1 files changed, 169 insertions, 6 deletions
diff --git a/rprt-engine/src/selection_functions/function_empty.rs b/rprt-engine/src/selection_functions/function_empty.rs
index bf0a45c..4b69dcf 100644
--- a/rprt-engine/src/selection_functions/function_empty.rs
+++ b/rprt-engine/src/selection_functions/function_empty.rs
@@ -1,12 +1,175 @@
 use crate::{
-    selection::Selection,
-    selection_functions::types::{SFArguments, SFResult},
+    buffer::BufferID,
+    expression::SearchModifier,
+    selection::{Interval, Selection},
+    selection_functions::types::{
+        SelectionFunction, SelectionFunctionError, UnparameterisedSelectionFunction,
+    },
+    state::EditorState,
 };
 
-pub fn empty_sequential(_: SFArguments) -> SFResult {
-    Ok(Selection::empty())
+pub struct Empty;
+
+impl UnparameterisedSelectionFunction for Empty {
+    const NAME: &'static str = "empty";
+
+    fn niladic(&self, _es: &EditorState) -> Result<Selection, SelectionFunctionError> {
+        Ok(Selection::empty())
+    }
+
+    fn monadic_rank0(
+        &self,
+        _es: &EditorState,
+        _buffer_id: BufferID,
+        _pos: usize,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(Selection::empty())
+    }
+
+    fn monadic_rank1(
+        &self,
+        _es: &EditorState,
+        _buffer_id: BufferID,
+        _interval: &Interval,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(Selection::empty())
+    }
+}
+
+pub struct ReverseEmpty;
+
+impl UnparameterisedSelectionFunction for ReverseEmpty {
+    const NAME: &'static str = "reverse_empty";
+
+    fn niladic(&self, es: &EditorState) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(es.current_buffer_id))
+    }
+
+    fn monadic_rank0(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _pos: usize,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+
+    fn monadic_rank1(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _interval: &Interval,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+}
+
+pub struct SequentialEmpty;
+
+impl UnparameterisedSelectionFunction for SequentialEmpty {
+    const NAME: &'static str = "sequential_empty";
+
+    fn niladic(&self, _es: &EditorState) -> Result<Selection, SelectionFunctionError> {
+        Err(SelectionFunctionError::NoNiladicForm(";e"))
+    }
+
+    fn monadic_rank0(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _pos: usize,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+
+    fn monadic_rank1(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _interval: &Interval,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+}
+
+pub struct SequentialReverseEmpty;
+
+impl UnparameterisedSelectionFunction for SequentialReverseEmpty {
+    const NAME: &'static str = "sequential_reverse_empty";
+
+    fn niladic(&self, _es: &EditorState) -> Result<Selection, SelectionFunctionError> {
+        Err(SelectionFunctionError::NoNiladicForm(";'e"))
+    }
+
+    fn monadic_rank0(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _pos: usize,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+
+    fn monadic_rank1(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _interval: &Interval,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+}
+
+pub struct ReverseSequentialEmpty;
+
+impl UnparameterisedSelectionFunction for ReverseSequentialEmpty {
+    const NAME: &'static str = "reverse_sequential_empty";
+
+    fn niladic(&self, _es: &EditorState) -> Result<Selection, SelectionFunctionError> {
+        Err(SelectionFunctionError::NoNiladicForm("';e"))
+    }
+
+    fn monadic_rank0(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _pos: usize,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+
+    fn monadic_rank1(
+        &self,
+        _es: &EditorState,
+        buffer_id: BufferID,
+        _interval: &Interval,
+    ) -> Result<Selection, SelectionFunctionError> {
+        Ok(empty_in_buffer(buffer_id))
+    }
+}
+
+fn empty_in_buffer(buffer_id: BufferID) -> Selection {
+    Selection::Vectors {
+        buffer_id,
+        ranges: Vec::new(),
+    }
 }
 
-pub fn empty_structural(_: SFArguments) -> SFResult {
-    Ok(Selection::empty())
+pub fn selection_function_empty(
+    es: &EditorState,
+    left: Option<&Selection>,
+    right: Option<&Selection>,
+    search_mod: Option<SearchModifier>,
+) -> Result<Selection, SelectionFunctionError> {
+    match search_mod {
+        None => Empty.apply(&(), es, left, right),
+        Some(SearchModifier::Sequential) => SequentialEmpty.apply(&(), es, left, right),
+        Some(SearchModifier::Reverse) => ReverseEmpty.apply(&(), es, left, right),
+        Some(SearchModifier::SequentialReverse) => {
+            SequentialReverseEmpty.apply(&(), es, left, right)
+        }
+        Some(SearchModifier::ReverseSequential) => {
+            ReverseSequentialEmpty.apply(&(), es, left, right)
+        }
+    }
 }