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<h1>Source code for apache_beam.typehints.native_type_compatibility</h1><div class="highlight"><pre>
<span></span><span class="c1">#</span>
<span class="c1"># Licensed to the Apache Software Foundation (ASF) under one or more</span>
<span class="c1"># contributor license agreements. See the NOTICE file distributed with</span>
<span class="c1"># this work for additional information regarding copyright ownership.</span>
<span class="c1"># The ASF licenses this file to You under the Apache License, Version 2.0</span>
<span class="c1"># (the &quot;License&quot;); you may not use this file except in compliance with</span>
<span class="c1"># the License. You may obtain a copy of the License at</span>
<span class="c1">#</span>
<span class="c1"># http://www.apache.org/licenses/LICENSE-2.0</span>
<span class="c1">#</span>
<span class="c1"># Unless required by applicable law or agreed to in writing, software</span>
<span class="c1"># distributed under the License is distributed on an &quot;AS IS&quot; BASIS,</span>
<span class="c1"># WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span>
<span class="c1"># See the License for the specific language governing permissions and</span>
<span class="c1"># limitations under the License.</span>
<span class="c1">#</span>
<span class="sd">&quot;&quot;&quot;Module to convert Python&#39;s native typing types to Beam types.&quot;&quot;&quot;</span>
<span class="kn">from</span> <span class="nn">__future__</span> <span class="k">import</span> <span class="n">absolute_import</span>
<span class="kn">import</span> <span class="nn">collections</span>
<span class="kn">import</span> <span class="nn">typing</span>
<span class="kn">from</span> <span class="nn">builtins</span> <span class="k">import</span> <span class="nb">next</span>
<span class="kn">from</span> <span class="nn">builtins</span> <span class="k">import</span> <span class="nb">range</span>
<span class="kn">from</span> <span class="nn">apache_beam.typehints</span> <span class="k">import</span> <span class="n">typehints</span>
<span class="c1"># Describes an entry in the type map in convert_to_beam_type.</span>
<span class="c1"># match is a function that takes a user type and returns whether the conversion</span>
<span class="c1"># should trigger.</span>
<span class="c1"># arity is the expected arity of the user type. -1 means it&#39;s variadic.</span>
<span class="c1"># beam_type is the Beam type the user type should map to.</span>
<span class="n">_TypeMapEntry</span> <span class="o">=</span> <span class="n">collections</span><span class="o">.</span><span class="n">namedtuple</span><span class="p">(</span>
<span class="s1">&#39;_TypeMapEntry&#39;</span><span class="p">,</span> <span class="p">[</span><span class="s1">&#39;match&#39;</span><span class="p">,</span> <span class="s1">&#39;arity&#39;</span><span class="p">,</span> <span class="s1">&#39;beam_type&#39;</span><span class="p">])</span>
<span class="k">def</span> <span class="nf">_get_arg</span><span class="p">(</span><span class="n">typ</span><span class="p">,</span> <span class="n">index</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Returns the index-th argument to the given type.&quot;&quot;&quot;</span>
<span class="k">return</span> <span class="n">typ</span><span class="o">.</span><span class="n">__args__</span><span class="p">[</span><span class="n">index</span><span class="p">]</span>
<span class="k">def</span> <span class="nf">_len_arg</span><span class="p">(</span><span class="n">typ</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Returns the length of the arguments to the given type.&quot;&quot;&quot;</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">return</span> <span class="nb">len</span><span class="p">(</span><span class="n">typ</span><span class="o">.</span><span class="n">__args__</span><span class="p">)</span>
<span class="k">except</span> <span class="ne">AttributeError</span><span class="p">:</span>
<span class="c1"># For Any type, which takes no arguments.</span>
<span class="k">return</span> <span class="mi">0</span>
<span class="k">def</span> <span class="nf">_safe_issubclass</span><span class="p">(</span><span class="n">derived</span><span class="p">,</span> <span class="n">parent</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Like issubclass, but swallows TypeErrors.</span>
<span class="sd"> This is useful for when either parameter might not actually be a class,</span>
<span class="sd"> e.g. typing.Union isn&#39;t actually a class.</span>
<span class="sd"> Args:</span>
<span class="sd"> derived: As in issubclass.</span>
<span class="sd"> parent: As in issubclass.</span>
<span class="sd"> Returns:</span>
<span class="sd"> issubclass(derived, parent), or False if a TypeError was raised.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">return</span> <span class="nb">issubclass</span><span class="p">(</span><span class="n">derived</span><span class="p">,</span> <span class="n">parent</span><span class="p">)</span>
<span class="k">except</span> <span class="ne">TypeError</span><span class="p">:</span>
<span class="k">return</span> <span class="kc">False</span>
<span class="k">def</span> <span class="nf">_match_issubclass</span><span class="p">(</span><span class="n">match_against</span><span class="p">):</span>
<span class="k">return</span> <span class="k">lambda</span> <span class="n">user_type</span><span class="p">:</span> <span class="n">_safe_issubclass</span><span class="p">(</span><span class="n">user_type</span><span class="p">,</span> <span class="n">match_against</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_match_same_type</span><span class="p">(</span><span class="n">match_against</span><span class="p">):</span>
<span class="c1"># For Union types. They can&#39;t be compared with isinstance either, so we</span>
<span class="c1"># have to compare their types directly.</span>
<span class="k">return</span> <span class="k">lambda</span> <span class="n">user_type</span><span class="p">:</span> <span class="nb">type</span><span class="p">(</span><span class="n">user_type</span><span class="p">)</span> <span class="o">==</span> <span class="nb">type</span><span class="p">(</span><span class="n">match_against</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_match_is_named_tuple</span><span class="p">(</span><span class="n">user_type</span><span class="p">):</span>
<span class="k">return</span> <span class="p">(</span><span class="n">_safe_issubclass</span><span class="p">(</span><span class="n">user_type</span><span class="p">,</span> <span class="n">typing</span><span class="o">.</span><span class="n">Tuple</span><span class="p">)</span> <span class="ow">and</span>
<span class="nb">hasattr</span><span class="p">(</span><span class="n">user_type</span><span class="p">,</span> <span class="s1">&#39;_field_types&#39;</span><span class="p">))</span>
<div class="viewcode-block" id="convert_to_beam_type"><a class="viewcode-back" href="../../../apache_beam.typehints.native_type_compatibility.html#apache_beam.typehints.native_type_compatibility.convert_to_beam_type">[docs]</a><span class="k">def</span> <span class="nf">convert_to_beam_type</span><span class="p">(</span><span class="n">typ</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Convert a given typing type to a Beam type.</span>
<span class="sd"> Args:</span>
<span class="sd"> typ (type): typing type.</span>
<span class="sd"> Returns:</span>
<span class="sd"> type: The given type converted to a Beam type as far as we can do the</span>
<span class="sd"> conversion.</span>
<span class="sd"> Raises:</span>
<span class="sd"> ~exceptions.ValueError: The type was malformed.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">type_map</span> <span class="o">=</span> <span class="p">[</span>
<span class="n">_TypeMapEntry</span><span class="p">(</span>
<span class="n">match</span><span class="o">=</span><span class="n">_match_same_type</span><span class="p">(</span><span class="n">typing</span><span class="o">.</span><span class="n">Any</span><span class="p">),</span>
<span class="n">arity</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span>
<span class="n">beam_type</span><span class="o">=</span><span class="n">typehints</span><span class="o">.</span><span class="n">Any</span><span class="p">),</span>
<span class="n">_TypeMapEntry</span><span class="p">(</span>
<span class="n">match</span><span class="o">=</span><span class="n">_match_issubclass</span><span class="p">(</span><span class="n">typing</span><span class="o">.</span><span class="n">Dict</span><span class="p">),</span>
<span class="n">arity</span><span class="o">=</span><span class="mi">2</span><span class="p">,</span>
<span class="n">beam_type</span><span class="o">=</span><span class="n">typehints</span><span class="o">.</span><span class="n">Dict</span><span class="p">),</span>
<span class="n">_TypeMapEntry</span><span class="p">(</span>
<span class="n">match</span><span class="o">=</span><span class="n">_match_issubclass</span><span class="p">(</span><span class="n">typing</span><span class="o">.</span><span class="n">List</span><span class="p">),</span>
<span class="n">arity</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span>
<span class="n">beam_type</span><span class="o">=</span><span class="n">typehints</span><span class="o">.</span><span class="n">List</span><span class="p">),</span>
<span class="n">_TypeMapEntry</span><span class="p">(</span>
<span class="n">match</span><span class="o">=</span><span class="n">_match_issubclass</span><span class="p">(</span><span class="n">typing</span><span class="o">.</span><span class="n">Set</span><span class="p">),</span>
<span class="n">arity</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span>
<span class="n">beam_type</span><span class="o">=</span><span class="n">typehints</span><span class="o">.</span><span class="n">Set</span><span class="p">),</span>
<span class="c1"># NamedTuple is a subclass of Tuple, but it needs special handling.</span>
<span class="c1"># We just convert it to Any for now.</span>
<span class="c1"># This MUST appear before the entry for the normal Tuple.</span>
<span class="n">_TypeMapEntry</span><span class="p">(</span>
<span class="n">match</span><span class="o">=</span><span class="n">_match_is_named_tuple</span><span class="p">,</span> <span class="n">arity</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span> <span class="n">beam_type</span><span class="o">=</span><span class="n">typehints</span><span class="o">.</span><span class="n">Any</span><span class="p">),</span>
<span class="n">_TypeMapEntry</span><span class="p">(</span>
<span class="n">match</span><span class="o">=</span><span class="n">_match_issubclass</span><span class="p">(</span><span class="n">typing</span><span class="o">.</span><span class="n">Tuple</span><span class="p">),</span>
<span class="n">arity</span><span class="o">=-</span><span class="mi">1</span><span class="p">,</span>
<span class="n">beam_type</span><span class="o">=</span><span class="n">typehints</span><span class="o">.</span><span class="n">Tuple</span><span class="p">),</span>
<span class="n">_TypeMapEntry</span><span class="p">(</span>
<span class="n">match</span><span class="o">=</span><span class="n">_match_same_type</span><span class="p">(</span><span class="n">typing</span><span class="o">.</span><span class="n">Union</span><span class="p">),</span>
<span class="n">arity</span><span class="o">=-</span><span class="mi">1</span><span class="p">,</span>
<span class="n">beam_type</span><span class="o">=</span><span class="n">typehints</span><span class="o">.</span><span class="n">Union</span><span class="p">)</span>
<span class="p">]</span>
<span class="c1"># Find the first matching entry.</span>
<span class="n">matched_entry</span> <span class="o">=</span> <span class="nb">next</span><span class="p">((</span><span class="n">entry</span> <span class="k">for</span> <span class="n">entry</span> <span class="ow">in</span> <span class="n">type_map</span> <span class="k">if</span> <span class="n">entry</span><span class="o">.</span><span class="n">match</span><span class="p">(</span><span class="n">typ</span><span class="p">)),</span> <span class="kc">None</span><span class="p">)</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">matched_entry</span><span class="p">:</span>
<span class="c1"># No match: return original type.</span>
<span class="k">return</span> <span class="n">typ</span>
<span class="k">if</span> <span class="n">matched_entry</span><span class="o">.</span><span class="n">arity</span> <span class="o">==</span> <span class="o">-</span><span class="mi">1</span><span class="p">:</span>
<span class="n">arity</span> <span class="o">=</span> <span class="n">_len_arg</span><span class="p">(</span><span class="n">typ</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">arity</span> <span class="o">=</span> <span class="n">matched_entry</span><span class="o">.</span><span class="n">arity</span>
<span class="k">if</span> <span class="n">_len_arg</span><span class="p">(</span><span class="n">typ</span><span class="p">)</span> <span class="o">!=</span> <span class="n">arity</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">&#39;expecting type </span><span class="si">%s</span><span class="s1"> to have arity </span><span class="si">%d</span><span class="s1">, had arity </span><span class="si">%d</span><span class="s1"> &#39;</span>
<span class="s1">&#39;instead&#39;</span> <span class="o">%</span> <span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="n">typ</span><span class="p">),</span> <span class="n">arity</span><span class="p">,</span> <span class="n">_len_arg</span><span class="p">(</span><span class="n">typ</span><span class="p">)))</span>
<span class="n">typs</span> <span class="o">=</span> <span class="p">[</span><span class="n">convert_to_beam_type</span><span class="p">(</span><span class="n">_get_arg</span><span class="p">(</span><span class="n">typ</span><span class="p">,</span> <span class="n">i</span><span class="p">))</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="n">arity</span><span class="p">)]</span>
<span class="k">if</span> <span class="n">arity</span> <span class="o">==</span> <span class="mi">0</span><span class="p">:</span>
<span class="c1"># Nullary types (e.g. Any) don&#39;t accept empty tuples as arguments.</span>
<span class="k">return</span> <span class="n">matched_entry</span><span class="o">.</span><span class="n">beam_type</span>
<span class="k">elif</span> <span class="n">arity</span> <span class="o">==</span> <span class="mi">1</span><span class="p">:</span>
<span class="c1"># Unary types (e.g. Set) don&#39;t accept 1-tuples as arguments</span>
<span class="k">return</span> <span class="n">matched_entry</span><span class="o">.</span><span class="n">beam_type</span><span class="p">[</span><span class="n">typs</span><span class="p">[</span><span class="mi">0</span><span class="p">]]</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="n">matched_entry</span><span class="o">.</span><span class="n">beam_type</span><span class="p">[</span><span class="nb">tuple</span><span class="p">(</span><span class="n">typs</span><span class="p">)]</span></div>
<div class="viewcode-block" id="convert_to_beam_types"><a class="viewcode-back" href="../../../apache_beam.typehints.native_type_compatibility.html#apache_beam.typehints.native_type_compatibility.convert_to_beam_types">[docs]</a><span class="k">def</span> <span class="nf">convert_to_beam_types</span><span class="p">(</span><span class="n">args</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Convert the given list or dictionary of args to Beam types.</span>
<span class="sd"> Args:</span>
<span class="sd"> args: Either an iterable of types, or a dictionary where the values are</span>
<span class="sd"> types.</span>
<span class="sd"> Returns:</span>
<span class="sd"> If given an iterable, a list of converted types. If given a dictionary,</span>
<span class="sd"> a dictionary with the same keys, and values which have been converted.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">args</span><span class="p">,</span> <span class="nb">dict</span><span class="p">):</span>
<span class="k">return</span> <span class="p">{</span><span class="n">k</span><span class="p">:</span> <span class="n">convert_to_beam_type</span><span class="p">(</span><span class="n">v</span><span class="p">)</span> <span class="k">for</span> <span class="n">k</span><span class="p">,</span> <span class="n">v</span> <span class="ow">in</span> <span class="n">args</span><span class="o">.</span><span class="n">items</span><span class="p">()}</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="p">[</span><span class="n">convert_to_beam_type</span><span class="p">(</span><span class="n">v</span><span class="p">)</span> <span class="k">for</span> <span class="n">v</span> <span class="ow">in</span> <span class="n">args</span><span class="p">]</span></div>
</pre></div>
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