20396078319

Committed 20 Dec 2025 03:02PM UTC coverage: 69.067% (+0.7%) from 68.377%

Build # 20396078319

Build Type

Pull #37

github

Committed by

web-flow

Commit Message

Merge 08a780d5b into 432d5e9ad

Pull Request Pull Request #37: Add automatic scrolling for `Input` component (`InputStates`)

Run Details

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/src/components/input.rs

//! ## Input
//!
//! `Input` represents a read-write input field. This component supports different input types, input length
//! and handles input events related to cursor position, backspace, canc, ...

use super::props::{INPUT_INVALID_STYLE, INPUT_PLACEHOLDER, INPUT_PLACEHOLDER_STYLE};
use crate::utils::calc_utf8_cursor_position;
use tuirealm::command::{Cmd, CmdResult, Direction, Position};
use tuirealm::props::{
    Alignment, AttrValue, Attribute, Borders, Color, InputType, Props, Style, TextModifiers,
};
use tuirealm::ratatui::{layout::Rect, widgets::Paragraph};
use tuirealm::{Frame, MockComponent, State, StateValue};

// -- states

/// The number of characters [`InputStates::display_offset`] will keep in view in a single direction.
const PREVIEW_DISTANCE: usize = 2;

#[derive(Default, Debug)]
pub struct InputStates {
    /// The current input text
    pub input: Vec<char>,
    /// The cursor into "input", used as a index on where a character gets added next
    pub cursor: usize,
    /// The display offset for scrolling, always tries to keep the cursor within bounds
    pub display_offset: usize,
    /// The last drawn width of the component that displays "input".
    ///
    /// This is necessary to keep "display_offset" from jumping around on width changes.
    pub last_width: Option<u16>,
}

impl InputStates {
    /// ### append
    ///
    /// Append, if possible according to input type, the character to the input vec
    pub fn append(&mut self, ch: char, itype: &InputType, max_len: Option<usize>) {
        // Check if max length has been reached
        if self.input.len() < max_len.unwrap_or(usize::MAX) {
            // Check whether can push
            if itype.char_valid(self.input.iter().collect::<String>().as_str(), ch) {
                self.input.insert(self.cursor, ch);
                self.incr_cursor();
            }
        }
    }

    /// ### backspace
    ///
    /// Delete element at cursor -1; then decrement cursor by 1
    pub fn backspace(&mut self) {
        if self.cursor > 0 && !self.input.is_empty() {
            self.input.remove(self.cursor - 1);
            // Decrement cursor
            self.cursor -= 1;

            if self.cursor < self.display_offset.saturating_add(PREVIEW_DISTANCE) {
                self.display_offset = self.display_offset.saturating_sub(1);
            }
        }
    }

    /// ### delete
    ///
    /// Delete element at cursor
    pub fn delete(&mut self) {
        if self.cursor < self.input.len() {
            self.input.remove(self.cursor);
        }
    }

    /// ### incr_cursor
    ///
    /// Increment cursor value by one if possible
    pub fn incr_cursor(&mut self) {
        if self.cursor < self.input.len() {
            self.cursor += 1;

            if let Some(last_width) = self.last_width {
                let input_with_width = self.input.len().saturating_sub(
                    usize::from(self.last_width.unwrap_or_default())
                        .saturating_sub(PREVIEW_DISTANCE),
                );
                // only increase the offset IF cursor is higher than last_width
                // and the remaining text does not fit within the last_width
                if self.cursor
                    > usize::from(last_width).saturating_sub(PREVIEW_DISTANCE) + self.display_offset
                    && self.display_offset < input_with_width
                {
                    self.display_offset += 1;
                }
            }
        }
    }

    /// ### cursoro_at_begin
    ///
    /// Place cursor at the begin of the input
    pub fn cursor_at_begin(&mut self) {
        self.cursor = 0;
        self.display_offset = 0;
    }

    /// ### cursor_at_end
    ///
    /// Place cursor at the end of the input
    pub fn cursor_at_end(&mut self) {
        self.cursor = self.input.len();
        self.display_offset = self.input.len().saturating_sub(
            usize::from(self.last_width.unwrap_or_default()).saturating_sub(PREVIEW_DISTANCE),
        );
    }

    /// ### decr_cursor
    ///
    /// Decrement cursor value by one if possible
    pub fn decr_cursor(&mut self) {
        if self.cursor > 0 {
            self.cursor -= 1;

            if self.cursor < self.display_offset.saturating_add(PREVIEW_DISTANCE) {
                self.display_offset = self.display_offset.saturating_sub(1);
            }
        }
    }

    /// ### update_width
    ///
    /// Update the last width used to display [`InputStates::input`].
    ///
    /// This is necessary to update [`InputStates::display_offset`] correctly and keep it
    /// from jumping around on width changes.
    ///
    /// Without using this function, no scrolling will effectively be applied.
    pub fn update_width(&mut self, new_width: u16) {
        let old_width = self.last_width;
        self.last_width = Some(new_width);

        // if the cursor would now be out-of-bounds, adjust the display offset to keep the cursor within bounds
        if self.cursor
            > (self.display_offset + usize::from(new_width)).saturating_sub(PREVIEW_DISTANCE)
        {
            let diff = if let Some(old_width) = old_width {
                usize::from(old_width.saturating_sub(new_width))
            } else {
                // there was no previous width, use new_width minus cursor.
                // this happens if "update_width" had never been called (like before the first draw)
                // but the value is longer than the current display width and the cursor is not within bounds.
                self.cursor.saturating_sub(usize::from(new_width))
            };
            self.display_offset += diff;
        }
    }

    /// ### render_value
    ///
    /// Get value as string to render
    #[must_use]
    pub fn render_value(&self, itype: InputType) -> String {
        self.render_value_chars(itype).iter().collect::<String>()
    }

    /// ### render_value_offset
    ///
    /// Get value as a string to render, with the [`InputStates::display_offset`] already skipped.
    #[must_use]
    pub fn render_value_offset(&self, itype: InputType) -> String {
        self.render_value_chars(itype)
            .iter()
            .skip(self.display_offset)
            .collect()
    }

    /// ### render_value_chars
    ///
    /// Render value as a vec of chars
    #[must_use]
    pub fn render_value_chars(&self, itype: InputType) -> Vec<char> {
        match itype {
            InputType::Password(ch) | InputType::CustomPassword(ch, _, _) => {
                (0..self.input.len()).map(|_| ch).collect()
            }
            _ => self.input.clone(),
        }
    }

    /// ### get_value
    ///
    /// Get value as string
    #[must_use]
    pub fn get_value(&self) -> String {
        self.input.iter().collect()
    }
}

// -- Component

/// ## Input
///
/// Input list component
#[derive(Default)]
#[must_use]
pub struct Input {
    props: Props,
    pub states: InputStates,
}

impl Input {
    pub fn foreground(mut self, fg: Color) -> Self {
        self.attr(Attribute::Foreground, AttrValue::Color(fg));
        self
    }

    pub fn background(mut self, bg: Color) -> Self {
        self.attr(Attribute::Background, AttrValue::Color(bg));
        self
    }

    pub fn inactive(mut self, s: Style) -> Self {
        self.attr(Attribute::FocusStyle, AttrValue::Style(s));
        self
    }

    pub fn borders(mut self, b: Borders) -> Self {
        self.attr(Attribute::Borders, AttrValue::Borders(b));
        self
    }

    pub fn title<S: Into<String>>(mut self, t: S, a: Alignment) -> Self {
        self.attr(Attribute::Title, AttrValue::Title((t.into(), a)));
        self
    }

    pub fn input_type(mut self, itype: InputType) -> Self {
        self.attr(Attribute::InputType, AttrValue::InputType(itype));
        self
    }

    pub fn input_len(mut self, ilen: usize) -> Self {
        self.attr(Attribute::InputLength, AttrValue::Length(ilen));
        self
    }

    pub fn value<S: Into<String>>(mut self, s: S) -> Self {
        self.attr(Attribute::Value, AttrValue::String(s.into()));
        self
    }

    pub fn invalid_style(mut self, s: Style) -> Self {
        self.attr(Attribute::Custom(INPUT_INVALID_STYLE), AttrValue::Style(s));
        self
    }

    pub fn placeholder<S: Into<String>>(mut self, placeholder: S, style: Style) -> Self {
        self.attr(
            Attribute::Custom(INPUT_PLACEHOLDER),
            AttrValue::String(placeholder.into()),
        );
        self.attr(
            Attribute::Custom(INPUT_PLACEHOLDER_STYLE),
            AttrValue::Style(style),
        );
        self
    }

    fn get_input_len(&self) -> Option<usize> {
        self.props
            .get(Attribute::InputLength)
            .map(|x| x.unwrap_length())
    }

    fn get_input_type(&self) -> InputType {
        self.props
            .get_or(Attribute::InputType, AttrValue::InputType(InputType::Text))
            .unwrap_input_type()
    }

    /// ### is_valid
    ///
    /// Checks whether current input is valid
    fn is_valid(&self) -> bool {
        let value = self.states.get_value();
        self.get_input_type().validate(value.as_str())
    }
}

impl MockComponent for Input {
    fn view(&mut self, render: &mut Frame, area: Rect) {
        if self.props.get_or(Attribute::Display, AttrValue::Flag(true)) == AttrValue::Flag(true) {
            let mut foreground = self
                .props
                .get_or(Attribute::Foreground, AttrValue::Color(Color::Reset))
                .unwrap_color();
            let mut background = self
                .props
                .get_or(Attribute::Background, AttrValue::Color(Color::Reset))
                .unwrap_color();
            let modifiers = self
                .props
                .get_or(
                    Attribute::TextProps,
                    AttrValue::TextModifiers(TextModifiers::empty()),
                )
                .unwrap_text_modifiers();
            let title = crate::utils::get_title_or_center(&self.props);
            let borders = self
                .props
                .get_or(Attribute::Borders, AttrValue::Borders(Borders::default()))
                .unwrap_borders();
            let focus = self
                .props
                .get_or(Attribute::Focus, AttrValue::Flag(false))
                .unwrap_flag();
            let inactive_style = self
                .props
                .get(Attribute::FocusStyle)
                .map(|x| x.unwrap_style());
            let itype = self.get_input_type();
            let mut block = crate::utils::get_block(borders, Some(&title), focus, inactive_style);
            // Apply invalid style
            if focus && !self.is_valid() {
                if let Some(style) = self
                    .props
                    .get(Attribute::Custom(INPUT_INVALID_STYLE))
                    .map(|x| x.unwrap_style())
                {
                    let borders = self
                        .props
                        .get_or(Attribute::Borders, AttrValue::Borders(Borders::default()))
                        .unwrap_borders()
                        .color(style.fg.unwrap_or(Color::Reset));
                    block = crate::utils::get_block(borders, Some(&title), focus, None);
                    foreground = style.fg.unwrap_or(Color::Reset);
                    background = style.bg.unwrap_or(Color::Reset);
                }
            }

            // Create input's area
            let block_inner_area = block.inner(area);

            self.states.update_width(block_inner_area.width);

            let text_to_display = self.states.render_value_offset(self.get_input_type());

            let show_placeholder = text_to_display.is_empty();
            // Choose whether to show placeholder; if placeholder is unset, show nothing
            let text_to_display = if show_placeholder {
                self.states.cursor = 0;
                self.props
                    .get_or(
                        Attribute::Custom(INPUT_PLACEHOLDER),
                        AttrValue::String(String::new()),
                    )
                    .unwrap_string()
            } else {
                text_to_display
            };
            // Choose paragraph style based on whether is valid or not and if has focus and if should show placeholder
            let paragraph_style = if focus {
                Style::default()
                    .fg(foreground)
                    .bg(background)
                    .add_modifier(modifiers)
            } else {
                inactive_style.unwrap_or_default()
            };
            let paragraph_style = if show_placeholder {
                self.props
                    .get_or(
                        Attribute::Custom(INPUT_PLACEHOLDER_STYLE),
                        AttrValue::Style(paragraph_style),
                    )
                    .unwrap_style()
            } else {
                paragraph_style
            };

            let p: Paragraph = Paragraph::new(text_to_display)
                .style(paragraph_style)
                .block(block);
            render.render_widget(p, area);

            // Set cursor, if focus
            if focus && !block_inner_area.is_empty() {
                let x: u16 = block_inner_area.x
                    + calc_utf8_cursor_position(
                        &self.states.render_value_chars(itype)[0..self.states.cursor],
                    )
                    .saturating_sub(u16::try_from(self.states.display_offset).unwrap_or(u16::MAX));
                let x = x.min(block_inner_area.x + block_inner_area.width);
                render.set_cursor_position(tuirealm::ratatui::prelude::Position {
                    x,
                    y: block_inner_area.y,
                });
            }
        }
    }

    fn query(&self, attr: Attribute) -> Option<AttrValue> {
        self.props.get(attr)
    }

    fn attr(&mut self, attr: Attribute, value: AttrValue) {
        let sanitize_input = matches!(
            attr,
            Attribute::InputLength | Attribute::InputType | Attribute::Value
        );
        // Check if new input
        let new_input = match attr {
            Attribute::Value => Some(value.clone().unwrap_string()),
            _ => None,
        };
        self.props.set(attr, value);
        if sanitize_input {
            let input = match new_input {
                None => self.states.input.clone(),
                Some(v) => v.chars().collect(),
            };
            self.states.input = Vec::new();
            self.states.cursor = 0;
            let itype = self.get_input_type();
            let max_len = self.get_input_len();
            for ch in input {
                self.states.append(ch, &itype, max_len);
            }
        }
    }

    fn state(&self) -> State {
        // Validate input
        if self.is_valid() {
            State::One(StateValue::String(self.states.get_value()))
        } else {
            State::None
        }
    }

    fn perform(&mut self, cmd: Cmd) -> CmdResult {
        match cmd {
            Cmd::Delete => {
                // Backspace and None
                let prev_input = self.states.input.clone();
                self.states.backspace();
                if prev_input == self.states.input {
                    CmdResult::None
                } else {
                    CmdResult::Changed(self.state())
                }
            }
            Cmd::Cancel => {
                // Delete and None
                let prev_input = self.states.input.clone();
                self.states.delete();
                if prev_input == self.states.input {
                    CmdResult::None
                } else {
                    CmdResult::Changed(self.state())
                }
            }
            Cmd::Submit => CmdResult::Submit(self.state()),
            Cmd::Move(Direction::Left) => {
                self.states.decr_cursor();
                CmdResult::None
            }
            Cmd::Move(Direction::Right) => {
                self.states.incr_cursor();
                CmdResult::None
            }
            Cmd::GoTo(Position::Begin) => {
                self.states.cursor_at_begin();
                CmdResult::None
            }
            Cmd::GoTo(Position::End) => {
                self.states.cursor_at_end();
                CmdResult::None
            }
            Cmd::Type(ch) => {
                // Push char to input
                let prev_input = self.states.input.clone();
                self.states
                    .append(ch, &self.get_input_type(), self.get_input_len());
                // Message on change
                if prev_input == self.states.input {
                    CmdResult::None
                } else {
                    CmdResult::Changed(self.state())
                }
            }
            _ => CmdResult::None,
        }
    }
}

#[cfg(test)]
mod tests {

    use super::*;

    use pretty_assertions::assert_eq;

    #[test]
    fn test_components_input_states() {
        let mut states: InputStates = InputStates::default();
        states.append('a', &InputType::Text, Some(3));
        assert_eq!(states.input, vec!['a']);
        states.append('b', &InputType::Text, Some(3));
        assert_eq!(states.input, vec!['a', 'b']);
        states.append('c', &InputType::Text, Some(3));
        assert_eq!(states.input, vec!['a', 'b', 'c']);
        // Reached length
        states.append('d', &InputType::Text, Some(3));
        assert_eq!(states.input, vec!['a', 'b', 'c']);
        // Push char to numbers
        states.append('d', &InputType::Number, None);
        assert_eq!(states.input, vec!['a', 'b', 'c']);
        // move cursor
        // decr cursor
        states.decr_cursor();
        assert_eq!(states.cursor, 2);
        states.cursor = 1;
        states.decr_cursor();
        assert_eq!(states.cursor, 0);
        states.decr_cursor();
        assert_eq!(states.cursor, 0);
        // Incr
        states.incr_cursor();
        assert_eq!(states.cursor, 1);
        states.incr_cursor();
        assert_eq!(states.cursor, 2);
        states.incr_cursor();
        assert_eq!(states.cursor, 3);
        // Render value
        assert_eq!(states.render_value(InputType::Text).as_str(), "abc");
        assert_eq!(
            states.render_value(InputType::Password('*')).as_str(),
            "***"
        );
    }

    #[test]
    fn test_components_input_text() {
        // Instantiate Input with value
        let mut component: Input = Input::default()
            .background(Color::Yellow)
            .borders(Borders::default())
            .foreground(Color::Cyan)
            .inactive(Style::default())
            .input_len(5)
            .input_type(InputType::Text)
            .title("pippo", Alignment::Center)
            .value("home");
        // Verify initial state
        assert_eq!(component.states.cursor, 4);
        assert_eq!(component.states.input.len(), 4);
        // Get value
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("home")))
        );
        // Character
        assert_eq!(
            component.perform(Cmd::Type('/')),
            CmdResult::Changed(State::One(StateValue::String(String::from("home/"))))
        );
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("home/")))
        );
        assert_eq!(component.states.cursor, 5);
        // Verify max length (shouldn't push any character)
        assert_eq!(component.perform(Cmd::Type('a')), CmdResult::None);
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("home/")))
        );
        assert_eq!(component.states.cursor, 5);
        // Submit
        assert_eq!(
            component.perform(Cmd::Submit),
            CmdResult::Submit(State::One(StateValue::String(String::from("home/"))))
        );
        // Backspace
        assert_eq!(
            component.perform(Cmd::Delete),
            CmdResult::Changed(State::One(StateValue::String(String::from("home"))))
        );
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("home")))
        );
        assert_eq!(component.states.cursor, 4);
        // Check backspace at 0
        component.states.input = vec!['h'];
        component.states.cursor = 1;
        assert_eq!(
            component.perform(Cmd::Delete),
            CmdResult::Changed(State::One(StateValue::String(String::new())))
        );
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::new()))
        );
        assert_eq!(component.states.cursor, 0);
        // Another one...
        assert_eq!(component.perform(Cmd::Delete), CmdResult::None);
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::new()))
        );
        assert_eq!(component.states.cursor, 0);
        // See del behaviour here
        assert_eq!(component.perform(Cmd::Cancel), CmdResult::None);
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::new()))
        );
        assert_eq!(component.states.cursor, 0);
        // Check del behaviour
        component.states.input = vec!['h', 'e'];
        component.states.cursor = 1;
        assert_eq!(
            component.perform(Cmd::Cancel),
            CmdResult::Changed(State::One(StateValue::String(String::from("h"))))
        );
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("h")))
        );
        assert_eq!(component.states.cursor, 1);
        // Another one (should do nothing)
        assert_eq!(component.perform(Cmd::Cancel), CmdResult::None);
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("h")))
        );
        assert_eq!(component.states.cursor, 1);
        // Move cursor right
        component.states.input = vec!['h', 'e', 'l', 'l', 'o'];
        // Update length to 16
        component.attr(Attribute::InputLength, AttrValue::Length(16));
        component.states.cursor = 1;
        assert_eq!(
            component.perform(Cmd::Move(Direction::Right)), // between 'e' and 'l'
            CmdResult::None
        );
        assert_eq!(component.states.cursor, 2);
        // Put a character here
        assert_eq!(
            component.perform(Cmd::Type('a')),
            CmdResult::Changed(State::One(StateValue::String(String::from("heallo"))))
        );
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("heallo")))
        );
        assert_eq!(component.states.cursor, 3);
        // Move left
        assert_eq!(
            component.perform(Cmd::Move(Direction::Left)),
            CmdResult::None
        );
        assert_eq!(component.states.cursor, 2);
        // Go at the end
        component.states.cursor = 6;
        // Move right
        assert_eq!(component.perform(Cmd::GoTo(Position::End)), CmdResult::None);
        assert_eq!(component.states.cursor, 6);
        // Move left
        assert_eq!(
            component.perform(Cmd::Move(Direction::Left)),
            CmdResult::None
        );
        assert_eq!(component.states.cursor, 5);
        // Go at the beginning
        component.states.cursor = 0;
        assert_eq!(
            component.perform(Cmd::Move(Direction::Left)),
            CmdResult::None
        );
        //assert_eq!(component.render().unwrap().cursor, 0); // Should stay
        assert_eq!(component.states.cursor, 0);
        // End - begin
        assert_eq!(component.perform(Cmd::GoTo(Position::End)), CmdResult::None);
        assert_eq!(component.states.cursor, 6);
        assert_eq!(
            component.perform(Cmd::GoTo(Position::Begin)),
            CmdResult::None
        );
        assert_eq!(component.states.cursor, 0);
        // Update value
        component.attr(Attribute::Value, AttrValue::String("new-value".to_string()));
        assert_eq!(
            component.state(),
            State::One(StateValue::String(String::from("new-value")))
        );
        // Invalidate input type
        component.attr(
            Attribute::InputType,
            AttrValue::InputType(InputType::Number),
        );
        assert_eq!(component.state(), State::None);
    }

    #[test]
    fn should_keep_cursor_within_bounds() {
        let text = "The quick brown fox jumps over the lazy dog";
        assert!(text.len() > 15);

        let mut states = InputStates::default();

        for ch in text.chars() {
            states.append(ch, &InputType::Text, None);
        }

        // at first, without any "width" set, both functions should return the same
        assert_eq!(states.cursor, text.len());
        assert_eq!(
            states.render_value(InputType::Text),
            states.render_value_offset(InputType::Text)
        );

        states.update_width(10);

        assert_eq!(
            states.render_value_offset(InputType::Text),
            text[text.len() - 10..]
        );

        // the displayed text should not change until being in PREVIEW_STEP
        for i in 1..8 {
            states.decr_cursor();
            assert_eq!(states.cursor, text.len() - i);
            let val = states.render_value_offset(InputType::Text);
            assert_eq!(val, text[text.len() - 10..]);
        }

        // preview step space at the end
        states.decr_cursor();
        assert_eq!(states.cursor, text.len() - 8);
        assert_eq!(
            states.render_value_offset(InputType::Text),
            text[text.len() - 10..]
        );

        states.decr_cursor();
        assert_eq!(states.cursor, text.len() - 9);
        assert_eq!(
            states.render_value_offset(InputType::Text),
            text[text.len() - 11..]
        );

        states.decr_cursor();
        assert_eq!(states.cursor, text.len() - 10);
        assert_eq!(
            states.render_value_offset(InputType::Text),
            text[text.len() - 12..]
        );

        states.cursor_at_begin();
        assert_eq!(states.cursor, 0);
        assert_eq!(states.render_value(InputType::Text), text);

        // the displayed text should not change until being in PREVIEW_STEP
        for i in 1..9 {
            states.incr_cursor();
            assert_eq!(states.cursor, i);
            let val = states.render_value_offset(InputType::Text);
            assert_eq!(val, text);
        }

        states.incr_cursor();
        assert_eq!(states.cursor, 9);
        assert_eq!(states.render_value_offset(InputType::Text), text[1..]);

        states.incr_cursor();
        assert_eq!(states.cursor, 10);
        assert_eq!(states.render_value_offset(InputType::Text), text[2..]);

        // increasing width should not change display_offset
        states.update_width(30);
        assert_eq!(states.cursor, 10);
        assert_eq!(states.render_value_offset(InputType::Text), text[2..]);

        // reset to 10, should also not change
        states.update_width(10);
        assert_eq!(states.cursor, 10);
        assert_eq!(states.render_value_offset(InputType::Text), text[2..]);

        // should change display_offset by 1
        states.update_width(9);
        assert_eq!(states.cursor, 10);
        assert_eq!(states.render_value_offset(InputType::Text), text[3..]);

        // reset to end
        states.update_width(10);
        states.cursor_at_end();

        // the displayed text should not change until being in PREVIEW_STEP
        for i in 1..=4 {
            states.decr_cursor();
            assert_eq!(states.cursor, text.len() - i);
            let val = states.render_value_offset(InputType::Text);
            assert_eq!(val, text[text.len() - 8..]);
        }

        assert_eq!(states.cursor, text.len() - 4);
        states.incr_cursor();
        assert_eq!(states.cursor, text.len() - 3);
        assert_eq!(
            states.render_value_offset(InputType::Text),
            text[text.len() - 8..]
        );

        // note any width below PREVIEW_STEP * 2 + 1 is undefined behavior
    }
}

veeso / tui-realm-stdlib / 20396078319

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