From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 27 Aug 2006 17:23:03 +0000 (+0000)
Subject: Add relative() to utils
X-Git-Tag: fs-1.0~21
X-Git-Url: http://git.tdb.fi/?p=libs%2Fcore.git;a=commitdiff_plain;h=bfbb7edfb2ae76d23f26e0b22787617ff621747d

Add relative() to utils
Unify init and operator/= with add_component
Allow a Path to start with ..
---

diff --git a/source/path.cpp b/source/path.cpp
index 1a9460a..6127f7a 100644
--- a/source/path.cpp
+++ b/source/path.cpp
@@ -34,6 +34,9 @@ bool Path::is_absolute() const
 	return false;
 }
 
+/**
+Extracts the given component range from the path.
+*/
 Path Path::subpath(unsigned start, unsigned count) const
 {
 	Path result;
@@ -60,26 +63,7 @@ Path &Path::operator/=(const Path &p)
 	else
 	{
 		for(iterator i=p.begin(); i!=p.end(); ++i)
-		{
-			if(*i=="..")
-			{
-				unsigned slash=path.rfind(DIRCHAR);
-#ifdef WIN32
-				if(is_windows_drive(path.substr(0,slash))) ++slash;
-#endif
-				if(slash==0) ++slash;
-				if(slash==string::npos)
-					path="";
-				else
-					path.erase(slash);
-			}
-			else if(*i!=".")
-			{
-				if(path.size()>1 || (path.size()==1 && path[0]!=DIRCHAR))
-					path+=DIRCHAR;
-				path+=*i;
-			}
-		}
+			add_component(*i);
 	}
 	return *this;
 }
@@ -116,20 +100,17 @@ bool Path::operator==(const Path &p) const
 #endif
 }
 
-void Path::init(const std::string &p)
+void Path::init(const string &p)
 {
 	unsigned start=0;
-	bool absolute=false;
-	if(p[0]==DIRCHAR)
-		absolute=true;
+	if(p[0]=='/' || p[0]=='\\')
+		add_component(string(1, DIRCHAR));
 	while(1)
 	{
 		unsigned slash=p.find_first_of("/\\",start);
 		if(slash>start)
 		{
-			if(path.size() || absolute)
-				path+=DIRCHAR;
-			path+=p.substr(start,slash-start);
+			add_component(p.substr(start, slash-start));
 		}
 		if(slash==string::npos)
 			break;
@@ -137,6 +118,62 @@ void Path::init(const std::string &p)
 	}
 }
 
+/**
+Adds a single component to the path, emulating the cd command.
+*/
+void Path::add_component(const string &comp)
+{
+	if(comp.empty())
+		;
+	else if(comp.size()==1 && comp[0]==DIRCHAR)
+	{
+		// Replace the path with the root directory
+#ifdef WIN32
+		unsigned slash=path.find(DIRCHAR);
+		if(is_windows_drive(path.substr(0, slash)))
+			path=path.substr(0,2);
+		else
+#endif
+		path=comp;
+	}
+#ifdef WIN32
+	else if(is_windows_drive(comp))
+		path=comp;
+#endif
+	else if(comp=="..")
+	{
+		if(path.empty())
+			path=comp;
+		// .. in root directory is a no-op
+		else if(path.size()==1 && path[0]==DIRCHAR)
+			;
+#ifdef WIN32
+		else if(is_windows_drive(path))
+			;
+#endif
+		else
+		{
+			unsigned slash=path.rfind(DIRCHAR);
+			unsigned start=(slash==string::npos)?0:slash+1;
+			if(path.compare(start, string::npos, ".."))
+			{
+				// If the last component already is a .., add another
+				path+=DIRCHAR;
+				path+=comp;
+			}
+			else
+				// Otherwise, erase the last component
+				path.erase(slash, string::npos);
+		}
+	}
+	else if(comp!=".")
+	{
+		if(path.size()>1 || (path.size()==1 && path[0]!=DIRCHAR))
+			path+=DIRCHAR;
+		path+=comp;
+	}
+}
+
 Path::iterator::iterator(const Path &p):
 	path(p),
 	start(0)
diff --git a/source/path.h b/source/path.h
index 9e1e374..0f33301 100644
--- a/source/path.h
+++ b/source/path.h
@@ -59,6 +59,7 @@ private:
 	std::string path;
 
 	void init(const std::string &);
+	void add_component(const std::string &);
 };
 
 inline std::ostream &operator<<(std::ostream &o, const Path &p) { o<<p.str(); return o; }
diff --git a/source/utils.cpp b/source/utils.cpp
index 08ab958..204f33b 100644
--- a/source/utils.cpp
+++ b/source/utils.cpp
@@ -158,5 +158,20 @@ int fnmatch(const string &pat, const Path &fn)
 #endif
 }
 
+Path relative(const Path &path, const Path &base)
+{
+	Path::iterator i=path.begin();
+	Path::iterator j=base.begin();
+	for(; (i!=path.end() && j!=base.end() && *i==*j); ++i,++j);
+
+	Path result;
+	for(; j!=base.end(); ++j)
+		result/="..";
+	for(; i!=path.end(); ++i)
+		result/=*i;
+
+	return result;
+}
+
 } // namespace Path
 } // namespace Msp
diff --git a/source/utils.h b/source/utils.h
index 961ad49..faf5ef7 100644
--- a/source/utils.h
+++ b/source/utils.h
@@ -28,6 +28,7 @@ extern std::list<std::string> list_files(const Path &);
 extern bool exists(const Path &);
 extern Filename splitext(const std::string &);
 extern int fnmatch(const std::string &, const Path &);
+extern Path relative(const Path &, const Path &);
 
 inline int stat(const Path &fn, struct stat &st)
 { return ::stat(fn.str().c_str(), &st); }