move AutoComplete

parsing/src/lib.rs

@@ -11,7 +11,7 @@ pub use crate::{
 	autocomplete_helper::compile_hashmap,
 	parsing::{process_func_str, BackingFunction},
 	suggestions::{
-		generate_hint, get_last_term, split_function, split_function_chars, Hint, HINT_EMPTY,
-		SUPPORTED_FUNCTIONS,
+		generate_hint, get_last_term, split_function, split_function_chars, AutoComplete, Hint,
+		Movement, HINT_EMPTY, SUPPORTED_FUNCTIONS,
 	},
 };

parsing/src/suggestions.rs

@@ -253,3 +253,110 @@ impl<'a> Hint<'a> {
 }
 
 include!(concat!(env!("OUT_DIR"), "/codegen.rs"));
+
+#[derive(PartialEq, Debug)]
+pub enum Movement {
+	Complete,
+	#[allow(dead_code)]
+	Down,
+	#[allow(dead_code)]
+	Up,
+	None,
+}
+
+impl Movement {
+	pub const fn is_none(&self) -> bool { matches!(&self, Self::None) }
+}
+
+impl const Default for Movement {
+	fn default() -> Self { Self::None }
+}
+
+#[derive(Clone)]
+pub struct AutoComplete<'a> {
+	pub i: usize,
+	pub hint: &'a Hint<'a>,
+	pub string: String,
+}
+
+impl<'a> const Default for AutoComplete<'a> {
+	fn default() -> AutoComplete<'a> { AutoComplete::EMPTY }
+}
+
+impl<'a> AutoComplete<'a> {
+	const EMPTY: AutoComplete<'a> = Self {
+		i: 0,
+		hint: &HINT_EMPTY,
+		string: String::new(),
+	};
+
+	#[allow(dead_code)]
+	pub fn update_string(&mut self, string: &str) {
+		if self.string != string {
+			// catch empty strings here to avoid call to `generate_hint` and unnecessary logic
+			if string.is_empty() {
+				*self = Self::EMPTY;
+			} else {
+				self.string = string.to_owned();
+				self.do_update_logic();
+			}
+		}
+	}
+
+	/// Runs update logic assuming that a change to `self.string` has been made
+	fn do_update_logic(&mut self) {
+		self.i = 0;
+		self.hint = generate_hint(&self.string);
+	}
+
+	#[allow(dead_code)]
+	pub fn register_movement(&mut self, movement: &Movement) {
+		if movement.is_none() {
+			return;
+		}
+
+		match self.hint {
+			Hint::Many(hints) => {
+				// Impossible for plural hints to be singular or non-existant
+				unsafe {
+					assume(hints.len() > 1);
+					assume(!hints.is_empty());
+				}
+
+				match movement {
+					Movement::Up => {
+						// if self.i is below 1, it's at
+						match self.i {
+							0 => self.i = hints.len() - 1,
+							_ => self.i -= 1,
+						}
+					}
+					Movement::Down => {
+						// add one, if resulting value is above maximum i value, set i to 0
+						self.i += 1;
+						if self.i > (hints.len() - 1) {
+							self.i = 0;
+						}
+					}
+					Movement::Complete => {
+						unsafe { assume(hints.len() >= (self.i + 1)) }
+
+						self.apply_hint(hints[self.i]);
+					}
+					_ => unreachable!(),
+				}
+			}
+			Hint::Single(hint) => {
+				if movement == &Movement::Complete {
+					self.apply_hint(hint);
+				}
+			}
+			_ => unreachable!(),
+		}
+	}
+
+	pub fn apply_hint(&mut self, hint: &str) {
+		self.string.push_str(hint);
+		self.do_update_logic();
+	}
+}