From 9037b0845443d867795dc503d7e295eed24895fe Mon Sep 17 00:00:00 2001
From: Pranav Srinivas Kumar <pranav.srinivas.kumar@gmail.com>
Date: Mon, 1 Apr 2019 20:41:14 -0400
Subject: [PATCH] Added support for parent parsers. Some basic unit tests

---
 src/argparse.hpp              | 25 +++++++++++++++++++++++++
 tests/main.cpp                |  3 ++-
 tests/test_parent_parsers.hpp | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_parent_parsers.hpp

diff --git a/src/argparse.hpp b/src/argparse.hpp
index 5abfbea..054aa0e 100644
--- a/src/argparse.hpp
+++ b/src/argparse.hpp
@@ -274,6 +274,30 @@ class ArgumentParser {
       return *tArgument;
     }
 
+    void add_parents() {
+      for (size_t i = 0; i < mParentParsers.size(); i++) {
+        auto tParentParser = mParentParsers[i];
+        auto tPositionalArguments = tParentParser.mPositionalArguments;
+        for (auto& tArgument : tPositionalArguments) {
+          mPositionalArguments.push_back(tArgument);
+        }
+        auto tOptionalArguments = tParentParser.mOptionalArguments;
+        for (auto& tArgument : tOptionalArguments) {
+          mOptionalArguments.push_back(tArgument);
+        }
+        auto tArgumentMap = tParentParser.mArgumentMap;
+        for (auto&[tKey, tValue] : tArgumentMap) {
+          upsert(mArgumentMap, tKey, tValue);
+        }
+      }
+    }
+
+    template<typename T, typename... Targs>
+    void add_parents(T aArgumentParser, Targs... Fargs) {
+      mParentParsers.push_back(aArgumentParser);
+      add_parents(Fargs...);
+    }
+
     void parse_args(const std::vector<std::string>& aArguments) {
       parse_args_internal(aArguments);
       parse_args_validate();
@@ -563,6 +587,7 @@ class ArgumentParser {
     }
 
     std::string mProgramName;
+    std::vector<ArgumentParser> mParentParsers;
     std::vector<std::shared_ptr<Argument>> mPositionalArguments;
     std::vector<std::shared_ptr<Argument>> mOptionalArguments;
     size_t mNextPositionalArgument;
diff --git a/tests/main.cpp b/tests/main.cpp
index 8892744..98c2408 100644
--- a/tests/main.cpp
+++ b/tests/main.cpp
@@ -6,4 +6,5 @@
 #include <test_optional_arguments.hpp>
 #include <test_compound_arguments.hpp>
 #include <test_actions.hpp>
-#include <test_container_arguments.hpp>
\ No newline at end of file
+#include <test_container_arguments.hpp>
+#include <test_parent_parsers.hpp>
\ No newline at end of file
diff --git a/tests/test_parent_parsers.hpp b/tests/test_parent_parsers.hpp
new file mode 100644
index 0000000..79a6d5c
--- /dev/null
+++ b/tests/test_parent_parsers.hpp
@@ -0,0 +1,34 @@
+#pragma once
+#include <catch.hpp>
+#include <argparse.hpp>
+
+TEST_CASE("Add parent parsers", "[parent_parsers]") {
+  argparse::ArgumentParser parent_parser("main");
+  parent_parser.add_argument("--verbose")
+    .default_value(false)
+    .implicit_value(true);
+
+  argparse::ArgumentParser child_parser("foo");
+  child_parser.add_parents(parent_parser);
+  child_parser.parse_args({ "./main", "--verbose"});
+  REQUIRE(child_parser["--verbose"] == true);
+}
+
+TEST_CASE("Add parent to multiple parent parsers", "[parent_parsers]") {
+  argparse::ArgumentParser parent_parser("main");
+  parent_parser.add_argument("--parent")
+    .default_value(0)
+    .action([](const std::string& value) { return std::stoi(value); });
+
+  argparse::ArgumentParser foo_parser("foo");
+  foo_parser.add_argument("foo");
+  foo_parser.add_parents(parent_parser);
+  foo_parser.parse_args({ "./main", "--parent", "2", "XXX" });
+  REQUIRE(foo_parser["--parent"] == 2);
+  REQUIRE(foo_parser["foo"] == std::string("XXX"));
+
+  argparse::ArgumentParser bar_parser("bar");
+  bar_parser.add_argument("--bar");
+  bar_parser.parse_args({ "./main", "--bar", "YYY" });
+  REQUIRE(bar_parser["--bar"] == std::string("YYY"));
+}
\ No newline at end of file