added Feature::Dedent

Author: dg

src/Latte/Compiler/TemplateParser.php

@@ -15,7 +15,7 @@
 use Latte\Policy;
 use Latte\Runtime\Template;
 use Latte\SecurityViolationException;
-use function array_keys, array_splice, count, end, in_array, preg_match, str_ends_with, str_starts_with, substr, trim, ucfirst;
+use function array_keys, array_splice, count, end, explode, implode, in_array, preg_match, str_ends_with, str_starts_with, strlen, substr, trim, ucfirst;
 
 
 /**
@@ -28,6 +28,7 @@ final class TemplateParser
 	public int $blockLayer = Template::LayerTop;
 	public bool $inHead = true;
 	public bool $strict = false;
+	public bool $dedent = false;
 	public ?Nodes\TextNode $lastIndentation = null;
 
 	/** @var array<string, \Closure(Tag, self): (Node|\Generator|void)> */
@@ -212,6 +213,9 @@ public function parseLatteStatement(?\Closure $resolver = null): ?Node
 				while ($res->valid()) {
 					$this->lookFor[$startTag] = $res->current() ?: null;
 					$content = $this->parseFragment($resolver ?? $this->lastResolver);
+					if ($this->dedent) {
+						$this->applyDedent($content);
+					}
 
 					if (!$this->stream->is(Token::Latte_TagOpen)) {
 						$this->checkEndTag($startTag, null);
@@ -490,4 +494,63 @@ public function isTagAllowed(string $name): bool
 	{
 		return !$this->policy || $this->policy->isTagAllowed($name);
 	}
+
+
+	private function applyDedent(FragmentNode $fragment): void
+	{
+		$baseIndent = null;
+		$atLineStart = true;
+
+		foreach ($fragment->children as $i => $child) {
+			if (!$child instanceof Nodes\TextNode) {
+				$atLineStart = false;
+				continue;
+			}
+
+			$lines = explode("\n", $child->content);
+			$lineCount = count($lines);
+
+			foreach ($lines as $j => &$line) {
+				$isLineStart = $j === 0 ? $atLineStart : true;
+				if (!$isLineStart || $line === '') {
+					continue;
+				}
+
+				$hasContent = trim($line) !== '';
+				$continuesWithExpr = !$hasContent
+					&& $j === $lineCount - 1
+					&& !str_ends_with($child->content, "\n")
+					&& $i + 1 < count($fragment->children);
+
+				if ($baseIndent === null) {
+					if ($hasContent) {
+						preg_match('/^([ \t]+)/', $line, $m);
+						$baseIndent = $m[1] ?? null;
+						if ($baseIndent === null) {
+							return; // first content line has no indent
+						}
+
+					} elseif ($continuesWithExpr) {
+						$baseIndent = $line;
+
+					} else {
+						continue; // blank line before detection
+					}
+
+				} elseif (!str_starts_with($line, $baseIndent)) {
+					if ($hasContent || $continuesWithExpr) {
+						throw new CompileException('Inconsistent indentation.', $child->position ? new Position($child->position->line + $j, 1) : null);
+					}
+
+					continue; // blank line — strip silently
+				}
+
+				$line = substr($line, strlen((string) $baseIndent));
+			}
+
+			unset($line);
+			$child->content = implode("\n", $lines);
+			$atLineStart = str_ends_with($child->content, "\n");
+		}
+	}
 }

src/Latte/Engine.php

@@ -158,6 +158,7 @@ public function parse(string $template): TemplateNode
 		$parser = new Compiler\TemplateParser;
 		$parser->getLexer()->setSyntax($this->syntax);
 		$parser->strict = $this->hasFeature(Feature::StrictParsing);
+		$parser->dedent = $this->hasFeature(Feature::Dedent);
 
 		foreach ($this->extensions as $extension) {
 			$extension->beforeCompile($this);

src/Latte/Feature.php

@@ -24,4 +24,7 @@ enum Feature
 
 	/** Variables from {foreach} exist only within the loop */
 	case ScopedLoopVariables;
+
+	/** Removes structural indentation from paired tag content */
+	case Dedent;
 }

tests/common/dedent.phpt

@@ -0,0 +1,113 @@
+<?php declare(strict_types=1);
+
+/**
+ * Test: Feature::Dedent
+ */
+
+use Tester\Assert;
+
+require __DIR__ . '/../bootstrap.php';
+
+
+function dedent(string $template, array $params = []): string
+{
+	$latte = createLatte();
+	$latte->setFeature(Latte\Feature::Dedent);
+	return $latte->renderToString($template, $params);
+}
+
+
+test('feature disabled by default', function () {
+	$latte = createLatte();
+	Assert::same("    Hello\n", $latte->renderToString("{if true}\n    Hello\n{/if}"));
+});
+
+
+test('basic dedent with spaces', function () {
+	Assert::same("Hello\n", dedent("{if true}\n    Hello\n{/if}"));
+});
+
+
+test('basic dedent with tab', function () {
+	Assert::same("Hello\n", dedent("{if true}\n\tHello\n{/if}"));
+});
+
+
+test('multiple lines', function () {
+	Assert::same("Hello\nWorld\n", dedent("{if true}\n\tHello\n\tWorld\n{/if}"));
+});
+
+
+test('deeper indentation preserved', function () {
+	Assert::same("Hello\n\tIndented\n", dedent("{if true}\n\tHello\n\t\tIndented\n{/if}"));
+});
+
+
+test('nested tags', function () {
+	Assert::same("Hello\n", dedent("{if true}\n\t{if true}\n\t\tHello\n\t{/if}\n{/if}"));
+});
+
+
+test('nested tags with expression', function () {
+	$result = dedent("{if true}\n\t{if true}\n\t\t{=\$x}\n\t{/if}\n{/if}", ['x' => 'val']);
+	Assert::same("val\n", $result);
+});
+
+
+test('if/else branches dedented independently', function () {
+	Assert::same("A\n", dedent("{if true}\n\tA\n{else}\n\tB\n{/if}"));
+	Assert::same("B\n", dedent("{if false}\n\tA\n{else}\n\tB\n{/if}"));
+});
+
+
+test('foreach', function () {
+	$result = dedent("{foreach \$items as \$item}\n\t{\$item}\n{/foreach}", ['items' => ['a', 'b']]);
+	Assert::same("a\nb\n", $result);
+});
+
+
+test('no indentation - no change', function () {
+	Assert::same("Hello\n", dedent("{if true}\nHello\n{/if}"));
+});
+
+
+test('expression on indented line', function () {
+	$result = dedent("{if true}\n\t{=\$x}\n{/if}", ['x' => 'val']);
+	Assert::same("val\n", $result);
+});
+
+
+test('mixed text and expression on same line', function () {
+	$result = dedent("{if true}\n\tHello {=\$x} World\n{/if}", ['x' => 'dear']);
+	Assert::same("Hello dear World\n", $result);
+});
+
+
+test('block tag', function () {
+	Assert::same("Hello\n", dedent("{block test}\n\tHello\n{/block}"));
+});
+
+
+test('capture tag', function () {
+	Assert::same("Hello\n", dedent("{capture \$var}\n\tHello\n{/capture}{\$var}"));
+});
+
+
+test('inconsistent indentation throws exception', function () {
+	Assert::exception(
+		fn() => dedent("{if true}\n\tHello\nWorld\n{/if}"),
+		Latte\CompileException::class,
+		'Inconsistent indentation%a%',
+	);
+});
+
+
+test('inconsistent indentation reports line number', function () {
+	try {
+		dedent("{if true}\n\tHello\nWorld\n{/if}");
+	} catch (Latte\CompileException $e) {
+		Assert::same(3, $e->position->line);
+		return;
+	}
+	Assert::fail('Exception expected');
+});