From 6bcbf18a6a67707c13d66b96770c8b210a45b9f4 Mon Sep 17 00:00:00 2001
From: Bent Bisballe Nyeng <deva@aasimon.org>
Date: Sat, 12 Jun 2021 16:16:41 +0200
Subject: Skip non-dirty tasks.

---
 libcppbuild.cc |  8 ++++-
 task.cc        | 95 +++++++++++++++++++++++++++++-----------------------------
 task.h         |  7 ++++-
 3 files changed, 61 insertions(+), 49 deletions(-)

diff --git a/libcppbuild.cc b/libcppbuild.cc
index 3cba49f..82a70d1 100644
--- a/libcppbuild.cc
+++ b/libcppbuild.cc
@@ -38,7 +38,7 @@ int main(int argc, const char* argv[])
 	for(const auto& file : files)
 	{
 		tasks.emplace_back(config, settings, file);
-		objects.push_back(tasks.back().targetFile);
+		objects.push_back(tasks.back().target());
 	}
 
 	if(argc == 2 && std::string(argv[1]) == "clean")
@@ -69,6 +69,12 @@ int main(int argc, const char* argv[])
 		while(processes.size() < settings.parallel_processes &&
 		      task != tasks.end())
 		{
+			if(!task->dirty())
+			{
+				++task;
+				continue;
+			}
+
 			processes.emplace_back(
 				std::async(std::launch::async,
 				           [task]()
diff --git a/task.cc b/task.cc
index 4728a1c..29e18cb 100644
--- a/task.cc
+++ b/task.cc
@@ -94,84 +94,80 @@ Task::Task(const BuildConfiguration& config, const Settings& settings,
 	depsFile += ".d";
 }
 
-int Task::run()
+bool Task::dirty()
 {
 	if(!std::filesystem::exists(sourceFile))
 	{
-		std::cout << "Missing source file: " << std::string(sourceFile) << "\n";
-		return 1;
+		//std::cout << "Missing source file: " << std::string(sourceFile) << "\n";
+		return true;
 	}
 
-	bool recompile{false};
-
-	if(!recompile &&
-	   !std::filesystem::exists(targetFile))
+	if(!std::filesystem::exists(targetFile))
 	{
-		recompile = true;
 		//std::cout << "Missing targetFile\n";
+		return true;
 	}
 
-	if(!recompile &&
-	   !std::filesystem::exists(depsFile))
+	if(!std::filesystem::exists(depsFile))
 	{
-		recompile = true;
 		//std::cout << "Missing depsFile\n";
+		return true;
 	}
 
-	if(!recompile &&
-	   std::filesystem::last_write_time(sourceFile) >
+	if(std::filesystem::last_write_time(sourceFile) >
 	   std::filesystem::last_write_time(depsFile))
 	{
-		recompile = true;
 		//std::cout << "The sourceFile newer than depsFile\n";
+		return true;
 	}
 
-	if(!recompile)
+	auto depList = readDeps(depsFile);
+	for(const auto& dep : depList)
 	{
-		auto depList = readDeps(depsFile);
-		for(const auto& dep : depList)
+		if(!std::filesystem::exists(dep) ||
+		   std::filesystem::last_write_time(targetFile) <
+		   std::filesystem::last_write_time(dep))
 		{
-			if(!std::filesystem::exists(dep) ||
-			   std::filesystem::last_write_time(targetFile) <
-			   std::filesystem::last_write_time(dep))
-			{
-				recompile = true;
-				//std::cout << "The targetFile older than dep\n";
-				break;
-			}
+			//std::cout << "The targetFile older than " << std::string(dep) << "\n";
+			return true;
 		}
 	}
 
-	if(!recompile &&
-	   std::filesystem::last_write_time(sourceFile) >
+	if(std::filesystem::last_write_time(sourceFile) >
 	   std::filesystem::last_write_time(targetFile))
 	{
-		recompile = true;
 		//std::cout << "The targetFile older than sourceFile\n";
+		return true;
 	}
 
-	if(recompile)
+	return false;
+}
+
+int Task::run()
+{
+	if(!std::filesystem::exists(sourceFile))
 	{
-		std::string comp = "g++";
-		std::string flags = config.cxxflags;
-		if(std::string(sourceFile.extension()) == ".c")
-		{
-			comp = "gcc";
-			flags = config.cflags;
-		}
-		std::string cmd = comp +
-			" -MMD -c " + std::string(sourceFile) + " " +
-			flags + " " +
-			"-o " + std::string(targetFile);
-		std::cout << cmd << "\n";
+		std::cout << "Missing source file: " << std::string(sourceFile) << "\n";
+		return 1;
+	}
 
-		if(system(cmd.data()))
-		{
-			return 1;
-		}
-		return 0;
+	std::string comp = "g++";
+	std::string flags = config.cxxflags;
+	if(std::string(sourceFile.extension()) == ".c")
+	{
+		comp = "gcc";
+		flags = config.cflags;
 	}
+	std::string cmd = comp +
+		" -MMD -c " + std::string(sourceFile) + " " +
+		flags + " " +
+		"-o " + std::string(targetFile);
+	std::cout << cmd << "\n";
 
+	if(system(cmd.data()))
+	{
+		return 1;
+	}
 	return 0;
 }
 
@@ -192,7 +188,12 @@ int Task::clean()
 	return 0;
 }
 
-std::vector<std::string> Task::depends()
+std::vector<std::string> Task::depends() const
 {
 	return {};
 }
+
+std::string Task::target() const
+{
+	return targetFile;
+}
diff --git a/task.h b/task.h
index ee67b5c..bdd881b 100644
--- a/task.h
+++ b/task.h
@@ -16,11 +16,16 @@ public:
 	     const Settings& settings,
 	     const std::string& source);
 
+	bool dirty();
+
 	int run();
 	int clean();
 
-	std::vector<std::string> depends();
+	std::vector<std::string> depends() const;
+
+	std::string target() const;
 
+private:
 	std::filesystem::path sourceFile;
 	std::filesystem::path targetFile;
 	std::filesystem::path depsFile;
-- 
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