feat: Add simple WHILE

Author: stackmystack

grammar.js

@@ -265,6 +265,7 @@ module.exports = grammar({
     keyword_main: _ => make_keyword("main"),
     keyword_storage: _ => make_keyword("storage"),
     keyword_compression: _ => make_keyword("compression"),
+    keyword_while: _ => make_keyword("while"),
 
     keyword_trigger: _ => make_keyword('trigger'),
     keyword_function: _ => make_keyword("function"),
@@ -696,9 +697,16 @@ module.exports = grammar({
         $._ddl_statement,
         $._dml_write,
         optional_parenthesis($._dml_read),
+        $.while_statement,
       ),
     ),
 
+    while_statement: $ => seq(
+      $.keyword_while,
+      optional_parenthesis($._expression),
+      $.statement,
+    ),
+
     var_declarations: $ => seq($.keyword_declare, repeat1($.var_declaration)),
     var_declaration: $ => seq(
       $.identifier,
@@ -712,7 +720,6 @@ module.exports = grammar({
       optional(','),
     ),
 
-
     _ddl_statement: $ => choice(
       $._create_statement,
       $._alter_statement,

test/corpus/while.txt

@@ -0,0 +1,75 @@
+================================================================================
+While in TSQL
+================================================================================
+
+WHILE @par < 1
+  SELECT endless FROM TABLE
+--------------------------------------------------------------------------------
+
+(program
+  (statement
+    (while_statement
+      (keyword_while)
+      (binary_expression
+        (field
+          (identifier))
+        (literal))
+      (statement
+        (select
+          (keyword_select)
+          (select_expression
+            (term
+              (field
+                (identifier)))))
+        (from
+          (keyword_from)
+          (relation
+            (object_reference
+              (identifier))))))))
+
+================================================================================
+While in TSQL with SELECT condition
+================================================================================
+
+WHILE (
+        SELECT AVG(ListPrice)
+        FROM Production.Product
+        ) < $300
+  SELECT endless FROM TABLE
+--------------------------------------------------------------------------------
+
+(program
+  (statement
+    (while_statement
+      (keyword_while)
+      (binary_expression
+        (subquery
+          (select
+            (keyword_select)
+            (select_expression
+              (term
+                (invocation
+                  (object_reference
+                    (identifier))
+                  (term
+                    (field
+                      (identifier)))))))
+          (from
+            (keyword_from)
+            (relation
+              (object_reference
+                (identifier)
+                (identifier)))))
+        (parameter))
+      (statement
+        (select
+          (keyword_select)
+          (select_expression
+            (term
+              (field
+                (identifier)))))
+        (from
+          (keyword_from)
+          (relation
+            (object_reference
+              (identifier))))))))