Bug: C module and Elisp produced different results for same text.
Root cause: Different condition checking order for single-box vs last-line:
- Elisp: single-box check comes BEFORE is-last check
- C: is_last check came BEFORE is_single_box check (now fixed)
When the last line has only one box, Elisp uses single-box calculation
while C was using last-line calculation, resulting in different demerits
and different final breakpoints.
Fix: Moved is_single_box check before is_last check in dp_process_position()
to match Elisp's ekp--dp-compute-line-demerits behavior.
Co-authored-by: Kinneyzhang <38454496+Kinneyzhang@users.noreply.github.com>
Extracted shared DP core algorithm into dp_process_position() function:
1. Added dp_input_t struct - unified input interface for DP algorithm
- Contains prefix arrays, glue arrays, hyphen info
- Contains K-P parameters (penalties, ratios)
2. Added dp_is_hyphen() function - unified hyphen position detection
- Uses O(log n) binary search
- Replaces is_hyphen_pos() function
3. Added dp_process_position() function - core DP algorithm
- Processes single start position i, tries all end positions k
- Contains complete demerits calculation, fitness classification
- Both entry functions now call this shared core
4. Refactored process_dp_range()
- Builds temporary glue arrays from ekp_paragraph_t
- Creates dp_input_t and calls dp_process_position()
5. Refactored ekp_break_with_prefixes()
- Directly uses input arrays to create dp_input_t
- Calls dp_process_position() for each position
Benefits:
- Single point of maintenance: DP bugs only need fixing once
- Consistency guaranteed: both paths use identical algorithm
- ~100 lines of duplicate code removed
- Better testability: core algorithm can be tested independently
Co-authored-by: Kinneyzhang <38454496+Kinneyzhang@users.noreply.github.com>
When is_last && ideal > line_width, the C module now correctly
triggers force break logic, matching ekp--dp-cache-elisp behavior.
This ensures consistent results between C module and pure Elisp paths.
Co-authored-by: Kinneyzhang <38454496+Kinneyzhang@users.noreply.github.com>
