1 files changed, 164 insertions, 0 deletions
diff --git a/src/makefile/lookup_internal.rs b/src/makefile/lookup_internal.rs
new file mode 100644
index 0000000..c0fc08b
--- /dev/null
+++ b/src/makefile/lookup_internal.rs
@@ -0,0 +1,164 @@
+use eyre::{bail, eyre, Result};
+use std::cell::RefCell;
+use std::path::Path;
+use std::rc::Rc;
+
+use super::target::Target;
+
+#[derive(Clone)]
+pub enum LookupInternal<'a> {
+    Partial {
+        targets: &'a Vec<&'a str>,
+    },
+    Complete {
+        target: Option<&'a Target>,
+        get_target: &'a dyn Fn(&str) -> Result<Rc<RefCell<Target>>>,
+    },
+}
+
+impl<'a> LookupInternal<'a> {
+    pub fn new_partial(targets: &'a Vec<&str>) -> Self {
+        Self::Partial { targets }
+    }
+
+    pub fn new(
+        target: Option<&'a Target>,
+        get_target: &'a dyn Fn(&str) -> Result<Rc<RefCell<Target>>>,
+    ) -> Self {
+        Self::Complete { target, get_target }
+    }
+
+    pub fn lookup(&self, macro_name: &str) -> Result<String> {
+        let macro_pieces = match macro_name.chars().next() {
+            Some('@') => self.target_name()?,
+            Some('?') => self.newer_prerequisites()?,
+            Some('<') => self.inference_prerequisite()?,
+            Some('*') => self.target_stem()?,
+            #[cfg(feature = "full")]
+            Some('^') => self.all_prerequisites()?,
+            _ => bail!("unknown internal macro {}", macro_name),
+        };
+
+        let macro_pieces = if macro_name.ends_with('D') {
+            macro_pieces
+                .into_iter()
+                .map(|x| {
+                    Path::new(&x)
+                        .parent()
+                        .ok_or_else(|| eyre!("no parent"))
+                        .map(|x| x.to_string_lossy().into())
+                })
+                .collect::<Result<_, _>>()?
+        } else if macro_name.ends_with('F') {
+            macro_pieces
+                .into_iter()
+                .map(|x| {
+                    Path::new(&x)
+                        .file_name()
+                        .ok_or_else(|| eyre!("no filename"))
+                        .map(|x| x.to_string_lossy().into())
+                })
+                .collect::<Result<_, _>>()?
+        } else {
+            macro_pieces
+        };
+
+        Ok(macro_pieces.join(" "))
+    }
+
+    /// POSIX: The $@ shall evaluate to the full target name of the current target.
+    fn target_name(&self) -> Result<Vec<String>> {
+        match self {
+            Self::Partial { targets } => {
+                Ok(targets.iter().map(|target| target.to_string()).collect())
+            }
+            Self::Complete {
+                target: Some(target),
+                ..
+            } => Ok(vec![target.name.clone()]),
+            Self::Complete { target: None, .. } => {
+                bail!("tried to expand internal macro with no target")
+            }
+        }
+    }
+
+    /// POSIX: The $? macro shall evaluate to the list of prerequisites that are newer than the current target.
+    fn newer_prerequisites(&self) -> Result<Vec<String>> {
+        match self {
+            Self::Partial { .. } => bail!("can’t expand $? when target not defined"),
+            Self::Complete {
+                target: Some(target),
+                get_target,
+            } => Ok(target
+                .prerequisites
+                .iter()
+                .filter(|prereq| {
+                    get_target(prereq)
+                        .ok()
+                        .and_then(|prereq| prereq.borrow().newer_than(target))
+                        .unwrap_or(false)
+                })
+                .cloned()
+                .collect()),
+            Self::Complete { target: None, .. } => {
+                bail!("tried to expand internal macro with no target")
+            }
+        }
+    }
+
+    /// POSIX: In an inference rule, the $< macro shall evaluate to the filename whose existence allowed the inference rule to be chosen for the target. In the .DEFAULT rule, the $< macro shall evaluate to the current target name.
+    ///
+    /// GNU: The name of the first prerequisite.
+    fn inference_prerequisite(&self) -> Result<Vec<String>> {
+        match self {
+            Self::Partial { .. } => bail!("can’t expand $< when target not defined"),
+            Self::Complete {
+                target: Some(target),
+                ..
+            } => {
+                // TODO check that exists_but_inferring_anyway won’t break this
+                Ok(vec![target
+                    .prerequisites
+                    .first()
+                    .cloned()
+                    .unwrap_or_default()])
+            }
+            Self::Complete { target: None, .. } => {
+                bail!("tried to expand internal macro with no target")
+            }
+        }
+    }
+
+    /// POSIX: The $* macro shall evaluate to the current target name with its suffix deleted.
+    fn target_stem(&self) -> Result<Vec<String>> {
+        match self {
+            Self::Partial { .. } => bail!("can’t expand $* when target not defined"),
+            Self::Complete {
+                target: Some(target),
+                ..
+            } => Ok(vec![target
+                .stem
+                .as_ref()
+                .unwrap_or(&target.name)
+                .to_owned()]),
+            Self::Complete { target: None, .. } => {
+                bail!("tried to expand internal macro with no target")
+            }
+        }
+    }
+
+    /// GNU: The names of all the prerequisites.
+    #[cfg(feature = "full")]
+    fn all_prerequisites(&self) -> Result<Vec<String>> {
+        match self {
+            Self::Partial { .. } => bail!("can’t expand $^ when target not defined"),
+            Self::Complete {
+                target: Some(target),
+                ..
+            } => Ok(target.prerequisites.clone()),
+            Self::Complete { target: None, .. } => {
+                bail!("tried to expand internal macro with no target")
+            }
+        }
+    }
+}