public final FrameBoundContext frameBound() throws RecognitionException {
		FrameBoundContext _localctx = new FrameBoundContext(_ctx, getState());
		enterRule(_localctx, 192, RULE_frameBound);
		int _la;
		try {
			setState(1825);
			_errHandler.sync(this);
			switch ( getInterpreter().adaptivePredict(_input,247,_ctx) ) {
			case 1:
				enterOuterAlt(_localctx, 1);
				{
				setState(1818);
				match(UNBOUNDED);
				setState(1819);
				((FrameBoundContext)_localctx).boundType = _input.LT(1);
				_la = _input.LA(1);
				if ( !(_la==FOLLOWING || _la==PRECEDING) ) {
					((FrameBoundContext)_localctx).boundType = (Token)_errHandler.recoverInline(this);
				}
				else {
					if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
					_errHandler.reportMatch(this);
					consume();
				}
				}
				break;
			case 2:
				enterOuterAlt(_localctx, 2);
				{
				setState(1820);
				((FrameBoundContext)_localctx).boundType = match(CURRENT);
				setState(1821);
				match(ROW);
				}
				break;
			case 3:
				enterOuterAlt(_localctx, 3);
				{
				setState(1822);
				expression();
				setState(1823);
				((FrameBoundContext)_localctx).boundType = _input.LT(1);
				_la = _input.LA(1);
				if ( !(_la==FOLLOWING || _la==PRECEDING) ) {
					((FrameBoundContext)_localctx).boundType = (Token)_errHandler.recoverInline(this);
				}
				else {
					if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
					_errHandler.reportMatch(this);
					consume();
				}
				}
				break;
			}
		}
		catch (RecognitionException re) {
			_localctx.exception = re;
			_errHandler.reportError(this, re);
			_errHandler.recover(this, re);
		}
		finally {
			exitRule();
		}
		return _localctx;
	}
When true, the behavior of keywords follows ANSI SQL standard.
amoro-format-mixed/amoro-mixed-spark/v3.5/amoro-mixed-spark-3.5/src/main/gen-antlr/org/apache/amoro/spark/sql/parser/MixedFormatSqlExtendParser.java