217 lines
6.5 KiB
C++
217 lines
6.5 KiB
C++
/** @example format.cc
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*
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* An example of using the string formatting system, including various
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* differences from C such as user defined type and range formatting.
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*/
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#include <unordered_map>
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#include <vector>
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#include <tuple>
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#include <clocale>
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#include <ostd/algorithm.hh>
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#include <ostd/range.hh>
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#include <ostd/io.hh>
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using namespace ostd;
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using namespace ostd::string_literals;
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struct Foo {
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};
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/* implementing formatting for custom objects */
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template<>
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struct ostd::format_traits<Foo> {
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template<typename R>
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static void to_format(Foo const &, R &writer, format_spec const &fs) {
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switch (fs.spec()) {
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case 'i':
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range_put_all(writer, "Foo_i"_sr);
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break;
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default:
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range_put_all(writer, "Foo_s"_sr);
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break;
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}
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if (fs.flags() & FMT_FLAG_AT) {
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range_put_all(writer, "_esc"_sr);
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}
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}
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};
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int main() {
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std::vector<int> x = { 5, 10, 15, 20 };
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/* prints [5|10|15|20] (using | as the delimiter and %s for each item),
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* the syntax for ranges is %(CONTENTS%) where CONTENTS is a sequence
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* up until and including the last format mark followed by a delimiter,
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* so for example "%s, " has "%s" for formatting and ", " for the delimiter
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* and "%d: %s, " has "%d: %s" for format and ", " for the delimiter; if
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* you need to specify a complicated manual delimiter, you can use the
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* "FORMAT%|DELIMITER" syntax, where %(%s, %) equals %(%s%|, %)
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*/
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writeln("-- range format --");
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writefln("[%(%s|%)]", x);
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/* prints a range with default format {item, item, item, ...}
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* you can enable item escaping by passing the @ flag
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*/
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writeln("\n-- range default format --");
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writefln("%s", x);
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int y[] = { 2, 4, 8, 16, 32 };
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/* prints { 2, 4, 8, 16, 32 } using ", " as the delimiter */
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writeln("\n-- range format of static array --");
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writefln("{ %(%s, %) }", y);
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/* nested range printing - prints each item of the main
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* range with [ %(%s, %) ] and ",\n" as the delimiter
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*/
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writeln("\n-- range format of nested range --");
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writefln("[\n%([ %(%s, %) ]%|,\n%)\n]", map(range(10), [](int v) {
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return range(v + 1);
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}));
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std::unordered_map<std::string, int> m = {
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{ "foo", 5 },
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{ "bar", 10 },
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{ "baz", 15 }
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};
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/* prints something like { "baz": 15, "bar": 10, "foo": 5 }, note that
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* the tuple is expanded into two formats (using the # flag) and the
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* items are escaped with the @ flag (applies to strings and chars)
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*/
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writeln("\n-- range format of hash table --");
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writefln("{ %#(%@s: %d, %) }", m);
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/* not escaped, you get { baz: 15, bar: 10, foo: 5} */
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writeln("\n-- range format of hash table (no escape) --");
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writefln("{ %#(%s: %d, %) }", m);
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/* no expansion of the items, print entire tuple with default format,
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* gets you something like { <"baz", 15>, <"bar", 10>, <"foo", 5> }
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* because the default tuple format is <item, item, item, ...>
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*/
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writeln("\n-- range format of hash table (no item expansion) --");
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writefln("{ %(%@s, %) }", m);
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/* as the @ flag enables escaping on strings and chars,
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* you can use it standalone outside of range/tuple format
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*/
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writeln("\n-- format item escaping --");
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writefln("not escaped: %s, escaped: %@s", "foo", "bar");
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std::tuple<std::string, int, float, std::string> tup{
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"hello world", 1337, 3.14f, "test"
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};
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/* you can expand tuples similarly to ranges, with %<CONTENTS%> where
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* CONTENTS is a regular format string like if the tuple was formatted
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* separately with each item of the tuple passed as a separate argument
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*/
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writeln("\n-- tuple format --");
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writefln("the tuple contains %<%@s, %d, %f, %s%>.", tup);
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writeln("\n-- tuple default format --");
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writefln("auto tuple: %s", tup);
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writeln("\n-- tuple default format (escaped) --");
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writefln("auto tuple with escape: %@s", tup);
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std::tuple<int, float, char const *> xt[] = {
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std::make_tuple(5, 3.14f, "foo"),
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std::make_tuple(3, 1.23f, "bar"),
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std::make_tuple(9, 8.66f, "baz")
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};
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/* formatting a range of tuples, with each tuple expanded using #
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*/
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writeln("\n-- range of tuples format --");
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writefln("[ %#(<%d|%f|%@s>%|, %) ]", xt);
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/* formatting custom objects, the information about the format mark
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* is passed into the to_format function and the object can read it
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*/
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writeln("\n-- custom object format --");
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writefln("%s", Foo{});
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writefln("%i", Foo{});
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writefln("%@s", Foo{});
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writefln("%@i", Foo{});
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auto s = appender<std::string>();
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/* formatting into a string sink (can be any output range, but
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* appender makes sure the capacity is unlimited so it's safe)
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*/
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writeln("\n-- format into a string --");
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format(s, "hello %s", "world");
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writeln(s.get());
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/* locale specific formatting */
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writeln("\n-- number format with C locale --");
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writefln(
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"\"%d\", \"%f\", \"%X\"", 123456789, 12345.6789123, 0x123456789ABCDEF
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);
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cout.imbue(std::locale{""});
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writefln("\n-- number format with system locale --");
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writefln(
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"\"%d\", \"%f\", \"%X\"", 123456789, 12345.6789123, 0x123456789ABCDEF
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);
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}
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/* output:
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-- range format --
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[5|10|15|20]
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-- range default format --
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{5, 10, 15, 20}
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-- range format of static array --
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{ 2, 4, 8, 16, 32 }
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-- range format of nested range --
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[
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[ 0 ],
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[ 0, 1 ],
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[ 0, 1, 2 ],
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[ 0, 1, 2, 3 ],
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[ 0, 1, 2, 3, 4 ],
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[ 0, 1, 2, 3, 4, 5 ],
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[ 0, 1, 2, 3, 4, 5, 6 ],
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[ 0, 1, 2, 3, 4, 5, 6, 7 ],
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[ 0, 1, 2, 3, 4, 5, 6, 7, 8 ],
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[ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
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]
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-- range format of hash table --
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{ "baz": 15, "bar": 10, "foo": 5 }
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-- range format of hash table (no escape) --
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{ baz: 15, bar: 10, foo: 5 }
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-- range format of hash table (no item expansion) --
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{ <"baz", 15>, <"bar", 10>, <"foo", 5> }
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-- format item escaping --
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not escaped: foo, escaped: "bar"
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-- tuple format --
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the tuple contains "hello world", 1337, 3.140000, test.
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-- tuple default format --
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auto tuple: <hello world, 1337, 3.14, test>
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-- tuple default format (escaped) --
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auto tuple with escape: <"hello world", 1337, 3.14, "test">
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-- range of tuples format --
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[ <5|3.140000|"foo">, <3|1.230000|"bar">, <9|8.660000|"baz"> ]
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-- custom object format --
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Foo_s
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Foo_i
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Foo_s_esc
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Foo_i_esc
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-- format into a string --
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hello world
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-- number format with C locale --
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"123456789", "12345.678912", "123456789ABCDEF"
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-- number format with system locale --
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"123 456 789", "12 345,678912", "123 456 789 ABC DEF"
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*/
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