/*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* limitations under the License.
*/
-#ifndef FOLLY_BASE_FOREACH_H_
-#define FOLLY_BASE_FOREACH_H_
+#pragma once
-/*
- * Iterim macros (until we have C++0x range-based for) that simplify
- * writing loops of the form
- *
- * for (Container<data>::iterator i = c.begin(); i != c.end(); ++i) statement
- *
- * Just replace the above with:
- *
- * FOR_EACH (i, c) statement
- *
- * and everything is taken care of.
- *
- * The implementation is a bit convoluted to make sure the container is
- * only evaluated once (however, keep in mind that c.end() is evaluated
- * at every pass through the loop). To ensure the container is not
- * evaluated multiple times, the macro defines one do-nothing if
- * statement to inject the Boolean variable FOR_EACH_state1, and then a
- * for statement that is executed only once, which defines the variable
- * FOR_EACH_state2 holding a reference to the container being
- * iterated. The workhorse is the last loop, which uses the just defined
- * reference FOR_EACH_state2.
+/**
+ * This header is deprecated
*
- * The state variables are nested so they don't interfere; you can use
- * FOR_EACH multiple times in the same scope, either at the same level or
- * nested.
+ * Use range-based for loops, and if necessary Ranges-v3.
*
- * In optimized builds g++ eliminates the extra gymnastics entirely and
- * generates code 100% identical to the handwritten loop.
+ * Some of the messaging here presumes that you have coded:
*
- * This will not work with temporary containers. Consider BOOST_FOREACH
- * if you need that.
+ * #include <range/v3/all.hpp>
+ * using namespace ranges;
*/
-#include <boost/type_traits/remove_cv.hpp>
-
-namespace folly { namespace detail {
+#include <folly/Preprocessor.h>
+#include <type_traits>
/*
- * Simple template for obtaining the unqualified type given a generic
- * type T. For example, if T is const int,
- * typeof(remove_cv_from_expression(T())) yields int. Due to a bug in
- * g++, you need to actually use
- * typeof(remove_cv_from_expression(T())) instead of typename
- * boost::remove_cv<T>::type. Note that the function
- * remove_cv_from_expression is never defined - use it only inside
- * typeof.
+ * Form a local variable name from "FOR_EACH_" x __LINE__, so that
+ * FOR_EACH can be nested without creating shadowed declarations.
*/
-template <class T> typename boost::remove_cv<T>::type
-remove_cv_from_expression(T value);
-
-}}
+#define _FE_ANON(x) FB_CONCATENATE(FOR_EACH_, FB_CONCATENATE(x, __LINE__))
/*
- * Use a "reference reference" (auto&&) to take advantage of reference
- * collapsing rules, if available. In this case, FOR_EACH* will work with
- * temporary containers.
- */
-#define FB_AUTO_RR(x, y) auto&& x = y
-
-/*
- * The first AUTO should be replaced by decltype((c)) &
- * FOR_EACH_state2, but bugs in gcc prevent that from functioning
- * properly. The second pair of parens in decltype is actually
- * required, see
- * cpp-next.com/archive/2011/04/appearing-and-disappearing-consts-in-c/
+ * If you just want the element values, please use:
+ *
+ * for (auto&& element : collection)
+ *
+ * If you need access to the iterators please write an explicit iterator loop
*/
-#define FOR_EACH(i, c) \
- if (bool FOR_EACH_state1 = false) {} else \
- for (auto & FOR_EACH_state2 = (c); \
- !FOR_EACH_state1; FOR_EACH_state1 = true) \
- for (auto i = FOR_EACH_state2.begin(); \
- i != FOR_EACH_state2.end(); ++i)
+#define FOR_EACH(i, c) \
+ if (bool _FE_ANON(s1_) = false) {} else \
+ for (auto && _FE_ANON(s2_) = (c); \
+ !_FE_ANON(s1_); _FE_ANON(s1_) = true) \
+ for (auto i = _FE_ANON(s2_).begin(); \
+ i != _FE_ANON(s2_).end(); ++i)
/*
- * Similar to FOR_EACH, but iterates the container backwards by
- * using rbegin() and rend().
+ * If you just want the element values, please use this (ranges-v3) construct:
+ *
+ * for (auto&& element : collection | view::reverse)
+ *
+ * If you need access to the iterators please write an explicit iterator loop
*/
#define FOR_EACH_R(i, c) \
- if (bool FOR_EACH_R_state1 = false) {} else \
- for (auto & FOR_EACH_R_state2 = (c); \
- !FOR_EACH_R_state1; FOR_EACH_R_state1 = true) \
- for (auto i = FOR_EACH_R_state2.rbegin(); \
- i != FOR_EACH_R_state2.rend(); ++i)
+ if (bool _FE_ANON(s1_) = false) {} else \
+ for (auto && _FE_ANON(s2_) = (c); \
+ !_FE_ANON(s1_); _FE_ANON(s1_) = true) \
+ for (auto i = _FE_ANON(s2_).rbegin(); \
+ i != _FE_ANON(s2_).rend(); ++i)
/*
- * Similar to FOR_EACH but also allows client to specify a 'count' variable
- * to track the current iteration in the loop (starting at zero).
- * Similar to python's enumerate() function. For example:
- * string commaSeparatedValues = "VALUES: ";
- * FOR_EACH_ENUMERATE(ii, value, columns) { // don't want comma at the end!
- * commaSeparatedValues += (ii == 0) ? *value : string(",") + *value;
- * }
+ * If you just want the element values, please use this (ranges-v3) construct:
+ *
+ * for (auto&& element : collection | view::zip(view::ints))
+ *
+ * If you need access to the iterators please write an explicit iterator loop
+ * and use a counter variable
*/
#define FOR_EACH_ENUMERATE(count, i, c) \
- if (bool FOR_EACH_state1 = false) {} else \
- for (auto & FOR_EACH_state2 = (c); \
- !FOR_EACH_state1; FOR_EACH_state1 = true) \
- if (size_t FOR_EACH_privateCount = 0) {} else \
- if (const size_t& count = FOR_EACH_privateCount) {} else \
+ if (bool _FE_ANON(s1_) = false) {} else \
+ for (auto && FOR_EACH_state2 = (c); \
+ !_FE_ANON(s1_); _FE_ANON(s1_) = true) \
+ if (size_t _FE_ANON(n1_) = 0) {} else \
+ if (const size_t& count = _FE_ANON(n1_)) {} else \
for (auto i = FOR_EACH_state2.begin(); \
- i != FOR_EACH_state2.end(); ++FOR_EACH_privateCount, ++i)
-
+ i != FOR_EACH_state2.end(); ++_FE_ANON(n1_), ++i)
/**
- * Similar to FOR_EACH, but gives the user the key and value for each entry in
- * the container, instead of just the iterator to the entry. For example:
- * map<string, string> testMap;
- * FOR_EACH_KV(key, value, testMap) {
- * cout << key << " " << value;
- * }
+ * If you just want the keys, please use this (ranges-v3) construct:
+ *
+ * for (auto&& element : collection | view::keys)
+ *
+ * If you just want the values, please use this (ranges-v3) construct:
+ *
+ * for (auto&& element : collection | view::values)
+ *
+ * If you need to see both, use:
+ *
+ * for (auto&& element : collection) {
+ * auto const& key = element.first;
+ * auto& value = element.second;
+ * ......
+ * }
+ *
*/
-#define FOR_EACH_KV(k, v, c) \
- if (unsigned int FOR_EACH_state1 = 0) {} else \
- for (FB_AUTO_RR(FOR_EACH_state2, (c)); \
- !FOR_EACH_state1; FOR_EACH_state1 = 1) \
- for (auto FOR_EACH_state3 = FOR_EACH_state2.begin(); \
- FOR_EACH_state3 != FOR_EACH_state2.end(); \
- FOR_EACH_state1 == 2 \
- ? ((FOR_EACH_state1 = 0), ++FOR_EACH_state3) \
- : (FOR_EACH_state3 = FOR_EACH_state2.end())) \
- for (auto &k = FOR_EACH_state3->first; \
- !FOR_EACH_state1; ++FOR_EACH_state1) \
- for (auto &v = FOR_EACH_state3->second; \
- !FOR_EACH_state1; ++FOR_EACH_state1)
+#define FOR_EACH_KV(k, v, c) \
+ if (unsigned int _FE_ANON(s1_) = 0) {} else \
+ for (auto && _FE_ANON(s2_) = (c); \
+ !_FE_ANON(s1_); _FE_ANON(s1_) = 1) \
+ for (auto _FE_ANON(s3_) = _FE_ANON(s2_).begin(); \
+ _FE_ANON(s3_) != _FE_ANON(s2_).end(); \
+ _FE_ANON(s1_) == 2 \
+ ? ((_FE_ANON(s1_) = 0), ++_FE_ANON(s3_)) \
+ : (_FE_ANON(s3_) = _FE_ANON(s2_).end())) \
+ for (auto &k = _FE_ANON(s3_)->first; \
+ !_FE_ANON(s1_); ++_FE_ANON(s1_)) \
+ for (auto &v = _FE_ANON(s3_)->second; \
+ !_FE_ANON(s1_); ++_FE_ANON(s1_))
namespace folly { namespace detail {
} }
/*
- * Iteration with given limits. end is assumed to be reachable from
- * begin. end is evaluated every pass through the loop.
+ * Look at the Ranges-v3 views and you'll probably find an easier way to build
+ * the view you want but the equivalent is roughly:
*
- * NOTE: The type of the loop variable should be the common type of "begin"
- * and "end". e.g. If "begin" is "int" but "end" is "long", we want "i"
- * to be "long". This is done by getting the type of (true ? begin : end)
+ * for (auto& element : make_iterator_range(begin, end))
*/
#define FOR_EACH_RANGE(i, begin, end) \
for (auto i = (true ? (begin) : (end)); \
++i)
/*
- * Iteration with given limits. begin is assumed to be reachable from
- * end by successive decrements. begin is evaluated every pass through
- * the loop.
+ * Look at the Ranges-v3 views and you'll probably find an easier way to build
+ * the view you want but the equivalent is roughly:
*
- * NOTE: The type of the loop variable should be the common type of "begin"
- * and "end". e.g. If "begin" is "int" but "end" is "long", we want "i"
- * to be "long". This is done by getting the type of (false ? begin : end)
+ * for (auto& element : make_iterator_range(begin, end) | view::reverse)
*/
#define FOR_EACH_RANGE_R(i, begin, end) \
for (auto i = (false ? (begin) : (end)); ::folly::detail::downTo(i, (begin));)
-
-#endif
projects / folly.git / blobdiff