Rewrite each_path to allow performance improvements in the future.

Instead of determining paths from the path tag, we iterate through
modules' children recursively in the metadata. This will allow for
lazy external module resolution.

src/libstd/str.rs

@@ -1140,6 +1140,17 @@ impl<'self> Str for @str {
     }
 }
 
+impl<'self> Container for &'self str {
+    #[inline]
+    fn len(&self) -> uint {
+        do as_buf(*self) |_p, n| { n - 1u }
+    }
+    #[inline]
+    fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+}
+
 #[allow(missing_doc)]
 pub trait StrSlice<'self> {
     fn contains<'a>(&self, needle: &'a str) -> bool;
@@ -1158,10 +1169,8 @@ pub trait StrSlice<'self> {
     fn any_line_iter(&self) -> AnyLineIterator<'self>;
     fn word_iter(&self) -> WordIterator<'self>;
     fn ends_with(&self, needle: &str) -> bool;
-    fn is_empty(&self) -> bool;
     fn is_whitespace(&self) -> bool;
     fn is_alphanumeric(&self) -> bool;
-    fn len(&self) -> uint;
     fn char_len(&self) -> uint;
 
     fn slice(&self, begin: uint, end: uint) -> &'self str;
@@ -1362,9 +1371,6 @@ impl<'self> StrSlice<'self> for &'self str {
         self.split_iter(char::is_whitespace).filter(|s| !s.is_empty())
     }
 
-    /// Returns true if the string has length 0
-    #[inline]
-    fn is_empty(&self) -> bool { self.len() == 0 }
     /**
      * Returns true if the string contains only whitespace
      *
@@ -1379,11 +1385,6 @@ impl<'self> StrSlice<'self> for &'self str {
      */
     #[inline]
     fn is_alphanumeric(&self) -> bool { self.iter().all(char::is_alphanumeric) }
-    /// Returns the size in bytes not counting the null terminator
-    #[inline]
-    fn len(&self) -> uint {
-        do as_buf(*self) |_p, n| { n - 1u }
-    }
     /// Returns the number of characters that a string holds
     #[inline]
     fn char_len(&self) -> uint { self.iter().len_() }