按提交注释和提交时间比较两个分支的差异，仅列出不同的部分

branch-diff.php

#!/usr/bin/env php
<?php
function usage() {
    global $argv;
    die("Usage: $argv[0] <branch1> <branch2>\n");
}

if ($argc < 3) {
    usage();
}

$branch1 = $argv[1];
$branch2 = $argv[2];

ob_start();
passthru("git log --format='%H %ai [%an] %s' -b ".escapeshellarg($branch1));
$gitLog1 = ob_get_clean();

ob_start();
passthru("git log --format='%H %ai [%an] %s' -b ".escapeshellarg($branch2));
$gitLog2 = ob_get_clean();

$gitLog1 = gitLogToArray($gitLog1, $branch1);
$gitLog2 = gitLogToArray($gitLog2, $branch2);

$gitLog1Size = count($gitLog1);
$gitLog2Size = count($gitLog2);
$maxSize = max($gitLog1Size, $gitLog2Size);


// merge two branch commits
$commentIndex = [];
for ($i=0; $i<$maxSize; $i++) {
    if (isset($gitLog1[$i])) {
        $log = $gitLog1[$i];
        $comment = $log['comment'];

        if (!isset($commentIndex[$comment])) {
            $commentIndex[$comment] = [];
        }
        
        $commentIndex[$comment][] = $log;
    }
    if (isset($gitLog2[$i])) {
        $log = $gitLog2[$i];
        $comment = $log['comment'];

        if (!isset($commentIndex[$comment])) {
            $commentIndex[$comment] = [];
        }

        $commentIndex[$comment][] = $log;
    }
}

// remove the same code base
foreach ($commentIndex as $comment => $commits) {
    $commitCount = count($commits);
    if ($commitCount < 2) {
        continue;
    }

    $hashIndex = [];
    $timeIndex = [];
    foreach ($commits as $commit) {
        $hash = $commit['hash'];
        $time = $commit['date'];
        if (!isset($hashIndex[$hash])) {
            $hashIndex[$hash] = 0;
        }
        if (!isset($timeIndex[$time])) {
            $timeIndex[$time] = 0;
        }
        $hashIndex[$hash]++;
        $timeIndex[$time]++;
    }
    // If all the committing times are exactly the same, they are considered the same commit.
    if (count($timeIndex) > 1) {
        foreach ($hashIndex as $times) {
            // If it is odd, only one branch has a commit for the hash.
            if ($times % 2 != 0) {
                continue 2;
            } 
        }
    }
    // All hashes are evenly times, indicating that both branches have the same commit.
    unset($commentIndex[$comment]);
}

foreach ($commentIndex as $comment => $commits) {
    echo $comment, "\n";

    foreach ($commits as $commit) {
        echo "\t$commit[branch]\t$commit[date]\t$commit[hash]\n";
    }
    echo "\n";
}

function gitLogToArray($lines, $branch) {
    $arr = [];
    $lines = explode("\n", $lines);
    foreach ($lines as $line) {
        $line = trim($line);
        if (empty($line)) {
            continue;
        }
        $hash = substr($line, 0, 40);
        $date = substr($line, 41, 25);
        $comment = substr($line, 67);
        $arr[] = [
            'hash' => $hash,
            'date' => $date,
            'comment' => $comment,
            'branch' => $branch,
        ];
    }
    return $arr;
}