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Can Boost spirit handle Postscript / PDF as languages?

I noticed that the Boost spirit offers some limitations, in the question here on SO, there is a user asking for help in improving the spirit, and another user who answered said that boost spirit works well with statements, and not with "general the text "" (Sorry if I do not remember it correctly).

Now I would like to think about Postscript and PDF in terms of tokens and simplify my approach to these formats in this way, the problem is that PDF is a kind of combination of a markup language and a programming language with jumps and tables in it, and I can’t think of what something like that, considering the most popular file formats such as XML, C ++ code and other languages ​​and formats.

There is one more fact: I can’t find people who have had any experience with boost :: spirit wiriting in the parser or pdf writer, so I ask if boost :: spirit is able to parse a PDF file and output elements as tokens?

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While this has nothing to do with Boost, let me assure you that parsing PDF (and PostScript) is about as trivial as you might want. Let's say you have a scanner object that returns a series of tokens. Types of tokens you will receive from the scanner:

  • Line
  • Dict begin (<<)
  • Dict End (→)
  • Name (/ whatever)
  • amount
  • Hex array
  • Left corner (<)
  • Right corner (>)
  • The beginning of the array ([)
  • Massive End (])
  • Start of procedure ({)
  • The end of the procedure (})
  • (% foo)

- , , , , , DictEnd Done.

, PDF, , . , "" ( #):

while (true) {
    MLPdfToken = scanner.GetToken();
    if (token == null)
        return MachineExit.EndOfFile;
    PdfObject obj = PdfObject.FromToken(token);
    PdfProcedure proc = obj as PdfProcedure;

    if (proc != null)
    {
        if (IsExecuting())
        {
            if (token.Type == PdfTokenType.RBrace)
                proc.Execute(this);
            else
                Push(obj);
        }
        else {
            proc.Execute(this);
        }
        if (proc.IsTerminal)
            return Machine.ParseComplete;
    }
    else {
        Push(obj);
    }
}

, PdfObject Execute(), machine.Push(this) IsTerminal, false, REPL :

while (true) {
    MLPdfToken = scanner.GetToken();
    if (token == null)
        return MachineExit.EndOfFile;
    PdfObject obj = PdfObject.FromToken(token);

    if (IsExecuting())
    {
        if (token.Type == PdfTokenType.RBrace)
           obj.Execute(this);
        else
           Push(obj);
    }
    else {
        obj.Execute(this);
        if (obj.IsTerminal)
            return Machine.ParseComplete;                
    }
}

Machine - Machine PdfObject (Push, Pop, Mark, CountToMark, Index, Dup, Swap), ExecProcBegin ExecProcEnd.

, . , , , PdfObject.FromToken , (, , , , bool), PdfObject. "proc set" , PdfProcedure. , <<, proc :

void DictBegin(PdfMachine machine)
{
    machine.Push(new PdfMark(PdfMarkType.Dictionary));
}

, << " . >> :

void DictEnd(PdfMachine machine)
{
    PdfDict dict = new PdfDict();
    // PopThroughMark pops the entire stack up to the first matching mark,
    // throws an exception if it fails.
    PdfObject[] arr = machine.PopThroughMark(PdfMarkType.Dictionary);
    if ((arr.Length & 1) != 0)
        throw new PdfException("dictionaries need an even number of objects.");
    for (int i=0; i < arr.Length; i += 2)
    {
        PdfObject key = arr[i], val = arr[i + 1];
        if (key.Type != PdfObjectType.Name)
            throw new PdfException("dictionaries need a /name for the key.");
        dict.put((PdfName)key, val);
    }
    machine.Push(dict);
}

So >> , . . -, , , .

, PDF , PostScript . , , . ( read-eval- (push) ) - '}'.

, PDF 14 0 obj << /Type /Annot /SubType /Square >> endobj, , , - :

  • Push 14
  • 0
  • obj ( " " ).
  • Push/Type
  • Push/Annot
  • Push/SubType
  • Push/Square
  • endobj ( , ( ) . - , "" , ).

"endobj" , .

, 14 PDF, , , . , .

, , PDF, :

<< [/key value]* >> stream ...raw data... endstream endobj

, . stream , PdfDict. , ( ), , dict ( , ) . endstream - -op. PdfDict PdfStream , PdfStream bool, , , .

PostScript , , . , : , . , exec, PS.

, ++, , , , , , , , , ++.

PDF- .NET, Acrobat 1-4, , , , Acrobat (, - C, ++, ).

xref ( xref), - , EOF , xref. ( CS 101), , /Prev, , , /Prev . xref .

- , . , , , xref. , , . , (.. 14 0 R). , , xref, <objnum> <generation> obj <object contents> endobj. , :

public override ToStream(PdfStreamingContext context)
{
    if (context.HasReference(this)) // is object referenced in xref
    {
        PdfUtils.WriteObjectDefinitionBegin(this, context);
    }
    context.Writer.Indent();
    context.Writer.WriteLine("<<");
    WriteContents(context);
    context.Writer.Exdent();
    context.Writer.Writeline(">>");
    if (context.HasReference(this))
    {
        PdfUtils.WriteObjectDefinitionEnd(this, context);
    }
}

, . - , xref, , , , ..

, , , . , : " , Acrobat ? , , , PDF , 't spec compliant Acrobat . , , . , , , - , , -. PDF PDF .

(, , ) , . , .

tl; dr. PDF, . , , REPL.

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