From 6a64e915b7f1c60e2465038a5c081c78a09a6bf0 Mon Sep 17 00:00:00 2001
From: Chapman Flack <chap@anastigmatix.net>
Date: Mon, 4 Sep 2023 21:29:57 -0400
Subject: [PATCH] Improve NEWLINE pattern

Old one could fail depending on previous matching activity, possibly
because of the use of \G (which I should have explained better in a
comment, back when I thought I knew why I was doing it). The documented
behavior of ^ $ and \z and reluctant quantifiers make for a simpler
and more dependable version.

Addresses issue #455.
---
 .../org/postgresql/pljava/sqlgen/Lexicals.java |  2 +-
 pljava-api/src/test/java/LexicalsTest.java     | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/pljava-api/src/main/java/org/postgresql/pljava/sqlgen/Lexicals.java b/pljava-api/src/main/java/org/postgresql/pljava/sqlgen/Lexicals.java
index 85bdc66bc..1b6e014a0 100644
--- a/pljava-api/src/main/java/org/postgresql/pljava/sqlgen/Lexicals.java
+++ b/pljava-api/src/main/java/org/postgresql/pljava/sqlgen/Lexicals.java
@@ -279,7 +279,7 @@ private Lexicals() { } // do not instantiate
 	 * engine, letting it handle the details.
 	 */
 	public static final Pattern NEWLINE = Pattern.compile(
-		"(?ms:$(?:(?<!^).|(?<=\\G).){1,2}+)"
+		"(?ms:$.{1,2}?(?:^|\\z))" // fewest of 1,2 chars between $ and ^ (or \z)
 	);
 
 	/** White space <em>except</em> newline, for any Java-recognized newline.
diff --git a/pljava-api/src/test/java/LexicalsTest.java b/pljava-api/src/test/java/LexicalsTest.java
index 174258115..89b94d07f 100644
--- a/pljava-api/src/test/java/LexicalsTest.java
+++ b/pljava-api/src/test/java/LexicalsTest.java
@@ -29,6 +29,8 @@
 
 import static
 	org.postgresql.pljava.sqlgen.Lexicals.ISO_AND_PG_IDENTIFIER_CAPTURING;
+import static
+	org.postgresql.pljava.sqlgen.Lexicals.NEWLINE;
 import static
 	org.postgresql.pljava.sqlgen.Lexicals.SEPARATOR;
 import static
@@ -45,6 +47,22 @@ public class LexicalsTest extends TestCase
 {
 	public LexicalsTest(String name) { super(name); }
 
+	public void testNewline() throws Exception
+	{
+		Matcher m = NEWLINE.matcher("abcd\nefgh");
+		m.region(4, 9);
+		assertTrue("newline 0", m.lookingAt());
+		assertTrue("newline 1", m.lookingAt());
+
+		m.reset("abcd\r\nefgh").region(4, 10);
+		assertTrue("newline 2", m.lookingAt());
+		assertEquals("\r\n", m.group());
+
+		m.reset("abcd\n\refgh").region(4, 10);
+		assertTrue("newline 3", m.lookingAt());
+		assertEquals("\n", m.group());
+	}
+
 	public void testSeparator() throws Exception
 	{
 		Pattern allTheRest = Pattern.compile(".*", Pattern.DOTALL);