307 lines
12 KiB
XML
307 lines
12 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
|
|
<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
|
|
"../../../tools/boostbook/dtd/boostbook.dtd">
|
|
|
|
<!-- Copyright (c) 2005 CrystalClear Software, Inc.
|
|
Subject to the Boost Software License, Version 1.0.
|
|
(See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
|
|
-->
|
|
|
|
<section id="date_time.io_tutorial"
|
|
xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
<title>Date Time IO Tutorial</title>
|
|
<bridgehead renderas="sect2">Date Time IO Tutorial</bridgehead>
|
|
|
|
<link linkend="basic_use">Basic Use</link> |
|
|
<link linkend="format_strings">Format Strings</link> |
|
|
<link linkend="content_strings">Content Strings</link> |
|
|
<link linkend="tut_sv">Special Values</link> |
|
|
<link linkend="tut_dper">Date/Time Periods</link> |
|
|
<link linkend="tut_dgen">Date Generators</link>
|
|
|
|
<anchor id="basic_use" />
|
|
<bridgehead renderas="sect4">Basic Use</bridgehead>
|
|
<para>Facets are automatically imbued when operators '>>' and '<<' are called. The list of date_time objects that can be streamed are:</para>
|
|
<bridgehead renderas="sect5">Gregorian</bridgehead>
|
|
<para>
|
|
<code>date</code>,
|
|
<code>days</code>,
|
|
<code>date_period</code>,
|
|
<code>greg_month</code>,
|
|
<code>greg_weekday</code>,
|
|
<code>greg_year</code>,
|
|
<code>partial_date</code>,
|
|
<code>nth_day_of_the_week_in_month</code>,
|
|
<code>first_day_of_the_week_in_month</code>,
|
|
<code>last_day_of_the_week_in_month</code>,
|
|
<code>first_day_of_the_week_after</code>,
|
|
<code>first_day_of_the_week_before</code>
|
|
</para>
|
|
<bridgehead renderas="sect5">Posix_time</bridgehead>
|
|
<para>
|
|
<code>ptime</code>,
|
|
<code>time_period</code>,
|
|
<code>time_duration</code>
|
|
</para>
|
|
<bridgehead renderas="sect5">Local_time</bridgehead>
|
|
<para>
|
|
<code>local_date_time</code>
|
|
</para>
|
|
|
|
<para>
|
|
The following example is of the basic use of the new IO code, utilizing all the defaults. (this example can be found in the <code>libs/date_time/example/tutorial</code> directory)
|
|
</para>
|
|
<programlisting>
|
|
<![CDATA[
|
|
date d(2004, Feb, 29);
|
|
time_duration td(12,34,56,789);
|
|
stringstream ss;
|
|
ss << d << ' ' << td;
|
|
ptime pt(not_a_date_time);
|
|
cout << pt << endl; // "not-a-date-time"
|
|
ss >> pt;
|
|
cout << pt << endl; // "2004-Feb-29 12:34:56.000789"
|
|
ss.str("");
|
|
ss << pt << " EDT-05EDT,M4.1.0,M10.5.0";
|
|
local_date_time ldt(not_a_date_time);
|
|
ss >> ldt;
|
|
cout << ldt << endl; // "2004-Feb-29 12:34:56.000789 EDT"
|
|
]]>
|
|
</programlisting>
|
|
|
|
<para>This example used the default settings for the input and output facets. The default formats are such that interoperability like that shown in the example is possible. NOTE: Input streaming of local_date_time can only be done with a <link linkend="date_time.local_time.posix_time_zone">posix time zone string</link>. The default output format uses a time zone abbreviation. The format can be changed so out and in match (as we will see later in this tutorial).</para>
|
|
|
|
<anchor id="format_strings" />
|
|
<bridgehead renderas="sect4">Format Strings</bridgehead>
|
|
<para>The format strings control the order, type, and style of the date/time elements used. The facets provide some predefined formats (iso_format_specifier, iso_format_extended_specifier, and default_date_format) but the user can easily create their own.</para>
|
|
(continued from previous example)
|
|
<programlisting>
|
|
<![CDATA[
|
|
local_time_facet* output_facet = new local_time_facet();
|
|
local_time_input_facet* input_facet = new local_time_input_facet();
|
|
ss.imbue(locale(locale::classic(), output_facet));
|
|
ss.imbue(locale(ss.getloc(), input_facet));
|
|
|
|
output_facet->format("%a %b %d, %H:%M %z");
|
|
ss.str("");
|
|
ss << ldt;
|
|
cout << ss.str() << endl; // "Sun Feb 29, 12:34 EDT"
|
|
|
|
output_facet->format(local_time_facet::iso_time_format_specifier);
|
|
ss.str("");
|
|
ss << ldt;
|
|
cout << ss.str() << endl; // "20040229T123456.000789-0500"
|
|
|
|
output_facet->format(local_time_facet::iso_time_format_extended_specifier);
|
|
ss.str("");
|
|
ss << ldt;
|
|
cout << ss.str() << endl; // "2004-02-29 12:34:56.000789-05:00"
|
|
]]>
|
|
</programlisting>
|
|
|
|
<para>Format strings are not limited to date/time elements. Extra verbiage can be placed in a format string. NOTE: When extra verbiage is present in an input format, the data being input must also contain the exact verbiage.</para>
|
|
(continued from previous example)
|
|
<programlisting>
|
|
<![CDATA[
|
|
// extra words in format
|
|
string my_format("The extended ordinal time %Y-%jT%H:%M can also be \
|
|
represented as %A %B %d, %Y");
|
|
output_facet->format(my_format.c_str());
|
|
input_facet->format(my_format.c_str());
|
|
ss.str("");
|
|
ss << ldt;
|
|
cout << ss.str() << endl;
|
|
|
|
// matching extra words in input
|
|
ss.str("The extended ordinal time 2005-128T12:15 can also be \
|
|
represented as Sunday May 08, 2005");
|
|
ss >> ldt;
|
|
cout << ldt << endl;
|
|
]]>
|
|
</programlisting>
|
|
|
|
<anchor id="content_strings" />
|
|
<bridgehead renderas="sect4">Content Strings</bridgehead>
|
|
<para>So far we've shown how a user can achieve a great deal of customization with very little effort by using formats. Further customization can be achieved through user defined elements (ie strings). The elements that can be customized are: Special value names, month names, month abbreviations, weekday names, weekday abbreviations, delimiters of the date/time periods, and the phrase elements of the date_generators.</para>
|
|
<para>The default values for these are as follows:</para>
|
|
<bridgehead renderas="sect5">Special values</bridgehead>
|
|
<para>
|
|
<code>not-a-date-time</code>,
|
|
<code>-infinity</code>,
|
|
<code>+infinity</code>,
|
|
<code>minimum-date-time</code>,
|
|
<code>maximum-date-time</code>
|
|
</para>
|
|
<bridgehead renderas="sect5">Months</bridgehead>
|
|
<para>
|
|
<code>English calendar and three letter abbreviations</code>
|
|
</para>
|
|
<bridgehead renderas="sect5">Weekdays</bridgehead>
|
|
<para>
|
|
<code>English calendar and three letter abbreviations</code>
|
|
</para>
|
|
<bridgehead renderas="sect5">Date generator phrase elements</bridgehead>
|
|
<para>
|
|
<code>first</code>,
|
|
<code>second</code>,
|
|
<code>third</code>,
|
|
<code>fourth</code>,
|
|
<code>fifth</code>,
|
|
<code>last</code>,
|
|
<code>before</code>,
|
|
<code>after</code>,
|
|
<code>of</code>
|
|
</para>
|
|
<para>NOTE: We've shown earlier that the components of a date/time representation can be re-ordered via the format string. This is not the case with date_generators. The elements themselves can be customized but their order cannot be changed.</para>
|
|
|
|
<bridgehead renderas="sect4">Content Strings</bridgehead>
|
|
<para>To illustrate the customization possibilities we will use custom strings for months and weekdays (we will only use long names, is all lowercase, for this example).</para>
|
|
(continued from previous example)
|
|
<programlisting>
|
|
<![CDATA[
|
|
// set up the collections of custom strings.
|
|
// only the full names are altered for the sake of brevity
|
|
string month_names[12] = { "january", "february", "march",
|
|
"april", "may", "june",
|
|
"july", "august", "september",
|
|
"october", "november", "december" };
|
|
vector<string> long_months(&month_names[0], &month_names[12]);
|
|
string day_names[7] = { "sunday", "monday", "tuesday", "wednesday",
|
|
"thursday", "friday", "saturday" };
|
|
vector<string> long_days(&day_names[0], &day_names[7]);
|
|
|
|
// create date_facet and date_input_facet using all defaults
|
|
date_facet* date_output = new date_facet();
|
|
date_input_facet* date_input = new date_input_facet();
|
|
ss.imbue(locale(ss.getloc(), date_output));
|
|
ss.imbue(locale(ss.getloc(), date_input));
|
|
|
|
// replace names in the output facet
|
|
date_output->long_month_names(long_months);
|
|
date_output->long_weekday_names(long_days);
|
|
|
|
// replace names in the input facet
|
|
date_input->long_month_names(long_months);
|
|
date_input->long_weekday_names(long_days);
|
|
|
|
// customize month, weekday and date formats
|
|
date_output->format("%Y-%B-%d");
|
|
date_input->format("%Y-%B-%d");
|
|
date_output->month_format("%B"); // full name
|
|
date_input->month_format("%B"); // full name
|
|
date_output->weekday_format("%A"); // full name
|
|
date_input->weekday_format("%A"); // full name
|
|
|
|
ss.str("");
|
|
ss << greg_month(3);
|
|
cout << ss.str() << endl; // "march"
|
|
ss.str("");
|
|
ss << greg_weekday(3);
|
|
cout << ss.str() << endl; // "tuesday"
|
|
ss.str("");
|
|
ss << date(2005,Jul,4);
|
|
cout << ss.str() << endl; // "2005-july-04"
|
|
]]>
|
|
</programlisting>
|
|
|
|
|
|
<anchor id="tut_sv" />
|
|
<bridgehead renderas="sect4">Special Values</bridgehead>
|
|
<para>Customizing the input and output of special values is best done by creating a new special_values_parser and special_values_formatter. The new strings can be set at construction time (as in the example below).</para>
|
|
(continued from previous example)
|
|
<programlisting>
|
|
<![CDATA[
|
|
// reset the formats to defaults
|
|
output_facet->format(local_time_facet::default_time_format);
|
|
input_facet->format(local_time_input_facet::default_time_input_format);
|
|
|
|
// create custom special_values parser and formatter objects
|
|
// and add them to the facets
|
|
string sv[5] = {"nadt","neg_inf", "pos_inf", "min_dt", "max_dt" };
|
|
vector<string> sv_names(&sv[0], &sv[5]);
|
|
special_values_parser sv_parser(sv_names.begin(), sv_names.end());
|
|
special_values_formatter sv_formatter(sv_names.begin(), sv_names.end());
|
|
output_facet->special_values_formatter(sv_formatter);
|
|
input_facet->special_values_parser(sv_parser);
|
|
|
|
ss.str("");
|
|
ldt = local_date_time(not_a_date_time);
|
|
ss << ldt;
|
|
cout << ss.str() << endl; // "nadt"
|
|
|
|
ss.str("min_dt");
|
|
ss >> ldt;
|
|
ss.str("");
|
|
ss << ldt;
|
|
cout << ss.str() << endl; // "1400-Jan-01 00:00:00 UTC"
|
|
]]>
|
|
</programlisting>
|
|
<para>NOTE: even though we sent in strings for min and max to the formatter, they are ignored because those special values construct to actual dates (as shown above).</para>
|
|
|
|
|
|
<anchor id="tut_dper" />
|
|
<bridgehead renderas="sect4">Date/Time Periods</bridgehead>
|
|
<para>Customizing the input and output of periods is best done by creating a new period_parser and period_formatter. The new strings can be set at construction time (as in the example below).</para>
|
|
(continued from previous example)
|
|
<programlisting>
|
|
<![CDATA[
|
|
// all formats set back to defaults (not shown for brevity)
|
|
|
|
// create our date_period
|
|
date_period dp(date(2005,Mar,1), days(31)); // month of march
|
|
|
|
// custom period formatter and parser
|
|
period_formatter per_formatter(period_formatter::AS_OPEN_RANGE,
|
|
" to ", "from ", " exclusive", " inclusive" );
|
|
period_parser per_parser(period_parser::AS_OPEN_RANGE,
|
|
" to ", "from ", " exclusive" , "inclusive" );
|
|
|
|
// default output
|
|
ss.str("");
|
|
ss << dp;
|
|
cout << ss.str() << endl; // "[2005-Mar-01/2005-Mar-31]"
|
|
|
|
// add out custom parser and formatter to the facets
|
|
date_output->period_formatter(per_formatter);
|
|
date_input->period_parser(per_parser);
|
|
|
|
// custom output
|
|
ss.str("");
|
|
ss << dp;
|
|
cout << ss.str() << endl; // "from 2005-Feb-01 to 2005-Apr-01 exclusive"
|
|
]]>
|
|
</programlisting>
|
|
|
|
<anchor id="tut_dgen" />
|
|
<bridgehead renderas="sect4">Date Generators</bridgehead>
|
|
<para>Customizing the input and output of date_generators is done by replacing the existing strings (in the facet) with new strings.</para>
|
|
<para>NOTE: We've shown earlier that the components of a date/time representation can be re-ordered via the format string. This is not the case with date_generators. The elements themselves can be customized but their order cannot be changed.</para>
|
|
(continued from previous example)
|
|
<programlisting>
|
|
<![CDATA[
|
|
// custom date_generator phrases
|
|
string dg_phrases[9] = { "1st", "2nd", "3rd", "4th", "5th",
|
|
"final", "prior to", "following", "in" };
|
|
vector<string> phrases(&dg_phrases[0], &dg_phrases[9]);
|
|
|
|
// create our date_generator
|
|
first_day_of_the_week_before d_gen(Monday);
|
|
|
|
// default output
|
|
ss.str("");
|
|
ss << d_gen;
|
|
cout << ss.str() << endl; // "Mon before"
|
|
|
|
// add our custom strings to the date facets
|
|
date_output->date_gen_phrase_strings(phrases);
|
|
date_input->date_gen_element_strings(phrases);
|
|
|
|
// custom output
|
|
ss.str("");
|
|
ss << d_gen;
|
|
cout << ss.str() << endl; // "Mon prior to"
|
|
]]>
|
|
</programlisting>
|
|
|
|
</section>
|