Add `Concat` to `CmdlineBuilder`.

(partially cherry picked from commit 7b6aef7770375817cfc245ed5f03c1c55218a7a1)

Bug: 291903090
Test: m test-art-host-gtest-art_libarttools_tests
Merged-In: Ia8068d804294debe0de6c947f3878da4dbf8c8ca
Change-Id: I4dd0b59fda1f3416b8d17a4715030d92db70b5b0

2 files changed, 26 insertions, 0 deletions

diff --git a/libarttools/tools/cmdline_builder.h b/libarttools/tools/cmdline_builder.h
index 13b79cacd0..fd11ee87ba 100644
--- a/libarttools/tools/cmdline_builder.h
+++ b/libarttools/tools/cmdline_builder.h
@@ -17,6 +17,8 @@
 #ifndef ART_LIBARTTOOLS_TOOLS_CMDLINE_BUILDER_H_
 #define ART_LIBARTTOOLS_TOOLS_CMDLINE_BUILDER_H_
 
+#include <algorithm>
+#include <iterator>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -135,6 +137,15 @@ class CmdlineBuilder {
     return *this;
   }
 
+  // Concatenates this builder with another. Returns the concatenated result and nullifies the input
+  // builder.
+  CmdlineBuilder& Concat(CmdlineBuilder&& other) {
+    elements_.reserve(elements_.size() + other.elements_.size());
+    std::move(other.elements_.begin(), other.elements_.end(), std::back_inserter(elements_));
+    other.elements_.clear();
+    return *this;
+  }
+
  private:
   std::vector<std::string> elements_;
 };
diff --git a/libarttools/tools/cmdline_builder_test.cc b/libarttools/tools/cmdline_builder_test.cc
index 8509f73e66..55518607db 100644
--- a/libarttools/tools/cmdline_builder_test.cc
+++ b/libarttools/tools/cmdline_builder_test.cc
@@ -16,6 +16,8 @@
 
 #include "cmdline_builder.h"
 
+#include <utility>
+
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
@@ -115,6 +117,19 @@ TEST_F(CmdlineBuilderTest, AddRuntimeIfFalse) {
   EXPECT_THAT(args_.Get(), IsEmpty());
 }
 
+TEST_F(CmdlineBuilderTest, Concat) {
+  args_.Add("--flag1");
+  args_.Add("--flag2");
+
+  CmdlineBuilder other;
+  other.Add("--flag3");
+  other.Add("--flag4");
+
+  args_.Concat(std::move(other));
+  EXPECT_THAT(args_.Get(), ElementsAre("--flag1", "--flag2", "--flag3", "--flag4"));
+  EXPECT_THAT(other.Get(), IsEmpty());
+}
+
 }  // namespace
 }  // namespace tools
 }  // namespace art