mark offset

src/action.rs

@@ -1,4 +1,4 @@
-use std::{cmp::min, convert::identity, fs::File, io::Write, iter, mem::{replace, swap}};
+use std::{cmp::min, collections::hash_set::Entry, convert::identity, fs::File, io::Write, iter, mem::{replace, swap}};
 use ratatui::{style::Stylize, text::Span};
 
 use crate::{BYTES_PER_LINE, app::WindowSize, buffer::{Buffer, Mode, PartialAction}, cursor::Cursor, edit_action::EditAction};
@@ -83,6 +83,8 @@ pub enum Action {
 	SplitSelectionsInto9s,
 	
 	JumpToSelectedOffset,
+	
+	ToggleMark,
 }
 
 // actions that act on the app as a whole, not just one buffer
@@ -175,6 +177,8 @@ impl Buffer {
 			Action::SplitSelectionsInto9s => self.split_selections_into_size(9),
 			
 			Action::JumpToSelectedOffset => self.jump_to_selected_offset(window_size),
+			
+			Action::ToggleMark => self.toggle_mark(),
 		}
 		
 		None
@@ -646,6 +650,20 @@ impl Buffer {
 		self.combine_cursors_if_overlapping();
 		self.clamp_screen_to_primary_cursor(window_size);
 	}
+	
+	fn toggle_mark(&mut self) {
+		match self.marks.entry(self.primary_cursor.lower_bound()) {
+			Entry::Occupied(occupied_entry) => { occupied_entry.remove(); },
+			Entry::Vacant(vacant_entry) => vacant_entry.insert(),
+		}
+		
+		for cursor in &self.cursors {
+			match self.marks.entry(cursor.lower_bound()) {
+				Entry::Occupied(occupied_entry) => { occupied_entry.remove(); },
+				Entry::Vacant(vacant_entry) => vacant_entry.insert(),
+			}
+		}
+	}
 }
 
 // helpers

src/buffer/mod.rs

@@ -1,5 +1,5 @@
 use core::slice::GetDisjointMutIndex;
-use std::{fs::File, io::Read, path::PathBuf};
+use std::{collections::HashSet, fs::File, io::Read, path::PathBuf};
 use crossterm::event::KeyEvent;
 use ratatui::{style::Color, text::Span};
 use crate::{action::AppAction, app::WindowSize, config::Config, cursor::Cursor, edit_action::EditAction};
@@ -16,6 +16,8 @@ pub struct Buffer {
 	pub primary_cursor: Cursor,
 	pub cursors: Vec<Cursor>,
 	
+	pub marks: HashSet<usize>,
+	
 	pub mode: Mode,
 	pub partial_action: Option<PartialAction>,
 	pub partial_replace: Option<u8>,
@@ -86,6 +88,8 @@ impl Buffer {
 			primary_cursor: Cursor::default(),
 			cursors: Vec::new(),
 			
+			marks: HashSet::from([0, 4, 12, 15, 16, 17]),
+			
 			mode: Mode::Normal,
 			partial_action: None,
 			partial_replace: None,

src/buffer/widget.rs

@@ -103,15 +103,9 @@ mod hex {
 				.iter()
 				.copied()
 				.zip((address..).step_by(BYTES_PER_CHUNK))
-				.map(|(chunk, address)| self.render_chunk(address, &chunk).collect())
+				.flat_map(|(chunk, address)| {
-				.interleave(
+					self.render_chunk(address, &chunk).collect::<Vec<_>>()
-					(address..)
+				})
-						.step_by(BYTES_PER_CHUNK)
-						.take(CHUNKS_PER_LINE)
-						.skip(1)
-						.map(|address| vec![self.render_large_space_before(address)])
-				)
-				.flatten()
 		}
 		
 		pub fn render_partial_chunks(
@@ -161,6 +155,8 @@ mod hex {
 			bytes: &[u8; BYTES_PER_CHUNK]
 		) -> impl Iterator<Item=Span<'static>> {
 			#[allow(unstable_name_collisions)]
+			iter::once(self.render_large_space_before(address))
+				.chain(
 					bytes
 						.iter()
 						.copied()
@@ -172,6 +168,7 @@ mod hex {
 								.skip(1)
 								.map(|address| self.render_space_before(address))
 						)
+				)
 		}
 		
 		fn render_partial_chunk(
@@ -244,30 +241,36 @@ mod hex {
 		}
 		
 		fn render_large_space_before(&self, address: usize) -> Span<'static> {
+			let span: Span = if self.marks.contains(&address) {
+				" →".into()
+			} else {
+				"  ".into()
+			};
+			
 			if iter::once(&self.primary_cursor)
 				.chain(&self.cursors)
 				.any(|cursor| cursor.contains_space_before(address))
 			{
-				Span {
+				span.bg(Color::select_grey())
-					style: Style::new().bg(Color::select_grey()),
-					content: "  ".into()
-				}
 			} else {
-				"  ".into()
+				span
 			}
 		}
 		
 		fn render_space_before(&self, address: usize) -> Span<'static> {
+			let span: Span = if self.marks.contains(&address) {
+				"→".into()
+			} else {
+				" ".into()
+			};
+			
 			if iter::once(&self.primary_cursor)
 				.chain(&self.cursors)
 				.any(|cursor| cursor.contains_space_before(address))
 			{
-				Span {
+				span.bg(Color::select_grey())
-					style: Style::new().bg(Color::select_grey()),
-					content: " ".into()
-				}
 			} else {
-				" ".into()
+				span
 			}
 		}
 	}

src/config.rs

@@ -163,6 +163,8 @@ impl Default for Config {
 					("9".try_into().unwrap(), Action::SplitSelectionsInto9s),
 					
 					("J".try_into().unwrap(), Action::JumpToSelectedOffset),
+					
+					("m".try_into().unwrap(), Action::ToggleMark),
 				].into()),
 				(Some(PartialAction::Goto), [
 					("j".try_into().unwrap(), Action::GotoLineStart),
@@ -234,6 +236,8 @@ impl Default for Config {
 					("9".try_into().unwrap(), Action::SplitSelectionsInto9s),
 					
 					("J".try_into().unwrap(), Action::JumpToSelectedOffset),
+					
+					("m".try_into().unwrap(), Action::ToggleMark),
 				].into()),
 				(Some(PartialAction::Space), [
 					("w".try_into().unwrap(), Action::Save),

src/main.rs

@@ -2,6 +2,7 @@
 #![allow(clippy::cast_possible_truncation)]
 #![feature(get_disjoint_mut_helpers)]
 #![feature(exact_bitshifts)]
+#![feature(hash_set_entry)]
 
 use app::App;