Issue 1083: Support BigQuery named arguments

CHANGELOG.md

@@ -22,6 +22,9 @@ Contributors:
 - Disabled models in the dbt templater are now skipped enitrely rather than
   returning an untemplated file.
 - Add a changelog check to SQLFluff continuous integration.
+- Fix bug [#1083](https://github.com/sqlfluff/sqlfluff/issues/1083), adding
+  support for BigQuery named function arguments, used with functions such as
+  [ST_GEOGFROMGEOJSON()](https://cloud.google.com/bigquery/docs/reference/standard-sql/geography_functions#st_geogfromgeojson)
 
 ## [0.6.0a1] - 2021-05-15
 ### Added

src/sqlfluff/dialects/dialect_bigquery.py

@@ -21,6 +21,7 @@
     Indent,
     SymbolSegment,
     RegexLexer,
+    StringLexer,
     CodeSegment,
     NamedParser,
     StringParser,
@@ -32,6 +33,14 @@
 ansi_dialect = load_raw_dialect("ansi")
 bigquery_dialect = ansi_dialect.copy_as("bigquery")
 
+bigquery_dialect.insert_lexer_matchers(
+    # JSON Operators: https://www.postgresql.org/docs/9.5/functions-json.html
+    [
+        StringLexer("right_arrow", "=>", CodeSegment),
+    ],
+    before="equals",
+)
+
 bigquery_dialect.patch_lexer_matchers(
     [
         # Quoted literals can have r or b (case insensitive) prefixes, in any order, to
@@ -68,6 +77,9 @@
     EndAngleBracketSegment=StringParser(
         ">", SymbolSegment, name="end_angle_bracket", type="end_angle_bracket"
     ),
+    RightArrowSegment=StringParser(
+        "=>", SymbolSegment, name="right_arrow", type="right_arrow"
+    ),
 )
 
 
@@ -78,6 +90,7 @@
             Ref("ExpressionSegment"),
             Sequence(OneOf("IGNORE", "RESPECT"), "NULLS", optional=True),
         ),
+        Ref("NamedArgumentSegment"),
     ),
     SimpleArrayTypeGrammar=Sequence(
         "ARRAY",
@@ -364,6 +377,21 @@ class TypelessStructSegment(BaseSegment):
     )
 
 
+@bigquery_dialect.segment()
+class NamedArgumentSegment(BaseSegment):
+    """Named argument to a function.
+
+    https://cloud.google.com/bigquery/docs/reference/standard-sql/geography_functions#st_geogfromgeojson
+    """
+
+    type = "named_argument"
+    match_grammar = Sequence(
+        Ref("NakedIdentifierSegment"),
+        Ref("RightArrowSegment"),
+        Ref("ExpressionSegment"),
+    )
+
+
 @bigquery_dialect.segment()
 class LiteralCoercionSegment(BaseSegment):
     """A casting operation with a type name preceding a string literal.

test/fixtures/parser/bigquery/select_function_with_named_arguments.sql

@@ -0,0 +1 @@
+SELECT ST_GEOGFROMGEOJSON('{"type":"LineString","coordinates":[[1,2],[4,5]]}', make_valid => true)

test/fixtures/parser/bigquery/select_function_with_named_arguments.yml

@@ -0,0 +1,20 @@
+file:
+  statement:
+    select_statement:
+      select_clause:
+        keyword: SELECT
+        select_clause_element:
+          function:
+            function_name:
+              function_name_identifier: ST_GEOGFROMGEOJSON
+            bracketed:
+              start_bracket: (
+              expression:
+                literal: "'{\"type\":\"LineString\",\"coordinates\":[[1,2],[4,5]]}'"
+              comma: ','
+              named_argument:
+                identifier: make_valid
+                right_arrow: =>
+                expression:
+                  literal: 'true'
+              end_bracket: )