From ac104eaa206f6b98631a2ef18bfdb0afb494bb9c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 30 Dec 2021 10:26:37 +0100
Subject: [PATCH v7 7/7] WIP: Underscores in numeric literals

Discussion: https://www.postgresql.org/message-id/flat/b239564c-cad0-b23e-c57e-166d883cb97d@enterprisedb.com
---
 src/backend/parser/Makefile              |  2 +-
 src/backend/parser/scan.l                | 26 +++++++++++++++---
 src/test/regress/expected/numerology.out | 34 +++++++++++++++++++++---
 src/test/regress/sql/numerology.sql      |  7 ++++-
 4 files changed, 59 insertions(+), 10 deletions(-)

diff --git a/src/backend/parser/Makefile b/src/backend/parser/Makefile
index 5ddb9a92f0..827bc4c189 100644
--- a/src/backend/parser/Makefile
+++ b/src/backend/parser/Makefile
@@ -56,7 +56,7 @@ gram.c: BISON_CHECK_CMD = $(PERL) $(srcdir)/check_keywords.pl $< $(top_srcdir)/s
 
 
 scan.c: FLEXFLAGS = -CF -p -p
-scan.c: FLEX_NO_BACKUP=yes
+#scan.c: FLEX_NO_BACKUP=yes
 scan.c: FLEX_FIX_WARNING=yes
 
 
diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index 2e1aa62d81..5b574c4233 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -395,10 +395,10 @@ hexdigit		[0-9A-Fa-f]
 octdigit		[0-7]
 bindigit		[0-1]
 
-decinteger		{decdigit}+
-hexinteger		0[xX]{hexdigit}+
-octinteger		0[oO]{octdigit}+
-bininteger		0[bB]{bindigit}+
+decinteger		{decdigit}(_?{decdigit})*
+hexinteger		0[xX](_?{hexdigit})+
+octinteger		0[oO](_?{octdigit})+
+bininteger		0[bB](_?{bindigit})+
 
 hexfail			0[xX]
 octfail			0[oO]
@@ -1372,6 +1372,24 @@ process_integer_literal(const char *token, YYSTYPE *lval, int base)
 	int			val;
 	char	   *endptr;
 
+	if (strchr(token, '_'))
+	{
+		char	   *newtoken = palloc(strlen(token));
+		const char *p1;
+		char	   *p2;
+
+		p1 = token;
+		p2 = newtoken;
+		while (*p1)
+		{
+			if (*p1 != '_')
+				*p2++ = *p1;
+			p1++;
+		}
+		*p2 = '\0';
+		token = newtoken;
+	}
+
 	errno = 0;
 	val = strtoint(token, &endptr, base);
 	if (*endptr != '\0' || errno == ERANGE)
diff --git a/src/test/regress/expected/numerology.out b/src/test/regress/expected/numerology.out
index d95b24c7b3..7289a325fc 100644
--- a/src/test/regress/expected/numerology.out
+++ b/src/test/regress/expected/numerology.out
@@ -23,6 +23,36 @@ SELECT 0x42F;
      1071
 (1 row)
 
+SELECT 1_000_000;
+ ?column? 
+----------
+  1000000
+(1 row)
+
+SELECT 1_2_3;
+ ?column? 
+----------
+      123
+(1 row)
+
+SELECT 0x1EEE_FFFF;
+ ?column?  
+-----------
+ 518979583
+(1 row)
+
+SELECT 0o2_73;
+ ?column? 
+----------
+      187
+(1 row)
+
+SELECT 0b_10_0101;
+ ?column? 
+----------
+       37
+(1 row)
+
 -- error cases
 SELECT 123abc;
 ERROR:  trailing junk after numeric literal at or near "123a"
@@ -32,10 +62,6 @@ SELECT 0x0o;
 ERROR:  trailing junk after numeric literal at or near "0x0o"
 LINE 1: SELECT 0x0o;
                ^
-SELECT 1_2_3;
-ERROR:  trailing junk after numeric literal at or near "1_"
-LINE 1: SELECT 1_2_3;
-               ^
 SELECT 0.a;
 ERROR:  trailing junk after numeric literal at or near "0.a"
 LINE 1: SELECT 0.a;
diff --git a/src/test/regress/sql/numerology.sql b/src/test/regress/sql/numerology.sql
index 0e12bcc7b7..f35ff31d9a 100644
--- a/src/test/regress/sql/numerology.sql
+++ b/src/test/regress/sql/numerology.sql
@@ -12,10 +12,15 @@
 SELECT 0o273;
 SELECT 0x42F;
 
+SELECT 1_000_000;
+SELECT 1_2_3;
+SELECT 0x1EEE_FFFF;
+SELECT 0o2_73;
+SELECT 0b_10_0101;
+
 -- error cases
 SELECT 123abc;
 SELECT 0x0o;
-SELECT 1_2_3;
 SELECT 0.a;
 SELECT 0.0a;
 SELECT .0a;
-- 
2.34.1