Add --pager option to set the pager

This patch adds the --pager command-line option to set the pager used by
the plain and rich viewers.

CHANGELOG.md

@@ -8,6 +8,7 @@ SPDX-License-Identifier: MIT
 ## Unreleased
 
 - Use the `LESS` environment variable to set the options for the pager.
+- Add the `--pager` option to set the pager for the plain and rich viewers.
 
 ## v0.4.0 (2020-10-09)
 

src/args.rs

@@ -119,6 +119,13 @@ pub struct ViewerArgs {
     /// width of the terminal with the maximum width set with this option.
     #[structopt(long)]
     pub max_width: Option<usize>,
+
+    /// The pager to use for the plain and rich viewers.
+    ///
+    /// Per default, rusty-man uses the pager set in the PAGER environment variable, or less if
+    /// this environment variable is not set.
+    #[structopt(long)]
+    pub pager: Option<String>,
 }
 
 impl Args {

src/viewer/text/mod.rs

@@ -33,11 +33,11 @@ impl TextViewer {
         F: FnOnce(Box<dyn utils::ManRenderer<Error = io::Error>>) -> io::Result<()>,
     {
         let viewer: Box<dyn utils::ManRenderer<Error = io::Error>> = match self.mode {
-            TextMode::Plain => Box::new(plain::PlainTextRenderer::new(args)),
-            TextMode::Rich => Box::new(rich::RichTextRenderer::new(args)?),
+            TextMode::Plain => Box::new(plain::PlainTextRenderer::new(&args)),
+            TextMode::Rich => Box::new(rich::RichTextRenderer::new(&args)?),
         };
 
-        spawn_pager();
+        spawn_pager(&args);
         op(viewer).or_else(ignore_pipe_error).map_err(Into::into)
     }
 }
@@ -63,11 +63,16 @@ impl viewer::Viewer for TextViewer {
     }
 }
 
-pub fn spawn_pager() {
+pub fn spawn_pager(args: &args::ViewerArgs) {
     if env::var_os("LESS").is_none() {
         env::set_var("LESS", "cR");
     }
-    pager::Pager::with_default_pager("less").setup()
+    let mut pager = if let Some(pager) = &args.pager {
+        pager::Pager::with_pager(&pager)
+    } else {
+        pager::Pager::with_default_pager("less")
+    };
+    pager.setup();
 }
 
 fn ignore_pipe_error(error: io::Error) -> io::Result<()> {

src/viewer/text/plain.rs

@@ -21,9 +21,9 @@ struct Decorator {
 }
 
 impl PlainTextRenderer {
-    pub fn new(args: args::ViewerArgs) -> Self {
+    pub fn new(args: &args::ViewerArgs) -> Self {
         Self {
-            line_length: utils::get_line_length(&args),
+            line_length: utils::get_line_length(args),
         }
     }
 }

src/viewer/text/rich.rs

@@ -16,10 +16,10 @@ pub struct RichTextRenderer {
 }
 
 impl RichTextRenderer {
-    pub fn new(args: args::ViewerArgs) -> anyhow::Result<Self> {
+    pub fn new(args: &args::ViewerArgs) -> anyhow::Result<Self> {
         Ok(Self {
-            line_length: utils::get_line_length(&args),
-            highlighter: utils::get_highlighter(&args)?,
+            line_length: utils::get_line_length(args),
+            highlighter: utils::get_highlighter(args)?,
         })
     }
 }