From c2cdaa56611c76c905c2368bee53c7bf8e7f8428 Mon Sep 17 00:00:00 2001
From: Julian Weigt <juw@posteo.de>
Date: Sat, 6 Nov 2021 17:31:28 +0200
Subject: [PATCH 1/3] sanitizing more possible input schemata of frac

---
 latexdiff | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/latexdiff b/latexdiff
index a7a27da..7f93773 100755
--- a/latexdiff
+++ b/latexdiff
@@ -2570,11 +2570,12 @@ sub take_comments_and_newline_from_frac() {
   # some special magic for common usage of frac, which does not conform to the latexdiff requirements but can be made to fit
   # note that this is a rare exception to the general rule that the new tex can be reconstructed from the diff file
 
-  # \frac12 -> \frac{1}{2}
-  s/\\frac(\d)(\w)/\\frac\{$1\}\{$2\}/g;
-
-  # \frac1{2b} -> \frac{1}{2b}
-  s/\\frac(\d)/\\frac\{$1\}/g;
+  # \frac1 -> \frac{1}
+  # \frac a -> \frac{a}
+  # \frac \lambda -> \frac{\lambda}
+  s/\\frac(?:\s*(\d)|\s+(\w)|\s*(\\[a-zA-Z]+))/\\frac\{$1$2$3\}/g;
+  # same as above for the second argument of frac
+  s/\\frac(\{$pat_n\})(?:\s*(\d)|\s+(\w)|\s*(\\[a-zA-Z]+))/\\frac$1\{$2$3$4\}/g;
 
   # delete space and comment characters between \frac arguments
 #  s/\\frac(?:\s*?%[^\n]*?)*?(\{$pat_n\})\s*(\{$pat_n\})/\\frac$1$2/g;

From f7ee1d57770911270bf87f506ce170fe841c9e90 Mon Sep 17 00:00:00 2001
From: Julian Weigt <juw@posteo.de>
Date: Sat, 6 Nov 2021 20:21:35 +0200
Subject: [PATCH 2/3] make frac sanitization work for comments plus newlines
 too

---
 latexdiff | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/latexdiff b/latexdiff
index 7f93773..01c5684 100755
--- a/latexdiff
+++ b/latexdiff
@@ -2570,16 +2570,15 @@ sub take_comments_and_newline_from_frac() {
   # some special magic for common usage of frac, which does not conform to the latexdiff requirements but can be made to fit
   # note that this is a rare exception to the general rule that the new tex can be reconstructed from the diff file
 
+  # regex that matches space and comment characters
+  my $space = qr/\s|%[^\n]*?/;
+  # \frac {abc} -> \frac{abc}
   # \frac1 -> \frac{1}
   # \frac a -> \frac{a}
   # \frac \lambda -> \frac{\lambda}
-  s/\\frac(?:\s*(\d)|\s+(\w)|\s*(\\[a-zA-Z]+))/\\frac\{$1$2$3\}/g;
+  s/\\frac(?:${space}+\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac\{$1$2$3$4\}/g;
   # same as above for the second argument of frac
-  s/\\frac(\{$pat_n\})(?:\s*(\d)|\s+(\w)|\s*(\\[a-zA-Z]+))/\\frac$1\{$2$3$4\}/g;
-
-  # delete space and comment characters between \frac arguments
-#  s/\\frac(?:\s*?%[^\n]*?)*?(\{$pat_n\})\s*(\{$pat_n\})/\\frac$1$2/g;
-  s/\\frac(?:\s|%[^\n]*?)*(\{$pat_n\})(?:\s|%[^\n]*?)*(\{$pat_n\})/\\frac$1$2/g;
+  s/\\frac(\{$pat_n\})(?:${space}*\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac$1\{$2$3$4$5\}/g;
 }
 
 # preprocess($string, ..)

From 1c9dc55b1d3ee772f73009963ac3b60ac752ff0a Mon Sep 17 00:00:00 2001
From: Julian Weigt <juw@posteo.de>
Date: Mon, 8 Nov 2021 13:35:32 +0200
Subject: [PATCH 3/3] fix uninitialized value warning

---
 latexdiff | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/latexdiff b/latexdiff
index 01c5684..b365c9c 100755
--- a/latexdiff
+++ b/latexdiff
@@ -2576,9 +2576,9 @@ sub take_comments_and_newline_from_frac() {
   # \frac1 -> \frac{1}
   # \frac a -> \frac{a}
   # \frac \lambda -> \frac{\lambda}
-  s/\\frac(?:${space}+\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac\{$1$2$3$4\}/g;
+  s/\\frac(?|${space}+\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac\{$1\}/g;
   # same as above for the second argument of frac
-  s/\\frac(\{$pat_n\})(?:${space}*\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac$1\{$2$3$4$5\}/g;
+  s/\\frac(\{$pat_n\})(?|${space}*\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac$1\{$2\}/g;
 }
 
 # preprocess($string, ..)