cweagans\Composer\Patches::gatherPatches PHP Method

    public function gatherPatches(PackageEvent $event)
    {
        // If we've already done this, then don't do it again.
        if (isset($this->patches['_patchesGathered'])) {
            $this->io->write('<info>Patches already gathered. Skipping</info>');
            return;
        } elseif (!$this->isPatchingEnabled()) {
            $this->io->write('<info>Patching is disabled. Skipping.</info>');
            return;
        }
        $this->patches = $this->grabPatches();
        if (empty($this->patches)) {
            $this->io->write('<info>No patches supplied.</info>');
        }
        $extra = $this->composer->getPackage()->getExtra();
        $patches_ignore = isset($extra['patches-ignore']) ? $extra['patches-ignore'] : [];
        // Now add all the patches from dependencies that will be installed.
        $operations = $event->getOperations();
        $this->io->write('<info>Gathering patches for dependencies. This might take a minute.</info>');
        foreach ($operations as $operation) {
            if ($operation->getJobType() == 'install' || $operation->getJobType() == 'update') {
                $package = $this->getPackageFromOperation($operation);
                $extra = $package->getExtra();
                if (isset($extra['patches'])) {
                    if (isset($patches_ignore[$package->getName()])) {
                        foreach ($patches_ignore[$package->getName()] as $package => $patches) {
                            if (isset($extra['patches'][$package])) {
                                $extra['patches'][$package] = array_diff($extra['patches'][$package], $patches);
                            }
                        }
                    }
                    $this->patches = array_merge_recursive($this->patches, $extra['patches']);
                }
                // Unset installed patches for this package
                if (isset($this->installedPatches[$package->getName()])) {
                    unset($this->installedPatches[$package->getName()]);
                }
            }
        }
        // Merge installed patches from dependencies that did not receive an update.
        foreach ($this->installedPatches as $patches) {
            $this->patches = array_merge_recursive($this->patches, $patches);
        }
        // If we're in verbose mode, list the projects we're going to patch.
        if ($this->io->isVerbose()) {
            foreach ($this->patches as $package => $patches) {
                $number = count($patches);
                $this->io->write('<info>Found ' . $number . ' patches for ' . $package . '.</info>');
            }
        }
        // Make sure we don't gather patches again. Extra keys in $this->patches
        // won't hurt anything, so we'll just stash it there.
        $this->patches['_patchesGathered'] = TRUE;
    }