Add support for custom parsing of APC, SOS and PM sequences.

src/definitions.rs

@@ -19,7 +19,7 @@ pub enum State {
     #[default]
     Ground = 12,
     OscString = 13,
-    SosPmApcString = 14,
+    OpaqueString = 14,
     Utf8 = 15,
 }
 
@@ -28,21 +28,34 @@ pub enum State {
 #[derive(Debug, Clone, Copy)]
 pub enum Action {
     None = 0,
-    Clear = 1,
-    Collect = 2,
-    CsiDispatch = 3,
-    EscDispatch = 4,
-    Execute = 5,
-    Hook = 6,
-    Ignore = 7,
-    OscEnd = 8,
-    OscPut = 9,
-    OscStart = 10,
-    Param = 11,
-    Print = 12,
-    Put = 13,
-    Unhook = 14,
-    BeginUtf8 = 15,
+    Collect = 1,
+    CsiDispatch = 2,
+    EscDispatch = 3,
+    Execute = 4,
+    Ignore = 5,
+    OscPut = 6,
+    Param = 7,
+    Print = 8,
+    Put = 9,
+    BeginUtf8 = 10,
+    OpaquePut = 11,
+
+    // Actions that do not need to be packed as 4 bits in the state table
+    // Can have values higher than 16
+    Clear = 16,
+    Hook = 17,
+    Unhook = 18,
+    OscStart = 19,
+    OscEnd = 20,
+    OpaqueStart = 21,
+    OpaqueEnd = 22,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum OpaqueSequenceKind {
+    Sos,
+    Pm,
+    Apc,
 }
 
 /// Unpack a u8 into a State and Action
@@ -75,8 +88,8 @@ mod tests {
 
     #[test]
     fn unpack_state_action() {
-        match unpack(0xee) {
-            (State::SosPmApcString, Action::Unhook) => (),
+        match unpack(0xaa) {
+            (State::Escape, Action::BeginUtf8) => (),
             _ => panic!("unpack failed"),
         }
 
@@ -85,27 +98,16 @@ mod tests {
             _ => panic!("unpack failed"),
         }
 
-        match unpack(0xff) {
-            (State::Utf8, Action::BeginUtf8) => (),
+        match unpack(0xbf) {
+            (State::Utf8, Action::OpaquePut) => (),
             _ => panic!("unpack failed"),
         }
     }
 
     #[test]
     fn pack_state_action() {
-        match unpack(0xee) {
-            (State::SosPmApcString, Action::Unhook) => (),
-            _ => panic!("unpack failed"),
-        }
-
-        match unpack(0x0f) {
-            (State::Utf8, Action::None) => (),
-            _ => panic!("unpack failed"),
-        }
-
-        match unpack(0xff) {
-            (State::Utf8, Action::BeginUtf8) => (),
-            _ => panic!("unpack failed"),
-        }
+        assert_eq!(pack(State::Escape, Action::BeginUtf8), 0xaa);
+        assert_eq!(pack(State::Utf8, Action::None), 0x0f);
+        assert_eq!(pack(State::Utf8, Action::OpaquePut), 0xbf);
     }
 }

src/lib.rs

@@ -49,6 +49,7 @@ pub mod ansi;
 pub use params::{Params, ParamsIter};
 
 use definitions::{unpack, Action, State};
+use crate::definitions::OpaqueSequenceKind;
 
 const MAX_INTERMEDIATES: usize = 2;
 const MAX_OSC_PARAMS: usize = 16;
@@ -187,6 +188,9 @@ impl<const OSC_RAW_BUF_SIZE: usize> Parser<OSC_RAW_BUF_SIZE> {
                     State::OscString => {
                         self.perform_action(performer, Action::OscEnd, byte);
                     },
+                    State::OpaqueString => {
+                        self.perform_action(performer, Action::OpaqueEnd, byte);
+                    },
                     _ => (),
                 }
 
@@ -202,6 +206,9 @@ impl<const OSC_RAW_BUF_SIZE: usize> Parser<OSC_RAW_BUF_SIZE> {
                     State::OscString => {
                         self.perform_action(performer, Action::OscStart, byte);
                     },
+                    State::OpaqueString => {
+                        self.perform_action(performer, Action::OpaqueStart, byte);
+                    },
                     _ => (),
                 }
 
@@ -364,6 +371,28 @@ impl<const OSC_RAW_BUF_SIZE: usize> Parser<OSC_RAW_BUF_SIZE> {
             Action::BeginUtf8 => self.process_utf8(performer, byte),
             Action::Ignore => (),
             Action::None => (),
+
+            // APC Actions are checked last, since they are relatively rare
+            Action::OpaqueStart => {
+                let kind = match byte {
+                    0x58 => OpaqueSequenceKind::Sos,
+                    0x5e => OpaqueSequenceKind::Pm,
+                    0x5f => OpaqueSequenceKind::Apc,
+
+                    // Changes to OpaqueString state which trigger this action are only possible
+                    // when one of the escape sequences above is detected (see Escape state changes
+                    // in table.rs). Since there is no other way to reach this action with any other
+                    // byte value, this branch is unreachable.
+                    _ => unreachable!("invalid opaque sequence kind"),
+                };
+                performer.opaque_start(kind)
+            },
+            Action::OpaquePut => {
+                performer.opaque_put(byte)
+            }
+            Action::OpaqueEnd => {
+                performer.opaque_end()
+            },
         }
     }
 }
@@ -428,6 +457,20 @@ pub trait Perform {
     /// The `ignore` flag indicates that more than two intermediates arrived and
     /// subsequent characters were ignored.
     fn esc_dispatch(&mut self, _intermediates: &[u8], _ignore: bool, _byte: u8) {}
+
+    /// The start of an opaque sequence (SOS, PM or APC) has been detected.
+    ///
+    /// The `kind` parameter indicates the type of sequence that was started.
+    ///
+    /// Until the opaque sequence ends (at which point `opaque_end` will be called), invalid
+    /// characters will be ignored while valid characters will be passed on to `opaque_put`.
+    fn opaque_start(&mut self, _kind: OpaqueSequenceKind) {}
+
+    /// We've reached the end of the ongoing opaque sequence (SOS, PM or APC).
+    fn opaque_end(&mut self) {}
+
+    /// A byte has been received as part of an ongoing opaque sequence.
+    fn opaque_put(&mut self, _byte: u8) {}
 }
 
 #[cfg(all(test, feature = "no_std"))]
@@ -460,6 +503,9 @@ mod tests {
         DcsHook(Vec<Vec<u16>>, Vec<u8>, bool, char),
         DcsPut(u8),
         DcsUnhook,
+        OpaqueStart(OpaqueSequenceKind),
+        OpaquePut(u8),
+        OpaqueEnd,
     }
 
     impl Perform for Dispatcher {
@@ -492,6 +538,18 @@ mod tests {
         fn unhook(&mut self) {
             self.dispatched.push(Sequence::DcsUnhook);
         }
+
+        fn opaque_start(&mut self, _kind: OpaqueSequenceKind) {
+            self.dispatched.push(Sequence::OpaqueStart(_kind));
+        }
+
+        fn opaque_put(&mut self, byte: u8) {
+            self.dispatched.push(Sequence::OpaquePut(byte));
+        }
+
+        fn opaque_end(&mut self) {
+            self.dispatched.push(Sequence::OpaqueEnd);
+        }
     }
 
     #[test]
@@ -628,6 +686,31 @@ mod tests {
         }
     }
 
+    #[test]
+    fn parse_apc() {
+        const INPUT: &[u8] = b"\x1b_abc\x1b\\";
+
+        // Test with ESC \ terminator.
+
+        let mut dispatcher = Dispatcher::default();
+        let mut parser = Parser::new();
+
+        for byte in INPUT {
+            parser.advance(&mut dispatcher, *byte);
+        }
+        assert_eq!(dispatcher.dispatched.len(), 6);
+        assert_eq!(
+            dispatcher.dispatched[0..5],
+            vec![
+                Sequence::OpaqueStart(OpaqueSequenceKind::Apc),
+                Sequence::OpaquePut(b'a'),
+                Sequence::OpaquePut(b'b'),
+                Sequence::OpaquePut(b'c'),
+                Sequence::OpaqueEnd,
+            ]
+        )
+    }
+
     #[test]
     fn exceed_max_buffer_size() {
         static NUM_BYTES: usize = MAX_OSC_RAW + 100;

src/table.rs

@@ -44,9 +44,9 @@ generate_state_changes!(state_changes, {
         0x5b        => (CsiEntry, None),
         0x5d        => (OscString, None),
         0x50        => (DcsEntry, None),
-        0x58        => (SosPmApcString, None),
-        0x5e        => (SosPmApcString, None),
-        0x5f        => (SosPmApcString, None),
+        0x58        => (OpaqueString, None),
+        0x5e        => (OpaqueString, None),
+        0x5f        => (OpaqueString, None),
     },
 
     EscapeIntermediate {
@@ -152,11 +152,11 @@ generate_state_changes!(state_changes, {
         0x9c        => (Ground, None),
     },
 
-    SosPmApcString {
+    OpaqueString {
         0x00..=0x17 => (Anywhere, Ignore),
         0x19        => (Anywhere, Ignore),
         0x1c..=0x1f => (Anywhere, Ignore),
-        0x20..=0x7f => (Anywhere, Ignore),
+        0x20..=0x7f => (Anywhere, OpaquePut),
         0x9c        => (Ground, None),
     },