Xterm.js: Improve search addon API

[Tyriar]

The find API introduced in #704 can be expanded upon in the future to support:

• Using a different selection type so that multiple instances can be highlighted at once
• Find multiple instances on the same line
• Find terms that are wrapped across 2 lines
• Options: regex, case sensitivity, etc.
• Return the number of results (may impact performance)
• Allow "find as you type", allowing the current selection to be expanded if it matches

[mofux]

It would also be great to have an api that gets the total number of matched instances, and the index of the currently active instance, as well as a mechanism to get notified when the total number or active index changes. This would allow a consumer to draw a find UI and provide some more info to the user.

[Tyriar]

@mofux this was one of the first thoughts I had, I left it out due to performance concerns as it's not the most efficient thing to convert a large buffer into searchable strings as each individual character is stored within it's own array. The buffer is basically structured like this: [number, string, number][][] so you need to iterate through the lines and then construct a string out of the line.

Definitely worth exploring later on whether my guesses around this are true though 👍. I added it to the list 😃

[mofux]

@Tyriar Interesting to see that a modern terminal emulator shares so many problems with code editors like ace or monaco, like line buffers, selection models, find api, tokenization. Actually, I remember that the cloud9 terminal does all the rendering through the Ace editor 😉

[Tyriar]

@mofux yeah it's been useful to have people who work on monaco to ask about things. A lot of stuff poses similar problems. The fact that the buffer is continuously trimmed and that it's common to run a command that get a crazy amount of data streamed in are biggest unique parts.

[FGasper]

It would be nice to have a browser-style “find-as-you-type” logic. I think it would work if a couple functions were added:

• findCurrentOrNext(needle)
• findCurrentOrPrevious(needle)

These would expand the current selection if the needle is present at the 0-index of the current selection; otherwise they’d do a normal findNext or findPrevious.

Thoughts?

[Tyriar]

@FGasper yeah this sort of thing would be good, probably best tackled after this one: Find multiple instances on the same line. Added it to the list

[jerch]

Coming from #1649 I suggest to split up the functionality of the search addon into:

• search: just do something like indexOf and return a cols/rows positions, feeding this back gives the next position, as an advantage this will not need any DOM related stuff.
• mark/highlight: takes some positions and can highlight/mark it in the output, This will depend on whatever frontend is active.

[Tyriar]

Most of this is done, let's track the rest in individual items: https://github.com/xtermjs/xterm.js/issues/1653, https://github.com/xtermjs/xterm.js/issues/1654, https://github.com/xtermjs/xterm.js/issues/1659