BlockSource

A block source represents the source for a block level element where each individual line might have a different x-offset to the root source.

This type of source is essential to preserve position tracking in recursive block parsing. For block level markup the first passes have to identify the type of block and remove their markup decoration. The remaining inline markup is then passed to inline parsers, but the input to those parsers is no longer a consecutive substring of the root input, making it hard to provide exact positions in error messages.

This type of source cursor solves this issue by providing a view to parsers that looks like a consecutive string of inline markup without the stripped decoration, while maintaining the x- and y-offsets of each line in relation to the root source.

Such a source will be used in multi-pass parsers, where the root parser might strip some markup decoration from each line and then pass the result down to the next recursion. In such a case each line might have a different x-offset from the root input. The use of this instance ensures that the correct position can still be tracked.