Create `iced_widget` subcrate and re-organize the whole codebase

3 files changed, 392 insertions, 0 deletions

diff --git a/widget/src/text_input/cursor.rs b/widget/src/text_input/cursor.rs
new file mode 100644
index 00000000..9680dfd7
--- /dev/null
+++ b/widget/src/text_input/cursor.rs
@@ -0,0 +1,189 @@
+//! Track the cursor of a text input.
+use crate::text_input::Value;
+
+/// The cursor of a text input.
+#[derive(Debug, Copy, Clone)]
+pub struct Cursor {
+    state: State,
+}
+
+/// The state of a [`Cursor`].
+#[derive(Debug, Copy, Clone)]
+pub enum State {
+    /// Cursor without a selection
+    Index(usize),
+
+    /// Cursor selecting a range of text
+    Selection {
+        /// The start of the selection
+        start: usize,
+        /// The end of the selection
+        end: usize,
+    },
+}
+
+impl Default for Cursor {
+    fn default() -> Self {
+        Cursor {
+            state: State::Index(0),
+        }
+    }
+}
+
+impl Cursor {
+    /// Returns the [`State`] of the [`Cursor`].
+    pub fn state(&self, value: &Value) -> State {
+        match self.state {
+            State::Index(index) => State::Index(index.min(value.len())),
+            State::Selection { start, end } => {
+                let start = start.min(value.len());
+                let end = end.min(value.len());
+
+                if start == end {
+                    State::Index(start)
+                } else {
+                    State::Selection { start, end }
+                }
+            }
+        }
+    }
+
+    /// Returns the current selection of the [`Cursor`] for the given [`Value`].
+    ///
+    /// `start` is guaranteed to be <= than `end`.
+    pub fn selection(&self, value: &Value) -> Option<(usize, usize)> {
+        match self.state(value) {
+            State::Selection { start, end } => {
+                Some((start.min(end), start.max(end)))
+            }
+            _ => None,
+        }
+    }
+
+    pub(crate) fn move_to(&mut self, position: usize) {
+        self.state = State::Index(position);
+    }
+
+    pub(crate) fn move_right(&mut self, value: &Value) {
+        self.move_right_by_amount(value, 1)
+    }
+
+    pub(crate) fn move_right_by_words(&mut self, value: &Value) {
+        self.move_to(value.next_end_of_word(self.right(value)))
+    }
+
+    pub(crate) fn move_right_by_amount(
+        &mut self,
+        value: &Value,
+        amount: usize,
+    ) {
+        match self.state(value) {
+            State::Index(index) => {
+                self.move_to(index.saturating_add(amount).min(value.len()))
+            }
+            State::Selection { start, end } => self.move_to(end.max(start)),
+        }
+    }
+
+    pub(crate) fn move_left(&mut self, value: &Value) {
+        match self.state(value) {
+            State::Index(index) if index > 0 => self.move_to(index - 1),
+            State::Selection { start, end } => self.move_to(start.min(end)),
+            _ => self.move_to(0),
+        }
+    }
+
+    pub(crate) fn move_left_by_words(&mut self, value: &Value) {
+        self.move_to(value.previous_start_of_word(self.left(value)));
+    }
+
+    pub(crate) fn select_range(&mut self, start: usize, end: usize) {
+        if start == end {
+            self.state = State::Index(start);
+        } else {
+            self.state = State::Selection { start, end };
+        }
+    }
+
+    pub(crate) fn select_left(&mut self, value: &Value) {
+        match self.state(value) {
+            State::Index(index) if index > 0 => {
+                self.select_range(index, index - 1)
+            }
+            State::Selection { start, end } if end > 0 => {
+                self.select_range(start, end - 1)
+            }
+            _ => {}
+        }
+    }
+
+    pub(crate) fn select_right(&mut self, value: &Value) {
+        match self.state(value) {
+            State::Index(index) if index < value.len() => {
+                self.select_range(index, index + 1)
+            }
+            State::Selection { start, end } if end < value.len() => {
+                self.select_range(start, end + 1)
+            }
+            _ => {}
+        }
+    }
+
+    pub(crate) fn select_left_by_words(&mut self, value: &Value) {
+        match self.state(value) {
+            State::Index(index) => {
+                self.select_range(index, value.previous_start_of_word(index))
+            }
+            State::Selection { start, end } => {
+                self.select_range(start, value.previous_start_of_word(end))
+            }
+        }
+    }
+
+    pub(crate) fn select_right_by_words(&mut self, value: &Value) {
+        match self.state(value) {
+            State::Index(index) => {
+                self.select_range(index, value.next_end_of_word(index))
+            }
+            State::Selection { start, end } => {
+                self.select_range(start, value.next_end_of_word(end))
+            }
+        }
+    }
+
+    pub(crate) fn select_all(&mut self, value: &Value) {
+        self.select_range(0, value.len());
+    }
+
+    pub(crate) fn start(&self, value: &Value) -> usize {
+        let start = match self.state {
+            State::Index(index) => index,
+            State::Selection { start, .. } => start,
+        };
+
+        start.min(value.len())
+    }
+
+    pub(crate) fn end(&self, value: &Value) -> usize {
+        let end = match self.state {
+            State::Index(index) => index,
+            State::Selection { end, .. } => end,
+        };
+
+        end.min(value.len())
+    }
+
+    fn left(&self, value: &Value) -> usize {
+        match self.state(value) {
+            State::Index(index) => index,
+            State::Selection { start, end } => start.min(end),
+        }
+    }
+
+    fn right(&self, value: &Value) -> usize {
+        match self.state(value) {
+            State::Index(index) => index,
+            State::Selection { start, end } => start.max(end),
+        }
+    }
+}
diff --git a/widget/src/text_input/editor.rs b/widget/src/text_input/editor.rs
new file mode 100644
index 00000000..f1fd641f
--- /dev/null
+++ b/widget/src/text_input/editor.rs
@@ -0,0 +1,70 @@
+use crate::text_input::{Cursor, Value};
+
+pub struct Editor<'a> {
+    value: &'a mut Value,
+    cursor: &'a mut Cursor,
+}
+
+impl<'a> Editor<'a> {
+    pub fn new(value: &'a mut Value, cursor: &'a mut Cursor) -> Editor<'a> {
+        Editor { value, cursor }
+    }
+
+    pub fn contents(&self) -> String {
+        self.value.to_string()
+    }
+
+    pub fn insert(&mut self, character: char) {
+        if let Some((left, right)) = self.cursor.selection(self.value) {
+            self.cursor.move_left(self.value);
+            self.value.remove_many(left, right);
+        }
+
+        self.value.insert(self.cursor.end(self.value), character);
+        self.cursor.move_right(self.value);
+    }
+
+    pub fn paste(&mut self, content: Value) {
+        let length = content.len();
+        if let Some((left, right)) = self.cursor.selection(self.value) {
+            self.cursor.move_left(self.value);
+            self.value.remove_many(left, right);
+        }
+
+        self.value.insert_many(self.cursor.end(self.value), content);
+
+        self.cursor.move_right_by_amount(self.value, length);
+    }
+
+    pub fn backspace(&mut self) {
+        match self.cursor.selection(self.value) {
+            Some((start, end)) => {
+                self.cursor.move_left(self.value);
+                self.value.remove_many(start, end);
+            }
+            None => {
+                let start = self.cursor.start(self.value);
+
+                if start > 0 {
+                    self.cursor.move_left(self.value);
+                    self.value.remove(start - 1);
+                }
+            }
+        }
+    }
+
+    pub fn delete(&mut self) {
+        match self.cursor.selection(self.value) {
+            Some(_) => {
+                self.backspace();
+            }
+            None => {
+                let end = self.cursor.end(self.value);
+
+                if end < self.value.len() {
+                    self.value.remove(end);
+                }
+            }
+        }
+    }
+}
diff --git a/widget/src/text_input/value.rs b/widget/src/text_input/value.rs
new file mode 100644
index 00000000..cf4da562
--- /dev/null
+++ b/widget/src/text_input/value.rs
@@ -0,0 +1,133 @@
+use unicode_segmentation::UnicodeSegmentation;
+
+/// The value of a [`TextInput`].
+///
+/// [`TextInput`]: crate::widget::TextInput
+// TODO: Reduce allocations, cache results (?)
+#[derive(Debug, Clone)]
+pub struct Value {
+    graphemes: Vec<String>,
+}
+
+impl Value {
+    /// Creates a new [`Value`] from a string slice.
+    pub fn new(string: &str) -> Self {
+        let graphemes = UnicodeSegmentation::graphemes(string, true)
+            .map(String::from)
+            .collect();
+
+        Self { graphemes }
+    }
+
+    /// Returns whether the [`Value`] is empty or not.
+    ///
+    /// A [`Value`] is empty when it contains no graphemes.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Returns the total amount of graphemes in the [`Value`].
+    pub fn len(&self) -> usize {
+        self.graphemes.len()
+    }
+
+    /// Returns the position of the previous start of a word from the given
+    /// grapheme `index`.
+    pub fn previous_start_of_word(&self, index: usize) -> usize {
+        let previous_string =
+            &self.graphemes[..index.min(self.graphemes.len())].concat();
+
+        UnicodeSegmentation::split_word_bound_indices(previous_string as &str)
+            .filter(|(_, word)| !word.trim_start().is_empty())
+            .next_back()
+            .map(|(i, previous_word)| {
+                index
+                    - UnicodeSegmentation::graphemes(previous_word, true)
+                        .count()
+                    - UnicodeSegmentation::graphemes(
+                        &previous_string[i + previous_word.len()..] as &str,
+                        true,
+                    )
+                    .count()
+            })
+            .unwrap_or(0)
+    }
+
+    /// Returns the position of the next end of a word from the given grapheme
+    /// `index`.
+    pub fn next_end_of_word(&self, index: usize) -> usize {
+        let next_string = &self.graphemes[index..].concat();
+
+        UnicodeSegmentation::split_word_bound_indices(next_string as &str)
+            .find(|(_, word)| !word.trim_start().is_empty())
+            .map(|(i, next_word)| {
+                index
+                    + UnicodeSegmentation::graphemes(next_word, true).count()
+                    + UnicodeSegmentation::graphemes(
+                        &next_string[..i] as &str,
+                        true,
+                    )
+                    .count()
+            })
+            .unwrap_or(self.len())
+    }
+
+    /// Returns a new [`Value`] containing the graphemes from `start` until the
+    /// given `end`.
+    pub fn select(&self, start: usize, end: usize) -> Self {
+        let graphemes =
+            self.graphemes[start.min(self.len())..end.min(self.len())].to_vec();
+
+        Self { graphemes }
+    }
+
+    /// Returns a new [`Value`] containing the graphemes until the given
+    /// `index`.
+    pub fn until(&self, index: usize) -> Self {
+        let graphemes = self.graphemes[..index.min(self.len())].to_vec();
+
+        Self { graphemes }
+    }
+
+    /// Converts the [`Value`] into a `String`.
+    pub fn to_string(&self) -> String {
+        self.graphemes.concat()
+    }
+
+    /// Inserts a new `char` at the given grapheme `index`.
+    pub fn insert(&mut self, index: usize, c: char) {
+        self.graphemes.insert(index, c.to_string());
+
+        self.graphemes =
+            UnicodeSegmentation::graphemes(&self.to_string() as &str, true)
+                .map(String::from)
+                .collect();
+    }
+
+    /// Inserts a bunch of graphemes at the given grapheme `index`.
+    pub fn insert_many(&mut self, index: usize, mut value: Value) {
+        let _ = self
+            .graphemes
+            .splice(index..index, value.graphemes.drain(..));
+    }
+
+    /// Removes the grapheme at the given `index`.
+    pub fn remove(&mut self, index: usize) {
+        let _ = self.graphemes.remove(index);
+    }
+
+    /// Removes the graphemes from `start` to `end`.
+    pub fn remove_many(&mut self, start: usize, end: usize) {
+        let _ = self.graphemes.splice(start..end, std::iter::empty());
+    }
+
+    /// Returns a new [`Value`] with all its graphemes replaced with the
+    /// dot ('•') character.
+    pub fn secure(&self) -> Self {
+        Self {
+            graphemes: std::iter::repeat(String::from("•"))
+                .take(self.graphemes.len())
+                .collect(),
+        }
+    }
+}