1 /*
2  * dates.lex: An example of using start states to
3  *            distinguish between different date formats.
4  */
5 
6 %{
7 #include <ctype.h>
8 
9 char month[20],dow[20],day[20],year[20];
10 
11 %}
12 
13 skip        of|the|[ \t,]*
14 
15 mon           (mon(day)?)
16 tue           (tue(sday)?)
17 wed           (wed(nesday)?)
18 thu           (thu(rsday)?)
19 fri           (fri(day)?)
20 sat           (sat(urday)?)
21 sun           (sun(day)?)
22 
23 day_of_the_week     ({mon}|{tue}|{wed}|{thu}|{fri}|{sat}|{sun})
24 
25 jan           (jan(uary)?)
26 feb           (feb(ruary)?)
27 mar           (mar(ch)?)
28 apr           (apr(il)?)
29 may           (may)
30 jun           (jun(e)?)
31 jul           (jul(y)?)
32 aug           (aug(ust)?)
33 sep           (sep(tember)?)
34 oct           (oct(ober)?)
35 nov           (nov(ember)?)
36 dec           (dec(ember)?)
37 
38 first_half  ({jan}|{feb}|{mar}|{apr}|{may}|{jun})
39 second_half ({jul}|{aug}|{sep}|{oct}|{nov}|{dec})
40 month         {first_half}|{second_half}
41 
42 nday         [1-9]|[1-2][0-9]|3[0-1]
43 nmonth       [1-9]|1[0-2]
44 nyear        [0-9]{1,4}
45 
46 year_ext    (ad|AD|bc|BC)?
47 day_ext     (st|nd|rd|th)?
48 
49 %s LONG SHORT
50 %s DAY DAY_FIRST YEAR_FIRST YEAR_LAST YFMONTH YLMONTH
51 
52 %%
53 
54   /* the default is month-day-year */
55 
56 <LONG>{day_of_the_week}    strcpy(dow,yytext);
57 <LONG>{month}              strcpy(month,yytext); BEGIN(DAY);
58 
59   /* handle the form: day-month-year */
60 
61 <LONG>{nday}{day_ext}      strcpy(day,yytext);   BEGIN(DAY_FIRST);
62 <DAY_FIRST>{month}         strcpy(month,yytext); BEGIN(LONG);
63 <DAY>{nday}{day_ext}       strcpy(day,yytext);   BEGIN(LONG);
64 
65 <LONG>{nyear}{year_ext}  {
66                            printf("Long:\n");
67                            printf("  DOW   : %s \n",dow);
68                            printf("  Day   : %s \n",day);
69                            printf("  Month : %s \n",month);
70                            printf("  Year  : %s \n",yytext);
71                            strcpy(dow,"");
72                            strcpy(day,"");
73                            strcpy(month,"");
74                          }
75 
76   /* handle dates of the form: day-month-year */
77 
78 <SHORT>{nday}              strcpy(day,yytext);  BEGIN(YEAR_LAST);
79 <YEAR_LAST>{nmonth}        strcpy(month,yytext);BEGIN(YLMONTH);
80 <YLMONTH>{nyear}           strcpy(year,yytext); BEGIN(SHORT);
81 
82   /* handle dates of the form: year-month-day */
83 
84 <SHORT>{nyear}             strcpy(year,yytext); BEGIN(YEAR_FIRST);
85 <YEAR_FIRST>{nmonth}       strcpy(month,yytext);BEGIN(YFMONTH);
86 <YFMONTH>{nday}            strcpy(day,yytext);  BEGIN(SHORT);
87 
88 
89 <SHORT>\n                {
90                            printf("Short:\n");
91                            printf("  Day   : %s \n",day);
92                            printf("  Month : %s \n",month);
93                            printf("  Year  : %s \n",year);
94                            strcpy(year,"");
95                            strcpy(day,"");
96                            strcpy(month,"");
97                          }
98 
99 long\n                      BEGIN(LONG);
100 short\n                     BEGIN(SHORT);
101 
102 {skip}*
103 \n
104 .
105 
106 
107