1 files changed, 68 insertions, 0 deletions
diff --git a/rprt-engine/src/selection_function.rs b/rprt-engine/src/selection_function.rs
index c46e781..95281ad 100644
--- a/rprt-engine/src/selection_function.rs
+++ b/rprt-engine/src/selection_function.rs
@@ -51,6 +51,28 @@ macro_rules! selection_function {
     };
 }
 
+macro_rules! selection_function_param {
+    (
+        name: $name:ident,
+        param_type: $P:ty,
+        niladic: $niladic_body:expr,
+        monadic_rank0: $monadic_rank0_body:expr,
+        monadic_rank1: $monadic_rank1_body:expr
+    ) => {
+        pub fn $name(param: $P, arg: SFArguments) -> SFResult {
+            match arg {
+                SFArguments::Niladic { es } => {
+                    rust_has_an_annoying_issue({ $niladic_body((param, es)) })
+                }
+                SFArguments::Monadic { es, left } => {
+                    left.vectorise(&(param, es), $monadic_rank0_body, $monadic_rank1_body)
+                }
+                SFArguments::Dyadic { .. } => Err(SFError::NoDyadicForm(stringify!($name)).into()),
+            }
+        }
+    };
+}
+
 // ----------------------------------------------------------------
 pub fn complement_transform(es: &EditorState, result: Selection, _: &SFArguments) -> SFResult {
     fn complement_rank0(
@@ -172,3 +194,49 @@ selection_function! {
             pos: int.end,
         })
 }
+
+selection_function_param! {
+    name: character_structural,
+    param_type: usize,
+    niladic: |(param, es): (usize, &EditorState)| {
+        if let Some(buf) = es.current_buffer() {
+                Ok(Selection::Position {
+                    buffer_id: es.current_buffer_id,
+                    pos: usize::min(param, buf.max_pos()),
+                })
+            } else {
+                Err(SFError::BufferNotFound(es.current_buffer_id).into())
+            }
+    },
+    monadic_rank0: |_, buffer_id, pos| Ok(Selection::Position {buffer_id, pos}),
+    monadic_rank1: |(param, _), buffer_id, int| Ok(Selection::Position {buffer_id, pos: usize::min(int.end, *param)})
+}
+
+selection_function_param! {
+    name: character_sequential,
+    param_type: usize,
+    niladic: |(param, es): (usize, &EditorState)| {
+        if let Some(buf) = es.current_buffer() {
+                Ok(Selection::Position {
+                    buffer_id: es.current_buffer_id,
+                    pos: usize::min(param, buf.max_pos()),
+                })
+            } else {
+                Err(SFError::BufferNotFound(es.current_buffer_id).into())
+            }
+    },
+    monadic_rank0: |(param, es), buffer_id, pos| {
+        if let Some(buf) = es.get_buffer(buffer_id) {
+            Ok(Selection::Position {buffer_id, pos: usize::min(pos+*param, buf.max_pos())})
+        } else {
+            Err(SFError::BufferNotFound(buffer_id).into())
+        }
+    },
+    monadic_rank1: |(param, es), buffer_id, int| {
+        if let Some(buf) = es.get_buffer(buffer_id) {
+            Ok(Selection::Position {buffer_id, pos: usize::min(int.end+*param, buf.max_pos())})
+        } else {
+            Err(SFError::BufferNotFound(buffer_id).into())
+        }
+    }
+}