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[libs/core.git] / source / fs / path.cpp
diff --git a/source/fs/path.cpp b/source/fs/path.cpp
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+/* $Id$
+
+This file is part of libmspfs
+Copyright © 2006-2008  Mikko Rasa, Mikkosoft Productions
+Distributed under the LGPL
+*/
+
+#include <msp/core/except.h>
+#include <msp/strings/utils.h>
+#include "path.h"
+#include "utils.h"
+
+using namespace std;
+
+namespace {
+
+inline bool is_windows_drive(const std::string &p)
+{ return (p.size()==2 && ((p[0]>='A' && p[0]<='Z') || (p[0]>='a' && p[0]<='z')) && p[1]==':'); }
+
+}
+
+namespace Msp {
+namespace FS {
+
+Path::Path()
+{ }
+
+Path::Path(const string &p)
+{
+       init(p);
+}
+
+Path::Path(const char *p)
+{
+       init(p);
+}
+
+unsigned Path::size() const
+{
+       if(path.empty())
+               return 0;
+       if(path.size()==1 && path[0]==DIRSEP)
+               return 1;
+
+       unsigned count = 1;
+       for(string::const_iterator i=path.begin(); i!=path.end(); ++i)
+               if(*i==DIRSEP) ++count;
+       return count;
+}
+
+bool Path::is_absolute() const
+{
+#ifdef WIN32
+       if(is_windows_drive((*this)[0]))
+               return true;
+#endif
+       if(path[0]==DIRSEP)
+               return true;
+       return false;
+}
+
+Path Path::subpath(unsigned start, unsigned count) const
+{
+       Path result;
+       Iterator i = begin();
+       for(unsigned j=0; (j<start && i!=end()); ++j)
+               ++i;
+       for(unsigned j=0; (j<count && i!=end()); ++j)
+       {
+               result /= *i;
+               ++i;
+       }
+       return result;
+}
+
+Path Path::operator/(const Path &p) const
+{
+       Path a = *this;
+       a /= p;
+       return a;
+}
+
+/**
+Attaches another path to the end of this one.  An absolute path replaces the
+existing data.  ".." elements annihilate the last component and "." elements
+are ignored.
+*/
+Path &Path::operator/=(const Path &p)
+{
+       if(p.is_absolute())
+               path = p.path;
+       else
+       {
+               for(Iterator i=p.begin(); i!=p.end(); ++i)
+                       add_component(*i);
+       }
+       return *this;
+}
+
+string Path::operator[](int n) const
+{
+       if(n>=0)
+       {
+               for(Iterator i=begin(); i!=end(); ++i, --n)
+                       if(!n)
+                               return *i;
+       }
+       else
+       {
+               for(Iterator i=end(); i!=begin();)
+               {
+                       --i;
+                       if(!++n)
+                               return *i;
+               }
+       }
+
+       throw InvalidParameterValue("Path component index out of range");
+}
+
+bool Path::operator==(const Path &p) const
+{
+#ifdef WIN32
+       return !strcasecmp(path, p.path);
+#else
+       return path==p.path;
+#endif
+}
+
+Path::Iterator Path::begin() const
+{
+       return Iterator(*this);
+}
+
+Path::Iterator Path::end() const
+{
+       Iterator i(*this);
+       i.start=i.end = std::string::npos;
+       return i;
+}
+
+void Path::init(const string &p)
+{
+       string::size_type start = 0;
+       if(p[0]=='/' || p[0]=='\\')
+               add_component(string(1, DIRSEP));
+       while(1)
+       {
+               string::size_type slash = p.find_first_of("/\\", start);
+               if(slash>start)
+                       add_component(p.substr(start, slash-start));
+               if(slash==string::npos)
+                       break;
+               start = slash+1;
+       }
+}
+
+/**
+Adds a single component to the path, emulating the cd command.  Fails horribly
+if comp contains a separator character.
+*/
+void Path::add_component(const string &comp)
+{
+       if(comp.empty())
+               ;
+       else if(comp.size()==1 && comp[0]==DIRSEP)
+       {
+               // Replace the path with the root directory
+#ifdef WIN32
+               unsigned slash = path.find(DIRSEP);
+               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==".")
+                       path = comp;
+               // .. in root directory is a no-op
+               else if(path.size()==1 && path[0]==DIRSEP)
+                       ;
+#ifdef WIN32
+               else if(is_windows_drive(path))
+                       ;
+#endif
+               else
+               {
+                       string::size_type slash = path.rfind(DIRSEP);
+                       string::size_type start = (slash==string::npos ? 0 : slash+1);
+                       if(!path.compare(start, string::npos, ".."))
+                       {
+                               // If the last component already is a .., add another
+                               path += DIRSEP;
+                               path += comp;
+                       }
+                       else if(slash==string::npos)
+                               path = ".";
+                       else
+                       {
+                               if(slash==0)
+                                       slash = 1;
+                               // Otherwise, erase the last component
+                               path.erase(slash, string::npos);
+                       }
+               }
+       }
+       else if(comp!="." || path.empty())
+       {
+               if(comp!="." && path.empty())
+                       path = ".";
+               if(path.size()>1 || (path.size()==1 && path[0]!=DIRSEP))
+                       path += DIRSEP;
+               path += comp;
+       }
+}
+
+
+Path::Iterator::Iterator(const Path &p):
+       path(p),
+       start(0)
+{
+       if(path.path.empty())
+               start=end = string::npos;
+       else if(path.path[0]==DIRSEP)
+               end = 1;
+#ifdef WIN32
+       else if(path.path.size()>2 && path.path[2]==DIRSEP && is_windows_drive(path.path.substr(0, 2)))
+               end = 2;
+#endif
+       else
+               end = path.path.find(DIRSEP);
+}
+
+Path::Iterator &Path::Iterator::operator++()
+{
+       start = end;
+       if(start>=path.path.size())
+               return *this;
+       if(path.path[start]==DIRSEP)
+               ++start;
+       end = path.path.find(DIRSEP, start);
+       return *this;
+}
+
+Path::Iterator &Path::Iterator::operator--()
+{
+       if(start==0)
+               return *this;
+
+       end = start;
+       if(end>1 && end<path.path.size() && path.path[end]!=DIRSEP)
+               --end;
+
+       start = path.path.rfind(DIRSEP, end-1);
+       if(start==string::npos)
+               start = 0;
+       else if(start<end-1)
+               ++start;
+
+       return *this;
+}
+
+string Path::Iterator::operator*() const
+{
+       if(start>=path.path.size())
+               return string();
+       if(start==end)
+               return string();
+       return path.path.substr(start, end-start);
+}
+
+} // namespace FS
+} // namespace Msp