Path Enhancement Project #2: parse, join and split (#3256)

* Add new path parse subcommand

This includes a slight refactor to all the path subcommand `action()`
functions.

* Remove filestem and extension; Fix example

* Add additional description to path parse

* Put join arg behind flag; Fix missing import (Win)

* Fix error when column path is passed as arg

* Add structured path joining

Structured path is implicitly joined at every patch subcommand call.

* Fix existing path join tests; Fix rustfmt

* Remove redundant 'static lifetime (clippy)

* Add initial impl of path split subcommand

* Add ability to join path from parts

* Fix wrong results in path split examples

* Fix remaining asyncs after engine change

* Do not wrap split path parts into table

When the input is just a list of values, the `path split` command will
split each value directly into the output stream, similar to
`split-row`. Column path--specified values are still wrapped into a
table so they can still be used to replace table fields.

* Join list of values instead of going one-by-one

When `path join` encounters a list of values, it attempts to join them,
instead of going one-by-one like the rest of the path commands. You can
still `each { echo $it | path join }` to join them one-by-one, if the
values are, e.g., tables.

Now, the behavior of `path split` and `path join` should match the
`split-row` and `str collect` counterparts and should hopefully align
better with user's expectations.

* Make sure path join detects structured path

* Fix panic on empty input stream

Also, doesn't collect input into vector unnecessarily.

* Fix path join not appending value

* Remove argument serialization

* Make better errors; Misc refactor

* OsStr -> String encoding is now lossy, instead of throwing an error
* The consequence is action() now always returns Value instead of Result
* Removed redundant handle_value() call in `path join`
* Fix possible incorrect error detection in `path split`
* Applied rustfmt + clippy

* Add more usage, examples & test; Fix type error

The 'parent' column was required to be a path but didn't work with
string.

* Add more help & examples; Maybe fix Windows error

* Refactor operate function

Reducing code repetition

* Review usages and examples

* Add the option to manually specify the extension

* Add more tests; Fix failures on Windows

* Move path commands to engine-p

* Small refactor

crates/nu-command/src/commands.rs

@@ -234,8 +234,8 @@ pub(crate) use nth::Nth;
 pub(crate) use open::Open;
 pub(crate) use parse::Parse;
 pub(crate) use path::{
-    PathBasename, PathCommand, PathDirname, PathExists, PathExpand, PathExtension, PathFilestem,
+    PathBasename, PathCommand, PathDirname, PathExists, PathExpand, PathJoin, PathParse, PathSplit,
-    PathJoin, PathType,
+    PathType,
 };
 pub(crate) use pivot::Pivot;
 pub(crate) use prepend::Prepend;

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

@@ -237,9 +237,9 @@ pub fn create_default_context(interactive: bool) -> Result<EvaluationContext, Bo
             whole_stream_command(PathDirname),
             whole_stream_command(PathExists),
             whole_stream_command(PathExpand),
-            whole_stream_command(PathExtension),
-            whole_stream_command(PathFilestem),
             whole_stream_command(PathJoin),
+            whole_stream_command(PathParse),
+            whole_stream_command(PathSplit),
             whole_stream_command(PathType),
             // Url
             whole_stream_command(UrlCommand),

crates/nu-command/src/commands/path/basename.rs

@@ -8,10 +8,9 @@ use std::path::Path;
 
 pub struct PathBasename;
 
-#[derive(Deserialize)]
 struct PathBasenameArguments {
-    replace: Option<Tagged<String>>,
     rest: Vec<ColumnPath>,
+    replace: Option<Tagged<String>>,
 }
 
 impl PathSubcommandArguments for PathBasenameArguments {
@@ -27,24 +26,28 @@ impl WholeStreamCommand for PathBasename {
 
     fn signature(&self) -> Signature {
         Signature::build("path basename")
+            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
             .named(
                 "replace",
                 SyntaxShape::String,
                 "Return original path with basename replaced by this string",
                 Some('r'),
             )
-            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
     }
 
     fn usage(&self) -> &str {
-        "Gets the final component of a path"
+        "Get the final component of a path"
     }
 
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let tag = args.call_info.name_tag.clone();
-        let (PathBasenameArguments { replace, rest }, input) = args.process()?;
+        let args = args.evaluate_once()?;
-        let args = Arc::new(PathBasenameArguments { replace, rest });
+        let cmd_args = Arc::new(PathBasenameArguments {
-        Ok(operate(input, &action, tag.span, args))
+            rest: args.rest_args()?,
+            replace: args.get_flag("replace")?,
+        });
+
+        Ok(operate(args.input, &action, tag.span, cmd_args))
     }
 
     #[cfg(windows)]
@@ -84,14 +87,16 @@ impl WholeStreamCommand for PathBasename {
     }
 }
 
-fn action(path: &Path, args: &PathBasenameArguments) -> UntaggedValue {
+fn action(path: &Path, tag: Tag, args: &PathBasenameArguments) -> Value {
-    match args.replace {
+    let untagged = match args.replace {
         Some(ref basename) => UntaggedValue::filepath(path.with_file_name(&basename.item)),
         None => UntaggedValue::string(match path.file_name() {
             Some(filename) => filename.to_string_lossy(),
             None => "".into(),
         }),
-    }
+    };
+
+    untagged.into_value(tag)
 }
 
 #[cfg(test)]

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

@@ -1,7 +1,7 @@
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, UntaggedValue};
+use nu_protocol::{Signature, UntaggedValue};
 
 pub struct Path;
 
@@ -18,10 +18,25 @@ impl WholeStreamCommand for Path {
         "Explore and manipulate paths."
     }
 
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
+    fn extra_usage(&self) -> &str {
-        Ok(ActionStream::one(ReturnSuccess::value(
+        r#"There are three ways to represent a path:
+
+* As a path literal, e.g., '/home/viking/spam.txt'
+* As a structured path: a table with 'parent', 'stem', and 'extension' (and
+* 'prefix' on Windows) columns. This format is produced by the 'path parse'
+  subcommand.
+* As an inner list of path parts, e.g., '[[ / home viking spam.txt ]]'.
+  Splitting into parts is done by the `path split` command.
+
+All subcommands accept all three variants as an input. Furthermore, the 'path
+join' subcommand can be used to join the structured path or path parts back into
+the path literal."#
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        Ok(OutputStream::one(
             UntaggedValue::string(get_full_help(&Path, &args.scope)).into_value(Tag::unknown()),
-        )))
+        ))
     }
 }
 

crates/nu-command/src/commands/path/dirname.rs

@@ -8,12 +8,10 @@ use std::path::Path;
 
 pub struct PathDirname;
 
-#[derive(Deserialize)]
 struct PathDirnameArguments {
-    replace: Option<Tagged<String>>,
-    #[serde(rename = "num-levels")]
-    num_levels: Option<Tagged<u32>>,
     rest: Vec<ColumnPath>,
+    replace: Option<Tagged<String>>,
+    num_levels: Option<Tagged<u32>>,
 }
 
 impl PathSubcommandArguments for PathDirnameArguments {
@@ -29,6 +27,7 @@ impl WholeStreamCommand for PathDirname {
 
     fn signature(&self) -> Signature {
         Signature::build("path dirname")
+            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
             .named(
                 "replace",
                 SyntaxShape::String,
@@ -41,29 +40,22 @@ impl WholeStreamCommand for PathDirname {
                 "Number of directories to walk up",
                 Some('n'),
             )
-            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
     }
 
     fn usage(&self) -> &str {
-        "Gets the parent directory of a path"
+        "Get the parent directory of a path"
     }
 
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let tag = args.call_info.name_tag.clone();
-        let (
+        let args = args.evaluate_once()?;
-            PathDirnameArguments {
+        let cmd_args = Arc::new(PathDirnameArguments {
-                replace,
+            rest: args.rest_args()?,
-                num_levels,
+            replace: args.get_flag("replace")?,
-                rest,
+            num_levels: args.get_flag("num-levels")?,
-            },
-            input,
-        ) = args.process()?;
-        let args = Arc::new(PathDirnameArguments {
-            replace,
-            num_levels,
-            rest,
         });
-        Ok(operate(input, &action, tag.span, args))
+
+        Ok(operate(args.input, &action, tag.span, cmd_args))
     }
 
     #[cfg(windows)]
@@ -77,12 +69,12 @@ impl WholeStreamCommand for PathDirname {
                 ))]),
             },
             Example {
-                description: "Set how many levels up to skip",
+                description: "Walk up two levels",
                 example: "echo 'C:\\Users\\joe\\code\\test.txt' | path dirname -n 2",
                 result: Some(vec![Value::from(UntaggedValue::filepath("C:\\Users\\joe"))]),
             },
             Example {
-                description: "Replace the part that would be returned with custom string",
+                description: "Replace the part that would be returned with a custom path",
                 example:
                     "echo 'C:\\Users\\joe\\code\\test.txt' | path dirname -n 2 -r C:\\Users\\viking",
                 result: Some(vec![Value::from(UntaggedValue::filepath(
@@ -101,12 +93,12 @@ impl WholeStreamCommand for PathDirname {
                 result: Some(vec![Value::from(UntaggedValue::filepath("/home/joe/code"))]),
             },
             Example {
-                description: "Set how many levels up to skip",
+                description: "Walk up two levels",
                 example: "echo '/home/joe/code/test.txt' | path dirname -n 2",
                 result: Some(vec![Value::from(UntaggedValue::filepath("/home/joe"))]),
             },
             Example {
-                description: "Replace the part that would be returned with custom string",
+                description: "Replace the part that would be returned with a custom path",
                 example: "echo '/home/joe/code/test.txt' | path dirname -n 2 -r /home/viking",
                 result: Some(vec![Value::from(UntaggedValue::filepath(
                     "/home/viking/code/test.txt",
@@ -116,7 +108,7 @@ impl WholeStreamCommand for PathDirname {
     }
 }
 
-fn action(path: &Path, args: &PathDirnameArguments) -> UntaggedValue {
+fn action(path: &Path, tag: Tag, args: &PathDirnameArguments) -> Value {
     let num_levels = args.num_levels.as_ref().map_or(1, |tagged| tagged.item);
 
     let mut dirname = path;
@@ -131,7 +123,7 @@ fn action(path: &Path, args: &PathDirnameArguments) -> UntaggedValue {
         }
     }
 
-    match args.replace {
+    let untagged = match args.replace {
         Some(ref newdir) => {
             let remainder = path.strip_prefix(dirname).unwrap_or(dirname);
             if !remainder.as_os_str().is_empty() {
@@ -141,7 +133,9 @@ fn action(path: &Path, args: &PathDirnameArguments) -> UntaggedValue {
             }
         }
         None => UntaggedValue::filepath(dirname),
-    }
+    };
+
+    untagged.into_value(tag)
 }
 
 #[cfg(test)]

crates/nu-command/src/commands/path/exists.rs

@@ -7,7 +7,6 @@ use std::path::Path;
 
 pub struct PathExists;
 
-#[derive(Deserialize)]
 struct PathExistsArguments {
     rest: Vec<ColumnPath>,
 }
@@ -29,20 +28,23 @@ impl WholeStreamCommand for PathExists {
     }
 
     fn usage(&self) -> &str {
-        "Checks whether a path exists"
+        "Check whether a path exists"
     }
 
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let tag = args.call_info.name_tag.clone();
-        let (PathExistsArguments { rest }, input) = args.process()?;
+        let args = args.evaluate_once()?;
-        let args = Arc::new(PathExistsArguments { rest });
+        let cmd_args = Arc::new(PathExistsArguments {
-        Ok(operate(input, &action, tag.span, args))
+            rest: args.rest_args()?,
+        });
+
+        Ok(operate(args.input, &action, tag.span, cmd_args))
     }
 
     #[cfg(windows)]
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Check if file exists",
+            description: "Check if a file exists",
             example: "echo 'C:\\Users\\joe\\todo.txt' | path exists",
             result: Some(vec![Value::from(UntaggedValue::boolean(false))]),
         }]
@@ -51,15 +53,15 @@ impl WholeStreamCommand for PathExists {
     #[cfg(not(windows))]
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Check if file exists",
+            description: "Check if a file exists",
             example: "echo '/home/joe/todo.txt' | path exists",
             result: Some(vec![Value::from(UntaggedValue::boolean(false))]),
         }]
     }
 }
 
-fn action(path: &Path, _args: &PathExistsArguments) -> UntaggedValue {
+fn action(path: &Path, tag: Tag, _args: &PathExistsArguments) -> Value {
-    UntaggedValue::boolean(path.exists())
+    UntaggedValue::boolean(path.exists()).into_value(tag)
 }
 
 #[cfg(test)]

crates/nu-command/src/commands/path/expand.rs

@@ -2,12 +2,11 @@ use super::{operate, PathSubcommandArguments};
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
-use nu_protocol::{ColumnPath, Signature, SyntaxShape, UntaggedValue};
+use nu_protocol::{ColumnPath, Signature, SyntaxShape, UntaggedValue, Value};
 use std::path::{Path, PathBuf};
 
 pub struct PathExpand;
 
-#[derive(Deserialize)]
 struct PathExpandArguments {
     rest: Vec<ColumnPath>,
 }
@@ -29,14 +28,17 @@ impl WholeStreamCommand for PathExpand {
     }
 
     fn usage(&self) -> &str {
-        "Expands a path to its absolute form"
+        "Expand a path to its absolute form"
     }
 
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let tag = args.call_info.name_tag.clone();
-        let (PathExpandArguments { rest }, input) = args.process()?;
+        let args = args.evaluate_once()?;
-        let args = Arc::new(PathExpandArguments { rest });
+        let cmd_args = Arc::new(PathExpandArguments {
-        Ok(operate(input, &action, tag.span, args))
+            rest: args.rest_args()?,
+        });
+
+        Ok(operate(args.input, &action, tag.span, cmd_args))
     }
 
     #[cfg(windows)]
@@ -60,11 +62,13 @@ impl WholeStreamCommand for PathExpand {
     }
 }
 
-fn action(path: &Path, _args: &PathExpandArguments) -> UntaggedValue {
+fn action(path: &Path, tag: Tag, _args: &PathExpandArguments) -> Value {
     let ps = path.to_string_lossy();
     let expanded = shellexpand::tilde(&ps);
     let path: &Path = expanded.as_ref().as_ref();
+
     UntaggedValue::filepath(dunce::canonicalize(path).unwrap_or_else(|_| PathBuf::from(path)))
+        .into_value(tag)
 }
 
 #[cfg(test)]

crates/nu-command/src/commands/path/extension.rs

@@ -1,97 +0,0 @@
-use super::{operate, PathSubcommandArguments};
-use crate::prelude::*;
-use nu_engine::WholeStreamCommand;
-use nu_errors::ShellError;
-use nu_protocol::{ColumnPath, Signature, SyntaxShape, UntaggedValue, Value};
-use nu_source::Tagged;
-use std::path::Path;
-
-pub struct PathExtension;
-
-#[derive(Deserialize)]
-struct PathExtensionArguments {
-    replace: Option<Tagged<String>>,
-    rest: Vec<ColumnPath>,
-}
-
-impl PathSubcommandArguments for PathExtensionArguments {
-    fn get_column_paths(&self) -> &Vec<ColumnPath> {
-        &self.rest
-    }
-}
-
-impl WholeStreamCommand for PathExtension {
-    fn name(&self) -> &str {
-        "path extension"
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build("path extension")
-            .named(
-                "replace",
-                SyntaxShape::String,
-                "Return original path with extension replaced by this string",
-                Some('r'),
-            )
-            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
-    }
-
-    fn usage(&self) -> &str {
-        "Gets the extension of a path"
-    }
-
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
-        let tag = args.call_info.name_tag.clone();
-        let (PathExtensionArguments { replace, rest }, input) = args.process()?;
-        let args = Arc::new(PathExtensionArguments { replace, rest });
-        Ok(operate(input, &action, tag.span, args))
-    }
-
-    fn examples(&self) -> Vec<Example> {
-        vec![
-            Example {
-                description: "Get extension of a path",
-                example: "echo 'test.txt' | path extension",
-                result: Some(vec![Value::from("txt")]),
-            },
-            Example {
-                description: "You get an empty string if there is no extension",
-                example: "echo 'test' | path extension",
-                result: Some(vec![Value::from("")]),
-            },
-            Example {
-                description: "Replace an extension with a custom string",
-                example: "echo 'test.txt' | path extension -r md",
-                result: Some(vec![Value::from(UntaggedValue::filepath("test.md"))]),
-            },
-            Example {
-                description: "To replace more complex extensions:",
-                example: "echo 'test.tar.gz' | path extension -r '' | path extension -r txt",
-                result: Some(vec![Value::from(UntaggedValue::filepath("test.txt"))]),
-            },
-        ]
-    }
-}
-
-fn action(path: &Path, args: &PathExtensionArguments) -> UntaggedValue {
-    match args.replace {
-        Some(ref extension) => UntaggedValue::filepath(path.with_extension(&extension.item)),
-        None => UntaggedValue::string(match path.extension() {
-            Some(extension) => extension.to_string_lossy(),
-            None => "".into(),
-        }),
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::PathExtension;
-    use super::ShellError;
-
-    #[test]
-    fn examples_work_as_expected() -> Result<(), ShellError> {
-        use crate::examples::test as test_examples;
-
-        test_examples(PathExtension {})
-    }
-}

crates/nu-command/src/commands/path/filestem.rs

@@ -1,176 +0,0 @@
-use super::{operate, PathSubcommandArguments};
-use crate::prelude::*;
-use nu_engine::WholeStreamCommand;
-use nu_errors::ShellError;
-use nu_protocol::{ColumnPath, Signature, SyntaxShape, UntaggedValue, Value};
-use nu_source::Tagged;
-use std::path::Path;
-
-pub struct PathFilestem;
-
-#[derive(Deserialize)]
-struct PathFilestemArguments {
-    prefix: Option<Tagged<String>>,
-    suffix: Option<Tagged<String>>,
-    replace: Option<Tagged<String>>,
-    rest: Vec<ColumnPath>,
-}
-
-impl PathSubcommandArguments for PathFilestemArguments {
-    fn get_column_paths(&self) -> &Vec<ColumnPath> {
-        &self.rest
-    }
-}
-
-impl WholeStreamCommand for PathFilestem {
-    fn name(&self) -> &str {
-        "path filestem"
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build("path filestem")
-            .named(
-                "replace",
-                SyntaxShape::String,
-                "Return original path with filestem replaced by this string",
-                Some('r'),
-            )
-            .named(
-                "prefix",
-                SyntaxShape::String,
-                "Strip this string from from the beginning of a file name",
-                Some('p'),
-            )
-            .named(
-                "suffix",
-                SyntaxShape::String,
-                "Strip this string from from the end of a file name",
-                Some('s'),
-            )
-            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
-    }
-
-    fn usage(&self) -> &str {
-        "Gets the file stem of a path"
-    }
-
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
-        let tag = args.call_info.name_tag.clone();
-        let (
-            PathFilestemArguments {
-                prefix,
-                suffix,
-                replace,
-                rest,
-            },
-            input,
-        ) = args.process()?;
-        let args = Arc::new(PathFilestemArguments {
-            prefix,
-            suffix,
-            replace,
-            rest,
-        });
-        Ok(operate(input, &action, tag.span, args))
-    }
-
-    #[cfg(windows)]
-    fn examples(&self) -> Vec<Example> {
-        vec![
-            Example {
-                description: "Get filestem of a path",
-                example: "echo 'C:\\Users\\joe\\bacon_lettuce.egg' | path filestem",
-                result: Some(vec![Value::from("bacon_lettuce")]),
-            },
-            Example {
-                description: "Get filestem of a path, stripped of prefix and suffix",
-                example: "echo 'C:\\Users\\joe\\bacon_lettuce.egg.gz' | path filestem -p bacon_ -s .egg.gz",
-                result: Some(vec![Value::from("lettuce")]),
-            },
-            Example {
-                description: "Replace the filestem that would be returned",
-                example: "echo 'C:\\Users\\joe\\bacon_lettuce.egg.gz' | path filestem -p bacon_ -s .egg.gz -r spam",
-                result: Some(vec![Value::from(UntaggedValue::filepath("C:\\Users\\joe\\bacon_spam.egg.gz"))]),
-            },
-        ]
-    }
-
-    #[cfg(not(windows))]
-    fn examples(&self) -> Vec<Example> {
-        vec![
-            Example {
-                description: "Get filestem of a path",
-                example: "echo '/home/joe/bacon_lettuce.egg' | path filestem",
-                result: Some(vec![Value::from("bacon_lettuce")]),
-            },
-            Example {
-                description: "Get filestem of a path, stripped of prefix and suffix",
-                example: "echo '/home/joe/bacon_lettuce.egg.gz' | path filestem -p bacon_ -s .egg.gz",
-                result: Some(vec![Value::from("lettuce")]),
-            },
-            Example {
-                description: "Replace the filestem that would be returned",
-                example: "echo '/home/joe/bacon_lettuce.egg.gz' | path filestem -p bacon_ -s .egg.gz -r spam",
-                result: Some(vec![Value::from(UntaggedValue::filepath("/home/joe/bacon_spam.egg.gz"))]),
-            },
-        ]
-    }
-}
-
-fn action(path: &Path, args: &PathFilestemArguments) -> UntaggedValue {
-    let basename = match path.file_name() {
-        Some(name) => name.to_string_lossy().to_string(),
-        None => "".to_string(),
-    };
-
-    let suffix = match args.suffix {
-        Some(ref suf) => match basename.rmatch_indices(&suf.item).next() {
-            Some((i, _)) => basename.split_at(i).1.to_string(),
-            None => "".to_string(),
-        },
-        None => match path.extension() {
-            // Prepend '.' since the extension returned comes without it
-            Some(ext) => ".".to_string() + &ext.to_string_lossy().to_string(),
-            None => "".to_string(),
-        },
-    };
-
-    let prefix = match args.prefix {
-        Some(ref pre) => match basename.matches(&pre.item).next() {
-            Some(m) => basename.split_at(m.len()).0.to_string(),
-            None => "".to_string(),
-        },
-        None => "".to_string(),
-    };
-
-    let basename_without_prefix = match basename.matches(&prefix).next() {
-        Some(m) => basename.split_at(m.len()).1.to_string(),
-        None => basename,
-    };
-
-    let stem = match basename_without_prefix.rmatch_indices(&suffix).next() {
-        Some((i, _)) => basename_without_prefix.split_at(i).0.to_string(),
-        None => basename_without_prefix,
-    };
-
-    match args.replace {
-        Some(ref replace) => {
-            let new_name = prefix + &replace.item + &suffix;
-            UntaggedValue::filepath(path.with_file_name(&new_name))
-        }
-        None => UntaggedValue::string(stem),
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::PathFilestem;
-    use super::ShellError;
-
-    #[test]
-    fn examples_work_as_expected() -> Result<(), ShellError> {
-        use crate::examples::test as test_examples;
-
-        test_examples(PathFilestem {})
-    }
-}

crates/nu-command/src/commands/path/join.rs

@@ -1,4 +1,4 @@
-use super::{operate, PathSubcommandArguments};
+use super::{handle_value, join_path, operate_column_paths, PathSubcommandArguments};
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
@@ -8,10 +8,9 @@ use std::path::Path;
 
 pub struct PathJoin;
 
-#[derive(Deserialize)]
 struct PathJoinArguments {
-    path: Tagged<String>,
     rest: Vec<ColumnPath>,
+    append: Option<Tagged<String>>,
 }
 
 impl PathSubcommandArguments for PathJoinArguments {
@@ -27,46 +26,141 @@ impl WholeStreamCommand for PathJoin {
 
     fn signature(&self) -> Signature {
         Signature::build("path join")
-            .required("path", SyntaxShape::String, "Path to join the input path")
             .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
+            .named(
+                "append",
+                SyntaxShape::String,
+                "Path to append to the input",
+                Some('a'),
+            )
     }
 
     fn usage(&self) -> &str {
-        "Joins an input path with another path"
+        "Join a structured path or a list of path parts."
     }
 
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
+    fn extra_usage(&self) -> &str {
+        r#"Optionally, append an additional path to the result. It is designed to accept
+the output of 'path parse' and 'path split' subdommands."#
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let tag = args.call_info.name_tag.clone();
-        let (PathJoinArguments { path, rest }, input) = args.process()?;
+        let args = args.evaluate_once()?;
-        let args = Arc::new(PathJoinArguments { path, rest });
+        let cmd_args = Arc::new(PathJoinArguments {
-        Ok(operate(input, &action, tag.span, args))
+            rest: args.rest_args()?,
+            append: args.get_flag("append")?,
+        });
+
+        Ok(operate_join(args.input, &action, tag, cmd_args))
     }
 
     #[cfg(windows)]
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
+        vec![
-            description: "Append a filename to a path",
+            Example {
-            example: "echo 'C:\\Users\\viking' | path join spam.txt",
+                description: "Append a filename to a path",
-            result: Some(vec![Value::from(UntaggedValue::filepath(
+                example: r"echo 'C:\Users\viking' | path join -a spam.txt",
-                "C:\\Users\\viking\\spam.txt",
+                result: Some(vec![Value::from(UntaggedValue::filepath(
-            ))]),
+                    r"C:\Users\viking\spam.txt",
-        }]
+                ))]),
+            },
+            Example {
+                description: "Join a list of parts into a path",
+                example: r"echo [ 'C:' '\' 'Users' 'viking' 'spam.txt' ] | path join",
+                result: Some(vec![Value::from(UntaggedValue::filepath(
+                    r"C:\Users\viking\spam.txt",
+                ))]),
+            },
+            Example {
+                description: "Join a structured path into a path",
+                example: r"echo [ [parent stem extension]; ['C:\Users\viking' 'spam' 'txt']] | path join",
+                result: Some(vec![Value::from(UntaggedValue::filepath(
+                    r"C:\Users\viking\spam.txt",
+                ))]),
+            },
+        ]
     }
 
     #[cfg(not(windows))]
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
+        vec![
-            description: "Append a filename to a path",
+            Example {
-            example: "echo '/home/viking' | path join spam.txt",
+                description: "Append a filename to a path",
-            result: Some(vec![Value::from(UntaggedValue::filepath(
+                example: r"echo '/home/viking' | path join -a spam.txt",
-                "/home/viking/spam.txt",
+                result: Some(vec![Value::from(UntaggedValue::filepath(
-            ))]),
+                    r"/home/viking/spam.txt",
-        }]
+                ))]),
+            },
+            Example {
+                description: "Join a list of parts into a path",
+                example: r"echo [ '/' 'home' 'viking' 'spam.txt' ] | path join",
+                result: Some(vec![Value::from(UntaggedValue::filepath(
+                    r"/home/viking/spam.txt",
+                ))]),
+            },
+            Example {
+                description: "Join a structured path into a path",
+                example: r"echo [[ parent stem extension ]; [ '/home/viking' 'spam' 'txt' ]] | path join",
+                result: Some(vec![Value::from(UntaggedValue::filepath(
+                    r"/home/viking/spam.txt",
+                ))]),
+            },
+        ]
     }
 }
 
-fn action(path: &Path, args: &PathJoinArguments) -> UntaggedValue {
+fn operate_join<F, T>(
-    UntaggedValue::filepath(path.join(&args.path.item))
+    input: crate::InputStream,
+    action: &'static F,
+    tag: Tag,
+    args: Arc<T>,
+) -> OutputStream
+where
+    T: PathSubcommandArguments + Send + Sync + 'static,
+    F: Fn(&Path, Tag, &T) -> Value + Send + Sync + 'static,
+{
+    let span = tag.span;
+
+    if args.get_column_paths().is_empty() {
+        let mut parts = input.peekable();
+        let has_rows = matches!(
+            parts.peek(),
+            Some(&Value {
+                value: UntaggedValue::Row(_),
+                ..
+            })
+        );
+
+        if has_rows {
+            // operate one-by-one like the other path subcommands
+            parts
+                .into_iter()
+                .map(
+                    move |v| match handle_value(&action, &v, span, Arc::clone(&args)) {
+                        Ok(v) => v,
+                        Err(e) => Value::error(e),
+                    },
+                )
+                .to_output_stream()
+        } else {
+            // join the whole input stream
+            match join_path(&parts.collect_vec(), &span) {
+                Ok(path_buf) => OutputStream::one(action(&path_buf, tag, &args)),
+                Err(e) => OutputStream::one(Value::error(e)),
+            }
+        }
+    } else {
+        operate_column_paths(input, action, span, args)
+    }
+}
+
+fn action(path: &Path, tag: Tag, args: &PathJoinArguments) -> Value {
+    if let Some(ref append) = args.append {
+        UntaggedValue::filepath(path.join(&append.item)).into_value(tag)
+    } else {
+        UntaggedValue::filepath(path).into_value(tag)
+    }
 }
 
 #[cfg(test)]

crates/nu-command/src/commands/path/mod.rs

@@ -3,16 +3,18 @@ mod command;
 mod dirname;
 mod exists;
 mod expand;
-mod extension;
-mod filestem;
 mod join;
+mod parse;
+mod split;
 mod r#type;
 
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ColumnPath, Primitive, ReturnSuccess, ShellTypeName, UntaggedValue, Value};
+use nu_protocol::{
+    ColumnPath, Dictionary, MaybeOwned, Primitive, ShellTypeName, UntaggedValue, Value,
+};
 use nu_source::Span;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 pub use basename::PathBasename;
@@ -20,39 +22,173 @@ pub use command::Path as PathCommand;
 pub use dirname::PathDirname;
 pub use exists::PathExists;
 pub use expand::PathExpand;
-pub use extension::PathExtension;
-pub use filestem::PathFilestem;
 pub use join::PathJoin;
+pub use parse::PathParse;
 pub use r#type::PathType;
+pub use split::PathSplit;
+
+#[cfg(windows)]
+const ALLOWED_COLUMNS: [&str; 4] = ["prefix", "parent", "stem", "extension"];
+#[cfg(not(windows))]
+const ALLOWED_COLUMNS: [&str; 3] = ["parent", "stem", "extension"];
 
 trait PathSubcommandArguments {
     fn get_column_paths(&self) -> &Vec<ColumnPath>;
 }
 
+fn encode_path(
+    entries: &Dictionary,
+    orig_span: Span,
+    new_span: Span,
+) -> Result<PathBuf, ShellError> {
+    if entries.length() == 0 {
+        return Err(ShellError::labeled_error_with_secondary(
+            "Empty table cannot be encoded as a path",
+            "got empty table",
+            new_span,
+            "originates from here",
+            orig_span,
+        ));
+    }
+
+    for col in entries.keys() {
+        if !ALLOWED_COLUMNS.contains(&col.as_str()) {
+            let msg = format!(
+                "Column '{}' is not valid for a structured path. Allowed columns are: {}",
+                col,
+                ALLOWED_COLUMNS.join(", ")
+            );
+            return Err(ShellError::labeled_error_with_secondary(
+                "Invalid column name",
+                msg,
+                new_span,
+                "originates from here",
+                orig_span,
+            ));
+        }
+    }
+
+    // At this point, the row is known to have >0 columns, all of them allowed
+    let mut result = PathBuf::new();
+
+    #[cfg(windows)]
+    if let MaybeOwned::Borrowed(val) = entries.get_data("prefix") {
+        let s = val.as_string()?;
+        if !s.is_empty() {
+            result.push(&s);
+        }
+    };
+
+    if let MaybeOwned::Borrowed(val) = entries.get_data("parent") {
+        let p = val.as_string()?;
+        if !p.is_empty() {
+            result.push(p);
+        }
+    };
+
+    let mut basename = String::new();
+
+    if let MaybeOwned::Borrowed(val) = entries.get_data("stem") {
+        let s = val.as_string()?;
+        if !s.is_empty() {
+            basename.push_str(&s);
+        }
+    };
+
+    if let MaybeOwned::Borrowed(val) = entries.get_data("extension") {
+        let s = val.as_string()?;
+        if !s.is_empty() {
+            basename.push('.');
+            basename.push_str(&s);
+        }
+    };
+
+    if !basename.is_empty() {
+        result.push(basename);
+    }
+
+    Ok(result)
+}
+
+fn join_path(parts: &[Value], new_span: &Span) -> Result<PathBuf, ShellError> {
+    parts
+        .iter()
+        .map(|part| match &part.value {
+            UntaggedValue::Primitive(Primitive::String(s)) => Ok(Path::new(s)),
+            UntaggedValue::Primitive(Primitive::FilePath(pb)) => Ok(pb.as_path()),
+            _ => {
+                let got = format!("got {}", part.type_name());
+                Err(ShellError::labeled_error_with_secondary(
+                    "Cannot join values that are not paths or strings.",
+                    got,
+                    new_span,
+                    "originates from here",
+                    part.tag.span,
+                ))
+            }
+        })
+        .collect()
+}
+
 fn handle_value<F, T>(action: &F, v: &Value, span: Span, args: Arc<T>) -> Result<Value, ShellError>
 where
-    T: PathSubcommandArguments + Send + 'static,
+    T: PathSubcommandArguments,
-    F: Fn(&Path, &T) -> UntaggedValue + Send + 'static,
+    F: Fn(&Path, Tag, &T) -> Value,
 {
-    let v = match &v.value {
+    match &v.value {
-        UntaggedValue::Primitive(Primitive::FilePath(buf)) => {
+        UntaggedValue::Primitive(Primitive::FilePath(buf)) => Ok(action(buf, v.tag(), &args)),
-            action(buf, &args).into_value(v.tag())
+        UntaggedValue::Primitive(Primitive::String(s)) => Ok(action(s.as_ref(), v.tag(), &args)),
+        UntaggedValue::Row(entries) => {
+            // implicit path join makes all subcommands understand the structured path
+            let path_buf = encode_path(entries, v.tag().span, span)?;
+            Ok(action(&path_buf, v.tag(), &args))
         }
-        UntaggedValue::Primitive(Primitive::String(s)) => {
+        UntaggedValue::Table(parts) => {
-            action(s.as_ref(), &args).into_value(v.tag())
+            // implicit path join makes all subcommands understand path split into parts
+            let path_buf = join_path(parts, &span)?;
+            Ok(action(&path_buf, v.tag(), &args))
         }
         other => {
             let got = format!("got {}", other.type_name());
-            return Err(ShellError::labeled_error_with_secondary(
+            Err(ShellError::labeled_error_with_secondary(
-                "value is not string or path",
+                "Value is a not string, path, row, or table",
                 got,
                 span,
-                "originates from here".to_string(),
+                "originates from here",
                 v.tag().span,
-            ));
+            ))
         }
-    };
+    }
-    Ok(v)
+}
+
+fn operate_column_paths<F, T>(
+    input: crate::InputStream,
+    action: &'static F,
+    span: Span,
+    args: Arc<T>,
+) -> OutputStream
+where
+    T: PathSubcommandArguments + Send + Sync + 'static,
+    F: Fn(&Path, Tag, &T) -> Value + Send + Sync + 'static,
+{
+    input
+        .map(move |v| {
+            let mut ret = v;
+
+            for path in args.get_column_paths() {
+                let cloned_args = Arc::clone(&args);
+                ret = match ret.swap_data_by_column_path(
+                    path,
+                    Box::new(move |old| handle_value(&action, &old, span, cloned_args)),
+                ) {
+                    Ok(v) => v,
+                    Err(e) => Value::error(e),
+                };
+            }
+
+            ret
+        })
+        .to_output_stream()
 }
 
 fn operate<F, T>(
@@ -60,28 +196,21 @@ fn operate<F, T>(
     action: &'static F,
     span: Span,
     args: Arc<T>,
-) -> ActionStream
+) -> OutputStream
 where
     T: PathSubcommandArguments + Send + Sync + 'static,
-    F: Fn(&Path, &T) -> UntaggedValue + Send + Sync + 'static,
+    F: Fn(&Path, Tag, &T) -> Value + Send + Sync + 'static,
 {
-    input
+    if args.get_column_paths().is_empty() {
-        .map(move |v| {
+        input
-            if args.get_column_paths().is_empty() {
+            .map(
-                ReturnSuccess::value(handle_value(&action, &v, span, Arc::clone(&args))?)
+                move |v| match handle_value(&action, &v, span, Arc::clone(&args)) {
-            } else {
+                    Ok(v) => v,
-                let mut ret = v;
+                    Err(e) => Value::error(e),
-
+                },
-                for path in args.get_column_paths() {
+            )
-                    let cloned_args = Arc::clone(&args);
+            .to_output_stream()
-                    ret = ret.swap_data_by_column_path(
+    } else {
-                        path,
+        operate_column_paths(input, action, span, args)
-                        Box::new(move |old| handle_value(&action, &old, span, cloned_args)),
+    }
-                    )?;
-                }
-
-                ReturnSuccess::value(ret)
-            }
-        })
-        .to_action_stream()
 }

crates/nu-command/src/commands/path/parse.rs

@@ -0,0 +1,177 @@
+use super::{operate, PathSubcommandArguments};
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{ColumnPath, Signature, SyntaxShape, TaggedDictBuilder, UntaggedValue, Value};
+use nu_source::Tagged;
+#[cfg(windows)]
+use std::path::Component;
+use std::path::Path;
+
+pub struct PathParse;
+
+struct PathParseArguments {
+    rest: Vec<ColumnPath>,
+    extension: Option<Tagged<String>>,
+}
+
+impl PathSubcommandArguments for PathParseArguments {
+    fn get_column_paths(&self) -> &Vec<ColumnPath> {
+        &self.rest
+    }
+}
+
+impl WholeStreamCommand for PathParse {
+    fn name(&self) -> &str {
+        "path parse"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("path parse")
+            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
+            .named(
+                "extension",
+                SyntaxShape::String,
+                "Manually supply the extension (without the dot)",
+                Some('e'),
+            )
+    }
+
+    fn usage(&self) -> &str {
+        "Convert a path into structured data."
+    }
+
+    fn extra_usage(&self) -> &str {
+        r#"Each path is split into a table with 'parent', 'stem' and 'extension' fields.
+On Windows, an extra 'prefix' column is added."#
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        let tag = args.call_info.name_tag.clone();
+        let args = args.evaluate_once()?;
+        let cmd_args = Arc::new(PathParseArguments {
+            rest: args.rest_args()?,
+            extension: args.get_flag("extension")?,
+        });
+
+        Ok(operate(args.input, &action, tag.span, cmd_args))
+    }
+
+    #[cfg(windows)]
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Parse a single path",
+                example: r"echo 'C:\Users\viking\spam.txt' | path parse",
+                result: None,
+            },
+            Example {
+                description: "Replace a complex extension",
+                example: r"echo 'C:\Users\viking\spam.tar.gz' | path parse -e tar.gz | update extension { = txt }",
+                result: None,
+            },
+            Example {
+                description: "Ignore the extension",
+                example: r"echo 'C:\Users\viking.d' | path parse -e ''",
+                result: None,
+            },
+            Example {
+                description: "Parse all paths under the 'name' column",
+                example: r"ls | path parse name",
+                result: None,
+            },
+        ]
+    }
+
+    #[cfg(not(windows))]
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Parse a path",
+                example: r"echo '/home/viking/spam.txt' | path parse",
+                result: None,
+            },
+            Example {
+                description: "Replace a complex extension",
+                example: r"echo '/home/viking/spam.tar.gz' | path parse -e tar.gz | update extension { = txt }",
+                result: None,
+            },
+            Example {
+                description: "Ignore the extension",
+                example: r"echo '/etc/conf.d' | path parse -e ''",
+                result: None,
+            },
+            Example {
+                description: "Parse all paths under the 'name' column",
+                example: r"ls | path parse name",
+                result: None,
+            },
+        ]
+    }
+}
+
+fn action(path: &Path, tag: Tag, args: &PathParseArguments) -> Value {
+    let mut dict = TaggedDictBuilder::new(&tag);
+
+    #[cfg(windows)]
+    {
+        // The prefix is only valid on Windows. On non-Windows, it's always empty.
+        let prefix = match path.components().next() {
+            Some(Component::Prefix(prefix_component)) => {
+                prefix_component.as_os_str().to_string_lossy()
+            }
+            _ => "".into(),
+        };
+        dict.insert_untagged("prefix", UntaggedValue::string(prefix));
+    }
+
+    let parent = path.parent().unwrap_or_else(|| "".as_ref());
+    dict.insert_untagged("parent", UntaggedValue::filepath(parent));
+
+    let basename = path
+        .file_name()
+        .unwrap_or_else(|| "".as_ref())
+        .to_string_lossy();
+
+    match &args.extension {
+        Some(Tagged { item: ext, .. }) => {
+            let ext_with_dot = [".", ext].concat();
+            if basename.ends_with(&ext_with_dot) && !ext.is_empty() {
+                let stem = basename.trim_end_matches(&ext_with_dot);
+                dict.insert_untagged("stem", UntaggedValue::string(stem));
+                dict.insert_untagged("extension", UntaggedValue::string(ext));
+            } else {
+                dict.insert_untagged("stem", UntaggedValue::string(basename));
+                dict.insert_untagged("extension", UntaggedValue::string(""));
+            }
+        }
+        None => {
+            let stem = path
+                .file_stem()
+                .unwrap_or_else(|| "".as_ref())
+                .to_string_lossy();
+            let extension = path
+                .extension()
+                .unwrap_or_else(|| "".as_ref())
+                .to_string_lossy();
+
+            dict.insert_untagged("stem", UntaggedValue::string(stem));
+            dict.insert_untagged("extension", UntaggedValue::string(extension));
+        }
+    }
+
+    dict.into_value()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::PathParse;
+    use super::ShellError;
+
+    #[test]
+    fn examples_work_as_expected() -> Result<(), ShellError> {
+        use crate::examples::test as test_examples;
+
+        test_examples(PathParse {})
+    }
+}

crates/nu-command/src/commands/path/split.rs

@@ -0,0 +1,146 @@
+use super::{handle_value, operate_column_paths, PathSubcommandArguments};
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{ColumnPath, Signature, SyntaxShape, UntaggedValue, Value};
+use std::path::Path;
+
+pub struct PathSplit;
+
+struct PathSplitArguments {
+    rest: Vec<ColumnPath>,
+}
+
+impl PathSubcommandArguments for PathSplitArguments {
+    fn get_column_paths(&self) -> &Vec<ColumnPath> {
+        &self.rest
+    }
+}
+
+impl WholeStreamCommand for PathSplit {
+    fn name(&self) -> &str {
+        "path split"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("path split")
+            .rest(SyntaxShape::ColumnPath, "Optionally operate by column path")
+    }
+
+    fn usage(&self) -> &str {
+        "Split a path into parts by a separator."
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        let tag = args.call_info.name_tag.clone();
+        let args = args.evaluate_once()?;
+        let cmd_args = Arc::new(PathSplitArguments {
+            rest: args.rest_args()?,
+        });
+
+        Ok(operate_split(args.input, &action, tag.span, cmd_args))
+    }
+
+    #[cfg(windows)]
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Split a path into parts",
+                example: r"echo 'C:\Users\viking\spam.txt' | path split",
+                result: Some(vec![
+                    Value::from(UntaggedValue::string("C:")),
+                    Value::from(UntaggedValue::string(r"\")),
+                    Value::from(UntaggedValue::string("Users")),
+                    Value::from(UntaggedValue::string("viking")),
+                    Value::from(UntaggedValue::string("spam.txt")),
+                ]),
+            },
+            Example {
+                description: "Split all paths under the 'name' column",
+                example: r"ls | path split name",
+                result: None,
+            },
+        ]
+    }
+
+    #[cfg(not(windows))]
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Split a path into parts",
+                example: r"echo '/home/viking/spam.txt' | path split",
+                result: Some(vec![
+                    Value::from(UntaggedValue::string("/")),
+                    Value::from(UntaggedValue::string("home")),
+                    Value::from(UntaggedValue::string("viking")),
+                    Value::from(UntaggedValue::string("spam.txt")),
+                ]),
+            },
+            Example {
+                description: "Split all paths under the 'name' column",
+                example: r"ls | path split name",
+                result: None,
+            },
+        ]
+    }
+}
+
+fn operate_split<F, T>(
+    input: crate::InputStream,
+    action: &'static F,
+    span: Span,
+    args: Arc<T>,
+) -> OutputStream
+where
+    T: PathSubcommandArguments + Send + Sync + 'static,
+    F: Fn(&Path, Tag, &T) -> Value + Send + Sync + 'static,
+{
+    if args.get_column_paths().is_empty() {
+        // Do not wrap result into a table
+        input
+            .flat_map(move |v| {
+                let split_result = handle_value(&action, &v, span, Arc::clone(&args));
+
+                match split_result {
+                    Ok(Value {
+                        value: UntaggedValue::Table(parts),
+                        ..
+                    }) => parts.into_iter().to_output_stream(),
+                    Err(e) => OutputStream::one(Value::error(e)),
+                    _ => OutputStream::one(Value::error(ShellError::labeled_error(
+                        "Internal Error",
+                        "unexpected result from the split function",
+                        span,
+                    ))),
+                }
+            })
+            .to_output_stream()
+    } else {
+        operate_column_paths(input, action, span, args)
+    }
+}
+
+fn action(path: &Path, tag: Tag, _args: &PathSplitArguments) -> Value {
+    let parts: Vec<Value> = path
+        .components()
+        .map(|comp| {
+            let s = comp.as_os_str().to_string_lossy();
+            UntaggedValue::string(s).into_value(&tag)
+        })
+        .collect();
+
+    UntaggedValue::table(&parts).into_value(tag)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::PathSplit;
+    use super::ShellError;
+
+    #[test]
+    fn examples_work_as_expected() -> Result<(), ShellError> {
+        use crate::examples::test as test_examples;
+
+        test_examples(PathSplit {})
+    }
+}

crates/nu-command/src/commands/path/type.rs

@@ -8,7 +8,6 @@ use std::path::Path;
 
 pub struct PathType;
 
-#[derive(Deserialize)]
 struct PathTypeArguments {
     rest: Vec<ColumnPath>,
 }
@@ -30,14 +29,17 @@ impl WholeStreamCommand for PathType {
     }
 
     fn usage(&self) -> &str {
-        "Gives the type of the object a path refers to (e.g., file, dir, symlink)"
+        "Get the type of the object a path refers to (e.g., file, dir, symlink)"
     }
 
-    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let tag = args.call_info.name_tag.clone();
-        let (PathTypeArguments { rest }, input) = args.process()?;
+        let args = args.evaluate_once()?;
-        let args = Arc::new(PathTypeArguments { rest });
+        let cmd_args = Arc::new(PathTypeArguments {
-        Ok(operate(input, &action, tag.span, args))
+            rest: args.rest_args()?,
+        });
+
+        Ok(operate(args.input, &action, tag.span, cmd_args))
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -49,12 +51,14 @@ impl WholeStreamCommand for PathType {
     }
 }
 
-fn action(path: &Path, _args: &PathTypeArguments) -> UntaggedValue {
+fn action(path: &Path, tag: Tag, _args: &PathTypeArguments) -> Value {
     let meta = std::fs::symlink_metadata(path);
-    UntaggedValue::string(match &meta {
+    let untagged = UntaggedValue::string(match &meta {
         Ok(md) => get_file_type(md),
         Err(_) => "",
-    })
+    });
+
+    untagged.into_value(tag)
 }
 
 #[cfg(test)]

crates/nu-command/tests/commands/path/extension.rs

@@ -1,37 +0,0 @@
-use nu_test_support::{nu, pipeline};
-
-#[test]
-fn returns_extension_of_path_ending_with_dot() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "bacon." | path extension
-        "#
-    ));
-
-    assert_eq!(actual.out, "");
-}
-
-#[test]
-fn replaces_extension_with_dot_of_path_ending_with_dot() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "bacon." | path extension -r .egg
-        "#
-    ));
-
-    assert_eq!(actual.out, "bacon..egg");
-}
-
-#[test]
-fn replaces_extension_of_empty_path() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "" | path extension -r egg
-        "#
-    ));
-
-    assert_eq!(actual.out, "");
-}

crates/nu-command/tests/commands/path/filestem.rs

@@ -1,95 +0,0 @@
-use nu_test_support::{nu, pipeline};
-
-use super::join_path_sep;
-
-#[test]
-fn returns_filestem_of_dot() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "menu/eggs/." 
-            | path filestem
-        "#
-    ));
-
-    assert_eq!(actual.out, "eggs");
-}
-
-#[test]
-fn returns_filestem_of_double_dot() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "menu/eggs/.." 
-            | path filestem
-        "#
-    ));
-
-    assert_eq!(actual.out, "");
-}
-
-#[test]
-fn returns_filestem_of_path_with_empty_prefix() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "menu/spam.txt" 
-            | path filestem -p ""
-        "#
-    ));
-
-    assert_eq!(actual.out, "spam");
-}
-
-#[test]
-fn returns_filestem_of_path_with_empty_suffix() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "menu/spam.txt" 
-            | path filestem -s ""
-        "#
-    ));
-
-    assert_eq!(actual.out, "spam.txt");
-}
-
-#[test]
-fn returns_filestem_of_path_with_empty_prefix_and_suffix() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "menu/spam.txt" 
-            | path filestem -p "" -s ""
-        "#
-    ));
-
-    assert_eq!(actual.out, "spam.txt");
-}
-
-#[test]
-fn returns_filestem_with_wrong_prefix_and_suffix() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "menu/spam.txt" 
-            | path filestem -p "bacon" -s "eggs"
-        "#
-    ));
-
-    assert_eq!(actual.out, "spam.txt");
-}
-
-#[test]
-fn replaces_filestem_stripped_to_dot() {
-    let actual = nu!(
-        cwd: "tests", pipeline(
-        r#"
-            echo "menu/spam.txt" 
-            | path filestem -p "spam" -s "txt" -r ".eggs."
-        "#
-    ));
-
-    let expected = join_path_sep(&["menu", "spam.eggs.txt"]);
-    assert_eq!(actual.out, expected);
-}

crates/nu-command/tests/commands/path/join.rs

@@ -8,7 +8,7 @@ fn returns_path_joined_with_column_path() {
         cwd: "tests", pipeline(
         r#"
             echo [ [name]; [eggs] ]
-            | path join spam.txt name
+            | path join -a spam.txt name
             | get name
         "#
     ));
@@ -17,13 +17,27 @@ fn returns_path_joined_with_column_path() {
     assert_eq!(actual.out, expected);
 }
 
+#[test]
+fn returns_path_joined_from_list() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo [ home viking spam.txt ]
+            | path join 
+        "#
+    ));
+
+    let expected = join_path_sep(&["home", "viking", "spam.txt"]);
+    assert_eq!(actual.out, expected);
+}
+
 #[test]
 fn appends_slash_when_joined_with_empty_path() {
     let actual = nu!(
         cwd: "tests", pipeline(
         r#"
             echo "/some/dir"
-            | path join ''
+            | path join -a ''
         "#
     ));
 
@@ -37,7 +51,7 @@ fn returns_joined_path_when_joining_empty_path() {
         cwd: "tests", pipeline(
         r#"
             echo ""
-            | path join foo.txt
+            | path join -a foo.txt
         "#
     ));
 

crates/nu-command/tests/commands/path/mod.rs

@@ -2,9 +2,9 @@ mod basename;
 mod dirname;
 mod exists;
 mod expand;
-mod extension;
-mod filestem;
 mod join;
+mod parse;
+mod split;
 mod type_;
 
 use std::path::MAIN_SEPARATOR;

crates/nu-command/tests/commands/path/parse.rs

@@ -0,0 +1,136 @@
+use nu_test_support::{nu, pipeline};
+
+#[cfg(windows)]
+#[test]
+fn parses_single_path_prefix() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'C:\users\viking\spam.txt'
+            | path parse
+            | get prefix
+        "#
+    ));
+
+    assert_eq!(actual.out, "C:");
+}
+
+#[test]
+fn parses_single_path_parent() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'home/viking/spam.txt'
+            | path parse
+            | get parent
+        "#
+    ));
+
+    assert_eq!(actual.out, "home/viking");
+}
+
+#[test]
+fn parses_single_path_stem() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'home/viking/spam.txt'
+            | path parse
+            | get stem
+        "#
+    ));
+
+    assert_eq!(actual.out, "spam");
+}
+
+#[test]
+fn parses_custom_extension_gets_extension() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'home/viking/spam.tar.gz' 
+            | path parse -e tar.gz
+            | get extension
+        "#
+    ));
+
+    assert_eq!(actual.out, "tar.gz");
+}
+
+#[test]
+fn parses_custom_extension_gets_stem() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'home/viking/spam.tar.gz' 
+            | path parse -e tar.gz
+            | get stem
+        "#
+    ));
+
+    assert_eq!(actual.out, "spam");
+}
+
+#[test]
+fn parses_ignoring_extension_gets_extension() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'home/viking/spam.tar.gz' 
+            | path parse -e ''
+            | get extension
+        "#
+    ));
+
+    assert_eq!(actual.out, "");
+}
+
+#[test]
+fn parses_ignoring_extension_gets_stem() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'home/viking/spam.tar.gz' 
+            | path parse -e ""
+            | get stem
+        "#
+    ));
+
+    assert_eq!(actual.out, "spam.tar.gz");
+}
+
+#[test]
+fn parses_column_path_extension() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo [[home, barn]; ['home/viking/spam.txt', 'barn/cow/moo.png']]
+            | path parse home barn
+            | get barn
+            | get extension
+        "#
+    ));
+
+    assert_eq!(actual.out, "png");
+}
+
+#[test]
+fn parses_into_correct_number_of_columns() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo 'home/viking/spam.txt'
+            | path parse
+            | pivot
+            | get Column0
+            | length
+        "#
+    ));
+
+    #[cfg(windows)]
+    let expected = "4";
+    #[cfg(not(windows))]
+    let expected = "3";
+
+    assert_eq!(actual.out, expected);
+}

crates/nu-command/tests/commands/path/split.rs

@@ -0,0 +1,47 @@
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn splits_empty_path() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo '' | path split
+        "#
+    ));
+
+    assert_eq!(actual.out, "");
+}
+
+#[test]
+fn splits_correctly_single_path() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo ['home/viking/spam.txt']
+            | path split 
+            | last
+        "#
+    ));
+
+    assert_eq!(actual.out, "spam.txt");
+}
+
+#[test]
+fn splits_correctly_with_column_path() {
+    let actual = nu!(
+        cwd: "tests", pipeline(
+        r#"
+            echo [
+                [home, barn];
+
+                ['home/viking/spam.txt', 'barn/cow/moo.png']
+                ['home/viking/eggs.txt', 'barn/goat/cheese.png']
+            ]
+            | path split home barn
+            | get barn
+            | length
+        "#
+    ));
+
+    assert_eq!(actual.out, "6");
+}