Support including a justfile from another justfile

.github/workflows/ci.yaml

@@ -30,9 +30,6 @@ jobs:
 
     - uses: Swatinem/rust-cache@v1
 
-    - name: Check Lockfile
-      run: cargo update --locked --package just
-
     - name: Clippy
       run: cargo clippy --all --all-targets
 

README.md

@@ -2175,6 +2175,47 @@ But they must match:
 $ just foo/a bar/b
 error: Conflicting path arguments: `foo/` and `bar/`
 ```
+### Include Directives
+
+The `!include` directive, currently unstable, can be used to include the
+verbatim text of another file.
+
+If you have the following `justfile`:
+
+```mf
+!include foo/bar.just
+
+a: b
+  @echo A
+
+```
+
+And the following text in `foo/bar.just`:
+
+```mf
+b:
+  @echo B
+```
+
+`foo/bar.just` will be included in `justfile` and recipe `b` will be defined:
+
+```sh
+$ just --unstable b
+B
+$ just --unstable a
+B
+A
+```
+
+The `!include` directive path can be absolute or relative to the location of
+the justfile containing it. `!include` directives must appear at the beginning
+of a line. line.
+
+`!include` directives are only processed before the first non-blank,
+non-comment line.
+
+Included files can themselves contain `!include` directives, which are
+processed recursively.
 
 ### Hiding `justfile`s
 

src/error.rs

@@ -31,6 +31,10 @@ pub(crate) enum Error<'src> {
     chooser: OsString,
     io_error: io::Error,
   },
+  CircularInclude {
+    current: PathBuf,
+    include: PathBuf,
+  },
   Code {
     recipe: &'src str,
     line_number: Option<usize>,
@@ -84,12 +88,19 @@ pub(crate) enum Error<'src> {
     function: Name<'src>,
     message: String,
   },
+  IncludeMissingPath {
+    file: PathBuf,
+    line: usize,
+  },
   InitExists {
     justfile: PathBuf,
   },
   Internal {
     message: String,
   },
+  InvalidDirective {
+    line: String,
+  },
   Io {
     recipe: &'src str,
     io_error: io::Error,
@@ -330,6 +341,12 @@ impl<'src> ColorDisplay for Error<'src> {
           io_error
         )?;
       }
+      CircularInclude { current, include } => {
+        write!(
+          f,
+          "Include `{}` in `{}` is a circular include", include.display(), current.display()
+        )?;
+      },
       Code {
         recipe,
         line_number,
@@ -482,6 +499,18 @@ impl<'src> ColorDisplay for Error<'src> {
           message
         )?;
       }
+      IncludeMissingPath {
+        file: justfile, line
+      } => {
+
+        write!(
+          f,
+          "!include directive on line {} of `{}` has no argument",
+          line.ordinal(),
+          justfile.display(),
+        )?;
+
+      },
       InitExists { justfile } => {
         write!(f, "Justfile `{}` already exists", justfile.display())?;
       }
@@ -493,6 +522,9 @@ impl<'src> ColorDisplay for Error<'src> {
           message
         )?;
       }
+      InvalidDirective { line } => {
+        write!(f, "Invalid directive: {line}")?;
+      }
       Io { recipe, io_error } => {
         match io_error.kind() {
           io::ErrorKind::NotFound => write!(

src/loader.rs

@@ -1,21 +1,216 @@
 use super::*;
+use std::collections::HashSet;
+
+struct LinesWithEndings<'a> {
+  input: &'a str,
+}
+
+impl<'a> LinesWithEndings<'a> {
+  fn new(input: &'a str) -> Self {
+    Self { input }
+  }
+}
+
+impl<'a> Iterator for LinesWithEndings<'a> {
+  type Item = &'a str;
+
+  fn next(&mut self) -> Option<&'a str> {
+    if self.input.is_empty() {
+      return None;
+    }
+    let split = self.input.find('\n').map_or(self.input.len(), |i| i + 1);
+    let (line, rest) = self.input.split_at(split);
+    self.input = rest;
+    Some(line)
+  }
+}
 
 pub(crate) struct Loader {
   arena: Arena<String>,
+  unstable: bool,
 }
 
 impl Loader {
-  pub(crate) fn new() -> Self {
+  pub(crate) fn new(unstable: bool) -> Self {
     Loader {
       arena: Arena::new(),
+      unstable,
     }
   }
 
   pub(crate) fn load<'src>(&'src self, path: &Path) -> RunResult<&'src str> {
-    let src = fs::read_to_string(path).map_err(|io_error| Error::Load {
+    let src = self.load_recursive(path, HashSet::new())?;
+    Ok(self.arena.alloc(src))
+  }
+
+  fn load_file<'a>(path: &Path) -> RunResult<'a, String> {
+    fs::read_to_string(path).map_err(|io_error| Error::Load {
       path: path.to_owned(),
       io_error,
-    })?;
-    Ok(self.arena.alloc(src))
+    })
+  }
+
+  fn load_recursive(&self, file: &Path, seen: HashSet<PathBuf>) -> RunResult<String> {
+    let src = Self::load_file(file)?;
+
+    let mut output = String::new();
+
+    let mut seen_content = false;
+
+    for (i, line) in LinesWithEndings::new(&src).enumerate() {
+      if !seen_content && line.starts_with('!') {
+        let include = line
+          .strip_prefix("!include")
+          .ok_or_else(|| Error::InvalidDirective { line: line.into() })?;
+
+        if !self.unstable {
+          return Err(Error::Unstable {
+            message: "The !include directive is currently unstable.".into(),
+          });
+        }
+
+        let argument = include.trim();
+
+        if argument.is_empty() {
+          return Err(Error::IncludeMissingPath {
+            file: file.to_owned(),
+            line: i,
+          });
+        }
+
+        let contents = self.process_include(file, Path::new(argument), &seen)?;
+
+        output.push_str(&contents);
+      } else {
+        if !(line.trim().is_empty() || line.trim().starts_with('#')) {
+          seen_content = true;
+        }
+        output.push_str(line);
+      }
+    }
+
+    Ok(output)
+  }
+
+  fn process_include(
+    &self,
+    file: &Path,
+    include: &Path,
+    seen: &HashSet<PathBuf>,
+  ) -> RunResult<String> {
+    let canonical_path = if include.is_relative() {
+      let current_dir = file.parent().ok_or(Error::Internal {
+        message: format!(
+          "Justfile path `{}` has no parent directory",
+          include.display()
+        ),
+      })?;
+      current_dir.join(include)
+    } else {
+      include.to_owned()
+    };
+
+    let canonical_path = canonical_path.lexiclean();
+
+    if seen.contains(&canonical_path) {
+      return Err(Error::CircularInclude {
+        current: file.to_owned(),
+        include: canonical_path,
+      });
+    }
+
+    let mut seen_paths = seen.clone();
+    seen_paths.insert(file.lexiclean());
+
+    self.load_recursive(&canonical_path, seen_paths)
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::{Error, Lexiclean, Loader};
+  use temptree::temptree;
+
+  #[test]
+  fn include_justfile() {
+    let justfile_a = r#"
+# A comment at the top of the file
+!include ./justfile_b
+
+some_recipe: recipe_b
+    echo "some recipe"
+"#;
+
+    let justfile_b = r#"!include ./subdir/justfile_c
+
+recipe_b: recipe_c
+    echo "recipe b"
+"#;
+
+    let justfile_c = r#"recipe_c:
+    echo "recipe c"
+"#;
+
+    let tmp = temptree! {
+        justfile: justfile_a,
+        justfile_b: justfile_b,
+        subdir: {
+            justfile_c: justfile_c
+        }
+    };
+
+    let full_concatenated_output = r#"
+# A comment at the top of the file
+recipe_c:
+    echo "recipe c"
+
+recipe_b: recipe_c
+    echo "recipe b"
+
+some_recipe: recipe_b
+    echo "some recipe"
+"#;
+
+    let loader = Loader::new(true);
+
+    let justfile_a_path = tmp.path().join("justfile");
+    let loader_output = loader.load(&justfile_a_path).unwrap();
+
+    assert_eq!(loader_output, full_concatenated_output);
+  }
+
+  #[test]
+  fn recursive_includes_fail() {
+    let justfile_a = r#"
+# A comment at the top of the file
+!include ./subdir/justfile_b
+
+some_recipe: recipe_b
+    echo "some recipe"
+
+"#;
+
+    let justfile_b = r#"
+!include ../justfile
+
+recipe_b:
+    echo "recipe b"
+"#;
+    let tmp = temptree! {
+        justfile: justfile_a,
+        subdir: {
+            justfile_b: justfile_b
+        }
+    };
+
+    let loader = Loader::new(true);
+
+    let justfile_a_path = tmp.path().join("justfile");
+    let loader_output = loader.load(&justfile_a_path).unwrap_err();
+
+    assert_matches!(loader_output, Error::CircularInclude { current, include }
+        if current == tmp.path().join("subdir").join("justfile_b").lexiclean() &&
+        include == tmp.path().join("justfile").lexiclean()
+    );
   }
 }

src/run.rs

@@ -17,14 +17,14 @@ pub fn run() -> Result<(), i32> {
   info!("Parsing command line arguments…");
   let matches = app.get_matches();
 
-  let loader = Loader::new();
-
   let config = Config::from_matches(&matches).map_err(Error::from);
 
-  let (color, verbosity) = config
+  let (color, verbosity, unstable) = config
     .as_ref()
-    .map(|config| (config.color, config.verbosity))
-    .unwrap_or((Color::auto(), Verbosity::default()));
+    .map(|config| (config.color, config.verbosity, config.unstable))
+    .unwrap_or((Color::auto(), Verbosity::default(), false));
+
+  let loader = Loader::new(unstable);
 
   config
     .and_then(|config| config.run(&loader))

tests/choose.rs

@@ -125,7 +125,7 @@ fn invoke_error_function() {
           echo bar
       ",
     )
-    .stderr_regex("error: Chooser `/ -cu fzf` invocation failed: .*")
+    .stderr_regex("error: Chooser `/ -cu fzf` invocation failed: .*\n")
     .status(EXIT_FAILURE)
     .shell(false)
     .args(["--shell", "/", "--choose"])

tests/error_messages.rs

@@ -26,11 +26,11 @@ test! {
 
 test! {
   name: unexpected_character,
-  justfile: "!~",
+  justfile: "&~",
   stderr: "
-    error: Expected character `=`
+    error: Expected character `&`
       |
-    1 | !~
+    1 | &~
       |  ^
   ",
   status: EXIT_FAILURE,