Html and Evcxr integration

Cargo.toml

@@ -12,6 +12,9 @@ keywords = ["tab", "table", "format", "pretty", "print"]
 categories = ["command-line-interface"]
 license = "BSD-3-Clause"
 edition = "2018"
+exclude = [
+    "prettytable-evcxr.png"
+]
 
 [badges]
 appveyor = { repository = "phsym/prettytable-rs", branch = "master", service = "github" }
@@ -20,6 +23,7 @@ codecov = { repository = "phsym/prettytable-rs", branch = "master", service = "g
 
 [features]
 default = ["win_crlf", "csv"]
+evcxr = []
 win_crlf = []
 
 [[bin]]

README.md

@@ -29,6 +29,7 @@ A formatted and aligned table printer library for [Rust](https://www.rust-lang.o
     * [Importing](#user-content-importing)
     * [Exporting](#user-content-exporting)
   * [Note on line endings](#user-content-note-on-line-endings)
+  * [Evcxr Integration](#evcxr-integration)
 
 ## Including
 
@@ -379,3 +380,19 @@ on any platform.
 This customization capability will probably move to Formatting API in a future release.
 
 Additional examples are provided in the documentation and in [examples](./examples/) directory.
+
+## Evcxr Integration
+
+[Evcxr][evcxr] is a Rust REPL and a [Jupyter notebook kernel][evcxr-jupyter].
+This crate integrates into Evcxr and the Jupyter notebooks using the `evcxr` feature flag, which enables native displays of tables.
+This includes support for displaying colors and various formattings.
+
+You can include prettytable as a dependency using this line:
+```
+:dep prettytable = { git = "https://github.com/phsym/prettytable-rs", package = "prettytable-rs", features = ["evcxr"] }
+```
+
+![prettytable being used in a Jupyter notebook with Evcxr Rust kernel.](./prettytable-evcxr.png)
+
+[evcxr]: https://github.com/google/evcxr/
+[evcxr-jupyter]: https://github.com/google/evcxr/blob/master/evcxr_jupyter/README.md

src/cell.rs

@@ -1,8 +1,7 @@
 //! This module contains definition of table/row cells stuff
 
 use super::format::Alignment;
-use super::utils::display_width;
-use super::utils::print_align;
+use super::utils::{display_width, print_align, HtmlEscape};
 use super::{color, Attr, Terminal};
 use std::io::{Error, Write};
 use std::string::ToString;
@@ -244,6 +243,79 @@ impl Cell {
             Err(e) => Err(term_error_to_io_error(e)),
         }
     }
+
+    /// Print the cell in HTML format to `out`.
+    pub fn print_html<T: Write + ?Sized>(&self, out: &mut T) -> Result<usize, Error> {
+        /// Convert the color to a hex value useful in CSS
+        fn color2hex(color: color::Color) -> &'static str {
+            match color {
+                color::BLACK => "#000000",
+                color::RED => "#aa0000",
+                color::GREEN => "#00aa00",
+                color::YELLOW => "#aa5500",
+                color::BLUE => "#0000aa",
+                color::MAGENTA => "#aa00aa",
+                color::CYAN => "#00aaaa",
+                color::WHITE => "#aaaaaa",
+                color::BRIGHT_BLACK => "#555555",
+                color::BRIGHT_RED => "#ff5555",
+                color::BRIGHT_GREEN => "#55ff55",
+                color::BRIGHT_YELLOW => "#ffff55",
+                color::BRIGHT_BLUE => "#5555ff",
+                color::BRIGHT_MAGENTA => "#ff55ff",
+                color::BRIGHT_CYAN => "#55ffff",
+                color::BRIGHT_WHITE => "#ffffff",
+
+                // Unknown colors, fallback to blakc
+                _ => "#000000",
+            }
+        };
+
+        let colspan = if self.hspan > 1 {
+            format!(" colspan=\"{}\"", self.hspan)
+        } else {
+            String::new()
+        };
+
+        // Process style properties like color
+        let mut styles = String::new();
+        for style in &self.style {
+            match style {
+                Attr::Bold => styles += "font-weight: bold;",
+                Attr::Italic(true) => styles += "font-style: italic;",
+                Attr::Underline(true) => styles += "text-decoration: underline;",
+                Attr::ForegroundColor(c) => {
+                    styles += "color: ";
+                    styles += color2hex(*c);
+                    styles += ";";
+                }
+                Attr::BackgroundColor(c) => {
+                    styles += "background-color: ";
+                    styles += color2hex(*c);
+                    styles += ";";
+                }
+                _ => {}
+            }
+        }
+        // Process alignment
+        match self.align {
+            Alignment::LEFT => styles += "text-align: left;",
+            Alignment::CENTER => styles += "text-align: center;",
+            Alignment::RIGHT => styles += "text-align: right;",
+        }
+
+        let content = self.content.join("<br />");
+        out.write_all(
+            format!(
+                "<td{1} style=\"{2}\">{0}</td>",
+                HtmlEscape(&content),
+                colspan,
+                styles
+            )
+            .as_bytes(),
+        )?;
+        Ok(self.hspan)
+    }
 }
 
 fn term_error_to_io_error(te: ::term::Error) -> Error {
@@ -360,6 +432,25 @@ mod tests {
         assert_eq!(out.as_string(), "由系统自动更新      ");
     }
 
+    #[test]
+    fn print_ascii_html() {
+        let ascii_cell = Cell::new("hello");
+        assert_eq!(ascii_cell.get_width(), 5);
+
+        let mut out = StringWriter::new();
+        let _ = ascii_cell.print_html(&mut out);
+        assert_eq!(out.as_string(), r#"<td style="text-align: left;">hello</td>"#);
+    }
+
+    #[test]
+    fn print_html_special_chars() {
+        let ascii_cell = Cell::new("<abc\">&'");
+
+        let mut out = StringWriter::new();
+        let _ = ascii_cell.print_html(&mut out);
+        assert_eq!(out.as_string(), r#"<td style="text-align: left;">&lt;abc&quot;&gt;&amp;&#39;</td>"#);
+    }
+
     #[test]
     fn align_left() {
         let cell = Cell::new_align("test", Alignment::LEFT);

src/evcxr.rs

@@ -0,0 +1,30 @@
+//! This modules contains traits and implementations to work within Evcxr
+
+use super::TableSlice;
+use super::utils::StringWriter;
+use std::io::Write;
+
+/// Evcxr specific output trait
+pub trait EvcxrDisplay {
+    /// Print self in one or multiple Evcxr compatile types.
+    fn evcxr_display(&self);
+}
+
+impl<'a, T> EvcxrDisplay for T
+where
+    T: AsRef<TableSlice<'a>>,
+{
+    fn evcxr_display(&self) {
+        let mut writer = StringWriter::new();
+        // Plain Text
+        let _ = writer.write_all(b"EVCXR_BEGIN_CONTENT text/plain\n");
+        let _ = self.as_ref().print(&mut writer);
+        let _ = writer.write_all(b"\nEVCXR_END_CONTENT\n");
+
+        // Html
+        let _ = writer.write_all(b"EVCXR_BEGIN_CONTENT text/html\n");
+        let _ = self.as_ref().print_html(&mut writer);
+        let _ = writer.write_all(b"\nEVCXR_END_CONTENT\n");
+        println!("{}", writer.as_string());
+    }
+}

src/lib.rs

@@ -24,6 +24,9 @@ mod utils;
 #[cfg(feature = "csv")]
 pub mod csv;
 
+#[cfg(feature = "evcxr")]
+pub mod evcxr;
+
 pub use row::Row;
 pub use cell::Cell;
 use format::{TableFormat, LinePosition, consts};
@@ -204,6 +207,28 @@ impl<'a> TableSlice<'a> {
     pub fn printstd(&self) -> usize {
         self.print_tty(false)
     }
+
+    /// Print table in HTML format to `out`.
+    pub fn print_html<T: Write + ?Sized>(&self, out: &mut T) -> Result<(), Error> {
+        // Compute column width
+        let column_num = self.get_column_num();
+        out.write_all(b"<table>")?;
+        // Print titles / table header
+        if let Some(ref t) = *self.titles {
+            out.write_all(b"<th>")?;
+            t.print_html(out, column_num)?;
+            out.write_all(b"</th>")?;
+        }
+        // Print rows
+        for r in self.rows {
+            out.write_all(b"<tr>")?;
+            r.print_html(out, column_num)?;
+            out.write_all(b"</tr>")?;
+        }
+        out.write_all(b"</table>")?;
+        out.flush()?;
+        Ok(())
+    }
 }
 
 impl<'a> IntoIterator for &'a TableSlice<'a> {
@@ -372,6 +397,10 @@ impl Table {
         self.as_ref().printstd()
     }
 
+    /// Print table in HTML format to `out`.
+    pub fn print_html<T: Write + ?Sized>(&self, out: &mut T) -> Result<(), Error> {
+        self.as_ref().print_html(out)
+    }
 }
 
 impl Index<usize> for Table {
@@ -980,4 +1009,69 @@ mod tests {
         assert_eq!(out, table.to_string().replace("\r\n","\n"));
         assert_eq!(7, table.print(&mut StringWriter::new()).unwrap());
     }
+
+    #[test]
+    fn table_html() {
+        let mut table = Table::new();
+        table.add_row(Row::new(vec![Cell::new("a"), Cell::new("bc"), Cell::new("def")]));
+        table.add_row(Row::new(vec![Cell::new("def"), Cell::new("bc"), Cell::new("a")]));
+        table.set_titles(Row::new(vec![Cell::new("t1"), Cell::new("t2"), Cell::new("t3")]));
+        let out = "\
+<table>\
+<th><td style=\"text-align: left;\">t1</td><td style=\"text-align: left;\">t2</td><td style=\"text-align: left;\">t3</td></th>\
+<tr><td style=\"text-align: left;\">a</td><td style=\"text-align: left;\">bc</td><td style=\"text-align: left;\">def</td></tr>\
+<tr><td style=\"text-align: left;\">def</td><td style=\"text-align: left;\">bc</td><td style=\"text-align: left;\">a</td></tr>\
+</table>";
+        let mut writer = StringWriter::new();
+        assert!(table.print_html(&mut writer).is_ok());
+        assert_eq!(writer.as_string().replace("\r\n", "\n"), out);
+        table.unset_titles();
+        let out = "\
+<table>\
+<tr><td style=\"text-align: left;\">a</td><td style=\"text-align: left;\">bc</td><td style=\"text-align: left;\">def</td></tr>\
+<tr><td style=\"text-align: left;\">def</td><td style=\"text-align: left;\">bc</td><td style=\"text-align: left;\">a</td></tr>\
+</table>";
+        let mut writer = StringWriter::new();
+        assert!(table.print_html(&mut writer).is_ok());
+        assert_eq!(writer.as_string().replace("\r\n", "\n"), out);
+    }
+
+    #[test]
+    fn table_html_colors() {
+        let mut table = Table::new();
+        table.add_row(Row::new(vec![
+            Cell::new("bold").style_spec("b"),
+            Cell::new("italic").style_spec("i"),
+            Cell::new("underline").style_spec("u"),
+        ]));
+        table.add_row(Row::new(vec![
+            Cell::new("left").style_spec("l"),
+            Cell::new("center").style_spec("c"),
+            Cell::new("right").style_spec("r"),
+        ]));
+        table.add_row(Row::new(vec![
+            Cell::new("red").style_spec("Fr"),
+            Cell::new("black").style_spec("Fd"),
+            Cell::new("yellow").style_spec("Fy"),
+        ]));
+        table.add_row(Row::new(vec![
+            Cell::new("bright magenta on cyan").style_spec("FMBc"),
+            Cell::new("white on bright green").style_spec("FwBG"),
+            Cell::new("default on blue").style_spec("Bb"),
+        ]));
+        table.set_titles(Row::new(vec![
+            Cell::new("span horizontal").style_spec("H3"),
+        ]));
+        let out = "\
+<table>\
+<th><td colspan=\"3\" style=\"text-align: left;\">span horizontal</td></th>\
+<tr><td style=\"font-weight: bold;text-align: left;\">bold</td><td style=\"font-style: italic;text-align: left;\">italic</td><td style=\"text-decoration: underline;text-align: left;\">underline</td></tr>\
+<tr><td style=\"text-align: left;\">left</td><td style=\"text-align: center;\">center</td><td style=\"text-align: right;\">right</td></tr>\
+<tr><td style=\"color: #aa0000;text-align: left;\">red</td><td style=\"color: #000000;text-align: left;\">black</td><td style=\"color: #aa5500;text-align: left;\">yellow</td></tr>\
+<tr><td style=\"color: #ff55ff;background-color: #00aaaa;text-align: left;\">bright magenta on cyan</td><td style=\"color: #aaaaaa;background-color: #55ff55;text-align: left;\">white on bright green</td><td style=\"background-color: #0000aa;text-align: left;\">default on blue</td></tr>\
+</table>";
+        let mut writer = StringWriter::new();
+        assert!(table.print_html(&mut writer).is_ok());
+        assert_eq!(writer.as_string().replace("\r\n", "\n"), out);
+    }
 }

src/row.rs

@@ -205,6 +205,21 @@ impl Row {
                                             -> Result<usize, Error> {
         self.__print(out, format, col_width, Cell::print_term)
     }
+
+    /// Print the row in HTML format to `out`.
+    ///
+    /// If the row is has fewer columns than `col_num`, the row is padded with empty cells.
+    pub fn print_html<T: Write + ?Sized>(&self, out: &mut T, col_num: usize) -> Result<(), Error> {
+        let mut printed_columns = 0;
+        for cell in self.iter() {
+            printed_columns += cell.print_html(out)?;
+        }
+        // Pad with empty cells, if target width is not reached
+        for _ in 0..col_num - printed_columns {
+            Cell::default().print_html(out)?;
+        }
+        Ok(())
+    }
 }
 
 impl Default for Row {

src/utils.rs

@@ -1,4 +1,5 @@
 //! Internal only utilities
+use std::fmt;
 use std::io::{Error, ErrorKind, Write};
 use std::str;
 
@@ -105,6 +106,43 @@ pub fn display_width(text: &str) -> usize {
     width - hidden
 }
 
+/// Wrapper struct which will emit the HTML-escaped version of the contained
+/// string when passed to a format string.
+pub struct HtmlEscape<'a>(pub &'a str);
+
+impl<'a> fmt::Display for HtmlEscape<'a> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        // Because the internet is always right, turns out there's not that many
+        // characters to escape: http://stackoverflow.com/questions/7381974
+        let HtmlEscape(s) = *self;
+        let pile_o_bits = s;
+        let mut last = 0;
+        for (i, ch) in s.bytes().enumerate() {
+            match ch as char {
+                '<' | '>' | '&' | '\'' | '"' => {
+                    fmt.write_str(&pile_o_bits[last.. i])?;
+                    let s = match ch as char {
+                        '>' => "&gt;",
+                        '<' => "&lt;",
+                        '&' => "&amp;",
+                        '\'' => "&#39;",
+                        '"' => "&quot;",
+                        _ => unreachable!()
+                    };
+                    fmt.write_str(s)?;
+                    last = i + 1;
+                }
+                _ => {}
+            }
+        }
+
+        if last < s.len() {
+            fmt.write_str(&pile_o_bits[last..])?;
+        }
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;