Add label matcher

CHANGELOG

@@ -1,9 +1,9 @@
-Version 0.6.0 (2019-12-18)
+Version 0.7.0 (2019-12-20)
 ==========================
 
 New features:
-- Added $allowSurrogates parameter to Encoding constructor
-- Added posErr public instance property to Encoding
+- Added \MensBeam\Intl\Encoding abstract class with createDecoder() and
+  matchLabel() static methods
 
 Version 0.5.0 (2019-12-13)
 ==========================

tools/mkindex.php

@@ -1,4 +1,7 @@
 <?php
+// This script produces the index lookup tables
+//  for a given encoding from the source data at WHATWG
+
 $labels = [
     'big5'                => "big5",
     //'euc-jp'              => "eucjp",
@@ -160,6 +163,7 @@ function make_decoder_point_array(array $entries): string {
 
 function make_decoder_char_array(array $entries): string {
     $out = [];
+    $i = 0;
     foreach ($entries as $match) {
         $index = (int) $match[1];
         $code = $match[2];

tools/mklabels.php

@@ -0,0 +1,40 @@
+<?php
+// this script read and names and labels from each concrete 
+// class in the Encoding set and generates tables mapping labels 
+// to names and names to classes
+
+use MensBeam\Intl\Encoding\Encoding;
+
+define("BASE", dirname(__DIR__).DIRECTORY_SEPARATOR);
+require_once BASE."vendor".DIRECTORY_SEPARATOR."autoload.php";
+
+$ns = "\\MensBeam\\Intl\\Encoding\\";
+$labels = [];
+$names = [];
+foreach (new \GlobIterator(BASE."/lib/Encoding/*.php", \FilesystemIterator::CURRENT_AS_PATHNAME) as $file) {
+    $file = basename($file, ".php");
+    $className = $ns.$file;
+    $class = new \ReflectionClass($className);
+    if ($class->implementsInterface(Encoding::class) && $class->isInstantiable()) {
+        $name = $class->getConstant("NAME");
+        $names[$name] = $className;
+        foreach ($class->getConstant("LABELS") as $label) {
+            $labels[$label] = $name;
+        }
+    }
+}
+
+$labelList = [];
+foreach ($labels as $k => $v) {
+    $labelList[] = "'$k'=>\"$v\"";
+}
+$labelList = "const LABEL_MAP = [".implode(",", $labelList)."];";
+
+$nameList = [];
+foreach ($names as $k => $v) {
+    $nameList[] = "'$k'=>$v::class";
+}
+$nameList = "const NAME_MAP = [".implode(",", $nameList)."];";
+
+echo "$labelList\n";
+echo "$nameList\n";