X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FMapUtil.h;h=b00bccff4d99b0122340397fcd7554fca89d2290;hb=140c62d25d930cdbdacaa337d254a2471875a4be;hp=fda6f3d704632f6cb328dad13599cae9b1920872;hpb=22afce906d7e98d95f8c45c3301072d9fd891d41;p=folly.git

diff --git a/folly/MapUtil.h b/folly/MapUtil.h
index fda6f3d7..b00bccff 100644
--- a/folly/MapUtil.h
+++ b/folly/MapUtil.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2015 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,9 @@
 #ifndef FOLLY_MAPUTIL_H_
 #define FOLLY_MAPUTIL_H_
 
+#include <folly/Conv.h>
+#include <folly/Optional.h>
+
 namespace folly {
 
 /**
@@ -32,6 +35,36 @@ typename Map::mapped_type get_default(
   return (pos != map.end() ? pos->second : dflt);
 }
 
+/**
+ * Given a map and a key, return the value corresponding to the key in the map,
+ * or throw an exception of the specified type.
+ */
+template <class E = std::out_of_range, class Map>
+typename Map::mapped_type get_or_throw(
+    const Map& map, const typename Map::key_type& key,
+    const std::string& exceptionStrPrefix = std::string()) {
+  auto pos = map.find(key);
+  if (pos != map.end()) {
+    return pos->second;
+  }
+  throw E(folly::to<std::string>(exceptionStrPrefix, key));
+}
+
+/**
+ * Given a map and a key, return a Optional<V> if the key exists and None if the
+ * key does not exist in the map.
+ */
+template <class Map>
+folly::Optional<typename Map::mapped_type> get_optional(
+    const Map& map, const typename Map::key_type& key) {
+  auto pos = map.find(key);
+  if (pos != map.end()) {
+    return folly::Optional<typename Map::mapped_type>(pos->second);
+  } else {
+    return folly::none;
+  }
+}
+
 /**
  * Given a map and a key, return a reference to the value corresponding to the
  * key in the map, or the given default reference if the key doesn't exist in
@@ -69,4 +102,3 @@ typename Map::mapped_type* get_ptr(
 }  // namespace folly
 
 #endif /* FOLLY_MAPUTIL_H_ */
-