feat(grammar): Support JSON_SCALAR (#182)

zpa-core/src/main/kotlin/org/sonar/plugins/plsqlopen/api/PlSqlKeyword.kt

@@ -281,6 +281,7 @@ enum class PlSqlKeyword(override val value: String, val isReserved: Boolean = fa
     JSON_MERGEPATCH("json_mergepatch"),
     JSON_OBJECT("json_object"),
     JSON_OBJECTAGG("json_objectagg"),
+    JSON_SCALAR("json_scalar"),
     JSON_QUERY("json_query"),
     KEEP("keep"),
     KEY("key"),

zpa-core/src/main/kotlin/org/sonar/plugins/plsqlopen/api/SingleRowSqlFunctionsGrammar.kt

@@ -56,6 +56,7 @@ enum class SingleRowSqlFunctionsGrammar : GrammarRuleKey {
     JSON_ARRAY_EXPRESSION,
     JSON_MERGEPATCH_EXPRESSION,
     JSON_OBJECT_EXPRESSION,
+    JSON_SCALAR_EXPRESSION,
     JSON_QUERY_EXPRESSION,
     XMLATTRIBUTES_EXPRESSION,
     XMLELEMENT_EXPRESSION,
@@ -93,6 +94,7 @@ enum class SingleRowSqlFunctionsGrammar : GrammarRuleKey {
                     JSON_ARRAY_EXPRESSION,
                     JSON_MERGEPATCH_EXPRESSION,
                     JSON_OBJECT_EXPRESSION,
+                    JSON_SCALAR_EXPRESSION,
                     JSON_QUERY_EXPRESSION,
                     XMLATTRIBUTES_EXPRESSION,
                     XMLELEMENT_EXPRESSION,
@@ -354,6 +356,18 @@ enum class SingleRowSqlFunctionsGrammar : GrammarRuleKey {
                 b.optional(FORMAT, JSON)
             )
 
+            b.rule(JSON_SCALAR_EXPRESSION).define(
+                JSON_SCALAR,
+                LPARENTHESIS,
+                EXPRESSION,
+                b.optional(b.firstOf(
+                    b.sequence(b.firstOf(JSON, SQL), NULL),
+                    b.sequence(EMPTY, STRING)
+                ), ON, NULL),
+                b.optional(b.firstOf(NULL, ERROR), ON, ERROR),
+                RPARENTHESIS
+            )
+
             b.rule(JSON_QUERY_EXPRESSION).define(
                 JSON_QUERY,
                 LPARENTHESIS,

zpa-core/src/test/kotlin/org/sonar/plugins/plsqlopen/api/expressions/JsonScalarTest.kt

@@ -0,0 +1,65 @@
+/**
+ * Z PL/SQL Analyzer
+ * Copyright (C) 2015-2024 Felipe Zorzo
+ * mailto:felipe AT felipezorzo DOT com DOT br
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.plugins.plsqlopen.api.expressions
+
+import com.felipebz.flr.tests.Assertions.assertThat
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.sonar.plugins.plsqlopen.api.PlSqlGrammar
+import org.sonar.plugins.plsqlopen.api.RuleTest
+
+class JsonScalarTest : RuleTest() {
+
+    @BeforeEach
+    fun init() {
+        setRootRule(PlSqlGrammar.EXPRESSION)
+    }
+
+    @Test
+    fun matchesJsonScalar() {
+        assertThat(p).matches("json_scalar(val)")
+    }
+
+    @Test
+    fun matchesJsonScalarJsonNullOnNull() {
+        assertThat(p).matches("json_scalar(val json null on null)")
+    }
+
+    @Test
+    fun matchesJsonScalarSqlNullOnNull() {
+        assertThat(p).matches("json_scalar(val sql null on null)")
+    }
+
+    @Test
+    fun matchesJsonScalarEmptyStringOnNull() {
+        assertThat(p).matches("json_scalar(val empty string on null)")
+    }
+
+    @Test
+    fun matchesJsonScalarJsonNullOnError() {
+        assertThat(p).matches("json_scalar(val null on error)")
+    }
+
+    @Test
+    fun matchesLongJsonScalar() {
+        assertThat(p).matches("json_scalar(val sql null on null error on error)")
+    }
+
+}