1 files changed, 85 insertions, 0 deletions
diff --git a/src/makefile/macro.rs b/src/makefile/macro.rs
index 2c8747c..5e7ea9c 100644
--- a/src/makefile/macro.rs
+++ b/src/makefile/macro.rs
@@ -1,6 +1,8 @@
 #[cfg(feature = "full")]
 use std::cell::RefCell;
 use std::collections::HashMap;
+#[cfg(feature = "full")]
+use std::collections::HashSet;
 use std::env;
 use std::fmt;
 #[cfg(feature = "full")]
@@ -33,6 +35,64 @@ pub trait LookupInternal: for<'a> Fn(&'a str) -> Result<String> {}
 
 impl<F: for<'a> Fn(&'a str) -> Result<String>> LookupInternal for F {}
 
+#[cfg(feature = "full")]
+#[derive(Clone)]
+pub enum ExportConfig {
+    Only(HashSet<String>),
+    AllBut(HashSet<String>),
+}
+
+#[cfg(feature = "full")]
+impl ExportConfig {
+    pub fn all_but() -> Self {
+        Self::AllBut(HashSet::new())
+    }
+
+    pub fn only() -> Self {
+        Self::Only(HashSet::new())
+    }
+
+    pub fn add_all<'a, I: IntoIterator<Item = &'a str>>(&mut self, iter: I) {
+        match self {
+            Self::Only(exported) => {
+                exported.extend(iter.into_iter().map(|x| x.to_owned()));
+            }
+            Self::AllBut(not_exported) => {
+                for added in iter {
+                    not_exported.remove(added);
+                }
+            }
+        }
+    }
+
+    pub fn remove_all<'a, I: IntoIterator<Item = &'a str>>(&mut self, iter: I) {
+        match self {
+            Self::Only(exported) => {
+                for removed in iter {
+                    exported.remove(removed);
+                }
+            }
+            Self::AllBut(not_exported) => {
+                not_exported.extend(iter.into_iter().map(|x| x.into()));
+            }
+        }
+    }
+
+    fn same_type(&self) -> Self {
+        match self {
+            Self::Only(_) => Self::only(),
+            Self::AllBut(_) => Self::all_but(),
+        }
+    }
+
+    fn should_export(&self, x: &str) -> bool {
+        match self {
+            Self::Only(exported) => exported.contains(x),
+            Self::AllBut(not_exported) => !not_exported.contains(x),
+        }
+    }
+}
+
 #[derive(Clone)]
 pub struct Set<'parent, 'lookup> {
     parent: Option<&'parent Set<'parent, 'lookup>>,
@@ -40,6 +100,8 @@ pub struct Set<'parent, 'lookup> {
     lookup_internal: Option<&'lookup dyn LookupInternal>,
     #[cfg(feature = "full")]
     pub to_eval: Rc<RefCell<Vec<String>>>,
+    #[cfg(feature = "full")]
+    pub exported: ExportConfig,
 }
 
 impl<'parent, 'lookup> Set<'parent, 'lookup> {
@@ -50,6 +112,8 @@ impl<'parent, 'lookup> Set<'parent, 'lookup> {
             lookup_internal: None,
             #[cfg(feature = "full")]
             to_eval: Rc::new(RefCell::new(Vec::new())),
+            #[cfg(feature = "full")]
+            exported: ExportConfig::only(),
         }
     }
 
@@ -209,6 +273,8 @@ impl<'parent, 'lookup> Set<'parent, 'lookup> {
             lookup_internal: Some(lookup),
             #[cfg(feature = "full")]
             to_eval: Rc::clone(&self.to_eval),
+            #[cfg(feature = "full")]
+            exported: self.exported.same_type(),
         }
     }
 
@@ -219,8 +285,27 @@ impl<'parent, 'lookup> Set<'parent, 'lookup> {
             lookup_internal: None,
             #[cfg(feature = "full")]
             to_eval: Rc::clone(&self.to_eval),
+            #[cfg(feature = "full")]
+            exported: self.exported.same_type(),
         }
     }
+
+    #[cfg(feature = "full")]
+    pub fn resolve_exports(&self) -> Result<Vec<(&str, String)>> {
+        let own_exports = self
+            .data
+            .iter()
+            .filter(|(name, _)| self.exported.should_export(name))
+            .map(|(name, value)| self.expand(&value.text).map(|text| (name.as_ref(), text)))
+            .collect::<Result<Vec<_>>>()?;
+        Ok(if let Some(parent) = self.parent {
+            let mut parent_exports = parent.resolve_exports()?;
+            parent_exports.extend(own_exports);
+            parent_exports
+        } else {
+            own_exports
+        })
+    }
 }
 
 impl fmt::Display for Set<'_, '_> {