一个简单的词法分析器

				      
				   PROGRAM TEST;
					CONST CONSTNUM = 1, CONSTREAL = 1.23;
					REAL: R1,R2;
					INTEGER: I;
					INTEGER: ARRAY STRING1[10], ARRAY STRING2[10,10];
					BOOLEAN: B1,B2;
					REAL: FUNCTION, REAL:R3
						BEGIN
							RETURN R3
						END	
				
					BEGIN
						R1 := 2.34;
						I := 0;
						IF R1 = 2.34 THEN B1 = TRUE;
						IF B1  TRUE THEN 
						WHILE(I < 10) DO STRING1[I] = STRING2[I],I++;
						FOR I := 1 TO 10 DO STRING1[I] = 1;
						READ I,R1,R2;
						R2 := FUNCTION, R1;
					END