git-co: batch Levenshtein calculations into a single python3 call

[Copilot]

_find_branches_by_levenshtein() spawned one python3 process per branch — O(n) process forks for n branches.

Changes

• Removed _levenshtein_distance() entirely
• Rewrote _find_branches_by_levenshtein() to pipe all branch names to a single python3 -c '...' invocation that computes, sorts, and filters all distances at once

echo "$all_branches" | python3 -c '
...
branches = [line.strip() for line in sys.stdin if line.strip()]
results = sorted([(levenshtein(input_str, b), b) for b in branches], key=lambda x: x[0])
for dist, branch in results:
    if dist <= max_dist:
        print(branch)
' "$input" "$max_distance"

Note: The python3 - <<'PYEOF' pattern from the issue spec is broken — the heredoc wins the stdin race and the piped branch data is silently discarded. Using python3 -c '...' keeps the script inline and leaves stdin available for the pipe.

Original prompt

git-co: batch Levenshtein calculations into a single python3 call

File to modify: git-co

Problem

_find_branches_by_levenshtein() calls _levenshtein_distance() once per branch in a while loop. Each call spawns a new python3 process, which is expensive — on a repo with 50 branches this spawns 50 Python processes.

Fix

Rewrite _levenshtein_distance() and _find_branches_by_levenshtein() so that all branch distances are computed in a single python3 invocation.

Replace both functions with the following:

_find_branches_by_levenshtein() {
  local input="$1"
  local all_branches="$2"
  local max_distance="${3:-5}"

  # Compute all Levenshtein distances in a single python3 call
  echo "$all_branches" | python3 - "$input" "$max_distance" <<'PYEOF'
import sys

def levenshtein(s1, s2):
    s1, s2 = s1.lower(), s2.lower()
    if len(s1) < len(s2):
        s1, s2 = s2, s1
    if len(s2) == 0:
        return len(s1)
    previous_row = range(len(s2) + 1)
    for i, c1 in enumerate(s1):
        current_row = [i + 1]
        for j, c2 in enumerate(s2):
            current_row.append(min(
                previous_row[j + 1] + 1,
                current_row[j] + 1,
                previous_row[j] + (c1 != c2)
            ))
        previous_row = current_row
    return previous_row[-1]

input_str = sys.argv[1]
max_dist = int(sys.argv[2])
branches = [line.strip() for line in sys.stdin if line.strip()]
results = sorted(
    [(levenshtein(input_str, b), b) for b in branches],
    key=lambda x: x[0]
)
for dist, branch in results:
    if dist <= max_dist:
        print(branch)
PYEOF
}

Also remove the now-unused _levenshtein_distance() function entirely.

Update the call site in _find_similar_branches() — the call _find_branches_by_levenshtein "$input" "$all_branches" "$max_distance" remains the same, no changes needed there.

No other changes.

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data:
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      url: https://github.com/mlutonsky/utils/pulls
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      url: https://github.com/mlutonsky/utils/pulls
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      url: https://github.com/mlutonsky/utils/pulls
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      url: https://github.com/mlutonsky/utils/pulls
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[Copilot]

Pull request overview

Optimizes git-co’s fuzzy branch matching by batching Levenshtein distance computations into a single Python invocation instead of spawning one python3 process per branch.

Changes:

• Removed the per-branch _levenshtein_distance() helper.
• Rewrote _find_branches_by_levenshtein() to compute/sort distances in one python3 -c call fed by stdin.

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