is_addition_symbol_bool &&
-            !\l__chemformula_is_symbol_bool &&
-            !\l__chemformula_is_arrow_bool &&
-            !\l__chemformula_is_name_bool &&
-            !\l__chemformula_first_last_text_bool &&
-            !\l__chemformula_first_last_math_bool
+            { \l__chemformula_is_option_bool }
+            { \l__chemformula_is_addition_symbol_bool }
+            { \l__chemformula_is_symbol_bool }
+            { \l__chemformula_is_arrow_bool }
+            { \l__chemformula_is_name_bool }
+            { \l__chemformula_first_last_text_bool }
+            { \l__chemformula_first_last_math_bool }
           }
           {
+            \chemformula_atom:
             \__chemformula_input_compound_no_check:Nn #1 {#2}
             \bool_if:NT \l__chemformula_options_bool
               {
@@ -2344,7 +2506,6 @@
                   {
                     % end group
                     \group_end:
-                    \tl_clear:N \l__chemformula_internal_options_tl
                   }
                 \bool_set_false:N \l__chemformula_options_bool
               }
@@ -2497,13 +2658,6 @@
     \__chemformula_if_only_parens:nTF {#2}
       { \tl_put_right:Nn #1 {#2} }
       {
-        % start with formatting:
-        \tl_put_right:Nn #1
-          {
-            \tl_use:N \l__chemformula_format_tl
-            \group_begin:
-              \l__chemformula_atom_format_tl
-          }
         \__chemformula_sanitize:Nn \l__chemformula_tmpa_tl {#2}
         % let's see if the compound starts with a sub- or superscript - if yes
         % this is an isotope:
@@ -2526,8 +2680,15 @@
                 \prop_get:NnNTF \l__chemformula_compound_prop
                   {##1}
                   \l__chemformula_tmpb_tl
-                  { \tl_put_right:NV #1 \l__chemformula_tmpb_tl }
-                  { \tl_put_right:Nn #1 {##1} }
+                  {
+                    \tl_put_right:NV #1
+                      \l__chemformula_tmpb_tl
+                  }
+                  {
+                    \token_if_letter:NTF ##1
+                      { \tl_put_right:Nn #1 {  ##1 } }
+                      { \tl_put_right:Nn #1 {##1} }
+                  }
               }
           }
         % if Kroeger-Vink notation is active:
@@ -2537,22 +2698,20 @@
               { \chemformula_prime: }
               { \chemformula_superscript:n { \chemformula_prime: } }
           }
-        % finish formatting:
-        \tl_put_right:Nn #1 { \group_end: }
       }
      \tl_clear:N \l__chemformula_tmpa_tl
   }
 \cs_generate_variant:Nn \__chemformula_input_compound_no_check:Nn {NV}
 
 % --------------------------------------------------------------------------
-% clean up chemmacros commands:
-\cs_new_protected:Npn \__chemformula_clean_chemmacros:n #1
+% clean up chemformula commands:
+\cs_new_protected:Npn \__chemformula_clean_chemformula:n #1
   {
-    \cs_set:Nn \chemmacros_text:n
+    \cs_set:Nn \chemformula_text:n
       { \mode_if_math:TF { \text {##1} } {##1} }
-    \cs_set:Npn \chemmacros_xspace: {}
+    \cs_set:Npn \chemformula_xspace: {}
   }
-\cs_generate_variant:Nn \__chemformula_clean_chemmacros:n {V}
+\cs_generate_variant:Nn \__chemformula_clean_chemformula:n {V}
 
 % --------------------------------------------------------------------------
 % input "and" sign
@@ -2733,11 +2892,11 @@
 % input arrow
 \cs_new_protected:Npn \__chemformula_input_arrow:n #1
   {
-    \bool_if:nT
+    \bool_lazy_all:nT
       {
-        \l__chemformula_is_arrow_bool &&
-        !\l__chemformula_first_last_text_bool &&
-        !\l__chemformula_first_last_math_bool
+        { \l__chemformula_is_arrow_bool }
+        { !\l__chemformula_first_last_text_bool }
+        { !\l__chemformula_first_last_math_bool }
       }
       {
         \__chemformula_generate_arrows:Nn \l__chemformula_tmpa_tl {#1}
@@ -2751,11 +2910,11 @@
 % input compound name
 \cs_new_protected:Npn \__chemformula_input_name:n #1
   {
-    \bool_if:nT
+    \bool_lazy_all:nT
       {
-        \l__chemformula_is_name_bool &&
-        !\l__chemformula_first_last_text_bool &&
-        !\l__chemformula_first_last_math_bool
+        { \l__chemformula_is_name_bool }
+        { !\l__chemformula_first_last_text_bool }
+        { !\l__chemformula_first_last_math_bool }
       }
       {
         \__chemformula_generate_name:Nn \l__chemformula_tmpa_tl {#1}
@@ -2961,25 +3120,24 @@
       \bool_set_false:N \l__chemformula_xfrac_bool
       \bool_set_true:N \l__chemformula_nicefrac_bool
       \bool_set_false:N \l__chemformula_mathfrac_bool ,
-    frac-math-cmd         .code:n     =
-      { \cs_set_eq:NN \chemformula_math_frac:nn #1 } ,
+    frac-math-cmd         .cs_set_protected:Np = \chemformula_math_frac:nn #1#2 ,
+    frac-math-cmd         .initial:n  = \frac {#1} {#2} ,
     stoich-paren-parse    .bool_set:N = \l__chemformula_stoich_parse_iupac_bool ,
     stoich-space          .skip_set:N = \l__chemformula_stoich_space_skip ,
+    stoich-format         .tl_set:N   = \l__chemformula_stoich_format_tl ,
     stoich-print          .code:n     =
-      \cs_set_eq:NN \chemformula_print_stoich:n #1 ,
+      \chemformula_remove_option:n {Use~ the~ option~ `stoich-format'~ instead.} ,
     adduct-space          .dim_set:N  = \l__chemformula_adduct_space_dim ,
     adduct-penalty        .tl_set:N   = \l__chemformula_adduct_penalty_tl ,
     math-space            .skip_set:N = \l__chemformula_math_space_skip ,
     name-format           .tl_set:N   = \l__chemformula_name_format_tl ,
     name-width            .code:n     =
-      {
-        \tl_if_eq:nnTF {#1} { auto }
-          { \bool_set_false:N \l__chemformula_name_width_bool }
-          {
-            \bool_set_true:N \l__chemformula_name_width_bool
-            \dim_set:Nn \l__chemformula_name_dim {#1}
-          }
-      } ,
+      \tl_if_eq:nnTF {#1} { auto }
+        { \bool_set_false:N \l__chemformula_name_width_bool }
+        {
+          \bool_set_true:N \l__chemformula_name_width_bool
+          \dim_set:Nn \l__chemformula_name_dim {#1}
+        } ,
     bond-length           .dim_set:N = \l__chemformula_bond_dim ,
     bond-offset           .dim_set:N = \l__chemformula_bond_space_dim ,
     bond-style            .code:n    =
@@ -3282,7 +3440,7 @@
 
 % --------------------------------------------------------------------------
 % hyperref support
-\hook_gput_code:nnn {package/after/hyperref} {chemformula}
+\hook_gput_code:nnn {package/hyperref/after} {chemformula}
   {
     \pdfstringdefDisableCommands
       {
@@ -3295,224 +3453,4 @@
   }
 
 \file_input_stop:
-
-% --------------------------------------------------------------------------
-VERSION HISTORY
-2012/01/28 - version 3.0   - bundled with packages `chemmacros' and `ghs'
-2012/01/30 - version 3.0a  - bugfix
-                           - renamed formula => chemformula
-                             (following a request by Karl Berry for TeXlive)
-2012/02/03 - version 3.0b  - stepped number with `chemmacros'
-2012/02/05 - version 3.0c  - stepped number with `chemmacros'
-2012/02/10 - version 3.0d  - several bugfixes
-                           - new arrow type <>
-2012/02/19 - version 3.1   - new arrow types -/>, </- and <o>
-                           - new commands \DeclareChemArrow, \RenewChemArrow and
-                             \ShowChemArrow
-2012/02/26 - version 3.1a  - stepped number with `chemmacros'
-2012/03/03 - version 3.1b  - arrow types are stored in a sequence to automate the
-                             search and replace in the right order 
-                           - new arrow type ==                                   
-                           - IUPAC compliance for stoichiometric factors
-                           - new handling of super- and subscripts to correct
-                             various flaws: clear distinction between isotope and
-                             formula
-                           - new option charge-vshift
-2012/03/14 - version 3.1c  - improved arrow labels
-2012/03/20 - version 3.2   - new: option input via @{<options>}
-2012/05/07 - version 3.3   - \ch now bypasses \ref{}, \label{}, and \intertext{}
-2012/05/13 - version 3.3a  - stepped number with `chemmacros'
-2012/05/18 - version 3.3b  - stepped number with `chemmacros'
-2012/05/18 - version 3.3c  - stepped number with `chemmacros'
-2012/07/24 - version 3.3d  - stepped number with `chemmacros'
-                           - default bond length set to 1.1667ex
-                           - bug fix in the bonds
-2012/08/21 - version 3.3e  - stepped number with `chemmacros'
-2012/09/11 - version 3.4   - cleaned a little, minor bug fixes
-                           - switched to internal scratch variables
-                           - new command \bond, more bond types
-                           - new commands \DeclareChemBond, \DeclareChemBondAlias,
-                             \RenewChemBond and \ShowChemBond
-                           - radical point thicker, new options `radical-style'
-                             and `radical-radius'
-2012/10/03 - version 3.4a  - stepped number with `chemmacros'
-2013/01/04 - version 3.4b  - bug fix in the sub- and superscript handling
-2013/01/28 - version 3.5   - disallow breaks at bonds
-                           - allow breaks after arrows
-                           - made some spaces in chemformulas stretch- and
-                             shrinkable
-                           - various internal code improvements
-                           - changed defaults for horizontal spaces that have in
-                             set in ex into corresponding values in em.
-                           - improvements to the placement of sub- and superscripts
-2013/02/19 - version 3.5a  - stepped number with `chemmacros'
-2013/02/26 - version 3.6   - support for use with the `breqn' package
-                           - math escaping also via \(\)
-                           - internal: clearer escaping macros
-                           - new options: `radical-vshift', `radical-hshift'
-                             and `radical-space'
-                           - bug fix: `radical-...' options are now correctly set
-                           - stoichiometric factors: add leading 0 if missing
-                           - new option: `stoich-paren-parse'
-                           - internal changes: be way more rigid about protected
-                             and expandable macros
-                           - internal changes: clearer distinction between
-                             private macros and accessable module macros
-                           - internal changes: clearer distinction between
-                             document commands and module level commands
-                           - !()() syntax now also works with babel's French
-2013/02/27 - version 3.6a  - bug fix: escaped text and math stays escaped, i.e.
-                             also arrow code like `<=>'
-2013/04/19 - version 3.6b  - new option `arrow-min-length'
-                           - bug fix: stoichiometric fractions correctly displayed
-2013/07/06 - version 4.0   - don't need `chemmacros' package any more,
-                             `chemformula' can be used stand-alone;
-                             this has lead to a few definitions that previously
-                             were done by chemmacros; chemmacros will get them
-                             now from chemformula when needed
-                           - bug fix: allow braces in subscripts and superscripts
-                             by disabling superfluous \chemformula_subscript:n
-                             and \chemformula_superscript:n in the scripts write
-                             commands
-                           - remove superfluous rescanning at the begin of the
-                             formula input; this is handled by the sanitize
-                             command later anyway
-                           - changed internal mathshifts from $ ... $ to \( ... \)
-                           - removed superfluous \textstyle from math-frac
-                             definition
-                           - new command \charrow{}[][] that allows direct
-                             access to chemformula's arrows
-                           - new command \chname()() that allows direct access
-                             to chemformula's naming
-                           - new command \chcpd[]{} that allows typesetting a
-                             simple single formula - also not nestable with \ch
-                           - new command \setchemformula
-                           - package option: `strict'
-                           - don't allow a line break before a plus
-                             (`chem-and')
-                           - don't allow a line break between a stoichiometric
-                             factor and a compound
-                           - changed formal charges to match ``plain'' charges
-2013/07/26 - version 4.0a  - added options `arrow-penalty' (0), `plus-penalty'
-                             (700) and `bond-penalty' (10000) that determine if
-                             there may be a break after an arrow, a bond or the
-                             plus
-2013/08/24 - version 4.1   - changed `0' values in TikZ coordinates into `0pt'
-                             see http://tex.stackexchange.com/q/128792/5049 and
-                             http://tex.stackexchange.com/q/118467/5049 for
-                             reference
-                           - new option `tikz-external-disable'
-                           - new option `frac-math-cmd'
-2013/10/24 - version 4.2   - \chemformula_font_inner: is only applied /once/ to
-                             a formula, and at the beginning, fixes
-                             https://bitbucket.org/cgnieder/chemmacros/issue/23
-                           - fixed wrong setting of the TikZ bond style
-                           - new option `arrow-style'
-                           - new command \chlewis
-2013/11/04 - version 4.2a  - bug fix in \chcpd,
-                           - change sanitizing/restoring of category codes
-2014/01/24 - version 4.3   - changed behaviour of \DeclareChem to match
-                             \DeclareRobustCommand, i.e., no check if command
-                             is defined; added a \NewChem variant to each that
-                             /does/ check; use \NewChem instead of \DeclareChem
-                             for definitions
-                           - new option stoich-print
-                           - new command \chstoich
-2014/01/29 - version 4.4   - treat a single `-' as a minus sign
-2014/04/07 - version 4.5   - make sure that < and > have catcode 12 when read
-                             as parts of arrows
-                           - new arrow types `>=<', `>=<<', `>>=<' and `<==>'
-                           - arrow lengths and compound offset now correctly
-                             adapts to new fontsize if relative lengths (em,ex)
-                             are used
-                           - allow optional arguments to \\ in equation
-                             environments
-                           - allow optional arguments to \label in equation
-                             environments
-                             (credits: http://tex.stackexchange.com/a/166661/5049)
-                           - support for Kröger-Vink notation
-2014/06/30 - version 4.6   - fix: a comma in a superscript is typeset according
-                             to `decimal-marker' again
-                           - fix charge type behaviour: option `circled' and
-                             `circletype' are now obeyed if the option is
-                             changed mid-document
-                           - new option `chemformula/circled' similar to
-                             `chemmacros/circled'
-                           - new option `chemformula/circletype' similar to
-                             `chemmacros/circletype'
-2014/08/04 - version 4.7   - change dependency: pgf library `arrows.meta'
-                             instead of `arrows'
-                           - new arrow tip definition allows redeclaration to
-                             other existing tips by \pgfkeys{cf/.tip=<tip>}
-2014/08/08 - version 4.8   - fix bug introduced in last update: `butt cap' now
-                             needs to be `Butt Cap' with the new `arrows.meta'
-                             library
-                           - split from `chemmacros' bundle as independent
-                             package
-2014/10/07 - version 4.9   - new options: `minus-space', `minus-penalty',
-                             `plus-output-symbol' and `minus-output-symbol'
-2015/03/16 - version 4.10  - new macros \NewChemCompoundProperty,
-                             \RenewChemCompoundProperty,
-                             \DeclareChemCompoundProperty,
-                             \RemoveChemCompoundProperty
-2015/04/03 - version 4.10a - bug fix in \__chemformula_input_stoich:n
-2015/06/30 - version 4.11  - small changes in \chcpd
-                           - remove unnecessary \mathchoice => noticable speed
-                             improvement
-                           - \NewChemAdditionSymbol
-                           - \NewChemSymbol
-2015/08/12 - version 4.12  - remove chemmacros' `circletype' and `circled'
-                             options. They really belong to chemmacros
-                           - change requirement amsmath -> amstext
-                           - shorten definition of double and triple bonds
-2015/08/29 - version 4.12a - \chemformula_formal_plus: ,
-                             \chemformula_formal_minus:
-                             \ProvideChem... equivalents to all \NewChem...
-                             macros 
-2015/09/08 - version 4.12b - trim spaces of \ch input -- due to a change in
-                             l3kernel
-2015/01/01 - version 4.13  - clean up code
-                           - check for blank input
-                           - drop support for \[ and \]
-                           - new option `atom-format'
-2015/10/21 - version 4.14  - fix issue
-                             https://github.com/cgnieder/chemformula/issues/2
-                           - new option `adduct-penalty'
-2016/01/07 - version 4.14a - \prop_get:Nn => \prop_item:Nn
-2016/05/03 - version 4.14b - local options now are correctly working again
-                           - `atom-format' is only applied to formulas
-2016/05/11 - version 4.15  - arrow definitions don't have to be made in a
-                             certain order any more
-                           - new quasi equilibria arrows
-                           - bug fix in \RenewChemArrow
-                           - meaningful error if \charrow if used with an
-                             unknown arrow type
-2016/06/08 - version 4.15a - change requirement amstext -> amsmath; \chname
-                             uses \underset which needs amsmath
-2016/06/08 - version 4.15b - add missing variant of kernel function
-2016/08/21 - version 4.15c - corrected redundant definition of
-                             \chemformula_single_bond:
-                           - fix problem with TikZ externalization and
-                             Kroeger-Vink notation
-2017/02/02 - version 4.15d - allow `name-format' to end with a macro that
-                             takes an argument
-2017/03/23 - version 4.15e - small bug fix (issue #5)
-                           - implement \shortintertext bypass
-2019/09/23 - version 4.15f - add missing definition for temporary variable
-2019/09/27 - version 4.15g - bug fix in fontspec option
-2019/10/13 - version 4.15h - new (undocumented) option `set-catcodes'
-                           - fix behaviour with category codes
-                             (https://tex.stackexchange.com/q/511592/)
-                           - fix bug: local format changes are now applied
-                             again
-2020/02/01 - version 4.15i - fix issue #12
-2020/03/07 - version 4.15j - make sure that < and > have catcode 12 when read
-                             as arrows -- again...
-2020/03/15 - version 4.15k - fix https://tex.stackexchange.com/questions/532674/
-2020/12/22 - version 4.16  - new option `math-scripts'
-                           - use LaTeX's new hooks
-                           - get rid of unnecessary package dependencies
-
 % --------------------------------------------------------------------------
-% IDEAS:
-- Addukte: Zahlen nach * und . automatisch erkennen?
-- 
cgit v1.2.3

