php的strtotime函数源码分析

最近想实现一个多语言版的strtotime函数，所以阅读了php源码中strtotime函数的实现，很感谢“胖胖”大大的文章（ http://www.phppan.com/2011/06/php-strtotime/ ），为本人分析strtotime提供了一个大概的思路，阅读本文前请先阅读 “胖胖”大大的文章。 先 最近想实现一个多语言版的strtotime函数，所以阅读了php源码中strtotime函数的实现，很感谢“胖胖”大大的文章（http://www.phppan.com/2011/06/php-strtotime/），为本人分析strtotime提供了一个大概的思路，阅读本文前请先阅读“胖胖”大大的文章。先贴上strtotime的分析结果:1. 使用词法分析器re2c对英文文本的日期时间描述进行分析（/ext/date/lib/parse_date.c中scan（））。2.针对分析的token，做出相应的操作，即计算出英文文本的日期时间描述与标准时间的差值，结果存在结构体timelib_rel_time。3.根据差值与标准时间，转换为一个时间戳。我们以例子strtotime("last sunday"）为例来说明。关键的三个结构如下：typedef struct Scanner { int fd; uchar *lim, *str, *ptr, *cur, *tok, *pos; unsigned int line, len; struct timelib_error_container *errors; struct timelib_time *time; const timelib_tzdb *tzdb;} Scanner;typedef struct timelib_time { timelib_sll y, m, d; /* Year, Month, Day */ timelib_sll h, i, s; /* Hour, mInute, Second */ double f; /* Fraction */ int z; /* GMT offset in minutes */ char *tz_abbr; /* Timezone abbreviation (display only) */ timelib_tzinfo *tz_info; /* Timezone structure */ signed int dst; /* Flag if we were parsing a DST zone */ timelib_rel_time relative; timelib_sll sse; /* Seconds since epoch */ unsigned int have_time, have_date, have_zone, have_relative, have_weeknr_day; unsigned int sse_uptodate; /* !0 if the sse member is up to date with the date/time members */ unsigned int tim_uptodate; /* !0 if the date/time members are up to date with the sse member */ unsigned int is_localtime; /* 1 if the current struct represents localtime, 0 if it is in GMT */ unsigned int zone_type; /* 1 time offset, * 3 TimeZone identifier, * 2 TimeZone abbreviation */} timelib_time;typedef struct timelib_rel_time { timelib_sll y, m, d; /* Years, Months and Days */ timelib_sll h, i, s; /* Hours, mInutes and Seconds */ int weekday; /* Stores the day in 'next monday' */ int weekday_behavior; /* 0: the current day should *not* be counted when advancing forwards; 1: the current day *should* be counted */ int first_last_day_of; int invert; /* Whether the difference should be inverted */ timelib_sll days; /* Contains the number of *days*, instead of Y-M-D differences */ timelib_special special; unsigned int have_weekday_relative, have_special_relative;} timelib_rel_time;登录后复制 strtotime函数，将任何英文文本的日期时间描述解析为 Unix 时间戳，既然这里涉及到英文文本，那么怎么把这个英文文本转换为计算机可以理解的逻辑呢？学过编译原理的同学都知道，在编译的过程中有词法分析阶段，通过词法分析，将字符串转换为token的过程。php解析英文文本的字符串使用了re2c，这个词法分析工具支持正则表达式，在/ext/date/lib/parse_date.re 中scan()就是负责词法分析的过程。 这里需要特别注意的是，/ext/date/lib/parse_date.re是没被re2c前的原始文件，/ext/date/lib/parse_date.c是被re2c解析后生成的文件，源码分析时阅读/ext/date/lib/parse_date.re就好了，/ext/date/lib/parse_date.c文件中有大量的词法分析代码，一大堆switch, goto, 单是scan（）函数就有两万多行，伤不起啊！！！ 既然是re2c是使用正则表达式的，我们来查看一下表示"last sunday"的正则表达式：reltextnumber = 'first'|'second'|'third'|'fourth'|'fifth'|'sixth'|'seventh'|'eight'|'eighth'|'ninth'|'tenth'|'eleventh'|'twelfth';reltexttext = 'next'|'last'|'previous'|'this';reltextunit = (('sec'|'second'|'min'|'minute'|'hour'|'day'|'fortnight'|'forthnight'|'month'|'year') 's'?) | 'weeks' | daytext;relativetext = (reltextnumber|reltexttext) space reltextunit;登录后复制"last"是reltexttext，“sunday”是reltextunit， 所以"last sunday"是被解析为relativetext，在/ext/date/lib/parse_date.re查找relativetext 对应的操作：relativetext{timelib_sll i;int behavior = 0;DEBUG_OUTPUT("relativetext");TIMELIB_INIT;TIMELIB_HAVE_RELATIVE();while(*ptr) {i = timelib_get_relative_text((char **) &ptr, &behavior);timelib_eat_spaces((char **) &ptr);timelib_set_relative((char **) &ptr, i, behavior, s);}TIMELIB_DEINIT;return TIMELIB_RELATIVE;}登录后复制timelib_get_relative_text（）是分析 “last”这个token，关键的结构如下：typedef struct _timelib_lookup_table { const char *name; int type; int value;} timelib_lookup_table;static timelib_lookup_table const timelib_reltext_lookup[] = {{ "first", 0, 1 },{ "next", 0, 1 },{ "second", 0, 2 },{ "third", 0, 3 },{ "fourth", 0, 4 },{ "fifth", 0, 5 },{ "sixth", 0, 6 },{ "seventh", 0, 7 },{ "eight", 0, 8 },{ "eighth", 0, 8 },{ "ninth", 0, 9 },{ "tenth", 0, 10 },{ "eleventh", 0, 11 },{ "twelfth", 0, 12 },{ "last", 0, -1 },{ "previous", 0, -1 },{ "this", 1, 0 },{ NULL, 1, 0 }};登录后复制代码如下：static timelib_sll timelib_get_relative_text(char **ptr, int *behavior){while (**ptr == ' ' || **ptr == '\t' || **ptr == '-' || **ptr == '/') {++*ptr;}return timelib_lookup_relative_text(ptr, behavior);}static timelib_sll timelib_lookup_relative_text(char **ptr, int *behavior){char *word;char *begin = *ptr, *end;timelib_sll value = 0;const timelib_lookup_table *tp;while ((**ptr >= 'A' && **ptr = 'a' && **ptr name; tp++) {if (strcasecmp(word, tp->name) == 0) {value = tp->value;*behavior = tp->type;}}free(word);return value;}登录后复制当运行完后i= -1, behavior=0(请注意 value = tp->value;*behavior = tp->type; )接着在static void timelib_set_relative(char **ptr, timelib_sll amount, int behavior, Scanner *s){const timelib_relunit* relunit;if (!(relunit = timelib_lookup_relunit(ptr))) { //分析“ sunday”return;}switch (relunit->unit) {case TIMELIB_SECOND: s->time->relative.s += amount * relunit->multiplier; break;case TIMELIB_MINUTE: s->time->relative.i += amount * relunit->multiplier; break;case TIMELIB_HOUR: s->time->relative.h += amount * relunit->multiplier; break;case TIMELIB_DAY: s->time->relative.d += amount * relunit->multiplier; break;case TIMELIB_MONTH: s->time->relative.m += amount * relunit->multiplier; break;case TIMELIB_YEAR: s->time->relative.y += amount * relunit->multiplier; break;case TIMELIB_WEEKDAY: //计算差值存放在结构体timelib_rel_timeTIMELIB_HAVE_WEEKDAY_RELATIVE();TIMELIB_UNHAVE_TIME();s->time->relative.d += (amount > 0 ? amount - 1 : amount) * 7;s->time->relative.weekday = relunit->multiplier;s->time->relative.weekday_behavior = behavior;break;case TIMELIB_SPECIAL:TIMELIB_HAVE_SPECIAL_RELATIVE();TIMELIB_UNHAVE_TIME();s->time->relative.special.type = relunit->multiplier;s->time->relative.special.amount = amount;}}登录后复制timelib_lookup_relunit的关键结构体和代码如下：typedef struct _timelib_relunit {const char *name;int unit;int multiplier;} timelib_relunitstatic timelib_relunit const timelib_relunit_lookup[] = {{ "sec", TIMELIB_SECOND, 1 },{ "secs", TIMELIB_SECOND, 1 },{ "second", TIMELIB_SECOND, 1 },{ "seconds", TIMELIB_SECOND, 1 },{ "min", TIMELIB_MINUTE, 1 },{ "mins", TIMELIB_MINUTE, 1 },{ "minute", TIMELIB_MINUTE, 1 },{ "minutes", TIMELIB_MINUTE, 1 },{ "hour", TIMELIB_HOUR, 1 },{ "hours", TIMELIB_HOUR, 1 },{ "day", TIMELIB_DAY, 1 },{ "days", TIMELIB_DAY, 1 },{ "week", TIMELIB_DAY, 7 },{ "weeks", TIMELIB_DAY, 7 },{ "fortnight", TIMELIB_DAY, 14 },{ "fortnights", TIMELIB_DAY, 14 },{ "forthnight", TIMELIB_DAY, 14 },{ "forthnights", TIMELIB_DAY, 14 },{ "month", TIMELIB_MONTH, 1 },{ "months", TIMELIB_MONTH, 1 },{ "year", TIMELIB_YEAR, 1 },{ "years", TIMELIB_YEAR, 1 },{ "monday", TIMELIB_WEEKDAY, 1 },{ "mon", TIMELIB_WEEKDAY, 1 },{ "tuesday", TIMELIB_WEEKDAY, 2 },{ "tue", TIMELIB_WEEKDAY, 2 },{ "wednesday", TIMELIB_WEEKDAY, 3 },{ "wed", TIMELIB_WEEKDAY, 3 },{ "thursday", TIMELIB_WEEKDAY, 4 },{ "thu", TIMELIB_WEEKDAY, 4 },{ "friday", TIMELIB_WEEKDAY, 5 },{ "fri", TIMELIB_WEEKDAY, 5 },{ "saturday", TIMELIB_WEEKDAY, 6 },{ "sat", TIMELIB_WEEKDAY, 6 },{ "sunday", TIMELIB_WEEKDAY, 0 },{ "sun", TIMELIB_WEEKDAY, 0 },{ "weekday", TIMELIB_SPECIAL, TIMELIB_SPECIAL_WEEKDAY },{ "weekdays", TIMELIB_SPECIAL, TIMELIB_SPECIAL_WEEKDAY },{ NULL, 0, 0 }};static const timelib_relunit* timelib_lookup_relunit(char **ptr){char *word;char *begin = *ptr, *end;const timelib_relunit *tp, *value = NULL;while (**ptr != '\0' && **ptr != ' ' && **ptr != ',' && **ptr != '\t') {++*ptr;}end = *ptr;word = calloc(1, end - begin + 1);memcpy(word, begin, end - begin);for (tp = timelib_relunit_lookup; tp->name; tp++) {if (strcasecmp(word, tp->name) == 0) {value = tp;break;}}free(word);return value;}登录后复制运行完，可得到结构体timelib_relunit，其中的值是{ "sunday", TIMELIB_WEEKDAY, 0 },最后在下面的代码中获取一个差值case TIMELIB_WEEKDAY: //计算差值存放在结构体timelib_rel_timeTIMELIB_HAVE_WEEKDAY_RELATIVE();TIMELIB_UNHAVE_TIME();s->time->relative.d += (amount > 0 ? amount - 1 : amount) * 7;s->time->relative.weekday = relunit->multiplier;s->time->relative.weekday_behavior = behavior;break;登录后复制得到差值后，通过下面的三个函数转换为一个时间戳：static void do_adjust_relative(timelib_time* time) //把差值转换为标准时间{if (time->relative.have_weekday_relative) {do_adjust_for_weekday(time);}timelib_do_normalize(time);if (time->have_relative) {time->s += time->relative.s;time->i += time->relative.i;time->h += time->relative.h;time->d += time->relative.d;time->m += time->relative.m;time->y += time->relative.y;}switch (time->relative.first_last_day_of) {case 1: /* first */time->d = 1;break;case 2: /* last */time->d = 0;time->m++;break;}timelib_do_normalize(time);}static void do_adjust_for_weekday(timelib_time* time) //对星期类型进行处理{timelib_sll current_dow, difference;current_dow = timelib_day_of_week(time->y, time->m, time->d);if (time->relative.weekday_behavior == 2){if (time->relative.weekday == 0) {time->relative.weekday = 7;}time->d -= current_dow;time->d += time->relative.weekday;return;}difference = time->relative.weekday - current_dow;if ((time->relative.d relative.d >= 0 && difference relative.weekday_behavior)) {difference += 7;}if (time->relative.weekday >= 0) {time->d += difference;} else {time->d -= (7 - (abs(time->relative.weekday) - current_dow));}time->relative.have_weekday_relative = 0;}void timelib_update_ts(timelib_time* time, timelib_tzinfo* tzi) //转换为时间戳{timelib_sll res = 0;do_adjust_special_early(time);do_adjust_relative(time);do_adjust_special(time);res += do_years(time->y);res += do_months(time->m, time->y);res += do_days(time->d);res += do_time(time->h, time->i, time->s);time->sse = res;res += do_adjust_timezone(time, tzi);time->sse = res;time->sse_uptodate = 1;time->have_relative = time->relative.have_weekday_relative = time->relative.have_special_relative = 0;}登录后复制[文章作者]曾健生[作者邮箱][email protected][作者QQ]190678908[博客] http://blog.csdn.net/newjueqi