Class VtParser

java.lang.Object
org.aesh.terminal.parser.VtParser
public final class VtParser extends Object
Table-driven ANSI/VT escape sequence parser based on Paul Flo Williams' DEC-compatible parser.

The parser uses a pre-computed short[14][256] transition table where each entry encodes (action << 4) | nextState. This guarantees completeness (every byte in every state has a defined transition) and correctness (matches DEC VT220-VT525 observable behavior).

Deviations from Williams:

  • Colon (0x3A) is treated as a subparameter separator in CSI/DCS sequences, not as an error. This is required for SGR extended color sequences (38:2:R:G:B).
  • BEL (0x07) terminates OSC strings (xterm convention).

Usage: 

VtParser parser = new VtParser(new VtHandler() {
    public void csiDispatch(int finalChar, int[] params, int paramCount,
            int[] intermediates, int intermediateCount,
            boolean hasSubParams) {
        // handle CSI sequence
    }
    // ... other callbacks
});
parser.advance(bytes, 0, length);
See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    VtParser(VtHandler handler)
    Creates a new parser with the given handler.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    advance(byte[] data, int offset, int length)
    Advances the parser with a block of input bytes.
    void
    advance(int b)
    Advances the parser with a single byte or code point.
    void
    advance(int[] codePoints, int offset, int length)
    Advances the parser with a block of code points.
    void
    reset()
    Resets the parser to ground state.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • VtParser

      public VtParser(VtHandler handler)
      Creates a new parser with the given handler.
      Parameters:
      handler - the callback handler for parsed sequences

  • Method Details

    • advance

      public void advance(byte[] data, int offset, int length)
      Advances the parser with a block of input bytes.
      Parameters:
      data - the input bytes
      offset - the start offset
      length - the number of bytes to process

    • advance

      public void advance(int[] codePoints, int offset, int length)
      Advances the parser with a block of code points. Code points > 255 are treated as printable characters in the ground state and as ignored characters in other states.
      Parameters:
      codePoints - the input code points
      offset - the start offset
      length - the number of code points to process

    • advance

      public void advance(int b)
      Advances the parser with a single byte or code point. Values 0-255 use the transition table directly. Values > 255 are treated as printable in ground state, ignored otherwise.
      Parameters:
      b - the byte (0-255) or code point (> 255)

    • reset

      public void reset()
      Resets the parser to ground state.