1//! `ep split-commit` implementation.
2//!
3//! This command generates a single evaluation example JSON object from a
4//! chronologically-ordered unified diff (a "commit").
5//!
6//! TODO: Port Python code to generate chronologically-ordered commits
7use crate::reorder_patch::{Patch, PatchLine, extract_edits, locate_edited_line};
8
9/// Find the largest valid UTF-8 char boundary at or before `index` in `s`.
10fn floor_char_boundary(s: &str, index: usize) -> usize {
11 if index >= s.len() {
12 s.len()
13 } else if s.is_char_boundary(index) {
14 index
15 } else {
16 // Find the nearest valid character boundary at or before index
17 (0..index)
18 .rev()
19 .find(|&i| s.is_char_boundary(i))
20 .unwrap_or(0)
21 }
22}
23use anyhow::{Context as _, Result};
24use clap::Args;
25use edit_prediction::example_spec::ExampleSpec;
26use rand::Rng;
27use rand::SeedableRng;
28use serde::{Deserialize, Serialize};
29use similar::{DiffTag, TextDiff};
30use std::collections::BTreeSet;
31use std::fs;
32use std::io::{self, Write};
33use std::path::Path;
34use std::path::PathBuf;
35
36/// `ep split-commit` CLI args.
37#[derive(Debug, Args, Clone)]
38pub struct SplitCommitArgs {
39 /// Split point (float 0.0-1.0 for fraction, or integer for index)
40 #[arg(long, short = 's')]
41 pub split_point: Option<String>,
42
43 /// Random seed for reproducibility
44 #[arg(long)]
45 pub seed: Option<u64>,
46
47 /// Pretty-print JSON output
48 #[arg(long, short = 'p')]
49 pub pretty: bool,
50
51 /// Number of samples to generate per commit (samples random split points)
52 #[arg(long, short = 'n')]
53 pub num_samples: Option<usize>,
54}
55
56/// Input format for annotated commits (JSON Lines).
57#[derive(Debug, Clone, Deserialize)]
58#[allow(dead_code)]
59pub struct AnnotatedCommit {
60 /// Repository path (e.g., "repos/zed")
61 pub repo: String,
62 /// Repository URL (e.g., "https://github.com/zed-industries/zed")
63 pub repo_url: String,
64 /// Commit SHA
65 pub commit_sha: String,
66 /// Chronologically reordered commit diff
67 pub reordered_commit: String,
68 /// Original commit diff
69 pub original_commit: String,
70 /// Whether diff stats match between original and reordered
71 pub diff_stats_match: bool,
72}
73
74/// Cursor position in a file.
75#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
76pub struct CursorPosition {
77 pub file: String,
78 pub line: usize,
79 pub column: usize,
80}
81
82impl std::fmt::Display for CursorPosition {
83 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
84 write!(f, "{}:{}:{}", self.file, self.line, self.column)
85 }
86}
87
88/// Represents a split commit with source and target patches.
89#[derive(Debug, Clone)]
90pub struct SplitCommit {
91 pub source_patch: String,
92 pub target_patch: String,
93}
94
95/// Split point specification for evaluation generation.
96#[derive(Debug, Clone)]
97pub enum SplitPoint {
98 /// Fraction of total edits (0.0 to 1.0)
99 Fraction(f64),
100 /// Absolute index
101 Index(usize),
102}
103
104fn parse_split_point(value: &str) -> Option<SplitPoint> {
105 if value.contains('.') {
106 value.parse::<f64>().ok().map(SplitPoint::Fraction)
107 } else {
108 value.parse::<usize>().ok().map(SplitPoint::Index)
109 }
110}
111
112/// Entry point for the `ep split-commit` subcommand.
113///
114/// This runs synchronously and outputs JSON Lines (one output per input line).
115pub fn run_split_commit(
116 args: &SplitCommitArgs,
117 inputs: &[PathBuf],
118 output_path: Option<&PathBuf>,
119) -> Result<()> {
120 use std::collections::HashSet;
121 use std::io::BufRead;
122
123 let stdin_path = PathBuf::from("-");
124 let inputs = if inputs.is_empty() {
125 std::slice::from_ref(&stdin_path)
126 } else {
127 inputs
128 };
129
130 let split_point = args.split_point.as_deref().and_then(parse_split_point);
131 let mut output_lines = Vec::new();
132
133 for input_path in inputs {
134 let input: Box<dyn BufRead> = if input_path.as_os_str() == "-" {
135 Box::new(io::BufReader::new(io::stdin()))
136 } else {
137 let file = fs::File::open(input_path)
138 .with_context(|| format!("failed to open input file {}", input_path.display()))?;
139 Box::new(io::BufReader::new(file))
140 };
141
142 for (line_num, line_result) in input.lines().enumerate() {
143 let line =
144 line_result.with_context(|| format!("failed to read line {}", line_num + 1))?;
145
146 if line.trim().is_empty() {
147 continue;
148 }
149
150 let annotated: AnnotatedCommit = serde_json::from_str(&line)
151 .with_context(|| format!("failed to parse JSON at line {}", line_num + 1))?;
152
153 // Generate multiple samples if num_samples is set
154 if let Some(num_samples) = args.num_samples {
155 let mut seen_samples: HashSet<String> = HashSet::new();
156 let base_seed = args.seed.unwrap_or_else(|| rand::random());
157
158 for sample_idx in 0..num_samples {
159 let sample_seed = base_seed.wrapping_add(sample_idx as u64);
160
161 let case = generate_evaluation_example_from_ordered_commit(
162 &annotated.reordered_commit,
163 &annotated.repo_url,
164 &annotated.commit_sha,
165 None, // Use random split point for multi-sample mode
166 Some(sample_seed),
167 Some(sample_idx),
168 )
169 .with_context(|| {
170 format!(
171 "failed to generate evaluation example for commit {} at line {} (sample {})",
172 annotated.commit_sha,
173 line_num + 1,
174 sample_idx
175 )
176 })?;
177
178 let json = if args.pretty {
179 serde_json::to_string_pretty(&case)
180 } else {
181 serde_json::to_string(&case)
182 }
183 .context("failed to serialize evaluation case as JSON")?;
184
185 // Only add unique samples (different split points may produce same result)
186 if seen_samples.insert(json.clone()) {
187 output_lines.push(json);
188 }
189 }
190 } else {
191 let case = generate_evaluation_example_from_ordered_commit(
192 &annotated.reordered_commit,
193 &annotated.repo_url,
194 &annotated.commit_sha,
195 split_point.clone(),
196 args.seed,
197 None,
198 )
199 .with_context(|| {
200 format!(
201 "failed to generate evaluation example for commit {} at line {}",
202 annotated.commit_sha,
203 line_num + 1
204 )
205 })?;
206
207 let json = if args.pretty {
208 serde_json::to_string_pretty(&case)
209 } else {
210 serde_json::to_string(&case)
211 }
212 .context("failed to serialize evaluation case as JSON")?;
213
214 output_lines.push(json);
215 }
216 }
217 }
218
219 let output_content = output_lines.join("\n") + if output_lines.is_empty() { "" } else { "\n" };
220
221 if let Some(path) = output_path {
222 fs::write(path, &output_content)
223 .with_context(|| format!("failed to write output to {}", path.display()))?;
224 } else {
225 io::stdout()
226 .write_all(output_content.as_bytes())
227 .context("failed to write to stdout")?;
228 }
229
230 Ok(())
231}
232
233/// Main function to generate an evaluation example from an ordered commit.
234///
235/// # Arguments
236/// * `commit` - Chronologically ordered unified diff of the commit
237/// * `repository_url` - URL of the repository
238/// * `commit_hash` - Hash of the commit
239/// * `split_point` - Point at which the commit will be split (None for random)
240/// * `seed` - Optional seed for randomness
241/// * `sample_num` - Optional sample number for generating unique names
242pub fn generate_evaluation_example_from_ordered_commit(
243 commit: &str,
244 repository_url: &str,
245 commit_hash: &str,
246 split_point: Option<SplitPoint>,
247 seed: Option<u64>,
248 sample_num: Option<usize>,
249) -> Result<ExampleSpec> {
250 let mut rng: Box<dyn rand::RngCore> = match seed {
251 Some(seed) => Box::new(rand::rngs::StdRng::seed_from_u64(seed)),
252 None => Box::new(rand::rngs::ThreadRng::default()),
253 };
254
255 // Parse and normalize the commit
256 let mut patch = Patch::parse_unified_diff(commit);
257
258 // Filter header to only keep lines starting with "//"
259 let header_lines: Vec<&str> = patch
260 .header
261 .lines()
262 .filter(|line| line.starts_with("//"))
263 .collect();
264 patch.header = if header_lines.is_empty() {
265 String::new()
266 } else {
267 header_lines.join("\n") + "\n"
268 };
269 let commit_normalized = patch.to_string();
270
271 // Compute the split point
272 let stats = patch.stats();
273 let num_edits = stats.added + stats.removed;
274
275 anyhow::ensure!(num_edits != 0, "no edits found in commit");
276
277 let split = match split_point {
278 None => rng.random_range(1..=num_edits),
279 Some(SplitPoint::Fraction(f)) => {
280 let v = (f * num_edits as f64).floor() as usize;
281 v.min(num_edits)
282 }
283 Some(SplitPoint::Index(i)) => i.min(num_edits),
284 };
285
286 // Split the commit into source and target patches
287 let (prefix, suffix) = split_ordered_commit(&commit_normalized, split);
288
289 let mut split_commit = SplitCommit {
290 source_patch: prefix,
291 target_patch: suffix,
292 };
293
294 // Imitate human edits
295 let human_edit_seed = rng.random_range(1..=10000u64);
296 let (src_patch, tgt_patch, cursor_opt) = imitate_human_edits(
297 &split_commit.source_patch,
298 &split_commit.target_patch,
299 human_edit_seed,
300 );
301 split_commit.source_patch = src_patch;
302 split_commit.target_patch = tgt_patch;
303
304 // Sample cursor position
305 let cursor = match cursor_opt {
306 Some(c) => c,
307 None => sample_cursor_position(&patch, &split_commit)
308 .context("failed to sample cursor position")?,
309 };
310
311 // Get cursor excerpt
312 let cursor_excerpt = get_cursor_excerpt(
313 &cursor,
314 &split_commit.source_patch,
315 &split_commit.target_patch,
316 )
317 .context("failed to generate cursor excerpt")?;
318
319 // Handle edge case where split_point == 0
320 if split == 0 {
321 split_commit.target_patch = String::new();
322 }
323
324 let repo_name = repository_url
325 .trim_end_matches('/')
326 .rsplit('/')
327 .next()
328 .unwrap_or("unknown");
329 let short_sha = &commit_hash[..commit_hash.len().min(8)];
330 let name = match sample_num {
331 Some(n) => format!("{}-{}-{}", repo_name, short_sha, n),
332 None => format!("{}-{}", repo_name, short_sha),
333 };
334
335 Ok(ExampleSpec {
336 name,
337 repository_url: repository_url.to_string(),
338 revision: format!("{}~1", commit_hash),
339 edit_history: split_commit.source_patch.clone(),
340 // cursor_position: cursor.to_string(),
341 cursor_path: Path::new(&cursor.file).into(),
342 cursor_position: cursor_excerpt,
343 expected_patches: vec![split_commit.target_patch],
344 tags: vec![],
345 reasoning: None,
346 uncommitted_diff: String::new(),
347 })
348}
349
350/// Split an ordered commit into source and target commits.
351///
352/// # Arguments
353/// * `commit` - Ordered commit string
354/// * `split_pos` - Position to split the commit (number of edited lines)
355///
356/// # Returns
357/// A tuple of (source_diff, target_diff)
358pub fn split_ordered_commit(commit: &str, split_pos: usize) -> (String, String) {
359 let patch = Patch::parse_unified_diff(commit);
360 let source_edits: BTreeSet<usize> = (0..split_pos).collect();
361 let (source, target) = extract_edits(&patch, &source_edits);
362
363 let mut source_str = source.to_string();
364 let target_str = target.to_string();
365
366 // Strip last group header from the source (lines starting with "//" at the end)
367 let source_lines: Vec<&str> = source_str.lines().collect();
368 let mut end_idx = source_lines.len();
369 for i in (0..source_lines.len()).rev() {
370 if source_lines[i].starts_with("//") {
371 end_idx = i;
372 } else {
373 break;
374 }
375 }
376 if end_idx < source_lines.len() {
377 source_str = source_lines[..end_idx].join("\n");
378 if !source_str.is_empty() {
379 source_str.push('\n');
380 }
381 }
382
383 (source_str, target_str)
384}
385
386/// Tokenize text into words and non-word characters.
387fn tokenize(text: &str) -> Vec<String> {
388 let mut tokens = Vec::new();
389 let mut current = String::new();
390
391 for ch in text.chars() {
392 if ch.is_alphanumeric() {
393 current.push(ch);
394 } else if ch == '_' {
395 // Include underscore with the current word, then flush
396 current.push(ch);
397 if !current.is_empty() {
398 tokens.push(std::mem::take(&mut current));
399 }
400 } else {
401 // Punctuation or whitespace - flush current word first
402 if !current.is_empty() {
403 tokens.push(std::mem::take(&mut current));
404 }
405 // Each punctuation/whitespace is its own token
406 tokens.push(ch.to_string());
407 }
408 }
409
410 if !current.is_empty() {
411 tokens.push(current);
412 }
413
414 tokens
415}
416
417/// Calculate the weight for a split position based on the character at that position.
418///
419/// Higher weights indicate more natural pause points (e.g., after punctuation,
420/// at identifier boundaries). Lower weights indicate less natural points
421/// (e.g., mid-identifier).
422fn position_weight(text: &str, pos: usize) -> u32 {
423 if pos == 0 || pos > text.len() {
424 return 1;
425 }
426
427 let chars: Vec<char> = text.chars().collect();
428 if pos > chars.len() {
429 return 1;
430 }
431
432 // Get the character just before this position (what we just "typed")
433 let prev_char = chars[pos - 1];
434
435 // High weight: natural pause points (end of statement/argument, opening brackets)
436 if matches!(prev_char, ',' | ';' | ':' | '(' | '[' | '{') {
437 return 10;
438 }
439
440 // High weight: closing brackets (finished a group)
441 if matches!(prev_char, ')' | ']' | '}') {
442 return 8;
443 }
444
445 // Medium weight: operators and method chains
446 if matches!(
447 prev_char,
448 '.' | '+' | '-' | '*' | '/' | '=' | '<' | '>' | '&' | '|' | '!'
449 ) {
450 return 5;
451 }
452
453 // Check if we're at the end of an identifier (word char followed by non-word char)
454 let is_prev_word_char = prev_char.is_alphanumeric() || prev_char == '_';
455 let is_next_word_char =
456 pos < chars.len() && (chars[pos].is_alphanumeric() || chars[pos] == '_');
457
458 if is_prev_word_char && !is_next_word_char {
459 // End of identifier - high weight
460 return 8;
461 }
462
463 // Whitespace is a natural pause
464 if prev_char.is_whitespace() {
465 return 6;
466 }
467
468 // Mid-identifier: low weight (rare autocomplete scenarios)
469 if is_prev_word_char && is_next_word_char {
470 return 1;
471 }
472
473 // Default medium-low weight
474 3
475}
476
477/// Select a weighted random index from a list of weights.
478///
479/// Returns an index based on the weights, using the provided seed for
480/// deterministic selection.
481fn weighted_select(weights: &[u32], seed: u64) -> usize {
482 if weights.is_empty() {
483 return 0;
484 }
485
486 let total_weight: u64 = weights.iter().map(|&w| w as u64).sum();
487 if total_weight == 0 {
488 // Fallback to uniform selection if all weights are zero
489 return seed as usize % weights.len();
490 }
491
492 // Use seed to select a value in [0, total_weight)
493 let target = seed % total_weight;
494 let mut cumulative: u64 = 0;
495
496 for (idx, &weight) in weights.iter().enumerate() {
497 cumulative += weight as u64;
498 if target < cumulative {
499 return idx;
500 }
501 }
502
503 // Fallback to last index
504 weights.len() - 1
505}
506
507/// Calculate similarity ratio between two strings (0-100).
508fn fuzzy_ratio(s1: &str, s2: &str) -> u32 {
509 if s1.is_empty() && s2.is_empty() {
510 return 100;
511 }
512 if s1.is_empty() || s2.is_empty() {
513 return 0;
514 }
515
516 let diff = TextDiff::from_chars(s1, s2);
517 let matching: usize = diff
518 .ops()
519 .iter()
520 .filter_map(|op| {
521 if matches!(op.tag(), DiffTag::Equal) {
522 Some(op.new_range().len())
523 } else {
524 None
525 }
526 })
527 .sum();
528
529 let total = s1.len() + s2.len();
530 ((2 * matching * 100) / total) as u32
531}
532
533/// Imitate human edits by introducing partial line edits.
534///
535/// This function simulates how a human might incrementally type code,
536/// rather than making complete line replacements.
537pub fn imitate_human_edits(
538 source_patch: &str,
539 target_patch: &str,
540 seed: u64,
541) -> (String, String, Option<CursorPosition>) {
542 let no_change = (source_patch.to_string(), target_patch.to_string(), None);
543
544 let src_patch = Patch::parse_unified_diff(source_patch);
545 let tgt_patch = Patch::parse_unified_diff(target_patch);
546
547 if tgt_patch.hunks.is_empty() {
548 return no_change;
549 }
550
551 // Try to locate the first edit in target
552 let tgt_edit_loc = match locate_edited_line(&tgt_patch, 0) {
553 Some(loc) => loc,
554 None => return no_change,
555 };
556
557 let tgt_is_addition = matches!(tgt_edit_loc.patch_line, PatchLine::Addition(_));
558 if !tgt_is_addition {
559 return no_change;
560 }
561
562 let tgt_line = match &tgt_edit_loc.patch_line {
563 PatchLine::Addition(s) => s.clone(),
564 _ => return no_change,
565 };
566
567 // Try to locate the last edit in source
568 let src_edit_loc = locate_edited_line(&src_patch, -1);
569
570 // Check if source has ANY edit at the same line as target's first edit
571 // We need to iterate through all edits to check this
572 let src_has_edit_at_target_line = {
573 let mut found = false;
574 let mut idx = 0isize;
575 while let Some(loc) = locate_edited_line(&src_patch, idx) {
576 if loc.filename == tgt_edit_loc.filename
577 && loc.target_line_number == tgt_edit_loc.target_line_number
578 {
579 found = true;
580 break;
581 }
582 idx += 1;
583 }
584 found
585 };
586
587 // Check if this is a replacement (deletion followed by insertion on the same line)
588 // or a pure insertion (no corresponding deletion in source)
589 let is_replacement = src_edit_loc.as_ref().map_or(false, |loc| {
590 matches!(loc.patch_line, PatchLine::Deletion(_))
591 && loc.filename == tgt_edit_loc.filename
592 && loc.target_line_number == tgt_edit_loc.target_line_number
593 });
594
595 // If source has an edit at the same line but it's not a replacement (i.e., it's an addition),
596 // we shouldn't process this as a pure insertion either
597 if !is_replacement && src_has_edit_at_target_line {
598 return no_change;
599 }
600
601 let src_line = if is_replacement {
602 match &src_edit_loc.as_ref().unwrap().patch_line {
603 PatchLine::Deletion(s) => s.clone(),
604 _ => return no_change,
605 }
606 } else {
607 // Pure insertion: source line is empty
608 String::new()
609 };
610
611 // Don't process if source and target are the same
612 if src_line == tgt_line {
613 return no_change;
614 }
615
616 // Tokenize both lines
617 let src_tokens = tokenize(&src_line);
618 let tgt_tokens = tokenize(&tgt_line);
619
620 // Convert to slices for similar
621 let src_refs: Vec<&str> = src_tokens.iter().map(|s| s.as_str()).collect();
622 let tgt_refs: Vec<&str> = tgt_tokens.iter().map(|s| s.as_str()).collect();
623
624 // Use similar to get diff operations
625 let diff = TextDiff::from_slices(&src_refs, &tgt_refs);
626
627 // Build weights for each possible split position
628 let mut position_weights: Vec<u32> = Vec::new();
629
630 // Simulate the edit process to collect weights for all possible split positions
631 {
632 let mut current_text = String::new();
633
634 for op in diff.ops() {
635 match op.tag() {
636 DiffTag::Equal => {
637 for i in op.old_range() {
638 current_text.push_str(&src_tokens[i]);
639 }
640 }
641 DiffTag::Replace => {
642 let ins: String = op.new_range().map(|i| tgt_tokens[i].as_str()).collect();
643 let del: String = op.old_range().map(|i| src_tokens[i].as_str()).collect();
644
645 // For insertion part
646 for ch in ins.chars() {
647 current_text.push(ch);
648 let weight = position_weight(¤t_text, current_text.len());
649 position_weights.push(weight);
650 }
651
652 // For deletion part (we're "untyping" from source)
653 for _ in del.chars() {
654 // Weight deletions lower as they represent removing text
655 position_weights.push(2);
656 }
657 }
658 DiffTag::Insert => {
659 let ins: String = op.new_range().map(|i| tgt_tokens[i].as_str()).collect();
660 for ch in ins.chars() {
661 current_text.push(ch);
662 let weight = position_weight(¤t_text, current_text.len());
663 position_weights.push(weight);
664 }
665 }
666 DiffTag::Delete => {
667 let del: String = op.old_range().map(|i| src_tokens[i].as_str()).collect();
668 for _ in del.chars() {
669 // Weight deletions lower
670 position_weights.push(2);
671 }
672 }
673 }
674 }
675 }
676
677 // Use weighted selection to choose split index
678 if position_weights.is_empty() {
679 return no_change;
680 }
681 let split_index = weighted_select(&position_weights, seed);
682
683 let mut edit_index = 0usize;
684 let mut new_src = String::new();
685 let mut split_found = false;
686 let mut last_old_end = 0usize;
687
688 for op in diff.ops() {
689 match op.tag() {
690 DiffTag::Equal => {
691 for i in op.old_range() {
692 new_src.push_str(&src_tokens[i]);
693 }
694 last_old_end = op.old_range().end;
695 }
696 DiffTag::Replace => {
697 // Handle replace as delete + insert
698 let del: String = op.old_range().map(|i| src_tokens[i].as_str()).collect();
699 let ins: String = op.new_range().map(|i| tgt_tokens[i].as_str()).collect();
700 let repl_len = del.len() + ins.len();
701 if edit_index + repl_len >= split_index {
702 // Split within this replace operation
703 let offset = split_index - edit_index;
704 if offset < ins.len() {
705 let safe_offset = floor_char_boundary(&ins, offset);
706 new_src.push_str(&ins[..safe_offset]);
707 } else {
708 new_src.push_str(&ins);
709 let del_offset = offset - ins.len();
710 let safe_del_offset = floor_char_boundary(&del, del_offset.min(del.len()));
711 new_src.push_str(&del[..safe_del_offset]);
712 }
713 split_found = true;
714 last_old_end = op.old_range().end;
715 break;
716 } else {
717 edit_index += repl_len;
718 new_src.push_str(&ins);
719 last_old_end = op.old_range().end;
720 }
721 }
722 DiffTag::Insert => {
723 let repl: String = op.new_range().map(|i| tgt_tokens[i].as_str()).collect();
724 if edit_index + repl.len() >= split_index {
725 let offset = split_index - edit_index;
726 let safe_offset = floor_char_boundary(&repl, offset);
727 new_src.push_str(&repl[..safe_offset]);
728 split_found = true;
729 break;
730 } else {
731 edit_index += repl.len();
732 new_src.push_str(&repl);
733 }
734 }
735 DiffTag::Delete => {
736 let repl: String = op.old_range().map(|i| src_tokens[i].as_str()).collect();
737 if edit_index + repl.len() >= split_index {
738 let offset = split_index - edit_index;
739 let safe_offset = floor_char_boundary(&repl, offset);
740 new_src.push_str(&repl[..safe_offset]);
741 split_found = true;
742 last_old_end = op.old_range().start + safe_offset.min(op.old_range().len());
743 break;
744 } else {
745 edit_index += repl.len();
746 new_src.push_str(&repl);
747 last_old_end = op.old_range().end;
748 }
749 }
750 }
751 }
752
753 if !split_found {
754 return no_change;
755 }
756
757 // Calculate cursor position
758 let cursor = CursorPosition {
759 file: tgt_edit_loc.filename.clone(),
760 line: if is_replacement {
761 src_edit_loc.as_ref().unwrap().source_line_number
762 } else {
763 tgt_edit_loc.target_line_number
764 },
765 column: new_src.len() + 1,
766 };
767
768 // Add remainder of source if similar enough to target remainder
769 let remainder_src: String = (last_old_end..src_tokens.len())
770 .map(|i| src_tokens[i].as_str())
771 .collect();
772 let remainder_tgt: String = (last_old_end..tgt_tokens.len())
773 .filter_map(|i| tgt_tokens.get(i).map(|s| s.as_str()))
774 .collect();
775
776 let ratio = fuzzy_ratio(&remainder_src, &remainder_tgt);
777 if ratio > 35 {
778 new_src.push_str(&remainder_src);
779 }
780
781 if new_src.trim().is_empty() {
782 return no_change;
783 }
784
785 if new_src == src_line {
786 return no_change;
787 }
788
789 // Build new source patch with the intermediate line
790 let mut new_src_patch = src_patch;
791 if is_replacement {
792 // For replacements, insert after the deletion line
793 let src_loc = src_edit_loc.as_ref().unwrap();
794 if let Some(hunk) = new_src_patch.hunks.get_mut(src_loc.hunk_index) {
795 hunk.lines.insert(
796 src_loc.line_index_within_hunk + 1,
797 PatchLine::Addition(new_src.clone()),
798 );
799 hunk.new_count += 1;
800 }
801 } else {
802 // For pure insertions, insert after the last edit in source patch
803 // This imitates human typing - the intermediate content is what the user is currently typing
804 let last_src_edit = locate_edited_line(&new_src_patch, -1);
805
806 if let Some(src_loc) = last_src_edit {
807 // Insert after the last edit in source
808 if let Some(hunk) = new_src_patch.hunks.get_mut(src_loc.hunk_index) {
809 hunk.lines.insert(
810 src_loc.line_index_within_hunk + 1,
811 PatchLine::Addition(new_src.clone()),
812 );
813 hunk.new_count += 1;
814 }
815 } else {
816 // Source patch is empty or has incompatible hunk structure, create a new hunk based on target
817 if let Some(tgt_hunk) = tgt_patch.hunks.get(tgt_edit_loc.hunk_index) {
818 let mut new_hunk = tgt_hunk.clone();
819 // Replace the full addition with the partial one
820 new_hunk.lines.clear();
821 for (i, line) in tgt_hunk.lines.iter().enumerate() {
822 if i == tgt_edit_loc.line_index_within_hunk {
823 new_hunk.lines.push(PatchLine::Addition(new_src.clone()));
824 } else {
825 match line {
826 PatchLine::Addition(_) => {
827 // Skip other additions from target
828 }
829 _ => new_hunk.lines.push(line.clone()),
830 }
831 }
832 }
833 new_hunk.new_count = new_hunk.old_count + 1;
834 new_src_patch.hunks.push(new_hunk);
835 // Copy header from target if source doesn't have one
836 if new_src_patch.header.is_empty() {
837 new_src_patch.header = tgt_patch.header.clone();
838 }
839 }
840 }
841 }
842
843 // Build new target patch with the intermediate line as deletion
844 let mut new_tgt_patch = tgt_patch;
845 if let Some(hunk) = new_tgt_patch.hunks.get_mut(tgt_edit_loc.hunk_index) {
846 hunk.lines.insert(
847 tgt_edit_loc.line_index_within_hunk,
848 PatchLine::Deletion(new_src),
849 );
850 hunk.old_count += 1;
851 }
852
853 (
854 new_src_patch.to_string(),
855 new_tgt_patch.to_string(),
856 Some(cursor),
857 )
858}
859
860/// Locate the end of the last edit in a patch.
861fn locate_end_of_last_edit(patch: &Patch) -> Option<CursorPosition> {
862 let loc = locate_edited_line(patch, -1)?;
863
864 let (line, col) = match &loc.patch_line {
865 PatchLine::Addition(content) => (loc.target_line_number, content.len()),
866 PatchLine::Deletion(_) => (loc.target_line_number, 1),
867 _ => return None,
868 };
869
870 Some(CursorPosition {
871 file: loc.filename,
872 line,
873 column: col,
874 })
875}
876
877/// Locate the beginning of the first edit in a patch.
878fn locate_beginning_of_first_edit(patch: &Patch) -> Option<CursorPosition> {
879 let loc = locate_edited_line(patch, 0)?;
880
881 let hunk = patch.hunks.get(loc.hunk_index)?;
882 let column = if loc.line_index_within_hunk > 0 {
883 if let Some(prev_line) = hunk.lines.get(loc.line_index_within_hunk - 1) {
884 let content = match prev_line {
885 PatchLine::Context(s) | PatchLine::Addition(s) | PatchLine::Deletion(s) => s,
886 _ => return None,
887 };
888 content.len().max(1) - 1
889 } else {
890 0
891 }
892 } else {
893 0
894 };
895
896 let line = loc.target_line_number.saturating_sub(1).max(1);
897
898 Some(CursorPosition {
899 file: loc.filename,
900 line,
901 column,
902 })
903}
904
905/// Sample cursor position according to the following rules:
906/// 1. 50% chance of cursor being at the end of the source patch
907/// 2. 50% chance of cursor being at the beginning of the target patch
908pub fn sample_cursor_position(patch: &Patch, split_commit: &SplitCommit) -> Option<CursorPosition> {
909 // Try end of history first
910 let src_patch = Patch::parse_unified_diff(&split_commit.source_patch);
911 if let Some(cursor) = locate_end_of_last_edit(&src_patch) {
912 return Some(cursor);
913 }
914
915 // Try beginning of target
916 let tgt_patch = Patch::parse_unified_diff(&split_commit.target_patch);
917 if let Some(cursor) = locate_beginning_of_first_edit(&tgt_patch) {
918 return Some(cursor);
919 }
920
921 // Fallback: use the original patch
922 locate_end_of_last_edit(patch)
923}
924
925/// Get cursor excerpt from the patches.
926///
927/// This extracts the lines around the cursor position with a cursor marker.
928pub fn get_cursor_excerpt(
929 cursor: &CursorPosition,
930 source_patch: &str,
931 target_patch: &str,
932) -> Option<String> {
933 let mut excerpt_lines: Vec<String> = Vec::new();
934 let mut excerpt_first_line: usize = 0;
935
936 // Search in the last hunk of source patch
937 let src = Patch::parse_unified_diff(source_patch);
938 if let Some(loc) = locate_edited_line(&src, -1) {
939 if loc.filename == cursor.file && loc.target_line_number == cursor.line {
940 if let Some(hunk) = src.hunks.get(loc.hunk_index) {
941 excerpt_first_line = hunk.new_start as usize;
942 for line in &hunk.lines {
943 match line {
944 PatchLine::Addition(s) | PatchLine::Context(s) => {
945 excerpt_lines.push(s.clone());
946 }
947 _ => {}
948 }
949 }
950 // If hunk only has deletions (file deletion), include deletion lines
951 if excerpt_lines.is_empty() {
952 excerpt_first_line = hunk.old_start as usize;
953 for line in &hunk.lines {
954 match line {
955 PatchLine::Deletion(s) => {
956 excerpt_lines.push(s.clone());
957 }
958 _ => {}
959 }
960 }
961 }
962 }
963 }
964 }
965
966 // Search in target patch if not found
967 if excerpt_lines.is_empty() {
968 let tgt = Patch::parse_unified_diff(target_patch);
969 // Search all hunks for the cursor file, not just the first edit's hunk
970 for hunk in &tgt.hunks {
971 if hunk.filename == cursor.file {
972 excerpt_first_line = hunk.new_start as usize;
973 // First try to collect deletions and context (what exists before edits)
974 for line in &hunk.lines {
975 match line {
976 PatchLine::Deletion(s) | PatchLine::Context(s) => {
977 excerpt_lines.push(s.clone());
978 }
979 _ => {}
980 }
981 }
982 // If hunk only has additions (no deletions/context), include all lines
983 // This handles cases like adding to an empty file or section
984 if excerpt_lines.is_empty() {
985 for line in &hunk.lines {
986 match line {
987 PatchLine::Addition(s)
988 | PatchLine::Deletion(s)
989 | PatchLine::Context(s) => {
990 excerpt_lines.push(s.clone());
991 }
992 _ => {}
993 }
994 }
995 }
996 if !excerpt_lines.is_empty() {
997 break;
998 }
999 }
1000 }
1001 }
1002
1003 // Also search source patch hunks if still not found (for fallback cursor case)
1004 if excerpt_lines.is_empty() {
1005 for hunk in &src.hunks {
1006 if hunk.filename == cursor.file {
1007 excerpt_first_line = hunk.new_start as usize;
1008 for line in &hunk.lines {
1009 match line {
1010 PatchLine::Addition(s) | PatchLine::Context(s) => {
1011 excerpt_lines.push(s.clone());
1012 }
1013 _ => {}
1014 }
1015 }
1016 // If hunk only has deletions, include deletion lines
1017 if excerpt_lines.is_empty() {
1018 excerpt_first_line = hunk.old_start as usize;
1019 for line in &hunk.lines {
1020 match line {
1021 PatchLine::Deletion(s) => {
1022 excerpt_lines.push(s.clone());
1023 }
1024 _ => {}
1025 }
1026 }
1027 }
1028 if !excerpt_lines.is_empty() {
1029 break;
1030 }
1031 }
1032 }
1033 }
1034
1035 if excerpt_lines.is_empty() {
1036 return None;
1037 }
1038
1039 // Add cursor marker
1040 for (i, line) in excerpt_lines.iter_mut().enumerate() {
1041 let line_num = excerpt_first_line + i;
1042 if line_num == cursor.line {
1043 let col = cursor.column.min(line.len());
1044 // Ensure we split at a valid UTF-8 character boundary
1045 let col = if line.is_char_boundary(col) {
1046 col
1047 } else {
1048 // Find the nearest valid character boundary
1049 (0..=col)
1050 .rev()
1051 .find(|&i| line.is_char_boundary(i))
1052 .unwrap_or(0)
1053 };
1054 let (before, after) = line.split_at(col);
1055 *line = format!("{}<|user_cursor|>{}", before, after);
1056 break;
1057 }
1058 }
1059
1060 Some(excerpt_lines.join("\n"))
1061}
1062
1063#[cfg(test)]
1064mod tests {
1065 use std::path::Path;
1066
1067 use edit_prediction::example_spec::ExampleSpec;
1068
1069 use super::*;
1070
1071 #[test]
1072 fn test_tokenize() {
1073 let tokens = tokenize("hello world");
1074 assert_eq!(tokens, vec!["hello", " ", "world"]);
1075
1076 let tokens = tokenize("foo_bar123 + baz");
1077 assert_eq!(tokens, vec!["foo_", "bar123", " ", "+", " ", "baz"]);
1078
1079 let tokens = tokenize("print(\"hello\")");
1080 assert_eq!(tokens, vec!["print", "(", "\"", "hello", "\"", ")"]);
1081
1082 let tokens = tokenize("hello_world");
1083 assert_eq!(tokens, vec!["hello_", "world"]);
1084
1085 let tokens = tokenize("fn();");
1086 assert_eq!(tokens, vec!["fn", "(", ")", ";"]);
1087 }
1088
1089 #[test]
1090 fn test_fuzzy_ratio() {
1091 assert_eq!(fuzzy_ratio("hello", "hello"), 100);
1092 assert_eq!(fuzzy_ratio("", ""), 100);
1093 assert!(fuzzy_ratio("hello", "world") < 50);
1094 assert!(fuzzy_ratio("hello world", "hello worl") > 80);
1095 }
1096
1097 #[test]
1098 fn test_split_ordered_commit() {
1099 let commit = r#"// First change
1100--- a/test.rs
1101+++ b/test.rs
1102@@ -1,3 +1,4 @@
1103 fn main() {
1104+ println!("hello");
1105+ println!("world");
1106 }
1107"#;
1108 let patch = Patch::parse_unified_diff(commit);
1109 let stats = patch.stats();
1110 assert_eq!(stats.added, 2);
1111
1112 let (source, target) = split_ordered_commit(commit, 1);
1113
1114 // Source should have 1 addition
1115 let src_patch = Patch::parse_unified_diff(&source);
1116 assert_eq!(src_patch.stats().added, 1);
1117
1118 // Target should have 1 addition
1119 let tgt_patch = Patch::parse_unified_diff(&target);
1120 assert_eq!(tgt_patch.stats().added, 1);
1121 }
1122
1123 #[test]
1124 fn test_split_ordered_commit_with_deletions() {
1125 let commit = r#"// Change
1126--- a/test.rs
1127+++ b/test.rs
1128@@ -1,3 +1,3 @@
1129 fn main() {
1130- println!("old");
1131+ println!("new");
1132 }
1133"#;
1134 let patch = Patch::parse_unified_diff(commit);
1135 let stats = patch.stats();
1136 assert_eq!(stats.added, 1);
1137 assert_eq!(stats.removed, 1);
1138
1139 // Split at position 1 (after the deletion)
1140 let (source, target) = split_ordered_commit(commit, 1);
1141
1142 let src_patch = Patch::parse_unified_diff(&source);
1143 let tgt_patch = Patch::parse_unified_diff(&target);
1144
1145 // Source should have the deletion
1146 assert_eq!(src_patch.stats().removed, 1);
1147 // Target should have the addition
1148 assert_eq!(tgt_patch.stats().added, 1);
1149 }
1150
1151 #[test]
1152 fn test_generate_evaluation_example() {
1153 let commit = r#"commit abc123
1154Author: Test <test@example.com>
1155Date: Mon Jan 1 00:00:00 2024
1156
1157 Test commit
1158
1159////////////////////////////////////////////////////////////////////////////////
1160// Add greeting
1161////////////////////////////////////////////////////////////////////////////////
1162--- a/test.rs
1163+++ b/test.rs
1164@@ -1,3 +1,5 @@
1165 fn main() {
1166+ println!("hello");
1167+ println!("world");
1168 }
1169"#;
1170
1171 let result = generate_evaluation_example_from_ordered_commit(
1172 commit,
1173 "https://github.com/test/repo",
1174 "abc123",
1175 Some(SplitPoint::Fraction(0.5)),
1176 Some(42),
1177 None,
1178 );
1179
1180 assert!(result.is_ok());
1181 let case = result.unwrap();
1182 assert_eq!(case.repository_url, "https://github.com/test/repo");
1183 assert_eq!(case.revision, "abc123~1");
1184 assert!(!case.edit_history.is_empty());
1185 }
1186
1187 #[test]
1188 fn test_generate_evaluation_example_reproducible() {
1189 let commit = r#"////////////////////////////////////////////////////////////////////////////////
1190// Add greeting
1191////////////////////////////////////////////////////////////////////////////////
1192--- a/test.rs
1193+++ b/test.rs
1194@@ -1,3 +1,5 @@
1195 fn main() {
1196+ println!("hello");
1197+ println!("world");
1198 }
1199"#;
1200
1201 // Run twice with the same seed
1202 let result1 = generate_evaluation_example_from_ordered_commit(
1203 commit,
1204 "https://github.com/test/repo",
1205 "abc123",
1206 Some(SplitPoint::Fraction(0.5)),
1207 Some(12345),
1208 None,
1209 )
1210 .unwrap();
1211
1212 let result2 = generate_evaluation_example_from_ordered_commit(
1213 commit,
1214 "https://github.com/test/repo",
1215 "abc123",
1216 Some(SplitPoint::Fraction(0.5)),
1217 Some(12345),
1218 None,
1219 )
1220 .unwrap();
1221
1222 // Results should be identical
1223 assert_eq!(result1.edit_history, result2.edit_history);
1224 assert_eq!(result1.expected_patches, result2.expected_patches);
1225 assert_eq!(result1.cursor_position, result2.cursor_position);
1226 }
1227
1228 #[test]
1229 fn test_cursor_position_display() {
1230 let cursor = CursorPosition {
1231 file: "src/main.rs".to_string(),
1232 line: 42,
1233 column: 10,
1234 };
1235 assert_eq!(cursor.to_string(), "src/main.rs:42:10");
1236 }
1237
1238 #[test]
1239 fn test_imitate_human_edits_no_change_when_no_replacement() {
1240 // Source and target patches that don't form a replacement pattern
1241 let source = r#"--- a/test.rs
1242+++ b/test.rs
1243@@ -1,3 +1,4 @@
1244 fn main() {
1245+ println!("hello");
1246 }
1247"#;
1248 let target = r#"--- a/test.rs
1249+++ b/test.rs
1250@@ -1,3 +1,4 @@
1251 fn main() {
1252+ println!("world");
1253 }
1254"#;
1255
1256 let (new_src, new_tgt, cursor) = imitate_human_edits(source, target, 42);
1257
1258 // Should return unchanged when not a replacement pattern
1259 assert_eq!(new_src, source);
1260 assert_eq!(new_tgt, target);
1261 assert!(cursor.is_none());
1262 }
1263
1264 #[test]
1265 fn test_split_point_fraction() {
1266 let commit = r#"// Change
1267--- a/test.rs
1268+++ b/test.rs
1269@@ -1,5 +1,10 @@
1270 fn main() {
1271+ line1();
1272+ line2();
1273+ line3();
1274+ line4();
1275+ line5();
1276 }
1277"#;
1278
1279 // Split at 20% should give first edit in source
1280 let result = generate_evaluation_example_from_ordered_commit(
1281 commit,
1282 "",
1283 "hash",
1284 Some(SplitPoint::Fraction(0.2)),
1285 Some(1),
1286 None,
1287 );
1288
1289 assert!(result.is_ok());
1290 let case = result.unwrap();
1291
1292 // Source should have some edits
1293 let src_patch = Patch::parse_unified_diff(&case.edit_history);
1294 assert!(src_patch.stats().added > 0);
1295 }
1296
1297 #[test]
1298 fn test_split_point_index() {
1299 let commit = r#"// Change
1300--- a/test.rs
1301+++ b/test.rs
1302@@ -1,5 +1,10 @@
1303 fn main() {
1304+ line1();
1305+ line2();
1306+ line3();
1307+ line4();
1308+ line5();
1309 }
1310"#;
1311
1312 // Split at index 2 should give first 2 edits in source
1313 // With pure insertion handling, source gets 2 original + 1 partial = 3 additions
1314 let result = generate_evaluation_example_from_ordered_commit(
1315 commit,
1316 "",
1317 "hash",
1318 Some(SplitPoint::Index(2)),
1319 Some(1),
1320 None,
1321 );
1322
1323 assert!(result.is_ok());
1324 let case = result.unwrap();
1325
1326 let src_patch = Patch::parse_unified_diff(&case.edit_history);
1327 // Pure insertion adds a partial line, so we expect 3 (2 original + 1 partial)
1328 assert_eq!(src_patch.stats().added, 3);
1329 }
1330
1331 #[test]
1332 fn test_cursor_excerpt_contains_marker() {
1333 let commit = r#"////////////////////////////////////////////////////////////////////////////////
1334// Add code
1335////////////////////////////////////////////////////////////////////////////////
1336--- a/test.rs
1337+++ b/test.rs
1338@@ -1,3 +1,5 @@
1339 fn main() {
1340+ println!("hello");
1341+ println!("world");
1342 }
1343"#;
1344
1345 let result = generate_evaluation_example_from_ordered_commit(
1346 commit,
1347 "",
1348 "hash",
1349 Some(SplitPoint::Fraction(0.5)),
1350 Some(42),
1351 None,
1352 )
1353 .unwrap();
1354
1355 // Cursor excerpt should contain the cursor marker
1356 assert!(
1357 result.cursor_position.contains("<|user_cursor|>"),
1358 "Cursor excerpt should contain marker: {}",
1359 result.cursor_position
1360 );
1361 }
1362
1363 #[test]
1364 fn test_evaluation_case_json_serialization() {
1365 let case = ExampleSpec {
1366 name: "test-abc123".to_string(),
1367 repository_url: "https://github.com/test/repo".to_string(),
1368 revision: "abc123~1".to_string(),
1369 edit_history: "patch1".to_string(),
1370 // cursor_position: "file.rs:10:5".to_string(),
1371 cursor_path: Path::new("file.rs").into(),
1372 cursor_position: "some code<|user_cursor|>".to_string(),
1373 expected_patches: vec!["patch".to_string()],
1374 tags: vec![],
1375 reasoning: None,
1376 uncommitted_diff: String::new(),
1377 };
1378
1379 let json = serde_json::to_string(&case).unwrap();
1380 let deserialized: ExampleSpec = serde_json::from_str(&json).unwrap();
1381
1382 assert_eq!(case.repository_url, deserialized.repository_url);
1383 assert_eq!(case.revision, deserialized.revision);
1384 assert_eq!(case.cursor_position, deserialized.cursor_position);
1385 }
1386
1387 #[test]
1388 fn test_empty_commit_returns_error() {
1389 let commit = "";
1390
1391 let result = generate_evaluation_example_from_ordered_commit(
1392 commit,
1393 "",
1394 "hash",
1395 Some(SplitPoint::Fraction(0.5)),
1396 Some(1),
1397 None,
1398 );
1399
1400 assert!(result.is_err());
1401 }
1402
1403 #[test]
1404 fn test_header_filtering() {
1405 let commit = r#"commit abc123
1406Author: Test
1407Date: Today
1408
1409 Message
1410
1411diff --git a/test.rs b/test.rs
1412index 123..456 789
1413////////////////////////////////////////////////////////////////////////////////
1414// First group
1415////////////////////////////////////////////////////////////////////////////////
1416--- a/test.rs
1417+++ b/test.rs
1418@@ -1,3 +1,4 @@
1419 fn main() {
1420+ code();
1421 }
1422"#;
1423
1424 let result = generate_evaluation_example_from_ordered_commit(
1425 commit,
1426 "",
1427 "hash",
1428 Some(SplitPoint::Index(1)),
1429 Some(1),
1430 None,
1431 );
1432
1433 assert!(result.is_ok());
1434 let case = result.unwrap();
1435
1436 // The edit history should contain the group header (// lines)
1437 // but not the commit metadata
1438 assert!(!case.edit_history.contains("Author:"));
1439 assert!(!case.edit_history.contains("Date:"));
1440 }
1441
1442 #[test]
1443 fn test_position_weight() {
1444 // High weight positions (natural pause points)
1445 assert_eq!(position_weight("foo(", 4), 10); // After '('
1446 assert_eq!(position_weight("a, b", 2), 10); // After ','
1447 assert_eq!(position_weight("x;", 2), 10); // After ';'
1448 assert_eq!(position_weight("a: b", 2), 10); // After ':'
1449 assert_eq!(position_weight("[", 1), 10); // After '['
1450 assert_eq!(position_weight("{", 1), 10); // After '{'
1451
1452 // High weight for closing brackets
1453 assert_eq!(position_weight("foo)", 4), 8); // After ')'
1454 assert_eq!(position_weight("]", 1), 8); // After ']'
1455 assert_eq!(position_weight("}", 1), 8); // After '}'
1456
1457 // High weight at end of identifier
1458 assert_eq!(position_weight("foo ", 3), 8); // End of 'foo' before space
1459 assert_eq!(position_weight("bar(", 3), 8); // End of 'bar' before '('
1460
1461 // Medium weight for operators
1462 assert_eq!(position_weight("a + b", 3), 5); // After '+'
1463 assert_eq!(position_weight("x.", 2), 5); // After '.'
1464 assert_eq!(position_weight("a=b", 2), 5); // After '='
1465
1466 // Medium weight for whitespace
1467 assert_eq!(position_weight("a ", 2), 6); // After space
1468
1469 // Low weight mid-identifier
1470 assert_eq!(position_weight("foobar", 3), 1); // Mid-identifier 'foo|bar'
1471
1472 // Edge cases
1473 assert_eq!(position_weight("", 0), 1); // Empty string
1474 assert_eq!(position_weight("a", 0), 1); // Position 0
1475 }
1476
1477 #[test]
1478 fn test_weighted_select() {
1479 // Test that weighted selection returns correct indices
1480 let weights = vec![1, 10, 1];
1481
1482 // With total weight 12, seed 0 should select index 0
1483 // seed 0 % 12 = 0, cumulative: 1 at idx 0, so returns 0
1484 assert_eq!(weighted_select(&weights, 0), 0);
1485
1486 // seed 1 % 12 = 1, cumulative: 1 at idx 0 (1 < 1 is false), 11 at idx 1 (1 < 11 is true)
1487 assert_eq!(weighted_select(&weights, 1), 1);
1488
1489 // seed 10 % 12 = 10, cumulative: 1, 11 at idx 1 (10 < 11 is true)
1490 assert_eq!(weighted_select(&weights, 10), 1);
1491
1492 // seed 11 % 12 = 11, cumulative: 1, 11 at idx 1 (11 < 11 is false), 12 at idx 2 (11 < 12 is true)
1493 assert_eq!(weighted_select(&weights, 11), 2);
1494
1495 // Empty weights should return 0
1496 let empty: Vec<u32> = vec![];
1497 assert_eq!(weighted_select(&empty, 42), 0);
1498
1499 // Single weight should always return index 0
1500 let single = vec![10];
1501 assert_eq!(weighted_select(&single, 0), 0);
1502 assert_eq!(weighted_select(&single, 100), 0);
1503 }
1504
1505 #[test]
1506 fn test_weighted_split_prefers_natural_boundaries() {
1507 // Test that with different seeds, weighted selection tends to prefer
1508 // positions after punctuation over mid-identifier positions
1509 let text_with_punctuation = "foo(bar, baz)";
1510 let text_mid_identifier = "foobar";
1511
1512 // Position after '(' should have high weight
1513 let weight_after_paren = position_weight(text_with_punctuation, 4);
1514 // Position after ',' should have high weight
1515 let weight_after_comma = position_weight(text_with_punctuation, 8);
1516 // Position mid-identifier should have low weight
1517 let weight_mid_ident = position_weight(text_mid_identifier, 3);
1518
1519 assert!(
1520 weight_after_paren > weight_mid_ident,
1521 "After '(' ({}) should be weighted higher than mid-identifier ({})",
1522 weight_after_paren,
1523 weight_mid_ident
1524 );
1525 assert!(
1526 weight_after_comma > weight_mid_ident,
1527 "After ',' ({}) should be weighted higher than mid-identifier ({})",
1528 weight_after_comma,
1529 weight_mid_ident
1530 );
1531 }
1532
1533 #[test]
1534 fn test_imitate_human_edits_pure_insertion() {
1535 // Source patch is empty (no edits yet)
1536 // Target patch has a pure insertion (adding a new line)
1537 let source = r#"--- a/test.rs
1538+++ b/test.rs
1539@@ -1,2 +1,2 @@
1540 fn main() {
1541 }
1542"#;
1543 let target = r#"--- a/test.rs
1544+++ b/test.rs
1545@@ -1,2 +1,3 @@
1546 fn main() {
1547+ println!("debug");
1548 }
1549"#;
1550
1551 let (new_src, new_tgt, cursor) = imitate_human_edits(source, target, 42);
1552
1553 // Should have transformed the patches
1554 assert_ne!(
1555 new_src, source,
1556 "Source should be modified for pure insertion"
1557 );
1558 assert_ne!(
1559 new_tgt, target,
1560 "Target should be modified for pure insertion"
1561 );
1562 assert!(cursor.is_some(), "Cursor should be set");
1563
1564 // Source should now have a partial addition
1565 let src_patch = Patch::parse_unified_diff(&new_src);
1566 assert!(
1567 src_patch.stats().added > 0,
1568 "Source should have added lines"
1569 );
1570
1571 // Target should have both a deletion (of partial) and addition (of full)
1572 let tgt_patch = Patch::parse_unified_diff(&new_tgt);
1573 assert!(
1574 tgt_patch.stats().removed > 0,
1575 "Target should have removed lines (partial)"
1576 );
1577 assert!(
1578 tgt_patch.stats().added > 0,
1579 "Target should have added lines (full)"
1580 );
1581
1582 // The cursor should be in test.rs
1583 let cursor = cursor.unwrap();
1584 assert_eq!(cursor.file, "test.rs");
1585 }
1586
1587 #[test]
1588 fn test_imitate_human_edits_pure_insertion_empty_source() {
1589 // Source patch has no hunks at all
1590 let source = "";
1591 let target = r#"--- a/test.rs
1592+++ b/test.rs
1593@@ -1,2 +1,3 @@
1594 fn main() {
1595+ println!("hello");
1596 }
1597"#;
1598
1599 let (new_src, _new_tgt, cursor) = imitate_human_edits(source, target, 123);
1600
1601 // Should have created a source patch with partial insertion
1602 assert!(!new_src.is_empty(), "Source should not be empty");
1603 assert!(cursor.is_some(), "Cursor should be set");
1604
1605 let src_patch = Patch::parse_unified_diff(&new_src);
1606 assert!(
1607 src_patch.stats().added > 0,
1608 "Source should have added lines"
1609 );
1610 }
1611
1612 #[test]
1613 fn test_imitate_human_edits_pure_insertion_intermediate_content() {
1614 // Verify the actual intermediate content is a realistic partial typing state
1615 let source = "";
1616 let target = r#"--- a/test.rs
1617+++ b/test.rs
1618@@ -1,2 +1,3 @@
1619 fn main() {
1620+ println!("hello world");
1621 }
1622"#;
1623
1624 // Test with multiple seeds to see different split points
1625 let mut found_partial = false;
1626 for seed in 1..=50 {
1627 let (new_src, new_tgt, cursor) = imitate_human_edits(source, target, seed);
1628
1629 if cursor.is_some() {
1630 let src_patch = Patch::parse_unified_diff(&new_src);
1631 let tgt_patch = Patch::parse_unified_diff(&new_tgt);
1632
1633 // Find the added line in source
1634 for hunk in &src_patch.hunks {
1635 for line in &hunk.lines {
1636 if let PatchLine::Addition(content) = line {
1637 // The partial line should be a prefix of the full line
1638 let full_line = " println!(\"hello world\");";
1639 if content != full_line && full_line.starts_with(content) {
1640 found_partial = true;
1641
1642 // Verify target has the partial as deletion
1643 let mut has_deletion = false;
1644 for tgt_hunk in &tgt_patch.hunks {
1645 for tgt_line in &tgt_hunk.lines {
1646 if let PatchLine::Deletion(del_content) = tgt_line {
1647 if del_content == content {
1648 has_deletion = true;
1649 }
1650 }
1651 }
1652 }
1653 assert!(
1654 has_deletion,
1655 "Target should have deletion of partial line"
1656 );
1657 }
1658 }
1659 }
1660 }
1661 }
1662 }
1663
1664 assert!(
1665 found_partial,
1666 "At least one seed should produce a partial intermediate state"
1667 );
1668 }
1669
1670 #[test]
1671 fn test_imitate_human_edits_inserts_after_last_source_edit() {
1672 // Regression test: intermediate content should appear after the last edit
1673 // in the source patch, not at the position of the first target edit.
1674 // This ensures the diff output correctly imitates human typing order.
1675 //
1676 // The bug was: when source has edits and target has a pure insertion,
1677 // the intermediate content was inserted at tgt_edit_loc.line_index_within_hunk
1678 // (position of first target edit) instead of after the last source edit.
1679 //
1680 // Source patch has edits at lines 1-4, target has a new edit at line 10
1681 // (different location to avoid the "same line" early return)
1682 let source = r#"--- a/test.py
1683+++ b/test.py
1684@@ -1,4 +1,5 @@
1685+import foo
1686 import bar
1687-import old
1688 import baz
1689+import qux
1690"#;
1691 // Target has a pure insertion at a different line (line 10, not overlapping with source)
1692 let target = r#"--- a/test.py
1693+++ b/test.py
1694@@ -10,3 +10,4 @@
1695 def main():
1696+ print("hello world")
1697 pass
1698"#;
1699
1700 // Use a seed that produces a partial result
1701 let (new_src, _new_tgt, cursor) = imitate_human_edits(source, target, 42);
1702
1703 // The function should produce a modified patch
1704 assert!(cursor.is_some(), "Should produce intermediate state");
1705
1706 let src_patch = Patch::parse_unified_diff(&new_src);
1707 let all_additions: Vec<_> = src_patch
1708 .hunks
1709 .iter()
1710 .flat_map(|h| h.lines.iter())
1711 .filter_map(|l| match l {
1712 PatchLine::Addition(s) => Some(s.as_str()),
1713 _ => None,
1714 })
1715 .collect();
1716
1717 // The intermediate content (partial 'print("hello world")') should be
1718 // the LAST addition, appearing after "+import qux" (the last source edit)
1719 let last_addition = all_additions.last().expect("Should have additions");
1720 assert!(
1721 last_addition.trim_start().starts_with("pr"),
1722 "Intermediate content should be the last addition (partial 'print'), but last was: {:?}",
1723 last_addition
1724 );
1725
1726 // Verify the original source edits are still in order before the intermediate
1727 let foo_pos = all_additions.iter().position(|s| *s == "import foo");
1728 let qux_pos = all_additions.iter().position(|s| *s == "import qux");
1729 let intermediate_pos = all_additions
1730 .iter()
1731 .position(|s| s.trim_start().starts_with("pr"));
1732
1733 assert!(foo_pos.is_some(), "Should have 'import foo'");
1734 assert!(qux_pos.is_some(), "Should have 'import qux'");
1735 assert!(
1736 intermediate_pos.is_some(),
1737 "Should have intermediate content"
1738 );
1739
1740 assert!(
1741 foo_pos < qux_pos && qux_pos < intermediate_pos,
1742 "Order should be: foo < qux < intermediate. Got foo={:?}, qux={:?}, intermediate={:?}",
1743 foo_pos,
1744 qux_pos,
1745 intermediate_pos
1746 );
1747 }
1748
1749 #[test]
1750 fn test_cursor_excerpt_with_multibyte_utf8() {
1751 // Test that cursor excerpt handles multi-byte UTF-8 characters correctly
1752 // The Chinese character '第' is 3 bytes (0..3)
1753 let cursor = CursorPosition {
1754 file: "test.md".to_string(),
1755 line: 1,
1756 column: 1, // Byte index 1 is inside '第' (bytes 0..3)
1757 };
1758
1759 let source_patch = r#"--- a/test.md
1760+++ b/test.md
1761@@ -1,1 +1,1 @@
1762+第 14 章 Flask 工作原理与机制解析**
1763"#;
1764
1765 let target_patch = "";
1766
1767 // This should not panic even though column=1 is not a char boundary
1768 let result = get_cursor_excerpt(&cursor, source_patch, target_patch);
1769
1770 // The function should handle the invalid byte index gracefully
1771 if let Some(excerpt) = result {
1772 assert!(
1773 excerpt.contains("<|user_cursor|>"),
1774 "Cursor excerpt should contain marker"
1775 );
1776 // The marker should be placed at a valid character boundary
1777 // (either at the start or after '第')
1778 }
1779 }
1780}