From 68e91c3eb25e9bf2ced78a2bd4920c2e5bbc2260 Mon Sep 17 00:00:00 2001
From: Tatsuo Ishii <ishii@postgresql.org>
Date: Tue, 23 Dec 2025 22:21:47 +0900
Subject: [PATCH v36 3/8] Row pattern recognition patch (rewriter).

---
 src/backend/utils/adt/ruleutils.c | 109 ++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 9f85eb86da1..b643c0c4bf0 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -438,6 +438,10 @@ static void get_rule_groupingset(GroupingSet *gset, List *targetlist,
 								 bool omit_parens, deparse_context *context);
 static void get_rule_orderby(List *orderList, List *targetList,
 							 bool force_colno, deparse_context *context);
+static void get_rule_pattern(List *patternVariable, List *patternRegexp,
+							 bool force_colno, deparse_context *context);
+static void get_rule_define(List *defineClause, List *patternVariables,
+							bool force_colno, deparse_context *context);
 static void get_rule_windowclause(Query *query, deparse_context *context);
 static void get_rule_windowspec(WindowClause *wc, List *targetList,
 								deparse_context *context);
@@ -6744,6 +6748,64 @@ get_rule_orderby(List *orderList, List *targetList,
 	}
 }
 
+/*
+ * Display a PATTERN clause.
+ */
+static void
+get_rule_pattern(List *patternVariable, List *patternRegexp,
+				 bool force_colno, deparse_context *context)
+{
+	StringInfo	buf = context->buf;
+	const char *sep;
+	ListCell   *lc_var,
+			   *lc_reg = list_head(patternRegexp);
+
+	sep = "";
+	appendStringInfoChar(buf, '(');
+	foreach(lc_var, patternVariable)
+	{
+		char	   *variable = strVal((String *) lfirst(lc_var));
+		char	   *regexp = NULL;
+
+		if (lc_reg != NULL)
+		{
+			regexp = strVal((String *) lfirst(lc_reg));
+
+			lc_reg = lnext(patternRegexp, lc_reg);
+		}
+
+		appendStringInfo(buf, "%s%s", sep, variable);
+		if (regexp !=NULL)
+			appendStringInfoString(buf, regexp);
+
+		sep = " ";
+	}
+	appendStringInfoChar(buf, ')');
+}
+
+/*
+ * Display a DEFINE clause.
+ */
+static void
+get_rule_define(List *defineClause, List *patternVariables,
+				bool force_colno, deparse_context *context)
+{
+	StringInfo	buf = context->buf;
+	const char *sep;
+	ListCell   *lc_def;
+
+	sep = "  ";
+
+	foreach(lc_def, defineClause)
+	{
+		TargetEntry *te = (TargetEntry *) lfirst(lc_def);
+
+		appendStringInfo(buf, "%s%s AS ", sep, te->resname);
+		get_rule_expr((Node *) te->expr, context, false);
+		sep = ",\n  ";
+	}
+}
+
 /*
  * Display a WINDOW clause.
  *
@@ -6824,6 +6886,7 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 		get_rule_orderby(wc->orderClause, targetList, false, context);
 		needspace = true;
 	}
+
 	/* framing clause is never inherited, so print unless it's default */
 	if (wc->frameOptions & FRAMEOPTION_NONDEFAULT)
 	{
@@ -6832,7 +6895,53 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 		get_window_frame_options(wc->frameOptions,
 								 wc->startOffset, wc->endOffset,
 								 context);
+		needspace = true;
 	}
+
+	/* RPR */
+	if (wc->rpSkipTo == ST_NEXT_ROW)
+	{
+		if (needspace)
+			appendStringInfoChar(buf, ' ');
+		appendStringInfoString(buf,
+							   "\n  AFTER MATCH SKIP TO NEXT ROW ");
+		needspace = true;
+	}
+	else if (wc->rpSkipTo == ST_PAST_LAST_ROW)
+	{
+		if (needspace)
+			appendStringInfoChar(buf, ' ');
+		appendStringInfoString(buf,
+							   "\n  AFTER MATCH SKIP PAST LAST ROW ");
+		needspace = true;
+	}
+	if (wc->initial)
+	{
+		if (needspace)
+			appendStringInfoChar(buf, ' ');
+		appendStringInfoString(buf, "\n  INITIAL");
+		needspace = true;
+	}
+	if (wc->patternVariable)
+	{
+		if (needspace)
+			appendStringInfoChar(buf, ' ');
+		appendStringInfoString(buf, "\n  PATTERN ");
+		get_rule_pattern(wc->patternVariable, wc->patternRegexp,
+						 false, context);
+		needspace = true;
+	}
+
+	if (wc->defineClause)
+	{
+		if (needspace)
+			appendStringInfoChar(buf, ' ');
+		appendStringInfoString(buf, "\n  DEFINE\n");
+		get_rule_define(wc->defineClause, wc->patternVariable,
+						false, context);
+		appendStringInfoChar(buf, ' ');
+	}
+
 	appendStringInfoChar(buf, ')');
 }
 
-- 
2.43.0