printer: add hyperlinks

This commit represents the initial work to get hyperlinks working and
was submitted as part of PR #2483. Subsequent commits largely retain the
functionality and structure of the hyperlink support added here, but
rejigger some things around.

crates/core/path_printer.rs

@@ -1,13 +1,16 @@
 use std::io;
 use std::path::Path;
 
-use grep::printer::{ColorSpecs, PrinterPath};
+use grep::printer::{
+    ColorSpecs, HyperlinkPattern, HyperlinkSpan, PrinterPath,
+};
 use termcolor::WriteColor;
 
 /// A configuration for describing how paths should be written.
 #[derive(Clone, Debug)]
 struct Config {
     colors: ColorSpecs,
+    hyperlink_pattern: HyperlinkPattern,
     separator: Option<u8>,
     terminator: u8,
 }
@@ -16,6 +19,7 @@ impl Default for Config {
     fn default() -> Config {
         Config {
             colors: ColorSpecs::default(),
+            hyperlink_pattern: HyperlinkPattern::default(),
             separator: None,
             terminator: b'\n',
         }
@@ -37,7 +41,7 @@ impl PathPrinterBuilder {
     /// Create a new path printer with the current configuration that writes
     /// paths to the given writer.
     pub fn build<W: WriteColor>(&self, wtr: W) -> PathPrinter<W> {
-        PathPrinter { config: self.config.clone(), wtr }
+        PathPrinter { config: self.config.clone(), wtr, buf: vec![] }
     }
 
     /// Set the color specification for this printer.
@@ -52,6 +56,17 @@ impl PathPrinterBuilder {
         self
     }
 
+    /// Set the hyperlink pattern to use for hyperlinks output by this printer.
+    ///
+    /// Colors need to be enabled for hyperlinks to be output.
+    pub fn hyperlink_pattern(
+        &mut self,
+        pattern: HyperlinkPattern,
+    ) -> &mut PathPrinterBuilder {
+        self.config.hyperlink_pattern = pattern;
+        self
+    }
+
     /// A path separator.
     ///
     /// When provided, the path's default separator will be replaced with
@@ -80,6 +95,7 @@ impl PathPrinterBuilder {
 pub struct PathPrinter<W> {
     config: Config,
     wtr: W,
+    buf: Vec<u8>,
 }
 
 impl<W: WriteColor> PathPrinter<W> {
@@ -89,10 +105,30 @@ impl<W: WriteColor> PathPrinter<W> {
         if !self.wtr.supports_color() {
             self.wtr.write_all(ppath.as_bytes())?;
         } else {
+            let mut hyperlink = self.start_hyperlink_span(&ppath)?;
             self.wtr.set_color(self.config.colors.path())?;
             self.wtr.write_all(ppath.as_bytes())?;
             self.wtr.reset()?;
+            hyperlink.end(&mut self.wtr)?;
         }
         self.wtr.write_all(&[self.config.terminator])
     }
+
+    /// Starts a hyperlink span when applicable.
+    fn start_hyperlink_span(
+        &mut self,
+        path: &PrinterPath,
+    ) -> io::Result<HyperlinkSpan> {
+        if self.wtr.supports_hyperlinks() {
+            if let Some(spec) = path.create_hyperlink_spec(
+                &self.config.hyperlink_pattern,
+                None,
+                None,
+                &mut self.buf,
+            ) {
+                return Ok(HyperlinkSpan::start(&mut self.wtr, &spec)?);
+            }
+        }
+        Ok(HyperlinkSpan::default())
+    }
 }