lua-widow-control (9nov21)

git-svn-id: svn://tug.org/texlive/trunk@61002 c570f23f-e606-0410-a88d-b1316a301751

4 files changed, 142 insertions, 14 deletions

diff --git a/Master/texmf-dist/tex/context/third/lua-widow-control/t-lua-widow-control.mkxl b/Master/texmf-dist/tex/context/third/lua-widow-control/t-lua-widow-control.mkxl
index 66eeadec579..62d091aea6c 100644
--- a/Master/texmf-dist/tex/context/third/lua-widow-control/t-lua-widow-control.mkxl
+++ b/Master/texmf-dist/tex/context/third/lua-widow-control/t-lua-widow-control.mkxl
@@ -1,11 +1,11 @@
 %D \module
 %D   [     file=t-lua-widow-control,
-%D      version=1.0.0, %%version
+%D      version=1.1.0, %%version
 %D        title=lua-widow-control,
 %D     subtitle=\ConTeXt module for lua-widow-control,
-%D       author=gucci-on-fleek,
-%D         date=2021-10-09, %%date
-%D    copyright=gucci-on-fleek,
+%D       author=Max Chernoff,
+%D         date=2021-11-08, %%date
+%D    copyright=Max Chernoff,
 %D      license=MPL-2.0+,
 %D          url=https://github.com/gucci-on-fleek/lua-widow-control]
 \startmodule[lua-widow-control]
@@ -28,6 +28,8 @@
     }
 \to\everysetuplwc
 
+\define\iflwc{\ctxlua{lwc.if_lwc_enabled()}}
+
 \ctxloadluafile{lua-widow-control}
 
 \setuplwc[emergencystretch=3em, \c!state=\v!start]
@@ -50,5 +52,22 @@
 \definefontfeature[default][default][expansion=quality]
 \setupalign[hz]
 
+% Expansion of some parts of the document, such as section headings, is quite
+% undesirable, so we'll disable \lwc/ for certain commands.
+% We should only reenable \lwc/ at the end if it was already enabled.
+\newif\iflwc@should@reenable
+
+\define\lwc@patch@pre{\iflwc%
+    \lwc@should@reenabletrue%
+    \setuplwc[state=stop]%
+\fi}
+
+\define\lwc@patch@post{\iflwc@should@reenable%
+    \setuplwc[state=start]%
+\fi}
+
+\prependtoks\lwc@patch@pre\to\everybeforesectionheadhandle % Sectioning
+\prependtoks\lwc@patch@post\to\everyaftersectionheadhandle
+
 \protect
 \stopmodule
diff --git a/Master/texmf-dist/tex/lualatex/lua-widow-control/lua-widow-control.sty b/Master/texmf-dist/tex/lualatex/lua-widow-control/lua-widow-control.sty
index d5ef8194f1b..ff3781944fa 100644
--- a/Master/texmf-dist/tex/lualatex/lua-widow-control/lua-widow-control.sty
+++ b/Master/texmf-dist/tex/lualatex/lua-widow-control/lua-widow-control.sty
@@ -1,11 +1,11 @@
 % lua-widow-control
 % https://github.com/gucci-on-fleek/lua-widow-control
 % SPDX-License-Identifier: MPL-2.0+
-% SPDX-FileCopyrightText: 2021 gucci-on-fleek
+% SPDX-FileCopyrightText: 2021 Max Chernoff
 
 \NeedsTeXFormat{LaTeX2e}[2015/01/01] % Formats built after 2015 include \LuaTeX{}Base
 \ProvidesPackage{lua-widow-control}%
-    [2021/10/09 v1.0.0] %%version %%date
+    [2021/11/08 v1.1.0] %%version %%date
 
 \setlength{\clubpenalty}{1}
 \setlength{\widowpenalty}{1}
@@ -24,10 +24,42 @@
 % lengthened paragraphs to not have terrible spacing. 
 \RequirePackage[final]{microtype}
 
+% Define \TeX{} wrappers for Lua functions
 \newcommand{\lwcenable}{\directlua{lwc.enable_callbacks()}}
 \newcommand{\lwcdisable}{\directlua{lwc.disable_callbacks()}}
+\newcommand{\iflwc}{\directlua{lwc.if_lwc_enabled()}}
 
 % Enable \lwc/ by default when the package is loaded.
 \lwcenable
 
+% Expansion of some parts of the document, such as section headings, is quite
+% undesirable, so we'll disable \lwc/ for certain commands.
+\RequirePackage{etoolbox}
+
+\newcommand{\lwc@patch@warning}[1]{\PackageWarning{lua-widow-control}{%
+    Patching the \protect#1 command failed%
+}}
+
+% We should only reenable \lwc/ at the end if it was already enabled.
+\newif\iflwc@should@reenable
+
+\newcommand{\lwc@patch@pre}{\iflwc%
+    \lwc@should@reenabletrue%
+    \lwcdisable%
+\fi}
+
+\newcommand{\lwc@patch@post}{\iflwc@should@reenable%
+    \lwcenable%
+\fi}
+
+\newcommand{\lwcdisablecmd}[1]{%
+    \ifdefined#1
+        \pretocmd{#1}{\lwc@patch@pre}{}{\lwc@patch@warning{#1}}%
+        \apptocmd{#1}{\lwc@patch@post}{}{\lwc@patch@warning{#1}}%
+    \fi
+}
+
+\lwcdisablecmd{\@sect} % Sectioning
+
+
 \endinput
diff --git a/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.lua b/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.lua
index a85793d3a9e..62f1867b62d 100644
--- a/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.lua
+++ b/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.lua
@@ -2,7 +2,7 @@
     lua-widow-control
     https://github.com/gucci-on-fleek/lua-widow-control
     SPDX-License-Identifier: MPL-2.0+
-    SPDX-FileCopyrightText: 2021 gucci-on-fleek
+    SPDX-FileCopyrightText: 2021 Max Chernoff
   ]]
 
 lwc = {}
@@ -34,6 +34,7 @@ local glue_id = node.id("glue")
 local set_attribute = node.set_attribute
 local has_attribute = node.has_attribute
 local flush_list = node.flush_list or node.flushlist
+local free = node.free
 local min_col_width = tex.sp("25em")
 local maxdimen = 1073741823 -- \\maxdimen in sp
 
@@ -63,8 +64,8 @@ if lwc.context then
 elseif lwc.plain or lwc.latex then
     luatexbase.provides_module {
         name = lwc.name,
-        date = "2021/10/09", --%%date
-        version = "1.0.0", --%%version
+        date = "2021/11/08", --%%date
+        version = "1.1.0", --%%version
         description = [[
 
     This module provides a LuaTeX-based solution to prevent
@@ -77,7 +78,11 @@ elseif lwc.plain or lwc.latex then
     lwc.attribute = luatexbase.new_attribute(lwc.name)
     lwc.contrib_head = 'contrib_head' -- For \LuaTeX{}
 else -- uh oh
-    error("Unsupported format. Please use (Lua)LaTeX, Plain (Lua)TeX, or ConTeXt (MKXL/LMTX)")
+    error [[
+        Unsupported format.
+
+        Please use (Lua)LaTeX, Plain (Lua)TeX, or ConTeXt (MKXL/LMTX)
+    ]]
 end
 
 lwc.paragraphs = {} -- List to hold the alternate paragraph versions
@@ -163,7 +168,7 @@ function lwc.save_paragraphs(head)
     local parfillskip = last(new_head)
     if parfillskip.id == glue_id and tex.hsize > min_col_width then
             parfillskip.stretch_order = 0
-            parfillskip.stretch = 0.9 * tex.hsize -- Last line must be at least 10% long
+            parfillskip.stretch = 0.8 * tex.hsize -- Last line must be at least 20% long
     end
 
     -- Break the paragraph 1 line longer than natural
@@ -211,6 +216,31 @@ function lwc.mark_paragraphs(head)
 end
 
 
+--- A "safe" version of the last/slide function.
+---
+--- Sometimes the node list can form a loop. Since there is no last element
+--- of a looped linked-list, the `last()` function will never terminate. This
+--- function provides a "safe" version of the `last()` function that returns
+--- `nil` if the list is circular.
+local function safe_last(head)
+    local ids = {}
+
+    while head.next do
+        local id = node.is_node(head) -- Returns the internal node id
+
+        if ids[id] then
+            lwc.warning("Circular node list detected!")
+            return nil
+        end
+
+        ids[id] = true
+        head = head.next
+    end
+
+    return head
+end
+
+
 --- Remove the widows and orphans from the page, just after the output routine.
 ---
 --- This function holds the "meat" of the module. It is called just after the
@@ -264,7 +294,16 @@ function lwc.remove_widows(head)
     while head do
         -- Insert the start of the replacement paragraph
         if has_attribute(head, lwc.attribute, paragraph_index) then
+            local current = head
             head.prev.next = target_node
+
+            -- Abort if we've created a loop
+            if not safe_last(target_node) then
+                head.prev.next = current
+                lwc.warning("Widow/Orphan NOT removed!")
+                break
+            end
+
             clear_flag = true
         end
 
@@ -286,7 +325,7 @@ function lwc.remove_widows(head)
         end
 
         if clear_flag then
-            head = node.free(head)
+            head = free(head)
         else
             head = head.next
         end
@@ -359,5 +398,13 @@ function lwc.disable_callbacks()
     end
 end
 
+function lwc.if_lwc_enabled()
+    if enabled then
+        tex.sprint("\\iftrue")
+    else
+        tex.sprint("\\iffalse")
+    end
+end
+
 
 return lwc
diff --git a/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.tex b/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.tex
index fc10ff0ebb6..904ee03c69f 100644
--- a/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.tex
+++ b/Master/texmf-dist/tex/luatex/lua-widow-control/lua-widow-control.tex
@@ -1,9 +1,9 @@
 % lua-widow-control
 % https://github.com/gucci-on-fleek/lua-widow-control
 % SPDX-License-Identifier: MPL-2.0+
-% SPDX-FileCopyrightText: 2021 gucci-on-fleek
+% SPDX-FileCopyrightText: 2021 Max Chernoff
 
-\wlog{lua-widow-control v1.0.0} %%version
+\wlog{lua-widow-control v1.1.0} %%version
 
 \input ltluatex % \LuaTeX{}Base
 
@@ -24,10 +24,40 @@
 \expandglyphsinfont\the\font 20 20 5
 \adjustspacing=2
 
+% Define \TeX{} wrappers for Lua functions
 \def\lwcenable{\directlua{lwc.enable_callbacks()}}
 \def\lwcdisable{\directlua{lwc.disable_callbacks()}}
+\def\iflwc{\directlua{lwc.if_lwc_enabled()}}
 
 % Enable \lwc/ by default when the package is loaded.
 \lwcenable
 
+% Expansion of some parts of the document, such as section headings, is quite
+% undesirable, so we'll disable \lwc/ for certain commands.
+\catcode`@=11
+
+% We should only reenable \lwc/ at the end if it was already enabled.
+\newif\iflwc@should@reenable
+
+\def\lwc@patch@pre{\iflwc%
+    \lwc@should@reenabletrue%
+    \lwcdisable%
+\fi}
+
+\def\lwc@patch@post{\iflwc@should@reenable%
+    \lwcenable%
+\fi}
+
+\def\lwcdisablecmd#1{%
+    \ifdefined#1
+        \expandafter\def\expandafter#1\expandafter{\lwc@patch@pre #1\lwc@patch@post}
+    \fi
+}
+\catcode`@=12
+
+\begingroup
+    \suppressoutererror=1
+    \lwcdisablecmd{\beginsection} % Sectioning
+\endgroup
+
 \endinput