From 49f31015ac6a088261d8730f4a8557e342a059ce Mon Sep 17 00:00:00 2001
From: "J. King" <jking@jkingweb.ca>
Date: Sat, 21 Dec 2019 14:53:51 -0500
Subject: [PATCH] Start on character encoding detection

---
 composer.lock                    |  6 +--
 lib/Charset.php                  | 86 ++++++++++++++++++++++++++++++++
 lib/Data.php                     | 22 +++++---
 tests/cases/TestCharset.php      | 48 ++++++++++++++++++
 tests/phpunit.dist.xml           |  1 +
 vendor-bin/phpunit/composer.lock | 10 ++--
 vendor-bin/robo/composer.lock    | 36 ++++++-------
 7 files changed, 177 insertions(+), 32 deletions(-)
 create mode 100644 lib/Charset.php
 create mode 100644 tests/cases/TestCharset.php

diff --git a/composer.lock b/composer.lock
index 44fdaac..33bd1eb 100644
--- a/composer.lock
+++ b/composer.lock
@@ -8,11 +8,11 @@
     "packages": [
         {
             "name": "mensbeam/intl",
-            "version": "0.6.0",
+            "version": "0.7.0",
             "source": {
                 "type": "git",
                 "url": "https://code.mensbeam.com/MensBeam/intl",
-                "reference": "200a310f72b086a63b84c4ca2af3b402852e3cce"
+                "reference": "c4a2ae17142a1846c841c5b5b9246e67d56c568e"
             },
             "require": {
                 "php": "^7.0"
@@ -49,7 +49,7 @@
                 "utf-8",
                 "utf8"
             ],
-            "time": "2019-12-18T19:57:54+00:00"
+            "time": "2019-12-21T01:56:59+00:00"
         }
     ],
     "packages-dev": [
diff --git a/lib/Charset.php b/lib/Charset.php
new file mode 100644
index 0000000..0ca26ad
--- /dev/null
+++ b/lib/Charset.php
@@ -0,0 +1,86 @@
+<?php
+declare(strict_types=1);
+namespace dW\HTML5;
+
+use MensBeam\Intl\Encoding;
+
+abstract class Charset {
+    /** Matches an encoding label (e.g. "utf-8") to a compatible decoder class.
+     * 
+     * @param string $value The encoding label to match
+     */
+    public static function fromCharset(string $value): ?string {
+        $encoding = Encoding::matchLabel($value);
+        if ($encoding) {
+            return $encoding['class'];
+        }
+        return null;
+    }
+
+    /** Extracts an encoding from an HTTP Content-Type header-field
+     * and returns the class name of a compatible decoder.
+     * 
+     * @param string $contentType The value of a Content-Type header-field
+     */
+    public static function fromTransport(string $contentType): ?string {
+        // Try to sniff out a charset from a Content-Type header-field.
+        // This does cut some corners, but should be sufficient for practical use
+        $s = preg_replace("/\s+/", " ", strtolower($contentType));
+        $pos = 0;
+        $end = strlen($s);
+        // skip the type
+        while ($pos < $end && @$s[$pos++] !== "/");
+        // skip the subtype
+        while ($pos < $end && @$s[$pos++] !== ";");
+        // check parameters in sequence
+        while ($pos < $end) {
+            // skip any leading whitespace
+            if (@$s[$pos] === " ") {
+                $pos++;
+            }
+            // collect characters for the parameter name
+            $param = "";
+            while ($pos < $end && @$s[$pos] !== "=") {
+                $param .= @$s[$pos++];
+            }
+            // skip the equals sign
+            $pos++;
+            if ($s[$pos] === '"') {
+                // Value is a quoted-string
+                $pos++;
+                $value = "";
+                while (!in_array($c = @$s[$pos++], ['"', ""])) {
+                    if ($c === "\\") {
+                        $value .= @$s[$pos++];
+                    } else {
+                        $value .= $c;
+                    }
+                }
+                // only interpret the value if a closing quotation mark was seen
+                if ($c !== '"') {
+                    $value = "";
+                }
+            } else {
+                // Value is a bare token
+                $value = "";
+                while (!in_array($c = @$s[$pos++], [';', " ", ""])) {
+                    $value .= $c;
+                }
+            }
+            // if the parameter was the character set, interpret its value and return
+            if ($param === "charset") {
+                $encoding = Encoding::matchLabel($value);
+                if ($encoding) {
+                    return $encoding['class'];
+                } else {
+                    return null;
+                }
+            }
+        }
+        return null;
+    }
+
+    public static function fromPrescan(string $data): ?string {
+        return null;
+    }
+}
diff --git a/lib/Data.php b/lib/Data.php
index 0ca5287..a837535 100644
--- a/lib/Data.php
+++ b/lib/Data.php
@@ -2,11 +2,14 @@
 declare(strict_types=1);
 namespace dW\HTML5;
 
+use MensBeam\Intl\Encoding;
+
 class Data {
     use ParseErrorEmitter;
 
     // Used to get the file path for error reporting.
     public $filePath;
+    public $encodingCertain = false;
 
     // Internal storage for the Intl data object.
     protected $data;
@@ -31,7 +34,7 @@ class Data {
     const WHITESPACE = "\t\n\x0c\x0d ";
 
 
-    public function __construct(string $data, string $filePath = 'STDIN', ParseError $errorHandler = null) {
+    public function __construct(string $data, string $filePath = 'STDIN', ParseError $errorHandler = null, string $encodingOrContentType = '') {
         $this->errorHandler = $errorHandler ?? new ParseError;
         if ($filePath !== 'STDIN') {
             $this->filePath = realpath($filePath);
@@ -40,13 +43,20 @@ class Data {
             $this->filePath = $filePath;
         }
 
-        // DEVIATION: The spec has steps for parsing and determining the character
-        // encoding. At this moment this implementation won't determine a character
-        // encoding and will just assume UTF-8.
-
-        $this->data = new \MensBeam\Intl\Encoding\UTF8($data, false, true);
+        if ($encoding = Charset::fromCharset($encodingOrContentType)) {
+            $this->encodingCertain = true;
+        } elseif ($encoding = Charset::fromTransport($encodingOrContentType)) {
+            $this->encodingCertain = true;
+        } elseif ($encoding = Charset::fromPrescan($data)) {
+            // Encoding is tentative
+        } else {
+            // Encoding is tentative; fall back to windows 1252
+            $encoding = \MensBeam\Intl\Encoding\Windows1252::class;
+        }
+        $this->data = new $encoding($data, false, true);
     }
 
+
     public function consume(int $length = 1, $advancePointer = true): string {
         assert($length > 0, new Exception(Exception::DATA_INVALID_DATA_CONSUMPTION_LENGTH, $length));
 
diff --git a/tests/cases/TestCharset.php b/tests/cases/TestCharset.php
new file mode 100644
index 0000000..3aa9d4f
--- /dev/null
+++ b/tests/cases/TestCharset.php
@@ -0,0 +1,48 @@
+<?php
+declare(strict_types=1);
+namespace dW\HTML5\TestCase;
+
+use dW\HTML5\Charset;
+use MensBeam\Intl\Encoding\UTF8;
+use MensBeam\Intl\Encoding\Windows1252;
+
+/** 
+ * @covers \dW\HTML5\Charset
+ */
+class TestCharset extends \PHPUnit\Framework\TestCase {
+    /** @dataProvider provideCharsets */
+    public function testDetermineEncodingFromEncodingLabel(string $in, ?string $exp) {
+        $this->assertSame($exp, Charset::fromCharset($in));
+    }
+
+    public function provideCharsets() {
+        return [
+            ["UTF-8",                   UTF8::class],
+            ["  utf8  ",                UTF8::class],
+            ["ISO-8859-1",              Windows1252::class],
+            ["text/html; charset=utf8", null],
+        ];
+    }
+
+    /** @dataProvider provideContentTypes */
+    public function testDetermineEncodingFromContentType(string $in, ?string $exp) {
+        $this->assertSame($exp, Charset::fromTransport($in));
+    }
+
+    public function provideContentTypes() {
+        return [
+            ["UTF-8",                                          null],
+            ["charset=utf8",                                   null],
+            ["text/html",                                      null],
+            ["text/html charset=utf8",                         null],
+            ["text/html; charset=utf8",                        UTF8::class],
+            ["text/html;charset=utf8",                         UTF8::class],
+            ["text/html; charset=\"utf8\"",                    UTF8::class],
+            ["image/svg+xml; param=value; charset=utf8",       UTF8::class],
+            ["image/svg+xml; charset=utf8; charset=big5",      UTF8::class],
+            ["image/svg+xml; charset=utf8;charset=big5",       UTF8::class],
+            ["text/html; charset=not-valid; charset=big5",     null],
+            ["text/html; charset=not-valid",                   null],
+        ];
+    }
+}
diff --git a/tests/phpunit.dist.xml b/tests/phpunit.dist.xml
index 74352ed..4befd79 100644
--- a/tests/phpunit.dist.xml
+++ b/tests/phpunit.dist.xml
@@ -17,6 +17,7 @@
 
 <testsuites>
     <testsuite name="Tokenizer">
+        <file>cases/TestCharset.php</file>
         <file>cases/TestTokenizer.php</file>
     </testsuite>
 </testsuites>
diff --git a/vendor-bin/phpunit/composer.lock b/vendor-bin/phpunit/composer.lock
index e45897e..25d6484 100644
--- a/vendor-bin/phpunit/composer.lock
+++ b/vendor-bin/phpunit/composer.lock
@@ -266,16 +266,16 @@
         },
         {
             "name": "phpdocumentor/reflection-docblock",
-            "version": "4.3.2",
+            "version": "4.3.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionDocBlock.git",
-                "reference": "b83ff7cfcfee7827e1e78b637a5904fe6a96698e"
+                "reference": "2ecaa9fef01634c83bfa8dc1fe35fb5cef223a62"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/b83ff7cfcfee7827e1e78b637a5904fe6a96698e",
-                "reference": "b83ff7cfcfee7827e1e78b637a5904fe6a96698e",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/2ecaa9fef01634c83bfa8dc1fe35fb5cef223a62",
+                "reference": "2ecaa9fef01634c83bfa8dc1fe35fb5cef223a62",
                 "shasum": ""
             },
             "require": {
@@ -313,7 +313,7 @@
                 }
             ],
             "description": "With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.",
-            "time": "2019-09-12T14:27:41+00:00"
+            "time": "2019-12-20T13:40:23+00:00"
         },
         {
             "name": "phpdocumentor/type-resolver",
diff --git a/vendor-bin/robo/composer.lock b/vendor-bin/robo/composer.lock
index 00ebcfe..d87acb6 100644
--- a/vendor-bin/robo/composer.lock
+++ b/vendor-bin/robo/composer.lock
@@ -763,16 +763,16 @@
         },
         {
             "name": "symfony/console",
-            "version": "v4.4.1",
+            "version": "v4.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "f0aea3df20d15635b3cb9730ca5eea1c65b7f201"
+                "reference": "82437719dab1e6bdd28726af14cb345c2ec816d0"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/f0aea3df20d15635b3cb9730ca5eea1c65b7f201",
-                "reference": "f0aea3df20d15635b3cb9730ca5eea1c65b7f201",
+                "url": "https://api.github.com/repos/symfony/console/zipball/82437719dab1e6bdd28726af14cb345c2ec816d0",
+                "reference": "82437719dab1e6bdd28726af14cb345c2ec816d0",
                 "shasum": ""
             },
             "require": {
@@ -835,11 +835,11 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2019-12-01T10:06:17+00:00"
+            "time": "2019-12-17T10:32:23+00:00"
         },
         {
             "name": "symfony/event-dispatcher",
-            "version": "v4.4.1",
+            "version": "v4.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/event-dispatcher.git",
@@ -967,7 +967,7 @@
         },
         {
             "name": "symfony/filesystem",
-            "version": "v4.4.1",
+            "version": "v4.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
@@ -1017,7 +1017,7 @@
         },
         {
             "name": "symfony/finder",
-            "version": "v4.4.1",
+            "version": "v4.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/finder.git",
@@ -1241,16 +1241,16 @@
         },
         {
             "name": "symfony/process",
-            "version": "v4.4.1",
+            "version": "v4.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/process.git",
-                "reference": "51c0135ef3f44c5803b33dc60e96bf4f77752726"
+                "reference": "b84501ad50adb72a94fb460a5b5c91f693e99c9b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/process/zipball/51c0135ef3f44c5803b33dc60e96bf4f77752726",
-                "reference": "51c0135ef3f44c5803b33dc60e96bf4f77752726",
+                "url": "https://api.github.com/repos/symfony/process/zipball/b84501ad50adb72a94fb460a5b5c91f693e99c9b",
+                "reference": "b84501ad50adb72a94fb460a5b5c91f693e99c9b",
                 "shasum": ""
             },
             "require": {
@@ -1286,7 +1286,7 @@
             ],
             "description": "Symfony Process Component",
             "homepage": "https://symfony.com",
-            "time": "2019-11-28T13:33:56+00:00"
+            "time": "2019-12-06T10:06:46+00:00"
         },
         {
             "name": "symfony/service-contracts",
@@ -1348,16 +1348,16 @@
         },
         {
             "name": "symfony/yaml",
-            "version": "v4.4.1",
+            "version": "v4.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/yaml.git",
-                "reference": "76de473358fe802578a415d5bb43c296cf09d211"
+                "reference": "a08832b974dd5fafe3085a66d41fe4c84bb2628c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/yaml/zipball/76de473358fe802578a415d5bb43c296cf09d211",
-                "reference": "76de473358fe802578a415d5bb43c296cf09d211",
+                "url": "https://api.github.com/repos/symfony/yaml/zipball/a08832b974dd5fafe3085a66d41fe4c84bb2628c",
+                "reference": "a08832b974dd5fafe3085a66d41fe4c84bb2628c",
                 "shasum": ""
             },
             "require": {
@@ -1403,7 +1403,7 @@
             ],
             "description": "Symfony Yaml Component",
             "homepage": "https://symfony.com",
-            "time": "2019-11-12T14:51:11+00:00"
+            "time": "2019-12-10T10:33:21+00:00"
         }
     ],
     "packages-dev": [],