commit 6c081f3aff64689ed3b77bfeec1d2e0005fe5286
Author: Evgeny Zinoviev <me@ch1p.io>
Date:   Thu Jul 7 20:31:22 2022 +0300

    initial

diff --git a/.gitignore b/.gitignore
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index 0000000..485dee6
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.idea
diff --git a/README.md b/README.md
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index 0000000..a27e6f0
--- /dev/null
+++ b/README.md
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+# pure_php_templates
+
+This isn't a ready-to-use library but rather a concept of native php templates with:
+- transparent string escaping
+- ability to "include" other templates
+- conditions and loops support
+
+PHP 8+ is required (it is not strictly necessary, but named arguments makes code much easier to write and understand).
+
+
+## License
+
+GPLv3
\ No newline at end of file
diff --git a/htdocs/index.php b/htdocs/index.php
new file mode 100644
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--- /dev/null
+++ b/htdocs/index.php
@@ -0,0 +1,28 @@
+<?php
+
+set_include_path(
+    get_include_path().PATH_SEPARATOR.realpath(__DIR__.'/..'));
+
+error_reporting(E_ALL);
+ini_set('display_errors', 1);
+
+spl_autoload_register(function($class) {
+    $path = __DIR__.'/../lib/'.$class.'.php';
+    if (is_file($path))
+        require_once $path;
+});
+
+SkinContext::setRootDirectory(realpath(__DIR__.'/../skin'));
+
+$skin = new Skin();
+$skin->title = 'hello world!';
+
+$cities = [
+    'Moscow',
+    'St. Petersburg',
+    '<b>New York</b>' // potential xss
+];
+echo $skin->renderPage('main/index',
+    name: "John",
+    show_cities: true,
+    cities: $cities);
diff --git a/lib/Skin.php b/lib/Skin.php
new file mode 100644
index 0000000..e04aa5b
--- /dev/null
+++ b/lib/Skin.php
@@ -0,0 +1,19 @@
+<?php
+
+class Skin {
+
+    public string $title = 'no title';
+
+    public function renderPage($f, ...$vars): string {
+        $f = str_replace('/', '\\', $f);
+        $ctx = new SkinContext(substr($f, 0, ($pos = strrpos($f, '\\'))));
+        $body = call_user_func_array([$ctx, substr($f, $pos+1)], $vars);
+
+        $layout_ctx = new SkinContext('base');
+        return $layout_ctx->layout(
+            title: $this->title,
+            unsafe_body: $body,
+        );
+    }
+
+}
diff --git a/lib/SkinContext.php b/lib/SkinContext.php
new file mode 100644
index 0000000..b4192c3
--- /dev/null
+++ b/lib/SkinContext.php
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+<?php
+
+class SkinContext {
+
+    protected string $ns;
+    protected array $data = [];
+    protected static ?string $root = null;
+
+    public static function setRootDirectory(string $root): void {
+        self::$root = $root;
+    }
+
+    public function __construct(string $namespace) {
+        $this->ns = $namespace;
+        require_once self::$root.'/'.str_replace('\\', '/', $namespace).'.skin.php';
+    }
+
+    public function __call($name, array $arguments) {
+        $plain_args = array_is_list($arguments);
+
+        $fn = '\\skin\\'.$this->ns.'\\'.$name;
+        $refl = new ReflectionFunction($fn);
+        $fparams = $refl->getParameters();
+        assert(count($fparams) == count($arguments)+1, "$fn: invalid number of arguments (".count($fparams)." != ".(count($arguments)+1).")");
+
+        foreach ($fparams as $n => $param) {
+            if ($n == 0)
+                continue; // skip $ctx
+
+            $key = $plain_args ? $n-1 : $param->name;
+            if (!$plain_args && !array_key_exists($param->name, $arguments))
+                throw new InvalidArgumentException('argument '.$param->name.' not found');
+
+            if (is_string($arguments[$key]) || $arguments[$key] instanceof SkinString) {
+                if (is_string($arguments[$key]))
+                    $arguments[$key] = new SkinString($arguments[$key]);
+
+                if (($pos = strpos($param->name, '_')) !== false) {
+                    $mod_type = match(substr($param->name, 0, $pos)) {
+                        'unsafe' => SkinStringModificationType::RAW,
+                        'urlencoded' => SkinStringModificationType::URL,
+                        default => SkinStringModificationType::HTML
+                    };
+                } else {
+                    $mod_type = SkinStringModificationType::HTML;
+                }
+                $arguments[$key]->setModType($mod_type);
+            }
+        }
+
+        array_unshift($arguments, $this);
+        return call_user_func_array($fn, $arguments);
+    }
+
+    public function __get(string $name) {
+        $fn = '\\skin\\'.$this->ns.'\\'.$name;
+        if (function_exists($fn))
+            return [$this, $name];
+
+        if (array_key_exists($name, $this->data))
+            return $this->data[$name];
+    }
+
+    public function __set(string $name, $value) {
+        $this->data[$name] = $value;
+    }
+
+    public function if_not($cond, $callback, ...$args) {
+        return $this->_if_condition(!$cond, $callback, ...$args);
+    }
+
+    public function if_true($cond, $callback, ...$args) {
+        return $this->_if_condition($cond, $callback, ...$args);
+    }
+
+    public function if_then_else($cond, $cb1, $cb2) {
+        return $cond ? $this->_return_callback($cb1) : $this->_return_callback($cb2);
+    }
+
+    protected function _if_condition($condition, $callback, ...$args) {
+        if ($condition)
+            return $this->_return_callback($callback, $args);
+        return '';
+    }
+
+    protected function _return_callback($callback, $args = []) {
+        if (is_callable($callback))
+            return call_user_func_array($callback, $args);
+        else if (is_string($callback))
+            return $callback;
+    }
+
+    public function for_each(array $iterable, callable $callback) {
+        $html = '';
+        foreach ($iterable as $k => $v)
+            $html .= call_user_func($callback, $v, $k);
+        return $html;
+    }
+
+}
diff --git a/lib/SkinString.php b/lib/SkinString.php
new file mode 100644
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--- /dev/null
+++ b/lib/SkinString.php
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+<?php
+
+class SkinString implements Stringable {
+
+    protected SkinStringModificationType $modType;
+
+    public function __construct(protected string $string) {}
+
+    public function setModType(SkinStringModificationType $modType) {
+        $this->modType = $modType;
+    }
+
+    public function __toString(): string {
+        return match ($this->modType) {
+            SkinStringModificationType::HTML => htmlspecialchars($this->string, ENT_QUOTES, 'UTF-8'),
+            SkinStringModificationType::URL => urlencode($this->string),
+            default => $this->string,
+        };
+    }
+
+}
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diff --git a/lib/SkinStringModificationType.php b/lib/SkinStringModificationType.php
new file mode 100644
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--- /dev/null
+++ b/lib/SkinStringModificationType.php
@@ -0,0 +1,7 @@
+<?php
+
+enum SkinStringModificationType {
+    case RAW;
+    case URL;
+    case HTML;
+}
\ No newline at end of file
diff --git a/skin/base.skin.php b/skin/base.skin.php
new file mode 100644
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--- /dev/null
+++ b/skin/base.skin.php
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+<?php
+
+namespace skin\base;
+
+function layout($ctx, $title, $unsafe_body) {
+return <<<HTML
+<!doctype html>
+<html lang="en">
+    <body>
+        <title>{$title}</title>
+    </body>
+    <body>{$unsafe_body}</body>
+</html>
+HTML;
+}
diff --git a/skin/main.skin.php b/skin/main.skin.php
new file mode 100644
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--- /dev/null
+++ b/skin/main.skin.php
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+<?php
+
+namespace skin\main;
+
+function index($ctx, $name, $show_cities, $cities) {
+return <<<HTML
+    Hello, {$name}!<br/>
+    
+    {$ctx->if_true($show_cities, 'line of truth<br/>')}
+    {$ctx->if_not(false, $ctx->renderIfFalse, '<b>safe<b>', '<b>unsafe<b>')}
+    
+    <ul>
+        {$ctx->for_each($cities, fn($city, $i) => $ctx->renderIndexCityItem($city, $i+1))}
+    </ul>
+HTML;
+}
+
+function renderIndexCityItem($ctx, $city, $index) {
+return <<<HTML
+    <li>{$index} {$city}</li>
+HTML;
+}
+
+function renderIfFalse($ctx, $str, $unsafe_str) {
+return <<<HTML
+safe: $str<br/>
+unsafe: $unsafe_str
+HTML;
+}
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