n:attribute Support in php-to-latte.php

[NoNoNo]

Summary

This PR significantly enhances the php-to-latte.php converter with intelligent n:attribute notation support, conditional attribute handling, and nested if optimization. The converter now produces cleaner, more idiomatic Latte templates.

Changes Overview

1. n:attribute Notation for Control Structures (LattePrinter.php)

Control structures that wrap single HTML elements are now converted to n:attribute notation:

Before:

{if $user}
    <div>{$user->name}</div>
{/if}

After:

<div n:if="$user">{$user->name}</div>

Supported structures:

• {if} → n:if
• {elseif} → n:elseif
• {else} → n:else
• {foreach} → n:foreach
• {for} → n:for
• {while} → n:while
• {try} → n:try

2. Conditional Attributes to n:attr (PhpConverter.php)

PHP templates with conditional output inside HTML attributes are now converted to n:attr notation:

Input:

<input type="text" value="<?php if (isset($a)) { echo $a->b; } ?>" />

Output:

<input type="text" n:attr="value: $a->b" />

Features:

• Supports isset() and !empty() conditions
• Works with property access ($obj->property), array access ($arr['key']), and simple variables
• Each attribute gets its own n:attr (cleaner output)
• Multiple attributes can be processed iteratively

3. Nested If Merging (PhpConverter.php)

Nested if statements are automatically merged into a single condition:

Input:

<?php if ($a) : ?>
    <?php if (isset($b)) : ?>
        <span>...</span>
    <?php endif; ?>
<?php endif; ?>

Output:

<span n:if="$a && isset($b)">...</span>

4. Enhanced String to HTML Conversion (PhpConverter.php)

The stringToHtml() transformation now handles:

• Simple string echoes
• Encapsed strings with embedded variables
• Concatenation expressions (echo '<div>' . $var . '</div>')
• Simple variable and property echoes (echo $user->id)

5. Self-Closing Element Support (LattePrinter.php)

Void/self-closing HTML elements (<input>, <br>, <img>, etc.) are now properly detected for n:attribute conversion even without closing tags.

Files Changed

• src/PhpConverter.php (+694 lines)

  • Added convertConditionalAttributes() - transforms conditional attributes to n:attr
  • Added mergeNestedIfs() - merges nested if statements
  • Enhanced stringToHtml() - better echo to HTML conversion
  • Enhanced expandConcat() - skips concatenations with string literals

• src/LattePrinter.php (+598 lines)

  • Added n:attribute generation for if/elseif/else/try
  • Added n:attribute generation for foreach/for/while
  • Added canGenerateNAttribute*() helpers
  • Added self-closing element detection
  • Added HTML pattern detection for complex elements

• tests/fixtures-php/n-attributes - 9 new tests

Test Results

all pass

Backward Compatibility

The changes are backward compatible - existing conversions that don't match the new patterns continue to work as before. The new features are additive optimizations.

Examples

Example 1: Simple conditional input

<input value="<?php if (isset($name)) echo $name; ?>" />

↓

<input n:attr="value: $name" />

Example 2: Control structure wrapping element

<?php if ($showError) : ?>
    <div class="error">Error!</div>
<?php endif; ?>

↓

<div n:if="$showError" class="error">Error!</div>

Example 3: Nested ifs

<?php if ($enabled) : ?>
    <?php if ($items) : ?>
        <ul>...</ul>
    <?php endif; ?>
<?php endif; ?>

↓

<ul n:if="$enabled && $items">...</ul>

Example 4: Loop with single element

<?php foreach ($users as $user) : ?>
    <li><?php echo $user->name; ?></li>
<?php endforeach; ?>

↓

<li n:foreach="$users as $user">{$user->name}</li>

Example 5: Try-catch with single element

<?php try : ?>
    <div>Success content</div>
<?php catch (Exception $e) : ?>
    <div>Error occurred</div>
<?php endtry; ?>

↓

<div n:try>Success content</div>
<div n:else>Error occurred</div>

Technical Details

AST Transformation Pipeline

The conversion pipeline in PhpConverter::convert() now runs:

1. expandEcho() - Split multiple echoes
2. removeHtmlSpecialChars() - Remove redundant htmlspecialchars
3. expandConcat() - Expand non-HTML concatenations
4. removeHtmlSpecialChars() - Second pass
5. mergeNestedIfs() - Merge nested if statements (NEW)
6. convertConditionalAttributes() - Transform conditional attributes (NEW)
7. stringToHtml() - Convert string echoes to HTML

Pattern Detection

The converter uses AST analysis to detect patterns:

• Single HTML element: One InlineHTML statement
• HTML pattern: Opening tag + content + closing tag (or self-closing)
• Conditional attribute: InlineHTML ending with attr=" + If with isset/!empty + InlineHTML starting with "

Future Improvements

Potential future enhancements:

• Support for n:else with n:attr attributes
• More complex conditional attribute patterns (ternary operators)
• Detection and optimization of {first}/{last} patterns
• Support for n:ifset (Latte 3.x specific)