Working state handling composer.json and .lock files

Author: balbuf

merge.php

@@ -0,0 +1,163 @@
+#!/usr/bin/env php
+<?php
+
+define('CONFLICT_PLACEHOLDER', '=c=o=n=f=(\d+)=l=i=c=t=');
+define('JSON_ENCODE_OPTIONS', JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE);
+// file states
+$states = ['ancestor', 'ours', 'theirs'];
+// unique object that represents a void
+$void = (object) [];
+// conflicts we have identified
+$conflicts = [];
+// options for json encode
+$markerLen = $argv[4];
+
+// grab the contents of each file state
+foreach ($states as $i => $state) {
+	// read and parse the composer file
+	$$state = json_decode(file_get_contents($argv[$i + 1]), true);
+
+	// check for malformed json
+	if (json_last_error() !== JSON_ERROR_NONE || !is_array($$state)) {
+		exit(1);
+	}
+}
+
+// determine whether an array is assoc
+function isAssoc($array) {
+	return array_keys($array) !== range(0, count($array) - 1);
+}
+
+// create an auto-incrementing conflict placeholder
+function conflictPlaceholder($ours, $theirs) {
+	global $conflicts;
+	$conflicts[] = [$ours, $theirs];
+	return str_replace('(\d+)', count($conflicts) - 1, CONFLICT_PLACEHOLDER);
+}
+
+// merge a set of assoc arrays
+function merge($ancestor, $ours, $theirs) {
+	global $states, $void, $conflict;
+
+	// get the unique union of all keys from theirs and ours
+	$keys = array_keys($ours + $theirs);
+
+	// reconcile each key
+	foreach ($keys as $key) {
+		// get the value of this key from each state
+		foreach ($states as $state) {
+			${rtrim($state, 's') . 'Value'} = is_array($$state) && array_key_exists($key, $$state) ? ${$state}[$key] : $void;
+		}
+
+		// same value? or theirs was the same as the ancestor? all good!
+		if ($ourValue === $theirValue || $theirValue === $ancestorValue) {
+			continue;
+		}
+
+		// is their value newer? (i.e. ours is the same as the ancestor)
+		if ($ourValue === $ancestorValue) {
+			// is this key absent in theirs?
+			if ($theirValue === $void) {
+				unset($ours[$key]);
+			} else {
+				$ours[$key] = $theirValue;
+			}
+		}
+		// are both values arrays?
+		else if (is_array($ourValue) && is_array($theirValue)) {
+			// are the arrays both assoc or both non-assoc?
+			if (($isAssoc = isAssoc($ourValue)) === isAssoc($theirValue)) {
+				// are they both assoc?
+				if ($isAssoc) {
+					$ours[$key] = merge($ancestorValue, $ourValue, $theirValue);
+				}
+				// both non-assoc
+				else {
+					// @todo provide option to merge these arrays?
+					$ours[$key] = conflictPlaceholder($ourValue, $theirValue);
+				}
+			}
+			// one is assoc, the other is non-assoc - that's a conflict!
+			else {
+				$ours[$key] = conflictPlaceholder($ourValue, $theirValue);
+			}
+		}
+		// differing values - we have a conflict!
+		else {
+			$ours[$key] = conflictPlaceholder($ourValue, $theirValue);
+		}
+	}
+
+	return $ours;
+}
+
+// special handling for lock files
+if (strtolower($argv[5]) === 'composer.lock') {
+	$packageKeys = ['packages', 'packages-dev', 'aliases'];
+
+	foreach ($states as $state) {
+		// ensure we don't get a conflict on the content hash
+		${$state}['content-hash'] = null;
+
+		// convert package array to assoc array, mapping package name to json-encoded package definition
+		foreach ($packageKeys as $key) {
+			$newArray = [];
+			foreach (${$state}[$key] as $package) {
+				// @todo this is different for alias
+				$newArray[$package['name']] = json_encode($package);
+			}
+			${$state}[$key] = $newArray;
+		}
+	}
+
+	// perform the merge
+	$merged = merge($ancestor, $ours, $theirs);
+
+	// convert the package arrays back
+	foreach ($packageKeys as $key) {
+		// sort the packages
+		ksort($merged[$key]);
+
+		$newArray = [];
+		foreach ($merged[$key] as $package) {
+			// if we have a conflict, convert the conflicting values back to package definition arrays
+			if (preg_match('/^' . CONFLICT_PLACEHOLDER . '$/', $package, $matches)) {
+				$conflicts[$matches[1]] = array_map(function($json) {
+					return json_decode($json, true);
+				}, $conflicts[$matches[1]]);
+				$newArray[] = $package;
+			}
+			// otherwise just convert the value back to a package definition array
+			else {
+				$newArray[] = json_decode($package, true);
+			}
+		}
+		$merged[$key] = $newArray;
+	}
+
+	// update the content-hash key
+	$merged['content-hash'] = (count($conflicts) ? 'Merge conflict!' : 'Auto-merged!') . ' Run `composer update --lock` to regenerate';
+
+	$merged = json_encode($merged, JSON_ENCODE_OPTIONS);
+} else {
+	$merged = json_encode(merge($ancestor, $ours, $theirs), JSON_ENCODE_OPTIONS);
+}
+
+// if we have conflicts, replace the conflict markers with the actual conflicting values
+if (count($conflicts)) {
+	$merged = preg_replace_callback('/^(\s+)(.+)"' . CONFLICT_PLACEHOLDER . '"(,?)$/m', function ($matches) use ($conflicts, $markerLen) {
+		list(, $space, $property, $conflictNum, $comma) = $matches;
+		// replace the conflict placeholder with theirs/ours values surrounded by conflict markers
+		return str_repeat('<', $markerLen) . " HEAD\n"
+			. $space . $property . preg_replace('/\n/', "\n$space", json_encode($conflicts[$conflictNum][1], JSON_ENCODE_OPTIONS)) . $comma . "\n"
+			. str_repeat('=', $markerLen) . "\n"
+			. $space . $property . preg_replace('/\n/', "\n$space", json_encode($conflicts[$conflictNum][0], JSON_ENCODE_OPTIONS)) . $comma . "\n"
+			. str_repeat('>', $markerLen);
+	}, $merged);
+}
+
+// update the file
+file_put_contents($argv[2], $merged . "\n");
+
+// determine exit status based on whether there were conflicts
+exit(count($conflicts) ? 1 : 0);