Previously, calculations related to the position of and difference between
SegmentMarkers required extensive computation based around the line,
line start positions and columns of each segment.
PR Close#36027
The merging algorithm needs to find, for a given segment, what the next
segment in the source file is. This change modifies the `generatedSegment`
properties in the mappings so that they have a link directly to the following
segment.
PR Close#36027
By computing and caching the start of each line, rather than the length
of each line, we can save a lot of duplicated computation in the `segmentDiff()`
and `offsetSegment()` functions.
PR Close#36027
Previously the list of original segments that was searched for incoming
mappings did not differentiate between different original source files.
Now there is a separate array of segments to search for each of the
original source files.
PR Close#36027
The `@angular/core` package has a large number of source files
and mappings which exposed performance issues in the new source-map
flattening algorithm.
This change uses a binary search (rather than linear) when finding
matching mappings to merge. Initial measurements indicate that this
reduces processing time for `@angular/core` by about 50%.
PR Close#36027
Previously when rendering flattened source-maps, it was assumed that no
mapping would come from a line that is outside the lines of the actual
source content. It turns out this is not a valid assumption.
Now the code that renders flattened source-maps will handle such
mappings, with the additional benefit that the rendered source-map
will only contain mapping lines up to the last mapping, rather than a
mapping line for every content line.
Fixes#35709
PR Close#35718
If a package has a source-map but it does not provide
the actual content of the sources, then the source-map
flattening was crashing.
Now we ignore such mappings that have no source
since we are not able to compute the merged
mapping if there is no source file.
Fixes#35709
PR Close#35718
The library used by ngcc to update the source files (MagicString) is able
to generate a source-map but it is not able to account for any previous
source-map that the input text is already associated with.
There have been various attempts to fix this but none have been very
successful, since it is not a trivial problem to solve.
This commit contains a novel approach that is able to load up a tree of
source-files connected by source-maps and flatten them down into a single
source-map that maps directly from the final generated file to the original
sources referenced by the intermediate source-maps.
PR Close#35132
Pete Bacon Darwin