Add --path-separator flag.

This flag permits setting the path separator used for all file paths
printed by ripgrep in normal operation.

Fixes #275

src/app.rs

@@ -125,7 +125,8 @@ fn app<F>(next_line_help: bool, doc: F) -> App<'static, 'static>
              .value_name("NUM").takes_value(true)
              .validator(validate_number))
         .arg(flag("column"))
-        .arg(flag("context-separator").value_name("ARG").takes_value(true))
+        .arg(flag("context-separator")
+             .value_name("SEPARATOR").takes_value(true))
         .arg(flag("debug"))
         .arg(flag("file").short("f")
              .value_name("FILE").takes_value(true)
@@ -154,6 +155,7 @@ fn app<F>(next_line_help: bool, doc: F) -> App<'static, 'static>
         .arg(flag("no-ignore-parent"))
         .arg(flag("no-ignore-vcs"))
         .arg(flag("null"))
+        .arg(flag("path-separator").value_name("SEPARATOR").takes_value(true))
         .arg(flag("pretty").short("p"))
         .arg(flag("replace").short("r").value_name("ARG").takes_value(true))
         .arg(flag("case-sensitive").short("s"))
@@ -410,6 +412,13 @@ lazy_static! {
               printing a list of matching files such as with --count, \
               --files-with-matches and --files. This option is useful for use \
               with xargs.");
+        doc!(h, "path-separator",
+             "Path separator to use when printing file paths.",
+             "The path separator to use when printing file paths. This \
+              defaults to your platform's path separator, which is / on Unix \
+              and \\ on Windows. This flag is intended for overriding the \
+              default when the environment demands it (e.g., cygwin). A path \
+              separator is limited to a single byte.");
         doc!(h, "pretty",
              "Alias for --color always --heading -n.");
         doc!(h, "replace",

src/args.rs

@@ -62,6 +62,7 @@ pub struct Args {
     no_ignore_vcs: bool,
     no_messages: bool,
     null: bool,
+    path_separator: Option<u8>,
     quiet: bool,
     quiet_matched: QuietMatched,
     replace: Option<Vec<u8>>,
@@ -151,6 +152,7 @@ impl Args {
             .heading(self.heading)
             .line_per_match(self.line_per_match)
             .null(self.null)
+            .path_separator(self.path_separator)
             .with_filename(self.with_filename);
         if let Some(ref rep) = self.replace {
             p = p.replace(rep.clone());
@@ -347,6 +349,7 @@ impl<'a> ArgMatches<'a> {
             no_ignore_vcs: self.no_ignore_vcs(),
             no_messages: self.is_present("no-messages"),
             null: self.is_present("null"),
+            path_separator: try!(self.path_separator()),
             quiet: quiet,
             quiet_matched: QuietMatched::new(quiet),
             replace: self.replace(),
@@ -616,6 +619,25 @@ impl<'a> ArgMatches<'a> {
         }
     }
 
+    /// Returns the unescaped path separator in UTF-8 bytes.
+    fn path_separator(&self) -> Result<Option<u8>> {
+        match self.value_of_lossy("path-separator") {
+            None => Ok(None),
+            Some(sep) => {
+                let sep = unescape(&sep);
+                if sep.is_empty() {
+                    Ok(None)
+                } else if sep.len() > 1 {
+                    Err(From::from(format!(
+                        "A path separator must be exactly one byte, but \
+                         the given separator is {} bytes.", sep.len())))
+                } else {
+                    Ok(Some(sep[0]))
+                }
+            }
+        }
+    }
+
     /// Returns the before and after contexts from the command line.
     ///
     /// If a context setting was absent, then `0` is returned.

src/printer.rs

@@ -44,6 +44,8 @@ pub struct Printer<W> {
     with_filename: bool,
     /// The color specifications.
     colors: ColorSpecs,
+    /// The separator to use for file paths. If empty, this is ignored.
+    path_separator: Option<u8>,
 }
 
 impl<W: WriteColor> Printer<W> {
@@ -62,6 +64,7 @@ impl<W: WriteColor> Printer<W> {
             replace: None,
             with_filename: false,
             colors: ColorSpecs::default(),
+            path_separator: None,
         }
     }
 
@@ -118,6 +121,13 @@ impl<W: WriteColor> Printer<W> {
         self
     }
 
+    /// A separator to use when printing file paths. When empty, use the
+    /// default separator for the current platform. (/ on Unix, \ on Windows.)
+    pub fn path_separator(mut self, sep: Option<u8>) -> Printer<W> {
+        self.path_separator = sep;
+        self
+    }
+
     /// Replace every match in each matching line with the replacement string
     /// given.
     ///
@@ -342,12 +352,29 @@ impl<W: WriteColor> Printer<W> {
         use std::os::unix::ffi::OsStrExt;
 
         let path = path.as_ref().as_os_str().as_bytes();
-        self.write(path);
+        match self.path_separator {
+            None => self.write(path),
+            Some(sep) => self.write_path_with_sep(path, sep),
+        }
     }
 
     #[cfg(not(unix))]
     fn write_path<P: AsRef<Path>>(&mut self, path: P) {
-        self.write(path.as_ref().to_string_lossy().as_bytes());
+        let path = path.as_ref().to_string_lossy();
+        match self.path_separator {
+            None => self.write(path.as_bytes()),
+            Some(sep) => self.write_path_with_sep(path.as_bytes(), sep),
+        }
+    }
+
+    fn write_path_with_sep(&mut self, path: &[u8], sep: u8) {
+        let mut path = path.to_vec();
+        for b in &mut path {
+            if *b == b'/' || (cfg!(windows) && *b == b'\\') {
+                *b = sep;
+            }
+        }
+        self.write(&path);
     }
 
     fn write(&mut self, buf: &[u8]) {