Added support for IS [NOT] NULL

Author: renecannao

include/mysql_parser/mysql_ast.h

@@ -93,8 +93,11 @@ enum class NodeType {
     NODE_SHOW_OPTION_FULL,      // For SHOW FULL ...
     NODE_SHOW_OPTION_FIELDS,    // For SHOW ... FIELDS
     NODE_SHOW_TARGET_DATABASES, // For SHOW DATABASES
-    NODE_TABLE_SPECIFICATION    // For FROM table_name in SHOW FIELDS
+    NODE_TABLE_SPECIFICATION,   // For FROM table_name in SHOW FIELDS
 
+    // Added for IS NULL / IS NOT NULL
+    NODE_IS_NULL_EXPRESSION,
+    NODE_IS_NOT_NULL_EXPRESSION
 };
 
 // Structure for an AST Node
@@ -211,6 +214,8 @@ inline void print_ast(const AstNode* node, int indent = 0) {
         case NodeType::NODE_SHOW_OPTION_FIELDS: type_str = "SHOW_OPT_FIELDS"; break;
         case NodeType::NODE_SHOW_TARGET_DATABASES: type_str = "SHOW_TARGET_DB"; break;
         case NodeType::NODE_TABLE_SPECIFICATION: type_str = "TABLE_SPEC"; break;
+        case NodeType::NODE_IS_NULL_EXPRESSION: type_str = "IS_NULL_EXPR"; break;
+        case NodeType::NODE_IS_NOT_NULL_EXPRESSION: type_str = "IS_NOT_NULL_EXPR"; break;
         default: type_str = "UNHANDLED_TYPE(" + std::to_string(static_cast<int>(node->type)) + ")"; break;
     }
     std::cout << "Type: " << type_str;

src/mysql_parser/mysql_lexer.l

@@ -51,13 +51,17 @@ union MYSQL_YYSTYPE;
   "PERSIST_ONLY"        { return TOKEN_PERSIST_ONLY;}
   "DEFAULT"             { return TOKEN_DEFAULT; }
   "COLLATE"             { return TOKEN_COLLATE; }
-
+  
   "SHOW"                { return TOKEN_SHOW; }
-  "FULL"                { return TOKEN_FULL; } /* Already present for JOIN, ensure it's usable here */
-  "FIELDS"              { return TOKEN_FIELDS; } /* Already present for INTO OUTFILE, ensure it's usable here */
+  /* FULL is already defined for JOINs, will be reused */
+  /* FIELDS is already defined for INTO OUTFILE, will be reused */
   "DATABASES"           { return TOKEN_DATABASES; }
   "BEGIN"               { return TOKEN_BEGIN; }
   "COMMIT"              { return TOKEN_COMMIT; }
+  "IS"                  { return TOKEN_IS; }
+  "NULL"                { return TOKEN_NULL_KEYWORD; }
+  "NOT"                 { return TOKEN_NOT; }
+
 
   "DELETE"              { return TOKEN_DELETE; }
   "LOW_PRIORITY"        { return TOKEN_LOW_PRIORITY; }
@@ -240,4 +244,3 @@ union MYSQL_YYSTYPE;
 %%
 /* C code to be included at the end of the lexer */
 
-

src/mysql_parser/mysql_parser.y

@@ -63,6 +63,7 @@ int mysql_yylex(union MYSQL_YYSTYPE* yylval_param, yyscan_t yyscanner, MysqlPars
 /* TOKEN_FIELDS is already declared */
 /* TOKEN_FULL is already declared */
 %token TOKEN_BEGIN TOKEN_COMMIT /* Added for BEGIN/COMMIT */
+%token TOKEN_IS TOKEN_NULL_KEYWORD TOKEN_NOT /* Added for IS NULL / IS NOT NULL */
 
 
 %token <str_val> TOKEN_QUIT
@@ -113,11 +114,11 @@ int mysql_yylex(union MYSQL_YYSTYPE* yylval_param, yyscan_t yyscanner, MysqlPars
 %type <node_val> values_clause value_row_list value_row expression_list
 
 // Precedence
-%left TOKEN_OR  // Assuming OR might be added
+%left TOKEN_OR
 %left TOKEN_AND
-%right TOKEN_NOT // Assuming NOT might be added
+%right TOKEN_NOT // For logical NOT
 
-%left TOKEN_EQUAL TOKEN_LESS TOKEN_GREATER TOKEN_LESS_EQUAL TOKEN_GREATER_EQUAL TOKEN_NOT_EQUAL
+%left TOKEN_EQUAL TOKEN_LESS TOKEN_GREATER TOKEN_LESS_EQUAL TOKEN_GREATER_EQUAL TOKEN_NOT_EQUAL TOKEN_IS // Added TOKEN_IS
 
 %left TOKEN_PLUS TOKEN_MINUS
 %left TOKEN_ASTERISK TOKEN_DIVIDE
@@ -1210,10 +1211,18 @@ expression_placeholder:
     }
     | expression_placeholder comparison_operator expression_placeholder {
         $$ = new MysqlParser::AstNode(MysqlParser::NodeType::NODE_COMPARISON_EXPRESSION, $2->value);
-        delete $2; // $2 is operator node, its value copied
+        delete $2;
         $$->addChild($1);
         $$->addChild($3);
     }
+    | expression_placeholder TOKEN_IS TOKEN_NULL_KEYWORD { // Covers `expr IS NULL`
+        $$ = new MysqlParser::AstNode(MysqlParser::NodeType::NODE_IS_NULL_EXPRESSION);
+        $$->addChild($1); // The expression part
+    }
+    | expression_placeholder TOKEN_IS TOKEN_NOT TOKEN_NULL_KEYWORD { // Covers `expr IS NOT NULL`
+        $$ = new MysqlParser::AstNode(MysqlParser::NodeType::NODE_IS_NOT_NULL_EXPRESSION);
+        $$->addChild($1); // The expression part
+    }
     | match_against_expression { $$ = $1; }
     ;
 
@@ -1227,7 +1236,7 @@ simple_expression:
     | TOKEN_DEFAULT         { $$ = new MysqlParser::AstNode(MysqlParser::NodeType::NODE_KEYWORD, "DEFAULT"); }
     | aggregate_function_call { $$ = $1; }
     | function_call_placeholder {$$ = $1; }
-    | TOKEN_LPAREN expression_placeholder TOKEN_RPAREN { $$ = $2; }
+    | TOKEN_LPAREN expression_placeholder TOKEN_RPAREN { $$ = $2; } // Important for `(expr IS NOT NULL)`
     | simple_expression TOKEN_PLUS simple_expression {
         $$ = new MysqlParser::AstNode(MysqlParser::NodeType::NODE_OPERATOR, "+");
         $$->addChild($1); $$->addChild($3);
@@ -1333,3 +1342,4 @@ opt_expression_placeholder_list:
 // }
 // The default yyerror or the one provided by %define parse.error verbose should be sufficient.
 // If you need custom error formatting or location tracking, you'd define mysql_yyerror here.
+