Adds PS::span and std::string_view to CmdLineArgs.

Patch By: phosit
Differential Revision: https://code.wildfiregames.com/D4677
This was SVN commit r27106.

source/main.cpp

@@ -108,8 +108,8 @@ typedef unsigned long DWORD;
 // Request the high performance GPU on Windows by default if no system override is specified.
 // See:
 // - https://github.com/supertuxkart/stk-code/pull/4693/commits/0a99c667ef513b2ce0f5755729a6e05df8aac48a
-// - https://docs.nvidia.com/gameworks/content/technologies/desktop/optimus.htm 
-// - https://gpuopen.com/learn/amdpowerxpressrequesthighperformance/ 
+// - https://docs.nvidia.com/gameworks/content/technologies/desktop/optimus.htm
+// - https://gpuopen.com/learn/amdpowerxpressrequesthighperformance/
 extern "C"
 {
 	__declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
@@ -496,9 +496,9 @@ static void StartRLInterface(CmdLineArgs args)
 
 // moved into a helper function to ensure args is destroyed before
 // exit(), which may result in a memory leak.
-static void RunGameOrAtlas(int argc, const char* argv[])
+static void RunGameOrAtlas(const PS::span<const char* const> argv)
 {
-	CmdLineArgs args(argc, argv);
+	const CmdLineArgs args(argv);
 
 	g_CmdLineArgs = args;
 
@@ -736,7 +736,8 @@ extern "C" int main(int argc, char* argv[])
 
 	EarlyInit();	// must come at beginning of main
 
-	RunGameOrAtlas(argc, const_cast<const char**>(argv));
+	// static_cast is ok, argc is never negative.
+	RunGameOrAtlas({argv, static_cast<std::size_t>(argc)});
 
 	// Shut down profiler initialised by EarlyInit
 	g_Profiler2.Shutdown();

source/ps/CStr.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2022 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -63,12 +63,9 @@ public:
 	using StrBase = std::tstring;
 	using Char = typename std::tstring::value_type;
 
-	CStr() {}
-	CStr(const Char* str) : StrBase(str) {}
-	CStr(const Char* str, size_t len) : StrBase(str, len) {}
 	CStr(const StrBase& str) : StrBase(str) {}
-	template<class InputIterator>
-	CStr (InputIterator first, InputIterator last) : StrBase(first, last) {}
+
+	using StrBase::StrBase;
 
 	/**
 	 * Repeat: Named constructor, to avoid overload overload.

source/ps/GameSetup/CmdLineArgs.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2022 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -20,6 +20,10 @@
 
 #include "lib/sysdep/sysdep.h"
 
+#include <algorithm>
+#include <iterator>
+#include <string_view>
+
 CmdLineArgs g_CmdLineArgs;
 
 namespace
@@ -42,41 +46,37 @@ private:
 
 } // namespace
 
-CmdLineArgs::CmdLineArgs(int argc, const char* argv[])
+CmdLineArgs::CmdLineArgs(const PS::span<const char* const> argv)
 {
-	if (argc >= 1)
-	{
-		std::string arg0(argv[0]);
-		// avoid OsPath complaining about mixing both types of separators,
-		// which happens when running in the VC2010 debugger
-		std::replace(arg0.begin(), arg0.end(), '/', SYS_DIR_SEP);
-		m_Arg0 = arg0;
-	}
+	if (argv.empty())
+		return;
 
-	for (int i = 1; i < argc; ++i)
+	std::string arg0(argv[0]);
+	// avoid OsPath complaining about mixing both types of separators,
+	// which happens when running in the VC2010 debugger
+	std::replace(arg0.begin(), arg0.end(), '/', SYS_DIR_SEP);
+	m_Arg0 = arg0;
+
+	// Implicit conversion from const char* to std::string_view.
+	for (const std::string_view arg : argv.subspan(1))
 	{
 		// Only accept arguments that start with '-'
-		if (argv[i][0] != '-')
+		if (arg[0] != '-')
 		{
-			m_ArgsWithoutName.emplace_back(argv[i]);
+			m_ArgsWithoutName.emplace_back(arg);
 			continue;
 		}
 
 		// Allow -arg and --arg
-		char offset = argv[i][1] == '-' ? 2 : 1;
-		CStr name, value;
+		const std::string_view afterDashes = arg.substr(arg[1] == '-' ? 2 : 1);
 
 		// Check for "-arg=value"
-		const char* eq = strchr(argv[i], '=');
-		if (eq)
-		{
-			name = CStr(argv[i]+offset, eq-argv[i]-offset);
-			value = CStr(eq+1);
-		}
-		else
-			name = CStr(argv[i]+offset);
+		const std::string_view::iterator eq =
+			std::find(afterDashes.begin(), afterDashes.end(), '=');
 
-		m_Args.emplace_back(std::move(name), std::move(value));
+		CStr value = (eq != afterDashes.end()) ? CStr{eq + 1, afterDashes.end()} : CStr{};
+
+		m_Args.emplace_back(CStr(afterDashes.begin(), eq), std::move(value));
 	}
 }
 

source/ps/GameSetup/CmdLineArgs.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2022 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -18,9 +18,11 @@
 #ifndef INCLUDED_CMDLINEARGS
 #define INCLUDED_CMDLINEARGS
 
-#include "ps/CStr.h"
 #include "lib/os_path.h"
+#include "ps/containers/Span.h"
+#include "ps/CStr.h"
 
+#include <utility>
 #include <vector>
 
 class CmdLineArgs
@@ -33,10 +35,9 @@ public:
 	 * All arguments are required to be of the form <tt>-name</tt> or
 	 * <tt>-name=value</tt> - anything else is ignored.
 	 *
-	 * @param argc size of argv array
-	 * @param argv array of arguments; argv[0] should be the program's name
+	 * @param argv span of arguments; argv[0] should be the program's name
 	 */
-	CmdLineArgs(int argc, const char* argv[]);
+	CmdLineArgs(const PS::span<const char* const> argv);
 
 	/**
 	 * Test whether the given name was specified, as either <tt>-name</tt> or

source/ps/GameSetup/tests/test_CmdLineArgs.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2018 Wildfire Games.
+/* Copyright (C) 2022 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -19,13 +19,15 @@
 
 #include "ps/GameSetup/CmdLineArgs.h"
 
+#include <array>
+
 class TestCmdLineArgs : public CxxTest::TestSuite
 {
 public:
 	void test_has()
 	{
-		const char* argv[] = { "program", "-test2" };
-		CmdLineArgs c(ARRAY_SIZE(argv), argv);
+		constexpr std::array<const char*, 2> argv = { "program", "-test2" };
+		CmdLineArgs c(argv);
 		TS_ASSERT(!c.Has("test1"));
 		TS_ASSERT(c.Has("test2"));
 		TS_ASSERT(!c.Has("test3"));
@@ -34,8 +36,11 @@ public:
 
 	void test_get()
 	{
-		const char* argv[] = { "program", "-test1=", "--test2=x", "-test3=-y=y-", "-=z" };
-		CmdLineArgs c(ARRAY_SIZE(argv), argv);
+		constexpr std::array<const char*, 5> argv =
+		{
+			"program", "-test1=", "--test2=x", "-test3=-y=y-", "-=z"
+		};
+		CmdLineArgs c(argv);
 		TS_ASSERT(!c.Has("program"));
 		TS_ASSERT_STR_EQUALS(c.Get("test0"), "");
 		TS_ASSERT_STR_EQUALS(c.Get("test1"), "");
@@ -46,8 +51,11 @@ public:
 
 	void test_multiple()
 	{
-		const char* argv[] = { "program", "-test1=one", "--test1=two", "-test2=none", "-test1=three" };
-		CmdLineArgs c(ARRAY_SIZE(argv), argv);
+		constexpr std::array<const char*, 5> argv =
+		{
+			"program", "-test1=one", "--test1=two", "-test2=none", "-test1=three"
+		};
+		CmdLineArgs c(argv);
 
 		TS_ASSERT_STR_EQUALS(c.Get("test1"), "one");
 		TS_ASSERT_STR_EQUALS(c.Get("test2"), "none");
@@ -66,10 +74,10 @@ public:
 
 	void test_get_invalid()
 	{
-		const char* argv[] = {
+		constexpr std::array<const char*, 6> argv = {
 			"-test1", "--test2", "test3-", " -test4", "--", "-=="
 		};
-		CmdLineArgs c(ARRAY_SIZE(argv), argv);
+		CmdLineArgs c(argv);
 
 		TS_ASSERT(!c.Has("test1"));
 		TS_ASSERT(c.Has("test2"));
@@ -79,15 +87,15 @@ public:
 
 	void test_arg0()
 	{
-		const char* argv[] = { "program" };
-		CmdLineArgs c(ARRAY_SIZE(argv), argv);
+		constexpr std::array<const char*, 1> argv = { "program" };
+		CmdLineArgs c(argv);
 		TS_ASSERT_WSTR_EQUALS(c.GetArg0().string(), L"program");
 
-		CmdLineArgs c2(0, NULL);
+		CmdLineArgs c2(PS::span<const char* const>{});
 		TS_ASSERT_WSTR_EQUALS(c2.GetArg0().string(), L"");
 
-		const char* argv3[] = { "ab/cd/ef/gh/../ij" };
-		CmdLineArgs c3(ARRAY_SIZE(argv3), argv3);
+		const std::array<const char*, 1> argv3 = { "ab/cd/ef/gh/../ij" };
+		CmdLineArgs c3(argv3);
 #if OS_WIN
 		TS_ASSERT_WSTR_EQUALS(c3.GetArg0().string(), L"ab\\cd\\ef\\gh\\..\\ij");
 #else
@@ -97,8 +105,11 @@ public:
 
 	void test_get_without_names()
 	{
-		const char* argv[] = { "program", "test0", "-test1", "test2", "test3", "--test4=test5" };
-		CmdLineArgs c(ARRAY_SIZE(argv), argv);
+		constexpr std::array<const char*, 6> argv =
+		{
+			"program", "test0", "-test1", "test2", "test3", "--test4=test5"
+		};
+		CmdLineArgs c(argv);
 		TS_ASSERT(c.Has("test1"));
 		TS_ASSERT_STR_EQUALS(c.Get("test4"), "test5");
 		CStr expected_args[] = { "test0", "test2", "test3" };

source/ps/containers/Span.h

@@ -38,7 +38,7 @@ class span
 public:
 	using element_type = T;
 	using value_type = std::remove_cv_t<T>;
-	using size_type = std::size_t;
+	using size_type = size_t;
 	using pointer = T*;
 	using reference = T&;
 	using iterator = pointer;
@@ -52,6 +52,10 @@ public:
 	constexpr span(iterator first, iterator last)
 		: m_Pointer(first), m_Extent(static_cast<size_type>(last - first)) {}
 
+	template<typename OtherT, size_t N>
+	constexpr span(const std::array<OtherT, N>& arr)
+		: m_Pointer(arr.data()), m_Extent(arr.size()) {}
+
 	constexpr span(const span& other) = default;
 
 	constexpr span& operator=(const span& other) = default;
@@ -66,11 +70,16 @@ public:
 	constexpr iterator begin() const { return m_Pointer; }
 	constexpr iterator end() const { return m_Pointer + m_Extent; }
 
+	constexpr span subspan(size_type offset) const { return {m_Pointer + offset, m_Extent - offset}; }
+
 private:
 	pointer m_Pointer;
 	size_type m_Extent;
 };
 
+template<typename T, size_t N>
+span(const std::array<T, N>&) -> span<const T>;
+
 } // namespace PS
 
 #endif // INCLUDED_PS_SPAN