Add lexer/syntax highlighting to visually distinguish the different components of a command

[donnemartin]

A lexer would make it easier to visually distinguish the different components of a command:

 aws [options] <command> <subcommand> [parameters]

Config File

Default theme: vim

# visual theme. possible values: manni, igor, xcode, vim,
# autumn,vs, rrt, native, perldoc, borland, tango, emacs,
# friendly, monokai, paraiso-dark, colorful, murphy, bw,
# pastie, paraiso-light, trac, default, fruity.
# to disable themes, set theme = none
theme = vim

Disable Syntax Highlighting

 theme = none

Sample: Dark Background

 theme = vim

Samples: Light Background

 theme = vim

Note: My terminal colors are customized which might be why we see light gray for aws>.

 theme = xcode

[jamesls]

I think this would be great. The only concern I have, as you mentioned in your TODO, is being able to have color themes. Either that or ensuring the color theme is neutral enough (for now) that it works for both dark and light backgrounds.

[donnemartin]

I tried a few themes on white background--some work better than others, which I think is expected. I'll do some more tweaks to try to make the lexer more neutral, at least for the default theme.

I've hooked it up so that setting theme = none will disable the lexer.

Below are the supported themes:

# visual theme. possible values: manni, igor, xcode, vim,
# autumn,vs, rrt, native, perldoc, borland, tango, emacs,
# friendly, monokai, paraiso-dark, colorful, murphy, bw,
# pastie, paraiso-light, trac, default, fruity.
# to disable themes, set theme = none
theme = vim

[donnemartin]

I updated the initial comment with the proposed UI.

[donnemartin]

Implementation merged in 9149483166ac1c294aa3e8a2392c3d350e7ee852.