From 839f2938a1c446c089ca795712dcb9aee22121de Mon Sep 17 00:00:00 2001
From: Keith Simmons <keith@the-simmons.net>
Date: Tue, 14 Sep 2021 00:57:31 -0700
Subject: [PATCH] make event handling forwards compatible and use constant
 generics to simplify parsing logic

---
 src/bridge/events.rs | 206 +++++++++++++++++--------------------------
 1 file changed, 82 insertions(+), 124 deletions(-)

diff --git a/src/bridge/events.rs b/src/bridge/events.rs
index 587cf79..ad93d24 100644
--- a/src/bridge/events.rs
+++ b/src/bridge/events.rs
@@ -228,7 +228,7 @@ pub enum RedrawEvent {
         bottom_line: f64,
         current_line: f64,
         current_column: f64,
-        line_count: f64,
+        line_count: Option<f64>,
     },
     CommandLineShow {
         content: StyledContent,
@@ -358,17 +358,38 @@ fn unpack_color(packed_color: u64) -> Color4f {
     }
 }
 
-fn extract_values<Arr: AsMut<[Value]>>(values: Vec<Value>, mut arr: Arr) -> Result<Arr> {
-    let arr_ref = arr.as_mut();
+fn extract_values<const REQ: usize>(values: Vec<Value>) -> Result<[Value; REQ]> {
+    if REQ > values.len() {
+        Err(ParseError::Format(format!("{:?}", values)))
+    } else {
+        let mut required_values = vec![Value::Nil; REQ];
+
+        for (index, value) in values.into_iter().enumerate() {
+            if index < REQ {
+                required_values[index] = value;
+            }
+        }
 
-    if values.len() != arr_ref.len() {
+        Ok(required_values.try_into().unwrap())
+    }
+}
+
+fn extract_values_with_optional<const REQ: usize, const OPT: usize>(values: Vec<Value>) -> Result<([Value; REQ], [Option<Value>; OPT])> {
+    if REQ > values.len() {
         Err(ParseError::Format(format!("{:?}", values)))
     } else {
-        for (i, val) in values.into_iter().enumerate() {
-            arr_ref[i] = val;
+        let mut required_values = vec![Value::Nil; REQ];
+        let mut optional_values = vec![None; OPT];
+
+        for (index, value) in values.into_iter().enumerate() {
+            if index < REQ {
+                required_values[index] = value;
+            } else {
+                optional_values[index - REQ] = Some(value);
+            }
         }
 
-        Ok(arr)
+        Ok((required_values.try_into().unwrap(), optional_values.try_into().unwrap()))
     }
 }
 
@@ -401,7 +422,7 @@ fn parse_bool(bool_value: Value) -> Result<bool> {
 }
 
 fn parse_set_title(set_title_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [title] = extract_values(set_title_arguments, [Value::Nil])?;
+    let [title] = extract_values(set_title_arguments)?;
 
     Ok(RedrawEvent::SetTitle {
         title: parse_string(title)?,
@@ -410,7 +431,7 @@ fn parse_set_title(set_title_arguments: Vec<Value>) -> Result<RedrawEvent> {
 
 fn parse_mode_info_set(mode_info_set_arguments: Vec<Value>) -> Result<RedrawEvent> {
     let [_cursor_style_enabled, mode_info] =
-        extract_values(mode_info_set_arguments, [Value::Nil, Value::Nil])?;
+        extract_values(mode_info_set_arguments)?;
 
     let mode_info_values = parse_array(mode_info)?;
     let mut cursor_modes = Vec::with_capacity(mode_info_values.len());
@@ -450,7 +471,7 @@ fn parse_mode_info_set(mode_info_set_arguments: Vec<Value>) -> Result<RedrawEven
 }
 
 fn parse_option_set(option_set_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [name, value] = extract_values(option_set_arguments, [Value::Nil, Value::Nil])?;
+    let [name, value] = extract_values(option_set_arguments)?;
 
     let name = parse_string(name)?;
 
@@ -472,7 +493,7 @@ fn parse_option_set(option_set_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_mode_change(mode_change_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [mode, mode_index] = extract_values(mode_change_arguments, [Value::Nil, Value::Nil])?;
+    let [mode, mode_index] = extract_values(mode_change_arguments)?;
     let mode_name = parse_string(mode)?;
 
     Ok(RedrawEvent::ModeChange {
@@ -490,7 +511,7 @@ fn parse_mode_change(mode_change_arguments: Vec<Value>) -> Result<RedrawEvent> {
 
 fn parse_grid_resize(grid_resize_arguments: Vec<Value>) -> Result<RedrawEvent> {
     let [grid_id, width, height] =
-        extract_values(grid_resize_arguments, [Value::Nil, Value::Nil, Value::Nil])?;
+        extract_values(grid_resize_arguments)?;
 
     Ok(RedrawEvent::Resize {
         grid: parse_u64(grid_id)?,
@@ -500,9 +521,8 @@ fn parse_grid_resize(grid_resize_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_default_colors(default_colors_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [Value::Nil, Value::Nil, Value::Nil, Value::Nil, Value::Nil];
     let [foreground, background, special, _term_foreground, _term_background] =
-        extract_values(default_colors_arguments, values)?;
+        extract_values(default_colors_arguments)?;
 
     Ok(RedrawEvent::DefaultColorsSet {
         colors: Colors {
@@ -550,9 +570,8 @@ fn parse_style(style_map: Value) -> Result<Style> {
 }
 
 fn parse_hl_attr_define(hl_attr_define_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [Value::Nil, Value::Nil, Value::Nil, Value::Nil];
     let [id, attributes, _terminal_attributes, _info] =
-        extract_values(hl_attr_define_arguments, values)?;
+        extract_values(hl_attr_define_arguments)?;
 
     let style = parse_style(attributes)?;
     Ok(RedrawEvent::HighlightAttributesDefine {
@@ -592,8 +611,7 @@ fn parse_grid_line_cell(grid_line_cell: Value) -> Result<GridLineCell> {
 }
 
 fn parse_grid_line(grid_line_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [Value::Nil, Value::Nil, Value::Nil, Value::Nil];
-    let [grid_id, row, column_start, cells] = extract_values(grid_line_arguments, values)?;
+    let [grid_id, row, column_start, cells] = extract_values(grid_line_arguments)?;
 
     Ok(RedrawEvent::GridLine {
         grid: parse_u64(grid_id)?,
@@ -607,7 +625,7 @@ fn parse_grid_line(grid_line_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_grid_clear(grid_clear_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [grid_id] = extract_values(grid_clear_arguments, [Value::Nil])?;
+    let [grid_id] = extract_values(grid_clear_arguments)?;
 
     Ok(RedrawEvent::Clear {
         grid: parse_u64(grid_id)?,
@@ -615,7 +633,7 @@ fn parse_grid_clear(grid_clear_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_grid_destroy(grid_destroy_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [grid_id] = extract_values(grid_destroy_arguments, [Value::Nil])?;
+    let [grid_id] = extract_values(grid_destroy_arguments)?;
 
     Ok(RedrawEvent::Destroy {
         grid: parse_u64(grid_id)?,
@@ -624,7 +642,7 @@ fn parse_grid_destroy(grid_destroy_arguments: Vec<Value>) -> Result<RedrawEvent>
 
 fn parse_grid_cursor_goto(cursor_goto_arguments: Vec<Value>) -> Result<RedrawEvent> {
     let [grid_id, row, column] =
-        extract_values(cursor_goto_arguments, [Value::Nil, Value::Nil, Value::Nil])?;
+        extract_values(cursor_goto_arguments)?;
 
     Ok(RedrawEvent::CursorGoto {
         grid: parse_u64(grid_id)?,
@@ -634,17 +652,8 @@ fn parse_grid_cursor_goto(cursor_goto_arguments: Vec<Value>) -> Result<RedrawEve
 }
 
 fn parse_grid_scroll(grid_scroll_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-    ];
     let [grid_id, top, bottom, left, right, rows, columns] =
-        extract_values(grid_scroll_arguments, values)?;
+        extract_values(grid_scroll_arguments)?;
     Ok(RedrawEvent::Scroll {
         grid: parse_u64(grid_id)?,
         top: parse_u64(top)?,
@@ -657,16 +666,8 @@ fn parse_grid_scroll(grid_scroll_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_win_pos(win_pos_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-    ];
     let [grid, _window, start_row, start_column, width, height] =
-        extract_values(win_pos_arguments, values)?;
+        extract_values(win_pos_arguments)?;
 
     Ok(RedrawEvent::WindowPosition {
         grid: parse_u64(grid)?,
@@ -689,58 +690,28 @@ fn parse_window_anchor(value: Value) -> Result<WindowAnchor> {
 }
 
 fn parse_win_float_pos(win_float_pos_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    if win_float_pos_arguments.len() == 8 {
-        let values = [
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-        ];
-
-        let [grid, _window, anchor, anchor_grid, anchor_row, anchor_column, focusable, sort_order] =
-            extract_values(win_float_pos_arguments, values)?;
-
-        Ok(RedrawEvent::WindowFloatPosition {
-            grid: parse_u64(grid)?,
-            anchor: parse_window_anchor(anchor)?,
-            anchor_grid: parse_u64(anchor_grid)?,
-            anchor_row: parse_f64(anchor_row)?,
-            anchor_column: parse_f64(anchor_column)?,
-            focusable: parse_bool(focusable)?,
-            sort_order: Some(parse_u64(sort_order)?),
-        })
+    let ([grid, _window, anchor, anchor_grid, anchor_row, anchor_column, focusable], [sort_order]) =
+        extract_values_with_optional(win_float_pos_arguments)?;
+
+    let sort_order = if let Some(sort_order) = sort_order {
+        Some(parse_u64(sort_order)?)
     } else {
-        let values = [
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-            Value::Nil,
-        ];
-
-        let [grid, _window, anchor, anchor_grid, anchor_row, anchor_column, focusable] =
-            extract_values(win_float_pos_arguments, values)?;
-
-        Ok(RedrawEvent::WindowFloatPosition {
-            grid: parse_u64(grid)?,
-            anchor: parse_window_anchor(anchor)?,
-            anchor_grid: parse_u64(anchor_grid)?,
-            anchor_row: parse_f64(anchor_row)?,
-            anchor_column: parse_f64(anchor_column)?,
-            focusable: parse_bool(focusable)?,
-            sort_order: None,
-        })
-    }
+        None
+    };
+
+    Ok(RedrawEvent::WindowFloatPosition {
+        grid: parse_u64(grid)?,
+        anchor: parse_window_anchor(anchor)?,
+        anchor_grid: parse_u64(anchor_grid)?,
+        anchor_row: parse_f64(anchor_row)?,
+        anchor_column: parse_f64(anchor_column)?,
+        focusable: parse_bool(focusable)?,
+        sort_order: sort_order,
+    })
 }
 
 fn parse_win_external_pos(win_external_pos_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [grid, _window] = extract_values(win_external_pos_arguments, [Value::Nil, Value::Nil])?;
+    let [grid, _window] = extract_values(win_external_pos_arguments)?;
 
     Ok(RedrawEvent::WindowExternalPosition {
         grid: parse_u64(grid)?,
@@ -748,7 +719,7 @@ fn parse_win_external_pos(win_external_pos_arguments: Vec<Value>) -> Result<Redr
 }
 
 fn parse_win_hide(win_hide_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [grid] = extract_values(win_hide_arguments, [Value::Nil])?;
+    let [grid] = extract_values(win_hide_arguments)?;
 
     Ok(RedrawEvent::WindowHide {
         grid: parse_u64(grid)?,
@@ -756,7 +727,7 @@ fn parse_win_hide(win_hide_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_win_close(win_close_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [grid] = extract_values(win_close_arguments, [Value::Nil])?;
+    let [grid] = extract_values(win_close_arguments)?;
 
     Ok(RedrawEvent::WindowClose {
         grid: parse_u64(grid)?,
@@ -764,8 +735,7 @@ fn parse_win_close(win_close_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_msg_set_pos(msg_set_pos_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [Value::Nil, Value::Nil, Value::Nil, Value::Nil];
-    let [grid, row, scrolled, separator_character] = extract_values(msg_set_pos_arguments, values)?;
+    let [grid, row, scrolled, separator_character] = extract_values(msg_set_pos_arguments)?;
 
     Ok(RedrawEvent::MessageSetPosition {
         grid: parse_u64(grid)?,
@@ -776,17 +746,14 @@ fn parse_msg_set_pos(msg_set_pos_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_win_viewport(win_viewport_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-    ];
-    let [grid, _window, top_line, bottom_line, current_line, current_column, line_count] =
-        extract_values(win_viewport_arguments, values)?;
+    let ([grid, _window, top_line, bottom_line, current_line, current_column], [line_count]) =
+        extract_values_with_optional(win_viewport_arguments)?;
+
+    let line_count = if let Some(line_count) = line_count {
+        Some(parse_f64(line_count)?)
+    } else {
+        None
+    };
 
     Ok(RedrawEvent::WindowViewport {
         grid: parse_u64(grid)?,
@@ -794,7 +761,7 @@ fn parse_win_viewport(win_viewport_arguments: Vec<Value>) -> Result<RedrawEvent>
         bottom_line: parse_f64(bottom_line)?,
         current_line: parse_f64(current_line)?,
         current_column: parse_f64(current_column)?,
-        line_count: parse_f64(line_count)?,
+        line_count,
     })
 }
 
@@ -802,7 +769,7 @@ fn parse_styled_content(line: Value) -> Result<StyledContent> {
     parse_array(line)?
         .into_iter()
         .map(|tuple| {
-            let [style_id, text] = extract_values(parse_array(tuple)?, [Value::Nil, Value::Nil])?;
+            let [style_id, text] = extract_values(parse_array(tuple)?)?;
 
             Ok((parse_u64(style_id)?, parse_string(text)?))
         })
@@ -810,16 +777,8 @@ fn parse_styled_content(line: Value) -> Result<StyledContent> {
 }
 
 fn parse_cmdline_show(cmdline_show_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let values = [
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-        Value::Nil,
-    ];
     let [content, position, first_character, prompt, indent, level] =
-        extract_values(cmdline_show_arguments, values)?;
+        extract_values(cmdline_show_arguments)?;
 
     Ok(RedrawEvent::CommandLineShow {
         content: parse_styled_content(content)?,
@@ -832,7 +791,7 @@ fn parse_cmdline_show(cmdline_show_arguments: Vec<Value>) -> Result<RedrawEvent>
 }
 
 fn parse_cmdline_pos(cmdline_pos_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [position, level] = extract_values(cmdline_pos_arguments, [Value::Nil, Value::Nil])?;
+    let [position, level] = extract_values(cmdline_pos_arguments)?;
 
     Ok(RedrawEvent::CommandLinePosition {
         position: parse_u64(position)?,
@@ -843,7 +802,6 @@ fn parse_cmdline_pos(cmdline_pos_arguments: Vec<Value>) -> Result<RedrawEvent> {
 fn parse_cmdline_special_char(cmdline_special_char_arguments: Vec<Value>) -> Result<RedrawEvent> {
     let [character, shift, level] = extract_values(
         cmdline_special_char_arguments,
-        [Value::Nil, Value::Nil, Value::Nil],
     )?;
 
     Ok(RedrawEvent::CommandLineSpecialCharacter {
@@ -854,7 +812,7 @@ fn parse_cmdline_special_char(cmdline_special_char_arguments: Vec<Value>) -> Res
 }
 
 fn parse_cmdline_block_show(cmdline_block_show_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [lines] = extract_values(cmdline_block_show_arguments, [Value::Nil])?;
+    let [lines] = extract_values(cmdline_block_show_arguments)?;
 
     Ok(RedrawEvent::CommandLineBlockShow {
         lines: parse_array(lines)?
@@ -865,7 +823,7 @@ fn parse_cmdline_block_show(cmdline_block_show_arguments: Vec<Value>) -> Result<
 }
 
 fn parse_cmdline_block_append(cmdline_block_append_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [line] = extract_values(cmdline_block_append_arguments, [Value::Nil])?;
+    let [line] = extract_values(cmdline_block_append_arguments)?;
 
     Ok(RedrawEvent::CommandLineBlockAppend {
         line: parse_styled_content(line)?,
@@ -874,7 +832,7 @@ fn parse_cmdline_block_append(cmdline_block_append_arguments: Vec<Value>) -> Res
 
 fn parse_msg_show(msg_show_arguments: Vec<Value>) -> Result<RedrawEvent> {
     let [kind, content, replace_last] =
-        extract_values(msg_show_arguments, [Value::Nil, Value::Nil, Value::Nil])?;
+        extract_values(msg_show_arguments)?;
 
     Ok(RedrawEvent::MessageShow {
         kind: MessageKind::parse(&parse_string(kind)?),
@@ -884,7 +842,7 @@ fn parse_msg_show(msg_show_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_msg_showmode(msg_showmode_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [content] = extract_values(msg_showmode_arguments, [Value::Nil])?;
+    let [content] = extract_values(msg_showmode_arguments)?;
 
     Ok(RedrawEvent::MessageShowMode {
         content: parse_styled_content(content)?,
@@ -892,7 +850,7 @@ fn parse_msg_showmode(msg_showmode_arguments: Vec<Value>) -> Result<RedrawEvent>
 }
 
 fn parse_msg_showcmd(msg_showcmd_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [content] = extract_values(msg_showcmd_arguments, [Value::Nil])?;
+    let [content] = extract_values(msg_showcmd_arguments)?;
 
     Ok(RedrawEvent::MessageShowCommand {
         content: parse_styled_content(content)?,
@@ -900,7 +858,7 @@ fn parse_msg_showcmd(msg_showcmd_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_msg_ruler(msg_ruler_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [content] = extract_values(msg_ruler_arguments, [Value::Nil])?;
+    let [content] = extract_values(msg_ruler_arguments)?;
 
     Ok(RedrawEvent::MessageRuler {
         content: parse_styled_content(content)?,
@@ -908,7 +866,7 @@ fn parse_msg_ruler(msg_ruler_arguments: Vec<Value>) -> Result<RedrawEvent> {
 }
 
 fn parse_msg_history_entry(entry: Value) -> Result<(MessageKind, StyledContent)> {
-    let [kind, content] = extract_values(parse_array(entry)?, [Value::Nil, Value::Nil])?;
+    let [kind, content] = extract_values(parse_array(entry)?)?;
 
     Ok((
         MessageKind::parse(&parse_string(kind)?),
@@ -917,7 +875,7 @@ fn parse_msg_history_entry(entry: Value) -> Result<(MessageKind, StyledContent)>
 }
 
 fn parse_msg_history_show(msg_history_show_arguments: Vec<Value>) -> Result<RedrawEvent> {
-    let [entries] = extract_values(msg_history_show_arguments, [Value::Nil])?;
+    let [entries] = extract_values(msg_history_show_arguments)?;
 
     Ok(RedrawEvent::MessageHistoryShow {
         entries: parse_array(entries)?