ansi: Designate and invoke graphic character sets

Implement the designation of graphic character sets G0-G3 to ASCII or the
Special character and line drawing glyphs. As well as the invokation/selection
of the character sets (shift in, shift out and lock shifting).

2 files changed, 236 insertions, 8 deletions

diff --git a/src/ansi.rs b/src/ansi.rs
index 81a48987..4f45fd62 100644
--- a/src/ansi.rs
+++ b/src/ansi.rs
@@ -238,6 +238,18 @@ pub trait Handler {
 
     /// DECKPNM - Set keypad to numeric mode (digits intead of ESCape seq)
     fn unset_keypad_application_mode(&mut self) {}
+
+    /// Set one of the graphic character sets, G0 to G3, as the active charset.
+    ///
+    /// 'Invoke' one of G0 to G3 in the GL area. Also refered to as shift in,
+    /// shift out and locking shift depending on the set being activated
+    fn set_active_charset(&mut self, CharsetIndex) {}
+
+    /// Assign a graphic character set to G0, G1, G2 or G3
+    ///
+    /// 'Designate' a graphic character set as one of G0 to G3, so that it can
+    /// later be 'invoked' by `set_active_charset`
+    fn configure_charset(&mut self, CharsetIndex, StandardCharset) {}
 }
 
 /// Terminal modes
@@ -436,6 +448,23 @@ pub enum Attr {
     Background(Color),
 }
 
+/// Identifiers which can be assigned to a graphic character set
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum CharsetIndex {
+    /// Default set, is designated as ASCII at startup
+    G0,
+    G1,
+    G2,
+    G3,
+}
+
+/// Standard or common character sets which can be designated as G0-G3
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum StandardCharset {
+    Ascii,
+    SpecialCharacterAndLineDrawing,
+}
+
 impl<'a, H, W> vte::Perform for Performer<'a, H, W>
     where H: Handler + TermInfo + 'a,
           W: io::Write + 'a
@@ -454,6 +483,8 @@ impl<'a, H, W> vte::Perform for Performer<'a, H, W>
             C0::LF | C0::VT | C0::FF => self.handler.linefeed(),
             C0::BEL => self.handler.bell(),
             C0::SUB => self.handler.substitute(),
+            C0::SI => self.handler.set_active_charset(CharsetIndex::G0),
+            C0::SO => self.handler.set_active_charset(CharsetIndex::G1),
             C1::NEL => self.handler.newline(),
             C1::HTS => self.handler.set_horizontal_tabstop(),
             C1::DECID => self.handler.identify_terminal(self.writer),
@@ -742,19 +773,41 @@ impl<'a, H, W> vte::Perform for Performer<'a, H, W>
         _ignore: bool,
         byte: u8
     ) {
+        macro_rules! unhandled {
+            () => {{
+                err_println!("[unhandled] esc_dispatch params={:?}, ints={:?}, byte={:?} ({:02x})",
+                             params, intermediates, byte as char, byte);
+                return;
+            }}
+        }
+
+        macro_rules! configure_charset {
+            ($charset:path) => {{
+                let index: CharsetIndex = match intermediates.first().cloned() {
+                    Some(b'(') => CharsetIndex::G0,
+                    Some(b')') => CharsetIndex::G1,
+                    Some(b'*') => CharsetIndex::G2,
+                    Some(b'+') => CharsetIndex::G3,
+                    _ => unhandled!(),
+                };
+                self.handler.configure_charset(index, $charset)
+            }}
+        }
+
         match byte {
+            b'B' => configure_charset!(StandardCharset::Ascii),
             b'D' => self.handler.linefeed(),
             b'E' => self.handler.newline(),
             b'H' => self.handler.set_horizontal_tabstop(),
             b'M' => self.handler.reverse_index(),
             b'Z' => self.handler.identify_terminal(self.writer),
             b'c' => self.handler.reset_state(),
+            b'0' => configure_charset!(StandardCharset::SpecialCharacterAndLineDrawing),
             b'7' => self.handler.save_cursor_position(),
             b'8' => self.handler.restore_cursor_position(),
             b'=' => self.handler.set_keypad_application_mode(),
             b'>' => self.handler.unset_keypad_application_mode(),
-            _ => err_println!("[unhandled] esc_dispatch params={:?}, ints={:?}, byte={:?} ({:02x})",
-                              params, intermediates, byte as char, byte),
+            _ => unhandled!(),
         }
     }
 }
@@ -969,7 +1022,7 @@ pub mod C1 {
 mod tests {
     use std::io;
     use index::{Line, Column};
-    use super::{Processor, Handler, Attr, TermInfo, Color};
+    use super::{Processor, Handler, Attr, TermInfo, Color, StandardCharset, CharsetIndex};
     use ::Rgb;
 
     /// The /dev/null of io::Write
@@ -1074,4 +1127,67 @@ mod tests {
             parser.advance(&mut handler, *byte, &mut Void);
         }
     }
+
+    struct CharsetHandler {
+        index: CharsetIndex,
+        charset: StandardCharset,
+    }
+
+    impl Default for CharsetHandler {
+        fn default() -> CharsetHandler {
+            CharsetHandler {
+                index: CharsetIndex::G0,
+                charset: StandardCharset::Ascii,
+            }
+        }
+    }
+
+    impl Handler for CharsetHandler {
+        fn configure_charset(&mut self, index: CharsetIndex, charset: StandardCharset) {
+            self.index = index;
+            self.charset = charset;
+        }
+
+        fn set_active_charset(&mut self, index: CharsetIndex) {
+            self.index = index;
+        }
+    }
+
+    impl TermInfo for CharsetHandler {
+        fn lines(&self) -> Line { Line(200) }
+        fn cols(&self) -> Column { Column(90) }
+    }
+
+    #[test]
+    fn parse_designate_g0_as_line_drawing() {
+        static BYTES: &'static [u8] = &[0x1b, b'(', b'0'];
+        let mut parser = Processor::new();
+        let mut handler = CharsetHandler::default();
+
+        for byte in &BYTES[..] {
+            parser.advance(&mut handler, *byte, &mut Void);
+        }
+
+        assert_eq!(handler.index, CharsetIndex::G0);
+        assert_eq!(handler.charset, StandardCharset::SpecialCharacterAndLineDrawing);
+    }
+
+    #[test]
+    fn parse_designate_g1_as_line_drawing_and_invoke() {
+        static BYTES: &'static [u8] = &[0x1b, 0x29, 0x30, 0x0e];
+        let mut parser = Processor::new();
+        let mut handler = CharsetHandler::default();
+
+        for byte in &BYTES[..3] {
+            parser.advance(&mut handler, *byte, &mut Void);
+        }
+
+        assert_eq!(handler.index, CharsetIndex::G1);
+        assert_eq!(handler.charset, StandardCharset::SpecialCharacterAndLineDrawing);
+
+        let mut handler = CharsetHandler::default();
+        parser.advance(&mut handler, BYTES[3], &mut Void);
+
+        assert_eq!(handler.index, CharsetIndex::G1);
+    }
 }
diff --git a/src/term/mod.rs b/src/term/mod.rs
index bb0bbc1b..45ce12e0 100644
--- a/src/term/mod.rs
+++ b/src/term/mod.rs
@@ -13,12 +13,12 @@
 // limitations under the License.
 //
 //! Exports the `Term` type which is a high-level API for the Grid
-use std::ops::{Deref, Range};
+use std::ops::{Deref, Range, Index, IndexMut};
 use std::ptr;
 use std::cmp::min;
 use std::io;
 
-use ansi::{self, Color, NamedColor, Attr, Handler};
+use ansi::{self, Color, NamedColor, Attr, Handler, CharsetIndex, StandardCharset};
 use grid::{Grid, ClearRegion, ToRange};
 use index::{self, Point, Column, Line, Linear, IndexRange, Contains, RangeInclusive};
 use selection::{Span, Selection};
@@ -200,6 +200,79 @@ pub use self::mode::TermMode;
 
 pub const TAB_SPACES: usize = 8;
 
+trait CharsetMapping {
+    fn map(&self, c: char) -> char {
+        c
+    }
+}
+
+impl CharsetMapping for StandardCharset {
+    /// Switch/Map character to the active charset. Ascii is the common case and
+    /// for that we want to do as little as possible.
+    #[inline]
+    fn map(&self, c: char) -> char {
+        match *self {
+            StandardCharset::Ascii => c,
+            StandardCharset::SpecialCharacterAndLineDrawing =>
+                match c {
+                    '`' => '◆',
+                    'a' => '▒',
+                    'b' => '\t',
+                    'c' => '\u{000c}',
+                    'd' => '\r',
+                    'e' => '\n',
+                    'f' => '°',
+                    'g' => '±',
+                    'h' => '\u{2424}',
+                    'i' => '\u{000b}',
+                    'j' => '┘',
+                    'k' => '┐',
+                    'l' => '┌',
+                    'm' => '└',
+                    'n' => '┼',
+                    'o' => '⎺',
+                    'p' => '⎻',
+                    'q' => '─',
+                    'r' => '⎼',
+                    's' => '⎽',
+                    't' => '├',
+                    'u' => '┤',
+                    'v' => '┴',
+                    'w' => '┬',
+                    'x' => '│',
+                    'y' => '≤',
+                    'z' => '≥',
+                    '{' => 'π',
+                    '|' => '≠',
+                    '}' => '£',
+                    '~' => '·',
+                    _ => c
+                },
+        }
+    }
+}
+
+struct Charsets([StandardCharset; 4]);
+
+impl Charsets {
+    fn new() -> Charsets {
+        Charsets([StandardCharset::Ascii; 4])
+    }
+}
+
+impl Index<CharsetIndex> for Charsets {
+    type Output = StandardCharset;
+    fn index(&self, index: CharsetIndex) -> &StandardCharset {
+        &self.0[index as usize]
+    }
+}
+
+impl IndexMut<CharsetIndex> for Charsets {
+    fn index_mut(&mut self, index: CharsetIndex) -> &mut StandardCharset {
+        &mut self.0[index as usize]
+    }
+}
+
 pub struct Term {
     /// The grid
     grid: Grid<Cell>,
@@ -228,6 +301,13 @@ pub struct Term {
     /// Alt cursor
     alt_cursor: Point,
 
+    /// Currently configured graphic character sets
+    charsets: Charsets,
+
+    /// The graphic character set, out of `charsets`, which ASCII is currently
+    /// being mapped to
+    active_charset: CharsetIndex,
+
     /// Tabstops
     tabs: Vec<bool>,
 
@@ -323,6 +403,8 @@ impl Term {
             alt: false,
             cursor: Point::default(),
             alt_cursor: Point::default(),
+            active_charset: CharsetIndex::G0,
+            charsets: Charsets::new(),
             tabs: tabs,
             mode: Default::default(),
             scroll_region: scroll_region,
@@ -695,7 +777,7 @@ impl ansi::Handler for Term {
         {
             let cell = &mut self.grid[&self.cursor];
             *cell = self.template_cell;
-            cell.c = c;
+            cell.c = self.charsets[self.active_charset].map(c);
         }
 
         if (self.cursor.col + 1) < self.grid.num_cols() {
@@ -1109,6 +1191,18 @@ impl ansi::Handler for Term {
         debug_println!("unset mode::APP_KEYPAD");
         self.mode.remove(mode::APP_KEYPAD);
     }
+
+    #[inline]
+    fn configure_charset(&mut self, index: CharsetIndex, charset: StandardCharset) {
+        debug_println!("designate {:?} character set as {:?}", index, charset);
+        self.charsets[index] = charset;
+    }
+
+    #[inline]
+    fn set_active_charset(&mut self, index: CharsetIndex) {
+        debug_println!("Activate {:?} character set", index);
+        self.active_charset = index;
+    }
 }
 
 #[cfg(test)]
@@ -1116,11 +1210,12 @@ mod tests {
     extern crate serde_json;
     extern crate test;
 
-    use super::limit;
+    use super::{Term, limit, SizeInfo};
 
     use grid::Grid;
-    use index::{Line, Column};
+    use index::{Point, Line, Column};
     use term::{Cell};
+    use ansi::{Handler, CharsetIndex, StandardCharset};
 
     /// Check that the grid can be serialized back and forth losslessly
     ///
@@ -1144,6 +1239,23 @@ mod tests {
         assert_eq!(limit(5, 6, 10), 6);
         assert_eq!(limit(5, 1, 4), 4);
     }
+
+    #[test]
+    fn input_line_drawing_character() {
+        let size = SizeInfo {
+            width: 21.0,
+            height: 51.0,
+            cell_width: 3.0,
+            cell_height: 3.0,
+        };
+        let mut term = Term::new(size);
+        let cursor = Point::new(Line(0), Column(0));
+        term.configure_charset(CharsetIndex::G0,
+                               StandardCharset::SpecialCharacterAndLineDrawing);
+        term.input('a');
+
+        assert_eq!(term.grid()[&cursor].c, '▒');
+    }
 }
 
 #[cfg(test)]