TypeScript library for handling source code strings.

It has its own String type that deals with unicode in a saner than JS's UTF16 strings.

This take in JS string, and makes it into a fat string SourceText that handles all the insanity of UTF16 in JS (like JS leaking UTF16 internals so that there are code-points spanning multiple indices in the string array).

• it handles NFC Normalization
• makes the original string easy to traverse in error-free way by introducing a character abstraction - type CodePoint and its position within the SourceText called CodePointIndex
• It also tracks where line start (handling various platform specific weirdness like \r\n)

It also allows for Spatial Tracking or verious sub-regions within the source. It introduces

• point-like SourceLocation abstraction (basically where a cursor could be)
• and interval-like Span abstraction (basically what a mouse selection could span)