fix(parser): support CAST and TRY_CAST expressions in SQL (#113)

Author: cpsievert

tree-sitter-ggsql/grammar.js

@@ -60,6 +60,7 @@ module.exports = grammar({
     select_body: $ => prec.left(repeat1(choice(
       $.from_clause,
       $.window_function,  // Window functions like ROW_NUMBER() OVER (...)
+      $.cast_expression,  // CAST(expr AS type), TRY_CAST(expr AS type)
       $.function_call,    // Regular function calls like COUNT(), SUM()
       $.sql_keyword,
       $.string,
@@ -175,6 +176,7 @@ module.exports = grammar({
     // Token-by-token fallback for any other subquery content
     subquery_body: $ => repeat1(choice(
       $.window_function,
+      $.cast_expression,
       $.function_call,
       $.sql_keyword,
       $.string,
@@ -185,6 +187,23 @@ module.exports = grammar({
       token(/[^\s;(),'\"]+/)
     )),
 
+    // CAST/TRY_CAST expression: CAST(expr AS type) or TRY_CAST(expr AS type)
+    // Higher precedence than function_call to win over treating CAST as a regular function
+    cast_expression: $ => prec(3, seq(
+      choice(caseInsensitive('CAST'), caseInsensitive('TRY_CAST')),
+      '(',
+      $.positional_arg,
+      caseInsensitive('AS'),
+      $.type_name,
+      ')'
+    )),
+
+    // Type name for CAST expressions: DATE, VARCHAR, DECIMAL(10,2), etc.
+    type_name: $ => seq(
+      $.identifier,
+      optional(seq('(', $.number, optional(seq(',', $.number)), ')'))
+    ),
+
     // Function call with parentheses (can be empty like ROW_NUMBER())
     // Used in window functions and general SQL
     function_call: $ => prec(2, seq(
@@ -288,6 +307,8 @@ module.exports = grammar({
       $.number,
       $.string,
       '*',
+      // CAST/TRY_CAST expression
+      $.cast_expression,
       // Nested function call
       $.function_call,
       // Arithmetic/comparison expression (binary operators)

tree-sitter-ggsql/test/corpus/basic.txt

@@ -2240,3 +2240,99 @@ SCALE DISCRETE x RENAMING 'A' => 'Alpha', * => 'Category {}'
             value: (string))
           (renaming_assignment
             value: (string)))))))
+
+================================================================================
+CAST expression
+================================================================================
+
+SELECT CAST(sale_date AS DATE) as period FROM sales VISUALISE period AS x DRAW point
+
+--------------------------------------------------------------------------------
+
+(query
+  (sql_portion
+    (sql_statement
+      (select_statement
+        (select_body
+          (cast_expression
+            (positional_arg
+              (qualified_name
+                (identifier
+                  (bare_identifier))))
+            (type_name
+              (identifier
+                (bare_identifier))))
+          (identifier
+            (bare_identifier))
+          (identifier
+            (bare_identifier))
+          (from_clause
+            (table_ref
+              table: (qualified_name
+                (identifier
+                  (bare_identifier)))))))))
+  (visualise_statement
+    (visualise_keyword)
+    (global_mapping
+      (mapping_list
+        (mapping_element
+          (explicit_mapping
+            value: (mapping_value
+              (column_reference
+                (identifier
+                  (bare_identifier))))
+            name: (aesthetic_name)))))
+    (viz_clause
+      (draw_clause
+        (geom_type)))))
+
+================================================================================
+TRY_CAST nested in function argument
+================================================================================
+
+SELECT SUM(TRY_CAST(price AS INTEGER)) as total FROM data VISUALISE DRAW bar MAPPING x AS x
+
+--------------------------------------------------------------------------------
+
+(query
+  (sql_portion
+    (sql_statement
+      (select_statement
+        (select_body
+          (function_call
+            (identifier
+              (bare_identifier))
+            (function_args
+              (function_arg
+                (positional_arg
+                  (cast_expression
+                    (positional_arg
+                      (qualified_name
+                        (identifier
+                          (bare_identifier))))
+                    (type_name
+                      (identifier
+                        (bare_identifier))))))))
+          (identifier
+            (bare_identifier))
+          (identifier
+            (bare_identifier))
+          (from_clause
+            (table_ref
+              table: (qualified_name
+                (identifier
+                  (bare_identifier)))))))))
+  (visualise_statement
+    (visualise_keyword)
+    (viz_clause
+      (draw_clause
+        (geom_type)
+        (mapping_clause
+          (mapping_list
+            (mapping_element
+              (explicit_mapping
+                value: (mapping_value
+                  (column_reference
+                    (identifier
+                      (bare_identifier))))
+                name: (aesthetic_name)))))))))