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[PATCH 7/6] userdiff-cpp: back out the digit-separators in numbers

From
Johannes Sixt <j6t@kdbg.org>
Date
Oct 24, 2021, 09:56 UTC
Message-ID
<a5a05e33-3ad9-e78c-69c0-a466eadeffec@kdbg.org>
In-Reply-To
<pull.1054.v3.git.1633885384.gitgitgadget@gmail.com>

The implementation of digit-separating single-quotes introduced a note-worthy regression: the change of a character literal with a digit would splice the digit and the closing single-quote. For example, the change from 'a' to '2' is now tokenized as '[-a'-]{+2'+} instead of '[-a-]{+2+}'.

The options to fix the regression are:
- Tighten the regular expression such that the single-quote can only
  occur between digits (that would match the official syntax).
- Remove support for digit separators.
I chose to remove support, because
- I have not seen a lot of code make use of digit separators.
- If code does use digit separators, then the numbers are typically
  long. If a change in one of the segments occurs, it is actually
  better visible if only that segment is highlighted as the word
  that changed instead of the whole long number.

This choice does introduce another minor regression, though, which is highlighted in the test case: when a change occurs in the second or later segment of a hexadecimal number where the segment begins with a digit, but also has letters, the segment is mistaken as consisting of a number and an identifier. I can live with that.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
 t/t4034/cpp/expect | 12 ++++++------
 t/t4034/cpp/post   | 10 +++++-----
 t/t4034/cpp/pre    |  8 ++++----
 userdiff.c         |  6 +++---
 4 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/t/t4034/cpp/expect b/t/t4034/cpp/expect
index 5ff4ce477b..dc500ae092 100644
--- a/t/t4034/cpp/expect
+++ b/t/t4034/cpp/expect
@@ -1,21 +1,21 @@
 <BOLD>diff --git a/pre b/post<RESET>
-<BOLD>index 144cd98..64e78af 100644<RESET>
+<BOLD>index a1a09b7..f1b6f3c 100644<RESET>
 <BOLD>--- a/pre<RESET>
 <BOLD>+++ b/post<RESET>
 <CYAN>@@ -1,30 +1,30 @@<RESET>
 Foo() : x(0<RED>&&1<RESET><GREEN>&42<RESET>) { <RED>foo0<RESET><GREEN>bar<RESET>(x.<RED>find<RESET><GREEN>Find<RESET>); }
 cout<<"Hello World<RED>!<RESET><GREEN>?<RESET>\n"<<endl;
-<GREEN>(<RESET>1 <RED>-<RESET><GREEN>+<RESET>1e10 0xabcdef<GREEN>)<RESET> '<RED>x<RESET><GREEN>.<RESET>'
+<GREEN>(<RESET>1 <RED>-<RESET><GREEN>+<RESET>1e10 0xabcdef<GREEN>)<RESET> '<RED>x<RESET><GREEN>2<RESET>'
 // long double<RESET>
-<RED>3.141'592'653e-10l<RESET><GREEN>3.141'592'654e+10l<RESET>
+<RED>3.141592653e-10l<RESET><GREEN>3.141592654e+10l<RESET>
 // float<RESET>
 <RED>120E5f<RESET><GREEN>120E6f<RESET>
 // hex<RESET>
-<RED>0xdead'beaf<RESET><GREEN>0xdead'Beaf<RESET>+<RED>8ULL<RESET><GREEN>7ULL<RESET>
+<RED>0xdead<RESET><GREEN>0xdeaf<RESET>'1<RED>eaF<RESET><GREEN>eaf<RESET>+<RED>8ULL<RESET><GREEN>7ULL<RESET>
 // octal<RESET>
-<RED>0123'4567<RESET><GREEN>0123'4560<RESET>
+<RED>01234567<RESET><GREEN>01234560<RESET>
 // binary<RESET>
-<RED>0b10'00<RESET><GREEN>0b11'00<RESET>+e1
+<RED>0b1000<RESET><GREEN>0b1100<RESET>+e1
 // expression<RESET>
 1.5-e+<RED>2<RESET><GREEN>3<RESET>+f
 // another one<RESET>
diff --git a/t/t4034/cpp/post b/t/t4034/cpp/post
index 64e78afbfb..f1b6f3c228 100644
--- a/t/t4034/cpp/post
+++ b/t/t4034/cpp/post
@@ -1,16 +1,16 @@
 Foo() : x(0&42) { bar(x.Find); }
 cout<<"Hello World?\n"<<endl;
-(1 +1e10 0xabcdef) '.'
+(1 +1e10 0xabcdef) '2'
 // long double
-3.141'592'654e+10l
+3.141592654e+10l
 // float
 120E6f
 // hex
-0xdead'Beaf+7ULL
+0xdeaf'1eaf+7ULL
 // octal
-0123'4560
+01234560
 // binary
-0b11'00+e1
+0b1100+e1
 // expression
 1.5-e+3+f
 // another one
diff --git a/t/t4034/cpp/pre b/t/t4034/cpp/pre
index 144cd980d6..a1a09b7712 100644
--- a/t/t4034/cpp/pre
+++ b/t/t4034/cpp/pre
@@ -2,15 +2,15 @@ Foo():x(0&&1){ foo0( x.find); }
 cout<<"Hello World!\n"<<endl;
 1 -1e10 0xabcdef 'x'
 // long double
-3.141'592'653e-10l
+3.141592653e-10l
 // float
 120E5f
 // hex
-0xdead'beaf+8ULL
+0xdead'1eaF+8ULL
 // octal
-0123'4567
+01234567
 // binary
-0b10'00+e1
+0b1000+e1
 // expression
 1.5-e+2+f
 // another one
diff --git a/userdiff.c b/userdiff.c
index 7b143ef36b..8578cb0d12 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -67,11 +67,11 @@
 	 /* identifiers and keywords */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 /* decimal and octal integers as well as floatingpoint numbers */
-	 "|[0-9][0-9.']*([Ee][-+]?[0-9]+)?[fFlLuU]*"
+	 "|[0-9][0-9.]*([Ee][-+]?[0-9]+)?[fFlLuU]*"
 	 /* hexadecimal and binary integers */
-	 "|0[xXbB][0-9a-fA-F']+[lLuU]*"
+	 "|0[xXbB][0-9a-fA-F]+[lLuU]*"
 	 /* floatingpoint numbers that begin with a decimal point */
-	 "|\\.[0-9][0-9']*([Ee][-+]?[0-9]+)?[fFlL]?"
+	 "|\\.[0-9][0-9]*([Ee][-+]?[0-9]+)?[fFlL]?"
 	 "|[-+*/<>%&^|=!]=|--|\\+\\+|<<=?|>>=?|&&|\\|\\||::|->\\*?|\\.\\*|<=>"),
 PATTERNS("csharp",
 	 /* Keywords */

-- 
2.33.0.129.g739793498e
Previous: Johannes Sixt via GitGitGadget
Message 24 of 24 in “Fun with cpp word regex”
  1. 0/3 Fun with cpp word regexJohannes Sixt via GitGitGadget, Oct 7, 2021
  2. 1/3 userdiff: tighten cpp word regexJohannes Sixt via GitGitGadget, Oct 7, 2021
  3. 2/3 userdiff: permit the digit-separating single-quote in numbersJohannes Sixt via GitGitGadget, Oct 7, 2021
  4. 3/3 userdiff: learn the C++ spaceship operatorJohannes Sixt via GitGitGadget, Oct 7, 2021
  5. Ævar Arnfjörð BjarmasonOct 7, 2021
  6. Johannes SixtOct 7, 2021
  7. 0/5 Fun with cpp word regexJohannes Sixt via GitGitGadget, Oct 8, 2021
  8. 1/5 t4034/cpp: actually test that operator tokens are not splitJohannes Sixt via GitGitGadget, Oct 8, 2021
  9. 2/5 t4034: add tests showing problematic cpp tokenizationsJohannes Sixt via GitGitGadget, Oct 8, 2021
  10. 3/5 userdiff-cpp: tighten word regexJohannes Sixt via GitGitGadget, Oct 8, 2021
  11. 4/5 userdiff-cpp: permit the digit-separating single-quote in numbersJohannes Sixt via GitGitGadget, Oct 8, 2021
  12. 5/5 userdiff-cpp: learn the C++ spaceship operatorJohannes Sixt via GitGitGadget, Oct 8, 2021
  13. Ævar Arnfjörð BjarmasonOct 8, 2021
  14. Johannes SixtOct 8, 2021
  15. Ævar Arnfjörð BjarmasonOct 9, 2021
  16. Johannes SixtOct 10, 2021
  17. 0/6 Fun with cpp word regexJohannes Sixt via GitGitGadget, Oct 10, 2021
  18. 1/6 t4034/cpp: actually test that operator tokens are not splitJohannes Sixt via GitGitGadget, Oct 10, 2021
  19. 2/6 t4034: add tests showing problematic cpp tokenizationsJohannes Sixt via GitGitGadget, Oct 10, 2021
  20. 4/6 userdiff-cpp: prepare test cases with yet unsupported featuresJohannes Sixt via GitGitGadget, Oct 10, 2021
  21. 3/6 userdiff-cpp: tighten word regexJohannes Sixt via GitGitGadget, Oct 10, 2021
  22. 5/6 userdiff-cpp: permit the digit-separating single-quote in numbersJohannes Sixt via GitGitGadget, Oct 10, 2021
  23. 6/6 userdiff-cpp: learn the C++ spaceship operatorJohannes Sixt via GitGitGadget, Oct 10, 2021
  24. 7/6 userdiff-cpp: back out the digit-separators in numbersJohannes Sixt, Oct 24, 2021

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