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parsedate.h File Reference

Date parsing functions. More...

Defines
#define	PARSEDATE_DAY_RELATIVE_TIME   PARSEDATE_RELATIVE_TIME
	day relative time
#define	PARSEDATE_INVALID_DATE   0x0100
	invalid date string
#define	PARSEDATE_MINUTE_RELATIVE_TIME   0x0002
	minute relative time
#define	PARSEDATE_RELATIVE_TIME   0x0001
	relative time
Functions
const char **	get_dateformats (void)
	returns the internal format table currently used by parsedate()
time_t	parsedate (const char *dateString, time_t now)
	Parses dateString relative to relativeTo.
time_t	parsedate_etc (const char *dateString, time_t now, int *_storedFlags)
	Parses dateString relative to relativeTo.
void	set_dateformats (const char *table[])
	sets the internal format table for parsedate()

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Detailed Description

Date parsing functions.

This is a set a functions for parsing date strings in various formats. It's mostly tailored for parsing user given data, although originally, it was developed to parse the date strings found in usenet messages.

The given date will be parsed relative to the specified time, and using a predefined set of time/date formats.

Valid Input Strings

The internal formats allow parsedate() to understand a wide range of input strings. The format list is ought to be compiled from the Date: line of 80.000 usenet messages.

But since this function is also used in end-user applications like the Tracker's find panel, it's helpful to know what this function accepts and what not.

Here are some examples of input strings that parsedate() will be able to convert along with some notes:

• "last friday", "this wednesday", "next July" "last", "next", and "this" refer to the week or year (depending on the context). So "last friday" means last week's friday. "This wednesday" is referring to this week's wednesday, no matter if it has already passed or not. "Next July" refers to next year's July. All of these dates are parsed relative to the specified time (usually "now"), and will be set to the first moment of that time span: "next monday" is monday, 0:00:00, midnight.
• "now" just returns the time all calculations are relative to.
• "next 5 minutes", "5 minutes", "+5 mins" all mean the same thing, that is, current time plus exactly 5 minutes.
• "5 weeks" means in 5 weeks from now on.
• "8/5/2003", "5.8.2003", "2003-08-05" are all referring to August 5th, 2003, again at 0:00 midnight.
• "Thursday 3:00" means this week's thursday, at 3 o'clock.

Format Specifier

While the get_dateformats() function allow you to retrieve the built-in formats, you can also define your own and use set_dateformats() to let parsedate() use them in all subsequent calls.

The following is a list valid format specifiers and their meanings.

• a/A weekday (Sunday, Monday, ...)
• d day of month (1-31)
• b/B month name (January, February, ...)
• month (1-12)
• y/Y year
• H/I hours (1-24)
• M minutes (0-60)
• S seconds (0-60)
• p meridian (am/pm)
• z/Z time zone (i.e. GMT)
• T time unit, like "last friday", "next 5 minutes", "-15 hours", etc.
• - dash or slash

Any of ",.:" is allowed and will be expected in the input string as is. You can enclose a single field with "[]" to mark it as being optional. A blank stands for white space. No other character is allowed. An invalid format string won't do any harm, but of course, no input string will ever match that format.

For example, "H:M [p]" will match against "21:33", "4:12 am", but not "30:30 pm" (hours out of range), "15:16 GMT" (this time zone is certainly not a valid meridian specifier), or "4:66" (minutes out of range).

Note:

At the time of this writing, the parsedate() functions are not localized and will only recognize English time specifications following the examples above.

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Define Documentation

#define PARSEDATE_DAY_RELATIVE_TIME   PARSEDATE_RELATIVE_TIME

day relative time

The time value was computed relative to the specified time, and it would vary with every day passed in the specified time.

#define PARSEDATE_INVALID_DATE   0x0100

invalid date string

This flag will be set if the specified date string could not be parsed correctly. For example, this may happen if there are some unknown words in that string.

#define PARSEDATE_MINUTE_RELATIVE_TIME   0x0002

minute relative time

The time value was computed relative to the specified time, and it would vary with every minute passed in the specified time.

#define PARSEDATE_RELATIVE_TIME   0x0001

relative time

The time value was computed relative to the specified time.

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Function Documentation

const char ** get_dateformats

(

void

)

returns the internal format table currently used by parsedate()

Returns the internal format table currently used by parsedate() - this is either a pointer to the built-in one, or one that you have previously set using set_dateformats().

See also:

set_dateformats()

time_t parsedate	(	const char *	dateString,
		time_t	relativeTo
	)

Parses dateString relative to relativeTo.

Parses the given dateString relative to the time specified by relativeTo using the internal formats table.

Parameters:

	dateString	the date that should be parsed, i.e. "next thursday".
	relativeTo	all relative dates will be relative to this time, if -1 is passed, the current time will be used.

Returns:

the parsed time value or -1 if the dateString could not be parsed.

time_t parsedate_etc	(	const char *	dateString,
		time_t	relativeTo,
		int *	_storedFlags
	)

Parses dateString relative to relativeTo.

This does basically the same as parsedate(), but will set the following flags in _storedFlags:

Constant	Meaning
PARSEDATE_RELATIVE_TIME	relative time The time value was computed relative to the specified time.
PARSEDATE_DAY_RELATIVE_TIME	day relative time The time value was computed relative to the specified time, and it would vary with every day passed in the specified time.
PARSEDATE_MINUTE_RELATIVE_TIME	minute relative time The time value was computed relative to the specified time, and it would vary with every minute passed in the specified time.
PARSEDATE_INVALID_DATE	invalid date string This flag will be set if the specified date string could not be parsed correctly. For example, this may happen if there are some unknown words in that string. This flag will only be set if the function returns -1.

void set_dateformats

(

const char *

formatTable[]

)

sets the internal format table for parsedate()

This function let you set the format table which is used by parsedate(). When formatTable is NULL, the standard built-in format table will be set again.

Parameters:

formatTable

the NULL terminated formats list. This list must stay valid when using parsedate() - it is not copied, but directly used.

See also:

parsedateFormats Format!

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The Haiku Book pre-R1 - parsedate.h File Reference
Generated on 14 Feb 2008