New termsize command (#3038)

* add term size command

* update w & h, add examples

* changed default to output table

crates/nu-command/src/commands.rs

@@ -115,6 +115,7 @@ pub(crate) mod split_by;
 pub(crate) mod str_;
 pub(crate) mod table;
 pub(crate) mod tags;
+pub(crate) mod termsize;
 pub(crate) mod to;
 pub(crate) mod to_csv;
 pub(crate) mod to_html;
@@ -265,6 +266,7 @@ pub(crate) use str_::{
 };
 pub(crate) use table::Table;
 pub(crate) use tags::Tags;
+pub(crate) use termsize::TermSize;
 pub(crate) use to::To;
 pub(crate) use to_csv::ToCSV;
 pub(crate) use to_html::ToHTML;

crates/nu-command/src/commands/default_context.rs

@@ -237,6 +237,7 @@ pub fn create_default_context(interactive: bool) -> Result<EvaluationContext, Bo
             whole_stream_command(UrlQuery),
             whole_stream_command(Seq),
             whole_stream_command(SeqDates),
+            whole_stream_command(TermSize),
         ]);
 
         #[cfg(feature = "clipboard-cli")]

crates/nu-command/src/commands/termsize.rs

@@ -0,0 +1,75 @@
+use crate::prelude::*;
+use indexmap::IndexMap;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{Dictionary, Signature, UntaggedValue};
+
+pub struct TermSize;
+
+#[derive(Deserialize, Clone)]
+pub struct TermSizeArgs {
+    wide: bool,
+    tall: bool,
+}
+
+#[async_trait]
+impl WholeStreamCommand for TermSize {
+    fn name(&self) -> &str {
+        "term size"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("term size")
+            .switch("wide", "Report only the width of the terminal", Some('w'))
+            .switch("tall", "Report only the height of the terminal", Some('t'))
+    }
+
+    fn usage(&self) -> &str {
+        "Returns the terminal size as W H"
+    }
+
+    async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        let tag = args.call_info.name_tag.clone();
+        let (TermSizeArgs { wide, tall }, _) = args.process().await?;
+
+        let size = term_size::dimensions();
+        match size {
+            Some((w, h)) => {
+                if wide && !tall {
+                    Ok(OutputStream::one(UntaggedValue::int(w).into_value(tag)))
+                } else if !wide && tall {
+                    Ok(OutputStream::one(UntaggedValue::int(h).into_value(tag)))
+                } else {
+                    let mut indexmap = IndexMap::with_capacity(2);
+                    indexmap.insert("width".to_string(), UntaggedValue::int(w).into_value(&tag));
+                    indexmap.insert("height".to_string(), UntaggedValue::int(h).into_value(&tag));
+                    let value = UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag);
+                    Ok(OutputStream::one(value))
+                }
+            }
+            _ => Ok(OutputStream::one(
+                UntaggedValue::string("0 0".to_string()).into_value(tag),
+            )),
+        }
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Return the width height of the terminal as W H",
+                example: "term size",
+                result: None,
+            },
+            Example {
+                description: "Return the width of the terminal",
+                example: "term size -w",
+                result: None,
+            },
+            Example {
+                description: "Return the height (t for tall) of the terminal",
+                example: "term size -t",
+                result: None,
+            },
+        ]
+    }
+}