From 996f7882ca6b5040ed9ac2844b921f23576b2b8e Mon Sep 17 00:00:00 2001
From: Pranav Srinivas Kumar <pranav.srinivas.kumar@gmail.com>
Date: Sat, 30 Mar 2019 21:09:05 -0400
Subject: [PATCH] Implemented support for parsing both positional and optional
 arguments

---
 src/argparse.hpp                    | 23 ++++++++++++++-
 tests/main.cpp                      |  1 +
 tests/test_positional_arguments.hpp | 45 +++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_positional_arguments.hpp

diff --git a/src/argparse.hpp b/src/argparse.hpp
index 85c1869..cfb3f73 100644
--- a/src/argparse.hpp
+++ b/src/argparse.hpp
@@ -140,7 +140,8 @@ struct Argument {
 class ArgumentParser {
   public:
     ArgumentParser(const std::string& aProgramName) :
-      mProgramName(aProgramName) {}
+      mProgramName(aProgramName),
+      mNextPositionalArgument(0) {}
 
     template<typename T, typename... Targs>
     Argument& add_argument(T value, Targs... Fargs) {
@@ -196,6 +197,25 @@ class ArgumentParser {
         else {
           // This is a positional argument. 
           // Parse and save into mPositionalArguments vector
+          auto tArgument = mPositionalArguments[mNextPositionalArgument];
+          auto tCount = tArgument->mNumArgs;
+          while (tCount > 0) {
+            if (i < argc) {
+              tArgument->mRawValues.push_back(argv[i]);
+              if (tArgument->mAction != nullptr)
+                tArgument->mValues.push_back(tArgument->mAction(argv[i]));
+              else {
+                if (tArgument->mDefaultValue.has_value())
+                  tArgument->mValues.push_back(tArgument->mDefaultValue);
+                else
+                  tArgument->mValues.push_back(std::string(argv[i]));
+              }
+            }
+            tCount -= 1;
+            if (tCount > 0) i += 1;
+          }
+          if (tCount == 0)
+            mNextPositionalArgument += 1;
         }
       }
     }
@@ -238,6 +258,7 @@ class ArgumentParser {
 
     std::string mProgramName;
     std::vector<std::shared_ptr<Argument>> mPositionalArguments;
+    size_t mNextPositionalArgument;
     std::map<std::string, std::shared_ptr<Argument>> mArgumentMap;
 };
 
diff --git a/tests/main.cpp b/tests/main.cpp
index 1858f58..06e37bd 100644
--- a/tests/main.cpp
+++ b/tests/main.cpp
@@ -3,3 +3,4 @@
 #include <argparse.hpp>
 #include <test_add_argument.hpp>
 #include <test_parse_args.hpp>
+#include <test_positional_arguments.hpp>
diff --git a/tests/test_positional_arguments.hpp b/tests/test_positional_arguments.hpp
new file mode 100644
index 0000000..4eeea94
--- /dev/null
+++ b/tests/test_positional_arguments.hpp
@@ -0,0 +1,45 @@
+#pragma once
+#include <catch.hpp>
+#include <argparse.hpp>
+
+TEST_CASE("Parse positional arguments", "[parse_args]") {
+  argparse::ArgumentParser program("test");
+  program.add_argument("input");
+  program.add_argument("output");
+  program.parse_args({ "test", "rocket.mesh", "thrust_profile.csv" });
+  auto arguments = program.get_arguments();
+  REQUIRE(arguments.size() == 2);
+  REQUIRE(program.get("input") == "rocket.mesh");
+  REQUIRE(program.get("output") == "thrust_profile.csv");
+}
+
+TEST_CASE("Parse positional arguments with fixed nargs", "[parse_args]") {
+  argparse::ArgumentParser program("test");
+  program.add_argument("input");
+  program.add_argument("output").nargs(2);
+  program.parse_args({ "test", "rocket.mesh", "thrust_profile.csv", "output.mesh" });
+  auto arguments = program.get_arguments();
+  REQUIRE(arguments.size() == 2);
+  REQUIRE(program.get("input") == "rocket.mesh");
+  auto outputs = program.get<std::vector<std::string>>("output");
+  REQUIRE(outputs.size() == 2);
+  REQUIRE(outputs[0] == "thrust_profile.csv");
+  REQUIRE(outputs[1] == "output.mesh");
+}
+
+TEST_CASE("Parse positional arguments with optional arguments", "[parse_args]") {
+  argparse::ArgumentParser program("test");
+  program.add_argument("input");
+  program.add_argument("output").nargs(2);
+  program.add_argument("--num_iterations")
+    .action([](const std::string& value) { return std::stoi(value); });
+  program.parse_args({ "test", "rocket.mesh", "--num_iterations", "15", "thrust_profile.csv", "output.mesh" });
+  auto arguments = program.get_arguments();
+  REQUIRE(arguments.size() == 3);
+  REQUIRE(program.get<int>("--num_iterations") == 15);
+  REQUIRE(program.get("input") == "rocket.mesh");
+  auto outputs = program.get<std::vector<std::string>>("output");
+  REQUIRE(outputs.size() == 2);
+  REQUIRE(outputs[0] == "thrust_profile.csv");
+  REQUIRE(outputs[1] == "output.mesh");
+}
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