From 60f4775badfc57e5d7225e70868cdd11e43e5db4 Mon Sep 17 00:00:00 2001
From: Alexander Shorin <kxepal@gmail.com>
Date: Thu, 3 Jan 2019 05:32:32 +0300
Subject: [PATCH] PoC of meta strategy, which draws others by a given weight
 distribution

---
 .../src/hypothesis/_strategies.py             |  6 +++
 .../src/hypothesis/provisional.py             | 37 +++++++++++++++++++
 .../src/hypothesis/strategies.py              |  2 +
 3 files changed, 45 insertions(+)

diff --git a/hypothesis-python/src/hypothesis/_strategies.py b/hypothesis-python/src/hypothesis/_strategies.py
index 0974873233..59c328619b 100644
--- a/hypothesis-python/src/hypothesis/_strategies.py
+++ b/hypothesis-python/src/hypothesis/_strategies.py
@@ -2319,3 +2319,9 @@ def emails():
     return builds(u"{}@{}".format, local_part, domains()).filter(
         lambda addr: len(addr) <= 255
     )
+
+
+def distributed(strategies, weights):
+    # type: (List[SearchStrategy], List[Union[int, float]]) -> SearchStrategy[Any]
+    from hypothesis.provisional import distributed
+    return distributed(strategies, weights)
diff --git a/hypothesis-python/src/hypothesis/provisional.py b/hypothesis-python/src/hypothesis/provisional.py
index 97d2625305..1aec7f178d 100644
--- a/hypothesis-python/src/hypothesis/provisional.py
+++ b/hypothesis-python/src/hypothesis/provisional.py
@@ -64,3 +64,40 @@ def ip6_addr_strings():
     """
     part = st.integers(0, 2 ** 16 - 1).map(u"{:04x}".format)
     return st.tuples(*[part] * 8).map(lambda a: u":".join(a).upper())
+
+
+def distributed(strategies, weights):
+    from hypothesis.internal.conjecture.utils import Sampler
+    from hypothesis.strategies import SearchStrategy
+    from hypothesis.searchstrategy.strategies import check_strategy
+    from hypothesis.internal.validation import check_type, InvalidArgument
+
+    class DistributedStrategy(SearchStrategy):
+        def __init__(self, strategies, weights):
+            SearchStrategy.__init__(self)
+            self.sampler = Sampler(weights)
+            self.strategies = strategies
+
+        def calc_has_reusable_values(self, recur):
+            return True
+
+        def do_draw(self, data):
+            strategy = self.strategies[self.sampler.sample(data)]
+            return strategy.do_draw(data)
+
+    assert strategies
+
+    for strategy in strategies:
+        check_strategy(strategy)
+
+    for weight in weights:
+        check_type((int, float), weight)
+        if weight < 0:
+            raise InvalidArgument("weight must be a positive number")
+
+    if len(strategies) != len(weights):
+        raise InvalidArgument(
+            "The number of weights must match the number of strategies"
+        )
+
+    return DistributedStrategy(strategies, weights)
diff --git a/hypothesis-python/src/hypothesis/strategies.py b/hypothesis-python/src/hypothesis/strategies.py
index 5015a016ed..1cffcd08d4 100644
--- a/hypothesis-python/src/hypothesis/strategies.py
+++ b/hypothesis-python/src/hypothesis/strategies.py
@@ -32,6 +32,7 @@
     decimals,
     deferred,
     dictionaries,
+    distributed,
     emails,
     fixed_dictionaries,
     floats,
@@ -83,6 +84,7 @@
     "decimals",
     "deferred",
     "dictionaries",
+    "distributed",
     "emails",
     "fixed_dictionaries",
     "floats",