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//! Text formatter.
use crate::util::{header_text, unwrap};
use crate::EventIter;
use anyhow::{bail, Error};
use pulldown_cmark::{Alignment, Event, HeadingLevel, LinkType, Tag};
use std::fmt::Write;
use std::mem;
use url::Url;
pub struct TextFormatter {
url: Option<Url>,
}
impl TextFormatter {
pub fn new(url: Option<Url>) -> TextFormatter {
TextFormatter { url }
}
}
impl super::Formatter for TextFormatter {
fn render(&self, input: &str) -> Result<String, Error> {
TextRenderer::render(input, self.url.clone(), 0)
}
fn render_options_start(&self) -> &'static str {
// Tell pulldown_cmark to ignore this.
// This will be stripped out later.
"<![CDATA["
}
fn render_options_end(&self) -> &'static str {
"]]>"
}
fn render_option(
&self,
params: &[&str],
block: &str,
_man_name: &str,
) -> Result<String, Error> {
let rendered_options = params
.iter()
.map(|param| TextRenderer::render(param, self.url.clone(), 0))
.collect::<Result<Vec<_>, Error>>()?;
let trimmed: Vec<_> = rendered_options.iter().map(|o| o.trim()).collect();
// Wrap in HTML tags, they will be stripped out during rendering.
Ok(format!(
"<dt>{}</dt>\n<dd>{}</dd>\n<br>\n",
trimmed.join(", "),
block
))
}
fn linkify_man_to_md(&self, name: &str, section: u8) -> Result<String, Error> {
Ok(format!("`{}`({})", name, section))
}
}
struct TextRenderer<'e> {
output: String,
indent: usize,
/// The current line being written. Once a line break is encountered (such
/// as starting a new paragraph), this will be written to `output` via
/// `flush`.
line: String,
/// The current word being written. Once a break is encountered (such as a
/// space) this will be written to `line` via `flush_word`.
word: String,
parser: EventIter<'e>,
/// The base URL used for relative URLs.
url: Option<Url>,
table: Table,
}
impl<'e> TextRenderer<'e> {
fn render(input: &str, url: Option<Url>, indent: usize) -> Result<String, Error> {
let parser = crate::md_parser(input, url.clone());
let output = String::with_capacity(input.len() * 3 / 2);
let mut mr = TextRenderer {
output,
indent,
line: String::new(),
word: String::new(),
parser,
url,
table: Table::new(),
};
mr.push_md()?;
Ok(mr.output)
}
fn push_md(&mut self) -> Result<(), Error> {
// If this is true, this is inside a cdata block used for hiding
// content from pulldown_cmark.
let mut in_cdata = false;
// The current list stack. None if unordered, Some if ordered with the
// given number as the current index.
let mut list: Vec<Option<u64>> = Vec::new();
// Used in some cases where spacing isn't desired.
let mut suppress_paragraph = false;
// Whether or not word-wrapping is enabled.
let mut wrap_text = true;
while let Some((event, range)) = self.parser.next() {
let this_suppress_paragraph = suppress_paragraph;
// Always reset suppression, even if the next event isn't a
// paragraph. This is in essence, a 1-token lookahead where the
// suppression is only enabled if the next event is a paragraph.
suppress_paragraph = false;
match event {
Event::Start(tag) => {
match tag {
Tag::Paragraph => {
if !this_suppress_paragraph {
self.flush();
}
}
Tag::Heading(level, ..) => {
self.flush();
if level == HeadingLevel::H1 {
let text = header_text(&mut self.parser)?;
self.push_to_line(&text.to_uppercase());
self.hard_break();
self.hard_break();
} else if level == HeadingLevel::H2 {
let text = header_text(&mut self.parser)?;
self.push_to_line(&text.to_uppercase());
self.flush();
self.indent = 7;
} else {
let text = header_text(&mut self.parser)?;
self.push_indent((level as usize - 2) * 3);
self.push_to_line(&text);
self.flush();
self.indent = (level as usize - 1) * 3 + 1;
}
}
Tag::BlockQuote => {
self.indent += 3;
}
Tag::CodeBlock(_kind) => {
self.flush();
wrap_text = false;
self.indent += 4;
}
Tag::List(start) => list.push(start),
Tag::Item => {
self.flush();
match list.last_mut().expect("item must have list start") {
// Ordered list.
Some(n) => {
self.push_indent(self.indent);
write!(self.line, "{}.", n)?;
*n += 1;
}
// Unordered list.
None => {
self.push_indent(self.indent);
self.push_to_line("o ")
}
}
self.indent += 3;
suppress_paragraph = true;
}
Tag::FootnoteDefinition(_label) => unimplemented!(),
Tag::Table(alignment) => {
assert!(self.table.alignment.is_empty());
self.flush();
self.table.alignment.extend(alignment);
let table = self.table.process(&mut self.parser, self.indent)?;
self.output.push_str(&table);
self.hard_break();
self.table = Table::new();
}
Tag::TableHead | Tag::TableRow | Tag::TableCell => {
bail!("unexpected table element")
}
Tag::Emphasis => {}
Tag::Strong => {}
// Strikethrough isn't usually supported for TTY.
Tag::Strikethrough => self.word.push_str("~~"),
Tag::Link(link_type, dest_url, _title) => {
if dest_url.starts_with('#') {
// In a man page, page-relative anchors don't
// have much meaning.
continue;
}
match link_type {
LinkType::Autolink | LinkType::Email => {
// The text is a copy of the URL, which is not needed.
match self.parser.next() {
Some((Event::Text(_), _range)) => {}
_ => bail!("expected text after autolink"),
}
}
LinkType::Inline
| LinkType::Reference
| LinkType::Collapsed
| LinkType::Shortcut => {}
// This is currently unused. This is only
// emitted with a broken link callback, but I
// felt it is too annoying to escape `[` in
// option descriptions.
LinkType::ReferenceUnknown
| LinkType::CollapsedUnknown
| LinkType::ShortcutUnknown => {
bail!(
"link with missing reference `{}` located at offset {}",
dest_url,
range.start
);
}
}
}
Tag::Image(_link_type, _dest_url, _title) => {
bail!("images are not currently supported")
}
}
}
Event::End(tag) => match &tag {
Tag::Paragraph => {
self.flush();
self.hard_break();
}
Tag::Heading(..) => {}
Tag::BlockQuote => {
self.indent -= 3;
}
Tag::CodeBlock(_kind) => {
self.hard_break();
wrap_text = true;
self.indent -= 4;
}
Tag::List(_) => {
list.pop();
}
Tag::Item => {
self.flush();
self.indent -= 3;
self.hard_break();
}
Tag::FootnoteDefinition(_label) => {}
Tag::Table(_) => {}
Tag::TableHead => {}
Tag::TableRow => {}
Tag::TableCell => {}
Tag::Emphasis => {}
Tag::Strong => {}
Tag::Strikethrough => self.word.push_str("~~"),
Tag::Link(link_type, dest_url, _title) => {
if dest_url.starts_with('#') {
continue;
}
match link_type {
LinkType::Autolink | LinkType::Email => {}
LinkType::Inline
| LinkType::Reference
| LinkType::Collapsed
| LinkType::Shortcut => self.flush_word(),
_ => {
panic!("unexpected tag {:?}", tag);
}
}
self.flush_word();
write!(self.word, "<{}>", dest_url)?;
}
Tag::Image(_link_type, _dest_url, _title) => {}
},
Event::Text(t) | Event::Code(t) => {
if wrap_text {
let chunks = split_chunks(&t);
for chunk in chunks {
if chunk == " " {
self.flush_word();
} else {
self.word.push_str(chunk);
}
}
} else {
for line in t.lines() {
self.push_indent(self.indent);
self.push_to_line(line);
self.flush();
}
}
}
Event::Html(t) => {
if t.starts_with("<![CDATA[") {
// CDATA is a special marker used for handling options.
in_cdata = true;
self.flush();
} else if in_cdata {
if t.trim().ends_with("]]>") {
in_cdata = false;
} else {
let trimmed = t.trim();
if trimmed.is_empty() {
continue;
}
if trimmed == "<br>" {
self.hard_break();
} else if trimmed.starts_with("<dt>") {
let opts = unwrap(trimmed, "<dt>", "</dt>");
self.push_indent(self.indent);
self.push_to_line(opts);
self.flush();
} else if trimmed.starts_with("<dd>") {
let mut def = String::new();
while let Some((Event::Html(t), _range)) = self.parser.next() {
if t.starts_with("</dd>") {
break;
}
def.push_str(&t);
}
let rendered =
TextRenderer::render(&def, self.url.clone(), self.indent + 4)?;
self.push_to_line(rendered.trim_end());
self.flush();
} else {
self.push_to_line(&t);
self.flush();
}
}
} else {
self.push_to_line(&t);
self.flush();
}
}
Event::FootnoteReference(_t) => {}
Event::SoftBreak => self.flush_word(),
Event::HardBreak => self.flush(),
Event::Rule => {
self.flush();
self.push_indent(self.indent);
self.push_to_line(&"_".repeat(79 - self.indent * 2));
self.flush();
}
Event::TaskListMarker(_b) => unimplemented!(),
}
}
Ok(())
}
fn flush(&mut self) {
self.flush_word();
if !self.line.is_empty() {
self.output.push_str(&self.line);
self.output.push('\n');
self.line.clear();
}
}
fn hard_break(&mut self) {
self.flush();
if !self.output.ends_with("\n\n") {
self.output.push('\n');
}
}
fn flush_word(&mut self) {
if self.word.is_empty() {
return;
}
if self.line.len() + self.word.len() >= 79 {
self.output.push_str(&self.line);
self.output.push('\n');
self.line.clear();
}
if self.line.is_empty() {
self.push_indent(self.indent);
self.line.push_str(&self.word);
} else {
self.line.push(' ');
self.line.push_str(&self.word);
}
self.word.clear();
}
fn push_indent(&mut self, indent: usize) {
for _ in 0..indent {
self.line.push(' ');
}
}
fn push_to_line(&mut self, text: &str) {
self.flush_word();
self.line.push_str(text);
}
}
/// Splits the text on whitespace.
///
/// Consecutive whitespace is collapsed to a single ' ', and is included as a
/// separate element in the result.
fn split_chunks(text: &str) -> Vec<&str> {
let mut result = Vec::new();
let mut start = 0;
while start < text.len() {
match text[start..].find(' ') {
Some(i) => {
if i != 0 {
result.push(&text[start..start + i]);
}
result.push(" ");
// Skip past whitespace.
match text[start + i..].find(|c| c != ' ') {
Some(n) => {
start = start + i + n;
}
None => {
break;
}
}
}
None => {
result.push(&text[start..]);
break;
}
}
}
result
}
struct Table {
alignment: Vec<Alignment>,
rows: Vec<Vec<String>>,
row: Vec<String>,
cell: String,
}
impl Table {
fn new() -> Table {
Table {
alignment: Vec::new(),
rows: Vec::new(),
row: Vec::new(),
cell: String::new(),
}
}
/// Processes table events and generates a text table.
fn process(&mut self, parser: &mut EventIter<'_>, indent: usize) -> Result<String, Error> {
while let Some((event, _range)) = parser.next() {
match event {
Event::Start(tag) => match tag {
Tag::TableHead
| Tag::TableRow
| Tag::TableCell
| Tag::Emphasis
| Tag::Strong => {}
Tag::Strikethrough => self.cell.push_str("~~"),
// Links not yet supported, they usually won't fit.
Tag::Link(_, _, _) => {}
_ => bail!("unexpected tag in table: {:?}", tag),
},
Event::End(tag) => match tag {
Tag::Table(_) => return self.render(indent),
Tag::TableCell => {
let cell = mem::replace(&mut self.cell, String::new());
self.row.push(cell);
}
Tag::TableHead | Tag::TableRow => {
let row = mem::replace(&mut self.row, Vec::new());
self.rows.push(row);
}
Tag::Strikethrough => self.cell.push_str("~~"),
_ => {}
},
Event::Text(t) | Event::Code(t) => {
self.cell.push_str(&t);
}
Event::Html(t) => bail!("html unsupported in tables: {:?}", t),
_ => bail!("unexpected event in table: {:?}", event),
}
}
bail!("table end not reached");
}
fn render(&self, indent: usize) -> Result<String, Error> {
// This is an extremely primitive layout routine.
// First compute the potential maximum width of each cell.
// 2 for 1 space margin on left and right.
let width_acc = vec![2; self.alignment.len()];
let mut col_widths = self
.rows
.iter()
.map(|row| row.iter().map(|cell| cell.len()))
.fold(width_acc, |mut acc, row| {
acc.iter_mut()
.zip(row)
// +3 for left/right margin and | symbol
.for_each(|(a, b)| *a = (*a).max(b + 3));
acc
});
// Shrink each column until it fits the total width, proportional to
// the columns total percent width.
let max_width = 78 - indent;
// Include total len for | characters, and +1 for final |.
let total_width = col_widths.iter().sum::<usize>() + col_widths.len() + 1;
if total_width > max_width {
let to_shrink = total_width - max_width;
// Compute percentage widths, and shrink each column based on its
// total percentage.
for width in &mut col_widths {
let percent = *width as f64 / total_width as f64;
*width -= (to_shrink as f64 * percent).ceil() as usize;
}
}
// Start rendering.
let mut result = String::new();
// Draw the horizontal line separating each row.
let mut row_line = String::new();
row_line.push_str(&" ".repeat(indent));
row_line.push('+');
let lines = col_widths
.iter()
.map(|width| "-".repeat(*width))
.collect::<Vec<_>>();
row_line.push_str(&lines.join("+"));
row_line.push('+');
row_line.push('\n');
// Draw top of the table.
result.push_str(&row_line);
// Draw each row.
for row in &self.rows {
// Word-wrap and fill each column as needed.
let filled = fill_row(row, &col_widths, &self.alignment);
// Need to transpose the cells across rows for cells that span
// multiple rows.
let height = filled.iter().map(|c| c.len()).max().unwrap();
for row_i in 0..height {
result.push_str(&" ".repeat(indent));
result.push('|');
for filled_row in &filled {
let cell = &filled_row[row_i];
result.push_str(cell);
result.push('|');
}
result.push('\n');
}
result.push_str(&row_line);
}
Ok(result)
}
}
/// Formats a row, filling cells with spaces and word-wrapping text.
///
/// Returns a vec of cells, where each cell is split into multiple lines.
fn fill_row(row: &[String], col_widths: &[usize], alignment: &[Alignment]) -> Vec<Vec<String>> {
let mut cell_lines = row
.iter()
.zip(col_widths)
.zip(alignment)
.map(|((cell, width), alignment)| fill_cell(cell, *width - 2, *alignment))
.collect::<Vec<_>>();
// Fill each cell to match the maximum vertical height of the tallest cell.
let max_lines = cell_lines.iter().map(|cell| cell.len()).max().unwrap();
for (cell, width) in cell_lines.iter_mut().zip(col_widths) {
if cell.len() < max_lines {
cell.extend(std::iter::repeat(" ".repeat(*width)).take(max_lines - cell.len()));
}
}
cell_lines
}
/// Formats a cell. Word-wraps based on width, and adjusts based on alignment.
///
/// Returns a vec of lines for the cell.
fn fill_cell(text: &str, width: usize, alignment: Alignment) -> Vec<String> {
let fill_width = |text: &str| match alignment {
Alignment::None | Alignment::Left => format!(" {:<width$} ", text, width = width),
Alignment::Center => format!(" {:^width$} ", text, width = width),
Alignment::Right => format!(" {:>width$} ", text, width = width),
};
if text.len() < width {
// No wrapping necessary, just format.
vec![fill_width(text)]
} else {
// Word-wrap the cell.
let mut result = Vec::new();
let mut line = String::new();
for word in text.split_whitespace() {
if line.len() + word.len() >= width {
// todo: word.len() > width
result.push(fill_width(&line));
line.clear();
}
if line.is_empty() {
line.push_str(word);
} else {
line.push(' ');
line.push_str(&word);
}
}
if !line.is_empty() {
result.push(fill_width(&line));
}
result
}
}