[planning] Add Anzu planning tools to planning/sampling_based/dev

common/parallelism.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <compare>
 #include <optional>
 #include <string_view>
 
@@ -90,6 +91,10 @@ class Parallelism {
   /** Returns the degree of parallelism. The result will always be >= 1. */
   int num_threads() const { return num_threads_; }
 
+  /** Provides the automatic comparison operator between Parallelisms, which
+  compares num_threads between this and the other instance of Parallelism. */
+  auto operator<=>(const Parallelism&) const = default;
+
  private:
   int num_threads_ = 1;
 };

common/test/parallelism_test.cc

@@ -61,6 +61,31 @@ GTEST_TEST(ParallelismTest, BoolConversionAssignmentTest) {
   EXPECT_EQ(assigned_parallelism.num_threads(), kNoneThreads);
 }
 
+// Test that all of the comparisons between Parallelism work.
+GTEST_TEST(ParallelismTest, ParallelismCompareTest) {
+  const Parallelism false_parallelism(false);
+  const Parallelism none_parallelism = Parallelism::None();
+  const Parallelism true_parallelism(true);
+  const Parallelism max_parallelism = Parallelism::Max();
+
+  EXPECT_EQ(false_parallelism, false_parallelism);
+  EXPECT_EQ(none_parallelism, none_parallelism);
+  EXPECT_EQ(false_parallelism, none_parallelism);
+
+  EXPECT_EQ(true_parallelism, true_parallelism);
+  EXPECT_EQ(max_parallelism, max_parallelism);
+  EXPECT_EQ(true_parallelism, max_parallelism);
+
+  EXPECT_NE(false_parallelism, true_parallelism);
+  EXPECT_NE(none_parallelism, max_parallelism);
+
+  EXPECT_LT(false_parallelism, true_parallelism);
+  EXPECT_LT(none_parallelism, max_parallelism);
+
+  EXPECT_GT(true_parallelism, false_parallelism);
+  EXPECT_GT(max_parallelism, none_parallelism);
+}
+
 // Tests all variety of environment variable string parsing.
 GTEST_TEST(ParallelismTest, ParsingLogicTest) {
   // When string parsing fails, this is what we get back.