nushell/crates/nu-term-grid/src/grid.rs

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2021-10-05 15:43:20 +02:00
// #![warn(future_incompatible)]
// #![warn(missing_copy_implementations)]
// #![warn(missing_docs)]
// #![warn(nonstandard_style)]
// #![warn(rust_2018_compatibility)]
// #![warn(rust_2018_idioms)]
// #![warn(trivial_casts, trivial_numeric_casts)]
// #![warn(unused)]
// #![deny(unsafe_code)]
//! This library arranges textual data in a grid format suitable for
//! fixed-width fonts, using an algorithm to minimise the amount of space
//! needed. For example:
//!
//! ```rust
//! use nu_term_grid::grid::{Grid, GridOptions, Direction, Filling, Cell};
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//!
//! let mut grid = Grid::new(GridOptions {
//! filling: Filling::Spaces(1),
//! direction: Direction::LeftToRight,
//! });
//!
//! for s in &["one", "two", "three", "four", "five", "six", "seven",
//! "eight", "nine", "ten", "eleven", "twelve"]
//! {
//! grid.add(Cell::from(*s));
//! }
//!
//! println!("{}", grid.fit_into_width(24).unwrap());
//! ```
//!
//! Produces the following tabular result:
//!
//! ```text
//! one two three four
//! five six seven eight
//! nine ten eleven twelve
//! ```
//!
//!
//! ## Creating a grid
//!
//! To add data to a grid, first create a new [`Grid`] value, and then add
//! cells to them with the `add` function.
//!
//! There are two options that must be specified in the [`GridOptions`] value
//! that dictate how the grid is formatted:
//!
//! - `filling`: what to put in between two columns — either a number of
//! spaces, or a text string;
//! - `direction`, which specifies whether the cells should go along
//! rows, or columns:
//! - `Direction::LeftToRight` starts them in the top left and
//! moves *rightwards*, going to the start of a new row after reaching the
//! final column;
//! - `Direction::TopToBottom` starts them in the top left and moves
//! *downwards*, going to the top of a new column after reaching the final
//! row.
//!
//!
//! ## Displaying a grid
//!
//! When display a grid, you can either specify the number of columns in advance,
//! or try to find the maximum number of columns that can fit in an area of a
//! given width.
//!
//! Splitting a series of cells into columns — or, in other words, starting a new
//! row every <var>n</var> cells — is achieved with the [`fit_into_columns`] function
//! on a `Grid` value. It takes as its argument the number of columns.
//!
//! Trying to fit as much data onto one screen as possible is the main use case
//! for specifying a maximum width instead. This is achieved with the
//! [`fit_into_width`] function. It takes the maximum allowed width, including
//! separators, as its argument. However, it returns an *optional* [`Display`]
//! value, depending on whether any of the cells actually had a width greater than
//! the maximum width! If this is the case, your best bet is to just output the
//! cells with one per line.
//!
//!
//! ## Cells and data
//!
//! Grids to not take `String`s or `&str`s — they take [`Cell`] values.
//!
//! A **Cell** is a struct containing an individual cells contents, as a string,
//! and its pre-computed length, which gets used when calculating a grids final
//! dimensions. Usually, you want the *Unicode width* of the string to be used for
//! this, so you can turn a `String` into a `Cell` with the `.into()` function.
//!
//! However, you may also want to supply your own width: when you already know the
//! width in advance, or when you want to change the measurement, such as skipping
//! over terminal control characters. For cases like these, the fields on the
//! `Cell` values are public, meaning you can construct your own instances as
//! necessary.
//!
//! [`Cell`]: ./struct.Cell.html
//! [`Display`]: ./struct.Display.html
//! [`Grid`]: ./struct.Grid.html
//! [`fit_into_columns`]: ./struct.Grid.html#method.fit_into_columns
//! [`fit_into_width`]: ./struct.Grid.html#method.fit_into_width
//! [`GridOptions`]: ./struct.GridOptions.html
use std::cmp::max;
use std::fmt;
use std::iter::repeat;
// extern crate unicode_width;
use unicode_width::UnicodeWidthStr;
/// Alignment indicate on which side the content should stick if some filling
/// is required.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Alignment {
/// The content will stick to the left.
Left,
/// The content will stick to the right.
Right,
}
/// A **Cell** is the combination of a string and its pre-computed length.
///
/// The easiest way to create a Cell is just by using `string.into()`, which
/// uses the **unicode width** of the string (see the `unicode_width` crate).
/// However, the fields are public, if you wish to provide your own length.
#[derive(PartialEq, Debug, Clone)]
pub struct Cell {
/// The string to display when this cell gets rendered.
pub contents: String,
/// The pre-computed length of the string.
pub width: Width,
/// The side (left/right) to align the content if some filling is required.
pub alignment: Alignment,
}
impl From<String> for Cell {
fn from(string: String) -> Self {
Self {
width: UnicodeWidthStr::width(&*string),
contents: string,
alignment: Alignment::Left,
}
}
}
impl<'a> From<&'a str> for Cell {
fn from(string: &'a str) -> Self {
Self {
width: UnicodeWidthStr::width(&*string),
contents: string.into(),
alignment: Alignment::Left,
}
}
}
/// Direction cells should be written in — either across, or downwards.
#[derive(PartialEq, Debug, Copy, Clone)]
pub enum Direction {
/// Starts at the top left and moves rightwards, going back to the first
/// column for a new row, like a typewriter.
LeftToRight,
/// Starts at the top left and moves downwards, going back to the first
/// row for a new column, like how `ls` lists files by default.
TopToBottom,
}
/// The width of a cell, in columns.
pub type Width = usize;
/// The text to put in between each pair of columns.
/// This does not include any spaces used when aligning cells.
#[derive(PartialEq, Debug)]
pub enum Filling {
/// A certain number of spaces should be used as the separator.
Spaces(Width),
/// An arbitrary string.
/// `"|"` is a common choice.
Text(String),
}
impl Filling {
fn width(&self) -> Width {
match *self {
Filling::Spaces(w) => w,
Filling::Text(ref t) => UnicodeWidthStr::width(&t[..]),
}
}
}
/// The user-assignable options for a grid view that should be passed to
/// [`Grid::new()`](struct.Grid.html#method.new).
#[derive(PartialEq, Debug)]
pub struct GridOptions {
/// The direction that the cells should be written in — either
/// across, or downwards.
pub direction: Direction,
/// The number of spaces to put in between each column of cells.
pub filling: Filling,
}
#[derive(PartialEq, Debug)]
struct Dimensions {
/// The number of lines in the grid.
num_lines: Width,
/// The width of each column in the grid. The length of this vector serves
/// as the number of columns.
widths: Vec<Width>,
}
impl Dimensions {
fn total_width(&self, separator_width: Width) -> Width {
if self.widths.is_empty() {
0
} else {
let values = self.widths.iter().sum::<Width>();
let separators = separator_width * (self.widths.len() - 1);
values + separators
}
}
}
/// Everything needed to format the cells with the grid options.
///
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/// For more information, see the [`grid` crate documentation](index.html).
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#[derive(PartialEq, Debug)]
pub struct Grid {
options: GridOptions,
cells: Vec<Cell>,
widest_cell_length: Width,
width_sum: Width,
cell_count: usize,
}
impl Grid {
/// Creates a new grid view with the given options.
pub fn new(options: GridOptions) -> Self {
let cells = Vec::new();
Self {
options,
cells,
widest_cell_length: 0,
width_sum: 0,
cell_count: 0,
}
}
/// Reserves space in the vector for the given number of additional cells
/// to be added. (See the `Vec::reserve` function.)
pub fn reserve(&mut self, additional: usize) {
self.cells.reserve(additional)
}
/// Adds another cell onto the vector.
pub fn add(&mut self, cell: Cell) {
if cell.width > self.widest_cell_length {
self.widest_cell_length = cell.width;
}
self.width_sum += cell.width;
self.cell_count += 1;
self.cells.push(cell)
}
/// Returns a displayable grid thats been packed to fit into the given
/// width in the fewest number of rows.
///
/// Returns `None` if any of the cells has a width greater than the
/// maximum width.
pub fn fit_into_width(&self, maximum_width: Width) -> Option<Display<'_>> {
self.width_dimensions(maximum_width).map(|dims| Display {
grid: self,
dimensions: dims,
})
}
/// Returns a displayable grid with the given number of columns, and no
/// maximum width.
pub fn fit_into_columns(&self, num_columns: usize) -> Display<'_> {
Display {
grid: self,
dimensions: self.columns_dimensions(num_columns),
}
}
fn columns_dimensions(&self, num_columns: usize) -> Dimensions {
let mut num_lines = self.cells.len() / num_columns;
if self.cells.len() % num_columns != 0 {
num_lines += 1;
}
self.column_widths(num_lines, num_columns)
}
fn column_widths(&self, num_lines: usize, num_columns: usize) -> Dimensions {
let mut widths: Vec<Width> = repeat(0).take(num_columns).collect();
for (index, cell) in self.cells.iter().enumerate() {
let index = match self.options.direction {
Direction::LeftToRight => index % num_columns,
Direction::TopToBottom => index / num_lines,
};
widths[index] = max(widths[index], cell.width);
}
Dimensions { num_lines, widths }
}
fn theoretical_max_num_lines(&self, maximum_width: usize) -> usize {
// TODO: Make code readable / efficient.
let mut theoretical_min_num_cols = 0;
let mut col_total_width_so_far = 0;
let mut cells = self.cells.clone();
cells.sort_unstable_by(|a, b| b.width.cmp(&a.width)); // Sort in reverse order
for cell in &cells {
if cell.width + col_total_width_so_far <= maximum_width {
theoretical_min_num_cols += 1;
col_total_width_so_far += cell.width;
} else {
let mut theoretical_max_num_lines = self.cell_count / theoretical_min_num_cols;
if self.cell_count % theoretical_min_num_cols != 0 {
theoretical_max_num_lines += 1;
}
return theoretical_max_num_lines;
}
col_total_width_so_far += self.options.filling.width()
}
// If we make it to this point, we have exhausted all cells before
// reaching the maximum width; the theoretical max number of lines
// needed to display all cells is 1.
1
}
fn width_dimensions(&self, maximum_width: Width) -> Option<Dimensions> {
if self.widest_cell_length > maximum_width {
// Largest cell is wider than maximum width; it is impossible to fit.
return None;
}
if self.cell_count == 0 {
return Some(Dimensions {
num_lines: 0,
widths: Vec::new(),
});
}
if self.cell_count == 1 {
let the_cell = &self.cells[0];
return Some(Dimensions {
num_lines: 1,
widths: vec![the_cell.width],
});
}
let theoretical_max_num_lines = self.theoretical_max_num_lines(maximum_width);
if theoretical_max_num_lines == 1 {
// This if—statement is neccesary for the function to work correctly
// for small inputs.
return Some(Dimensions {
num_lines: 1,
// I clone self.cells twice. Once here, and once in
// self.theoretical_max_num_lines. Perhaps not the best for
// performance?
widths: self
.cells
.clone()
.into_iter()
.map(|cell| cell.width)
.collect(),
});
}
// Instead of numbers of columns, try to find the fewest number of *lines*
// that the output will fit in.
let mut smallest_dimensions_yet = None;
for num_lines in (1..=theoretical_max_num_lines).rev() {
// The number of columns is the number of cells divided by the number
// of lines, *rounded up*.
let mut num_columns = self.cell_count / num_lines;
if self.cell_count % num_lines != 0 {
num_columns += 1;
}
// Early abort: if there are so many columns that the width of the
// *column separators* is bigger than the width of the screen, then
// dont even try to tabulate it.
// This is actually a necessary check, because the width is stored as
// a usize, and making it go negative makes it huge instead, but it
// also serves as a speed-up.
let total_separator_width = (num_columns - 1) * self.options.filling.width();
if maximum_width < total_separator_width {
continue;
}
// Remove the separator width from the available space.
let adjusted_width = maximum_width - total_separator_width;
let potential_dimensions = self.column_widths(num_lines, num_columns);
if potential_dimensions.widths.iter().sum::<Width>() < adjusted_width {
smallest_dimensions_yet = Some(potential_dimensions);
} else {
return smallest_dimensions_yet;
}
}
None
}
}
/// A displayable representation of a [`Grid`](struct.Grid.html).
///
/// This type implements `Display`, so you can get the textual version
/// of the grid by calling `.to_string()`.
#[derive(PartialEq, Debug)]
pub struct Display<'grid> {
/// The grid to display.
grid: &'grid Grid,
/// The pre-computed column widths for this grid.
dimensions: Dimensions,
}
impl Display<'_> {
/// Returns how many columns this display takes up, based on the separator
/// width and the number and width of the columns.
pub fn width(&self) -> Width {
self.dimensions
.total_width(self.grid.options.filling.width())
}
/// Returns how many rows this display takes up.
pub fn row_count(&self) -> usize {
self.dimensions.num_lines
}
/// Returns whether this display takes up as many columns as were allotted
/// to it.
///
/// Its possible to construct tables that dont actually use up all the
/// columns that they could, such as when there are more columns than
/// cells! In this case, a column would have a width of zero. This just
/// checks for that.
pub fn is_complete(&self) -> bool {
self.dimensions.widths.iter().all(|&x| x > 0)
}
}
impl fmt::Display for Display<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
for y in 0..self.dimensions.num_lines {
for x in 0..self.dimensions.widths.len() {
let num = match self.grid.options.direction {
Direction::LeftToRight => y * self.dimensions.widths.len() + x,
Direction::TopToBottom => y + self.dimensions.num_lines * x,
};
// Abandon a line mid-way through if thats where the cells end
if num >= self.grid.cells.len() {
continue;
}
let cell = &self.grid.cells[num];
if x == self.dimensions.widths.len() - 1 {
match cell.alignment {
Alignment::Left => {
// The final column doesnt need to have trailing spaces,
// as long as its left-aligned.
write!(f, "{}", cell.contents)?;
}
Alignment::Right => {
let extra_spaces = self.dimensions.widths[x] - cell.width;
write!(
f,
"{}",
pad_string(&cell.contents, extra_spaces, Alignment::Right)
)?;
}
}
} else {
assert!(self.dimensions.widths[x] >= cell.width);
match (&self.grid.options.filling, cell.alignment) {
(Filling::Spaces(n), Alignment::Left) => {
let extra_spaces = self.dimensions.widths[x] - cell.width + n;
write!(
f,
"{}",
pad_string(&cell.contents, extra_spaces, cell.alignment)
)?;
}
(Filling::Spaces(n), Alignment::Right) => {
let s = spaces(*n);
let extra_spaces = self.dimensions.widths[x] - cell.width;
write!(
f,
"{}{}",
pad_string(&cell.contents, extra_spaces, cell.alignment),
s
)?;
}
(Filling::Text(ref t), _) => {
let extra_spaces = self.dimensions.widths[x] - cell.width;
write!(
f,
"{}{}",
pad_string(&cell.contents, extra_spaces, cell.alignment),
t
)?;
}
}
}
}
writeln!(f)?;
}
Ok(())
}
}
/// Pad a string with the given number of spaces.
fn spaces(length: usize) -> String {
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" ".repeat(length)
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}
/// Pad a string with the given alignment and number of spaces.
///
/// This doesnt take the width the string *should* be, rather the number
/// of spaces to add.
fn pad_string(string: &str, padding: usize, alignment: Alignment) -> String {
if alignment == Alignment::Left {
format!("{}{}", string, spaces(padding))
} else {
format!("{}{}", spaces(padding), string)
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn no_items() {
let grid = Grid::new(GridOptions {
direction: Direction::TopToBottom,
filling: Filling::Spaces(2),
});
let display = grid.fit_into_width(40).unwrap();
assert_eq!(display.dimensions.num_lines, 0);
assert!(display.dimensions.widths.is_empty());
assert_eq!(display.width(), 0);
}
#[test]
fn one_item() {
let mut grid = Grid::new(GridOptions {
direction: Direction::TopToBottom,
filling: Filling::Spaces(2),
});
grid.add(Cell::from("1"));
let display = grid.fit_into_width(40).unwrap();
assert_eq!(display.dimensions.num_lines, 1);
assert_eq!(display.dimensions.widths, vec![1]);
assert_eq!(display.width(), 1);
}
#[test]
fn one_item_exact_width() {
let mut grid = Grid::new(GridOptions {
direction: Direction::TopToBottom,
filling: Filling::Spaces(2),
});
grid.add(Cell::from("1234567890"));
let display = grid.fit_into_width(10).unwrap();
assert_eq!(display.dimensions.num_lines, 1);
assert_eq!(display.dimensions.widths, vec![10]);
assert_eq!(display.width(), 10);
}
#[test]
fn one_item_just_over() {
let mut grid = Grid::new(GridOptions {
direction: Direction::TopToBottom,
filling: Filling::Spaces(2),
});
grid.add(Cell::from("1234567890!"));
assert_eq!(grid.fit_into_width(10), None);
}
#[test]
fn two_small_items() {
let mut grid = Grid::new(GridOptions {
direction: Direction::TopToBottom,
filling: Filling::Spaces(2),
});
grid.add(Cell::from("1"));
grid.add(Cell::from("2"));
let display = grid.fit_into_width(40).unwrap();
assert_eq!(display.dimensions.num_lines, 1);
assert_eq!(display.dimensions.widths, vec![1, 1]);
assert_eq!(display.width(), 1 + 2 + 1);
}
#[test]
fn two_medium_size_items() {
let mut grid = Grid::new(GridOptions {
direction: Direction::TopToBottom,
filling: Filling::Spaces(2),
});
grid.add(Cell::from("hello there"));
grid.add(Cell::from("how are you today?"));
let display = grid.fit_into_width(40).unwrap();
assert_eq!(display.dimensions.num_lines, 1);
assert_eq!(display.dimensions.widths, vec![11, 18]);
assert_eq!(display.width(), 11 + 2 + 18);
}
#[test]
fn two_big_items() {
let mut grid = Grid::new(GridOptions {
direction: Direction::TopToBottom,
filling: Filling::Spaces(2),
});
grid.add(Cell::from(
"nuihuneihsoenhisenouiuteinhdauisdonhuisudoiosadiuohnteihaosdinhteuieudi",
));
grid.add(Cell::from(
"oudisnuthasuouneohbueobaugceoduhbsauglcobeuhnaeouosbubaoecgueoubeohubeo",
));
assert_eq!(grid.fit_into_width(40), None);
}
#[test]
fn that_example_from_earlier() {
let mut grid = Grid::new(GridOptions {
filling: Filling::Spaces(1),
direction: Direction::LeftToRight,
});
for s in &[
"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
"eleven", "twelve",
] {
grid.add(Cell::from(*s));
}
let bits = "one two three four\nfive six seven eight\nnine ten eleven twelve\n";
assert_eq!(grid.fit_into_width(24).unwrap().to_string(), bits);
assert_eq!(grid.fit_into_width(24).unwrap().row_count(), 3);
}
#[test]
fn number_grid_with_pipe() {
let mut grid = Grid::new(GridOptions {
filling: Filling::Text("|".into()),
direction: Direction::LeftToRight,
});
for s in &[
"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
"eleven", "twelve",
] {
grid.add(Cell::from(*s));
}
let bits = "one |two|three |four\nfive|six|seven |eight\nnine|ten|eleven|twelve\n";
assert_eq!(grid.fit_into_width(24).unwrap().to_string(), bits);
assert_eq!(grid.fit_into_width(24).unwrap().row_count(), 3);
}
#[test]
fn numbers_right() {
let mut grid = Grid::new(GridOptions {
filling: Filling::Spaces(1),
direction: Direction::LeftToRight,
});
for s in &[
"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
"eleven", "twelve",
] {
let mut cell = Cell::from(*s);
cell.alignment = Alignment::Right;
grid.add(cell);
}
let bits = " one two three four\nfive six seven eight\nnine ten eleven twelve\n";
assert_eq!(grid.fit_into_width(24).unwrap().to_string(), bits);
assert_eq!(grid.fit_into_width(24).unwrap().row_count(), 3);
}
#[test]
fn numbers_right_pipe() {
let mut grid = Grid::new(GridOptions {
filling: Filling::Text("|".into()),
direction: Direction::LeftToRight,
});
for s in &[
"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
"eleven", "twelve",
] {
let mut cell = Cell::from(*s);
cell.alignment = Alignment::Right;
grid.add(cell);
}
let bits = " one|two| three| four\nfive|six| seven| eight\nnine|ten|eleven|twelve\n";
assert_eq!(grid.fit_into_width(24).unwrap().to_string(), bits);
assert_eq!(grid.fit_into_width(24).unwrap().row_count(), 3);
}
#[test]
fn huge_separator() {
let mut grid = Grid::new(GridOptions {
filling: Filling::Spaces(100),
direction: Direction::LeftToRight,
});
grid.add("a".into());
grid.add("b".into());
assert_eq!(grid.fit_into_width(99), None);
}
#[test]
fn huge_yet_unused_separator() {
let mut grid = Grid::new(GridOptions {
filling: Filling::Spaces(100),
direction: Direction::LeftToRight,
});
grid.add("abcd".into());
let display = grid.fit_into_width(99).unwrap();
assert_eq!(display.dimensions.num_lines, 1);
assert_eq!(display.dimensions.widths, vec![4]);
assert_eq!(display.width(), 4);
}
}