trellis 0.2.0

Template engine for Dart, using natural HTML templates. Fragment-first for hypermedia-driven frameworks like HTMX. Inspired by Thymeleaf.

Changelog

All notable changes to trellis are documented here. This project follows Semantic Versioning.

Format: Keep a Changelog

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0.2.0 — 2026-03-01

Added

• Expression enhancements: arithmetic operators (+ - * / %), literal substitution (|Hello, ${name}!|), dynamic index expressions (${list[index]}), selection expressions (*{field} with tl:object), comparison aliases (gt, lt, ge, le, eq, ne), no-op token (_)
• tl:switch / tl:case: multi-branch conditional rendering
• tl:classappend / tl:styleappend: append to existing class/style attributes
• tl:block: virtual element that renders only its children (no host element in output)
• tl:remove: remove elements or content from output (all, body, tag, all-but-first, none)
• tl:inline: inline expression processing in text, JavaScript, and CSS contexts ([[${expr}]] escaped, [(${expr})] unescaped)
• tl:object / *{}: object context and selection expressions for scoped field access; auto-conversion via toMap()/toJson()
• Parameterized fragments: tl:fragment="card(title, body)" with argument passing at inclusion time
• CSS selector targeting: tl:insert="~{file :: #id}" and tl:insert="~{file :: .class}"
• Cycle detection: fragment inclusion stack replaces depth-only guard — recursive inclusions detected immediately
• renderFragments(): render multiple named fragments from a single template string in one call
• renderFileFragments(): async variant loading from the filesystem
• Strict mode: Trellis(strict: true) — undefined variables, members, and keys throw ExpressionException
• LRU cache: configurable max cache size via maxCacheSize parameter; evicts least-recently-used entries
• CacheStats: expose cache hit/miss/size metrics via engine.cacheStats
• clearCache(): clear DOM cache and reset statistics
• TrellisContext: fluent builder for constructing rendering context maps
• data-tl-* prefix mode: Trellis(prefix: 'data-tl') for strict HTML5-valid attribute names

Fixed

• Expression parser: alias/keyword words (gt, eq, and, true, etc.) now work as member names after . — e.g. ${obj.eq}, ${stats.gt}
• README: corrected TrellisContext example, renderFragments return types, tl:switch case syntax, tl:classappend ternary, maxCacheSize default, removed nonexistent separator parameter

Changed

• Fragment registry entries now carry parameter names for parameterized fragment resolution
• Inclusion depth guard replaced by cycle detection stack (still enforces max depth 32 as hard limit)

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0.1.0 — 2026-02-27

Added

• Core template engine with 15 tl:* attributes for natural HTML templating
• Text substitution: tl:text (escaped) and tl:utext (unescaped HTML)
• Conditionals: tl:if and tl:unless
• Iteration: tl:each with status variables (index, count, size, first, last, odd, even, current)
• Fragment system: tl:fragment, tl:insert, tl:replace with cross-file inclusion
• Local variable binding: tl:with
• Attribute setting: tl:attr, tl:href, tl:src, tl:value, tl:class, tl:id
• Expression evaluator: ${var} variables, @{/url} URL expressions, string literals, ternary, Elvis, comparisons, boolean operators
• Four public API methods: render(), renderFile(), renderFragment(), renderFileFragment()
• DOM caching with deep-clone for performance
• Configurable attribute prefix (default tl)
• FileSystemLoader with security boundary enforcement (path traversal, symlink escape protection)
• MapLoader for in-memory templates and testing
• Typed exception hierarchy: TemplateException, ExpressionException, FragmentNotFoundException, TemplateNotFoundException, TemplateSecurityException

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0.0.1-dev.1

• Name reservation on pub.dev