5944: Add support for databricks named parameters (sqlfluff#5946)

Co-authored-by: Adam Weeden <adam.weeden@encoura.org>

src/sqlfluff/dialects/dialect_databricks.py

@@ -16,6 +16,9 @@
     OneOf,
     Ref,
     Sequence,
+    StringLexer,
+    StringParser,
+    SymbolSegment,
     TypedParser,
 )
 from sqlfluff.dialects import dialect_ansi as ansi
@@ -39,6 +42,15 @@
 databricks_dialect.sets("date_part_function_name").update(["TIMEDIFF"])
 
 
+databricks_dialect.insert_lexer_matchers(
+    # Named Function Parameters:
+    # https://docs.databricks.com/en/sql/language-manual/sql-ref-function-invocation.html#named-parameter-invocation
+    [
+        StringLexer("right_arrow", "=>", CodeSegment),
+    ],
+    before="equals",
+)
+
 databricks_dialect.add(
     DoubleQuotedUDFBody=TypedParser(
         "double_quote",
@@ -58,6 +70,14 @@
         type="udf_body",
         trim_chars=("$",),
     ),
+    RightArrowSegment=StringParser("=>", SymbolSegment, type="right_arrow"),
+)
+
+databricks_dialect.replace(
+    FunctionContentsExpressionGrammar=OneOf(
+        Ref("ExpressionSegment"),
+        Ref("NamedArgumentSegment"),
+    ),
 )
 
 
@@ -302,3 +322,17 @@ class CreateDatabricksFunctionStatementSegment(BaseSegment):
         ),
         Ref("FunctionDefinitionGrammar"),
     )
+
+
+class NamedArgumentSegment(BaseSegment):
+    """Named argument to a function.
+
+    https://docs.databricks.com/en/sql/language-manual/sql-ref-function-invocation.html#named-parameter-invocation
+    """
+
+    type = "named_argument"
+    match_grammar = Sequence(
+        Ref("NakedIdentifierSegment"),
+        Ref("RightArrowSegment"),
+        Ref("ExpressionSegment"),
+    )

test/fixtures/dialects/databricks/named_argument.sql

@@ -0,0 +1,7 @@
+--https://docs.databricks.com/en/sql/language-manual/sql-ref-function-invocation.html#named-parameter-invocation
+
+select my_function(arg1 => 3, arg2 => 4) from dual;
+
+select my_function(3, arg2 => 4) from dual;
+
+select my_function(arg1 => 3, 4) from dual;

test/fixtures/dialects/databricks/named_argument.yml

@@ -0,0 +1,91 @@
+# YML test files are auto-generated from SQL files and should not be edited by
+# hand. To help enforce this, the "hash" field in the file must match a hash
+# computed by SQLFluff when running the tests. Please run
+# `python test/generate_parse_fixture_yml.py`  to generate them after adding or
+# altering SQL files.
+_hash: 96a8a90d5cb19753570b96e0b15c0390b1676bb54dd1a8c226a75f998e31ea54
+file:
+- statement:
+    select_statement:
+      select_clause:
+        keyword: select
+        select_clause_element:
+          function:
+            function_name:
+              function_name_identifier: my_function
+            bracketed:
+            - start_bracket: (
+            - named_argument:
+                naked_identifier: arg1
+                right_arrow: =>
+                expression:
+                  numeric_literal: '3'
+            - comma: ','
+            - named_argument:
+                naked_identifier: arg2
+                right_arrow: =>
+                expression:
+                  numeric_literal: '4'
+            - end_bracket: )
+      from_clause:
+        keyword: from
+        from_expression:
+          from_expression_element:
+            table_expression:
+              table_reference:
+                naked_identifier: dual
+- statement_terminator: ;
+- statement:
+    select_statement:
+      select_clause:
+        keyword: select
+        select_clause_element:
+          function:
+            function_name:
+              function_name_identifier: my_function
+            bracketed:
+              start_bracket: (
+              expression:
+                numeric_literal: '3'
+              comma: ','
+              named_argument:
+                naked_identifier: arg2
+                right_arrow: =>
+                expression:
+                  numeric_literal: '4'
+              end_bracket: )
+      from_clause:
+        keyword: from
+        from_expression:
+          from_expression_element:
+            table_expression:
+              table_reference:
+                naked_identifier: dual
+- statement_terminator: ;
+- statement:
+    select_statement:
+      select_clause:
+        keyword: select
+        select_clause_element:
+          function:
+            function_name:
+              function_name_identifier: my_function
+            bracketed:
+              start_bracket: (
+              named_argument:
+                naked_identifier: arg1
+                right_arrow: =>
+                expression:
+                  numeric_literal: '3'
+              comma: ','
+              expression:
+                numeric_literal: '4'
+              end_bracket: )
+      from_clause:
+        keyword: from
+        from_expression:
+          from_expression_element:
+            table_expression:
+              table_reference:
+                naked_identifier: dual
+- statement_terminator: ;