From 023d233c407b99199fc2d854df6e760d1ce24705 Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Sun, 1 Feb 2015 19:42:16 -0500
Subject: [PATCH] cxx string_splitter

---
 bin/loader.cpp        | 47 +++++++++----------------
 cxx/string_splitter.h | 82 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 98 insertions(+), 31 deletions(-)
 create mode 100644 cxx/string_splitter.h

diff --git a/bin/loader.cpp b/bin/loader.cpp
index be425d6..2f63d1a 100644
--- a/bin/loader.cpp
+++ b/bin/loader.cpp
@@ -59,6 +59,8 @@
 #include "loader.h"
 #include "debugger.h"
 
+#include <cxx/string_splitter.h>
+
 
 #define LOADER_LOAD
 
@@ -687,43 +689,26 @@ std::string find_exe(const std::string &name)
 
 
 	// otherwise, check the Commands variable for locations.
-	std::string command = MPW::GetEnv("Commands");
-	if (command.empty()) return old_find_exe(name);
+	std::string commands = MPW::GetEnv("Commands");
+	if (commands.empty()) return old_find_exe(name);
 
 
 	// string is , separated, possibly in MacOS format.
-	std::string::size_type begin = 0;
-	std::string::size_type end = 0;
-	for(;;)
+
+	for (auto iter = string_splitter(commands, ','); iter; ++iter)
 	{
-		std::string path;
-		end = command.find(',', begin);
+		if (iter->empty()) continue;
+		std::string path = *iter;
 
-		if (end == std::string::npos) {
-
-			if (begin >= command.length()) return "";
-
-			path = command.substr(begin);
-		}
-		else
-		{
-			size_t count = end - begin - 1;
-			path = command.substr(begin, count);
-		}
-
-		if (!path.empty())
-		{
-			// convert to unix.
-			path = ToolBox::MacToUnix(path);
-			// should always have a length...
-			if (path.length() && path.back() != '/') path.push_back('/');
-			path.append(name);
-			if (file_exists(path)) return path;
-		}
-
-		if (end == std::string::npos) return "";
-		begin = end + 1;
+		// convert to unix.
+		path = ToolBox::MacToUnix(path);
+		// should always have a length...
+		if (path.length() && path.back() != '/') path.push_back('/');
+		path.append(name);
+		if (file_exists(path)) return path;
 	}
+
+	return "";
 }
 
 
diff --git a/cxx/string_splitter.h b/cxx/string_splitter.h
new file mode 100644
index 0000000..6473153
--- /dev/null
+++ b/cxx/string_splitter.h
@@ -0,0 +1,82 @@
+#ifndef __string_splitter__
+#define __string_splitter__
+
+#include <string>
+
+class string_splitter {
+public:
+	string_splitter(const std::string &str, char sep) :
+		_parent(str), _sep(sep)
+	{
+		_begin = 0;
+		_end = _parent.find(_sep);
+		_str = _parent.substr(_begin, _end);
+		// _begin is 0, _end is either npos or offset from 0,
+		// so no need to calculate a count.
+	}
+	
+	operator bool() const {
+		return _begin != npos;
+	}
+
+	string_splitter &operator++() {
+		increment();
+		return *this;
+	}
+
+	const std::string &operator *() const {
+		return _str;
+	}
+
+	const std::string *operator ->() const {
+		return &_str;
+	}
+	
+private:
+	void increment() {
+		_str.clear();
+		if (_begin == npos) return;
+		if (_end == npos) { _begin = _end; return; }
+
+		_begin = _end + 1;
+		_end = _parent.find(_sep, _begin);
+		auto count = _end == npos ? _end : _end - _begin;
+		_str = _parent.substr(_begin, count);
+	}
+
+	const static auto npos = std::string::npos;
+	std::string _str;
+	const std::string &_parent;
+	char _sep;
+	std::string::size_type _begin = 0;
+	std::string::size_type _end = 0;
+};
+
+
+#ifdef TEST
+#include <cstdio>
+#include <cstring>
+
+int main(int argc, char **argv)
+{
+	if (argc != 3) {
+		fprintf(stderr, "Usage: %s sep string\n", argv[0]);
+		return 1;
+	}
+	if (strlen(argv[1]) != 1) {
+		fprintf(stderr, "Separator must be a single character\n");
+		return 1;
+	}
+	char sep = argv[1][0];
+	std::string str(argv[2]);
+
+	for (auto iter = string_splitter(str, sep); iter; ++iter) {
+		printf("%s\n", iter->c_str());
+	}
+
+	return 0;
+}
+#endif
+
+#endif
+