Two recent PRs are now part of devel. Work continues on PR #3347
<https://github.com/leo-editor/leo-editor/pull/3347>, optimistically called
finish *all* importers :-) The mods are picky and tedious, but there have
been only happy surprises!
*The new design*
The new design is a great success. Most importers contain only a few
class-level constants:
- The name of the importer: used in @language directives.
- A tuple of compiled patterns: used to discover the start of blocks.
For example, here are the top-level constants for the C language:
language = 'c'
string_list = ['"'] # Not single quotes.
block_patterns = (
('class', re.compile(r'.*?\bclass\s+(\w+)\s*\{')),
('func', re.compile(r'.*?\b(\w+)\s*\(.*?\)\s*(const)?\s*{')),
('namespace', re.compile(r'.*?\bnamespace\s*(\w+)?\s*\{')),
('struct', re.compile(r'.*?\bstruct\s*(\w+)?\s*\{')),
)
In short, regex patterns encapsulate most differences between languages!
*Finding blocks*
The patterns above will fail if the parameter list spans multiple lines.
*Aha!* Have the patterns match *less.* *find_blocks* will *validate*
potential matches by looking ahead by (say) at most five lines for the
opening curly bracket.
*Simple generality*
Previous importer architectures were overly clever. Importers overrode too
many methods of the base class. In this go-round, importers override just
three:
- *i.import_from_string*: These importers do *all* the work.
- *i.find_end_of_block*: typical.
- *i.find_block*: for larger mods.
Several importers override no methods at all. The top-level class constants
do all the work!
*Summary*
Most importers detect the start of blocks using regex patterns.
Aha! Use *simpler *regexes (for C-like languages) to detect *potential*
starting points. i.find_blocks will look ahead (skipping the argument list)
to find the opening curly brace.
Previous importer architectures were overly complicated. The new importers
typically override just one or two methods. Several importers override no
methods at all: top-level constants do all the work.
Edward
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