support typed array in parser

[jerch]

This PR moves the parser to typed array support instead of JS strings.
Changes the internal API for the parse method, the print handler and the DCS handler.

Parser speedup: runtime from 120 ms down to 45 ms (ls -lR /use/lib)

With a later change of the BufferLine API this enables the possibility to completely remove any string processing from InputHandler.print, which will give the input chain another nice speedup (>50%). This is not possible until we removed the JSArray variant of BufferLine.
It also opens the possibility to evaluate other array buffer based input encodings later on.

Part of #791.

[Tyriar]

A very impressive freak out happens when you open vim:

[jerch]

@Tyriar At least it runs fast 😊

[jerch]

@Tyriar Should be fixed now, problem was that I mixed up the input data array with the result concat array.

[Tyriar]

LGTM after the String.fromCharCode.apply change is done. I think we should hold off on this until 3.9.0 goes out as it hasn't had any real testing yet.

[jerch]

@Tyriar Yeah we can hold it back, also it will not show its real potential until we switched over to typed array only buffer.

[jerch]

I think we should hold this back until 3.11, it does not make much sense with the JS Array based buffer lines.

[Tyriar]

@jerch sounds good, try to periodically merge in changes so the branches don't diverge too much

[jerch]

Part one - the transition to UTF32 parser buffer is done. Here are some speed numbers from xterm-benchmark:

• master

   Context "lib/xterm_perfcases/parser.js"
      Context "Parser performance - 50MB data"
         Context "print - a"
            Case "throughput" : 1 - throughput: 52.04 MB/s
            Case "throughput" : 2 - throughput: 53.34 MB/s
            Case "throughput" : 3 - throughput: 53.04 MB/s
         Context "execute - \n"
            Case "throughput" : 1 - throughput: 39.98 MB/s
            Case "throughput" : 2 - throughput: 43.69 MB/s
            Case "throughput" : 3 - throughput: 44.55 MB/s
         Context "escape - ESC E"
            Case "throughput" : 1 - throughput: 29.48 MB/s
            Case "throughput" : 2 - throughput: 35.94 MB/s
            Case "throughput" : 3 - throughput: 36.81 MB/s
         Context "escape with collect - ESC % G"
            Case "throughput" : 1 - throughput: 11.70 MB/s
            Case "throughput" : 2 - throughput: 13.80 MB/s
            Case "throughput" : 3 - throughput: 13.88 MB/s
         Context "simple csi - CSI A"
            Case "throughput" : 1 - throughput: 28.55 MB/s
            Case "throughput" : 2 - throughput: 34.29 MB/s
            Case "throughput" : 3 - throughput: 34.54 MB/s
         Context "csi with collect - CSI ? p"
            Case "throughput" : 1 - throughput: 31.80 MB/s
            Case "throughput" : 2 - throughput: 37.38 MB/s
            Case "throughput" : 3 - throughput: 37.95 MB/s
         Context "csi with params - CSI 1;2 m"
            Case "throughput" : 1 - throughput: 41.37 MB/s
            Case "throughput" : 2 - throughput: 54.89 MB/s
            Case "throughput" : 3 - throughput: 56.10 MB/s
         Context "osc - OSC 0;hi ST"
            Case "throughput" : 1 - throughput: 27.59 MB/s
            Case "throughput" : 2 - throughput: 28.94 MB/s
            Case "throughput" : 3 - throughput: 29.04 MB/s

• UTF32 typed array

   Context "lib/xterm_perfcases/parser_typedarray.js"
      Context "Parser performance - 50MB data"
         Context "print - a"
            Case "throughput" : 1 - throughput: 340.81 MB/s
            Case "throughput" : 2 - throughput: 413.12 MB/s
            Case "throughput" : 3 - throughput: 447.50 MB/s
         Context "execute - \n"
            Case "throughput" : 1 - throughput: 70.81 MB/s
            Case "throughput" : 2 - throughput: 84.29 MB/s
            Case "throughput" : 3 - throughput: 84.04 MB/s
         Context "escape - ESC E"
            Case "throughput" : 1 - throughput: 47.19 MB/s
            Case "throughput" : 2 - throughput: 55.65 MB/s
            Case "throughput" : 3 - throughput: 55.97 MB/s
         Context "escape with collect - ESC % G"
            Case "throughput" : 1 - throughput: 14.79 MB/s
            Case "throughput" : 2 - throughput: 15.33 MB/s
            Case "throughput" : 3 - throughput: 15.49 MB/s
         Context "simple csi - CSI A"
            Case "throughput" : 1 - throughput: 31.11 MB/s
            Case "throughput" : 2 - throughput: 39.01 MB/s
            Case "throughput" : 3 - throughput: 38.56 MB/s
         Context "csi with collect - CSI ? p"
            Case "throughput" : 1 - throughput: 43.34 MB/s
            Case "throughput" : 2 - throughput: 51.73 MB/s
            Case "throughput" : 3 - throughput: 51.43 MB/s
         Context "csi with params - CSI 1;2 m"
            Case "throughput" : 1 - throughput: 66.76 MB/s
            Case "throughput" : 2 - throughput: 111.24 MB/s
            Case "throughput" : 3 - throughput: 112.88 MB/s
         Context "osc - OSC 0;hi ST"
            Case "throughput" : 1 - throughput: 39.81 MB/s
            Case "throughput" : 2 - throughput: 43.46 MB/s
            Case "throughput" : 3 - throughput: 43.33 MB/s

Almost every testcase doubles the throughput rate, PRINT is even 8 times faster. The lame ducks are those sequences that do an interim string conversion, esp. ESC % G, which uses '%G' for a property lookup, seems multi char strings are not any good as property keys?

Up for review.

Next steps (in separate PRs):

• apply 32 bit layout as discussed in Buffer performance improvements #791 to terminal buffer
• add UTF8 input support

[jerch]

@Tyriar Did some more cleanup, ready for review.

[Tyriar]

Onwards!