[fs.path.generic] Refactor generic pathname grammar to remove redundancy and ambiguity.

Author: zygoloid

source/iostreams.tex

@@ -10651,9 +10651,7 @@
 
 \begin{ncbnf}
 \nontermdef{pathname}\br
-    root-name root-directory\opt relative-path\opt\br
-    root-directory relative-path\opt\br
-    relative-path
+    root-name\opt{} root-directory\opt{} relative-path
 \end{ncbnf}
 
 \begin{ncbnf}
@@ -10670,8 +10668,7 @@
 \begin{ncbnf}
 \nontermdef{relative-path}\br
     filename\br
-    relative-path directory-separator\br
-    relative-path directory-separator filename\br
+    filename directory-separator relative-path\br
     \textnormal{an empty path}
 \end{ncbnf}
 
@@ -10682,20 +10679,18 @@
 
 \begin{ncbnf}
 \nontermdef{directory-separator}\br
-    slash\br
-    slash directory-separator\br
-    preferred-separator\br
-    preferred-separator directory-separator
+    preferred-separator directory-separator\opt\br
+    fallback-separator directory-separator\opt
 \end{ncbnf}
 
 \begin{ncbnf}
 \nontermdef{preferred-separator}\br
-    \textnormal{operating system dependent directory separator character\footnote{May be a synonym for \grammarterm{slash}.}}
+    \textnormal{operating system dependent directory separator character}
 \end{ncbnf}
 
 \begin{ncbnf}
-\nontermdef{slash}\br
-    \tcode{/}
+\nontermdef{fallback-separator}\br
+    \textnormal{\tcode{/}, if \grammarterm{preferred-separator} is not \tcode{/}}
 \end{ncbnf}
 
 \pnum
@@ -11281,8 +11276,8 @@
 p.make_preferred();
 std::cout << p << '\n';
 \end{codeblock}
-On an operating system where \grammarterm{preferred-separator} is the same as
-\grammarterm{directory-separator}, the output is:
+On an operating system where \grammarterm{preferred-separator} is a slash,
+the output is:
 \begin{codeblock}
 "foo/bar"
 "foo/bar"
@@ -11470,8 +11465,8 @@
 \pnum
 Generic format observer functions return strings formatted according to the
 generic pathname format (\ref{fs.path.generic}).
-The forward slash (\tcode{'/'}) character is used as
-the \grammarterm{directory-separator} character.
+A single slash (\tcode{'/'}) character is used as
+the \grammarterm{directory-separator}.
 
 \pnum
 \begin{example} On an operating system that uses backslash as
@@ -11908,7 +11903,7 @@
 \end{codeblock}
 The above assertions will succeed.
 On Windows, the returned path's \grammarterm{directory-separator} characters
-will be backslashes rather than forward slashes,
+will be backslashes rather than slashes,
 but that does not affect \tcode{path} equality.
 \end{example}
 
@@ -11976,8 +11971,8 @@
 The generic format is required to ensure lexicographical
 comparison works correctly. \end{note}
 \item Each successive \grammarterm{filename} element, if present.
-\item An empty element, if one or more trailing non-root \grammarterm{slash}
-characters are present.
+\item An empty element, if a trailing non-root \grammarterm{directory-separator}
+is present.
 \end{itemize}
 
 \pnum