Compiler

MMO\client\scs · 1 symbol · generated 5 Oct 2026

class

Compiler

The Simple CSS compiler: one instance compiles one stylesheet.

class MMO\client\scs\Compiler

Namespace: MMO\client\scs

It runs the pipeline the language is specified with -- parse, register the definitions, evaluate the compile-time expressions (including the php bridge), expand the reusable styles, resolve the themes, the nesting and the responsive blocks, sort by `@order`, emit css: ```text .scs -> Lexer -> Parser -> ast -> Compiler (+ Evaluator) -> Emitter -> css ``` Applications normally go through [`SCSCompiler`](https://mcp.mmoframework.fr/documentation/mmo.client/php/SCSCompiler.md#scscompiler), the configurable module that owns the options, the authorized php functions and the caching -- this class is what it drives.

$compiler = new Compiler(['screens' => ['tablet' => '768px']]); echo $compiler->compile('@let $s = 16px' . "\n" . '.card {padding: $s}')->css();

Index

	CSS_FUNCTIONS	The css functions a value may call.
	DECLARATION_AT_RULES	at-rules whose body is a declaration block rather than a set of rules
	MAX_DEPTH
	MAX_ITERATIONS	how many times a single `@for` may run, so a mistyped range cannot hang a page
	NESTED_AT_RULES	at-rules whose body holds rules that must not be prefixed by the enclosing selector
	OPTIONS	the options a `@config` instruction is allowed to set
	PAGE_MARGIN_AT_RULES	The sixteen margin boxes of `@page`.
	context
	emitter
	evaluator
	expanding
	files
	functions
	global
	imported
	index
	namespace
	namespaces
	options
	registry
	scopes
	sources
	styles
	themes
	tokens
	atRule($node, $scope, $frame)	A css at-rule the language does not interpret: `@media`, `@supports`, `@keyframes`, `@font-face`...
	bind($params, $args, $parent, $node, $name)	Bind the arguments of a `@style` or a `@fn` call to a new scope.
	callFunction($name, $args, $node, $namespace)	Call an `@fn`.
	callPhp($node, $args, $scope, $selector)	Call an authorized php function (`PhpFunctionRegistry`).
	circular($key, $node)
	compile($source, $filename)	Compile a .scs source.
	component($node, $scope, $frame)	`@component button { ...
	configure($node)	Apply a `@config` instruction.
	context()
	declare($node, $scope, $frame)	Emit a declaration into the frame's rule.
	declareNamespace($filename, $statements, $alias, $merge, $node)	Give a file its namespace, and remember it: from `@namespace`, else from an `as` alias, else from the file name (`lib.scs` holds `lib`), else the anonymous namespace of a source with no name of its…
	define($kind, $namespace, $node)	Register a `@style` or a `@fn` in a namespace.
	emitter()
	error($message, $context, $location, $previous)	Build a located compilation error, with the source line it happened on.
	evaluate($expression, $selector)	Evaluate a single scs expression, without generating any css.
	exec($statements, $scope, $frame)	Execute a list of statements.
	execNode($statement, $scope, $frame)
	execStatement($statement, $scope, $frame)
	hasFunction($name, $namespace)
	hoist($statements)	Step 4 of the pipeline: register `@config`, `@theme` paths, `@style` and `@fn` before anything is generated, so they can be referenced regardless of where they are declared.
	import($node, $directory, $namespace)	Resolve, read and parse an `@import`ed file.
	isCssFunction($name)
	Key($namespace, $name) static
	load($source, $filename)	Parse a source and merge everything it `@import`s, in place.
	lookup($kind, $namespace, $name)	Find a `@style` or a `@fn`: qualified, in the namespace it names; unqualified, in the namespace of the file the reference is written in.
	loop($node, $scope, $frame)	`@for $i in 1..6` / `@for $key:$value in $collection`.
	merge($ast, $directory, $namespace)
	namespaceOf($node)
	NamespaceOfFile($filename) static
	namespaceScope($namespace)
	options()
	query($target, $scope, $frame)	Turn a `@screen` target into a media query.
	registry()
	resolve($path, $directory, $node)
	scope()
	scopeOf($namespace)
	selectors($selector, $frame)	Resolve a (possibly nested) selector against the frame it is declared in.
	split($selector)	Split a selector list on its top level commas (a comma inside `:is(...)` or `[attr=","]` is not one).
	theme($node, $scope, $frame)	`@theme { ... }` -- emit the design tokens as css custom properties.
	themeValue($path)	Resolve a `$path` against the declared design tokens.
	undefined($kind, $namespace, $name, $node)	The error for a reference that resolves to nothing -- naming the namespace the definition really lives in, which is the whole point of writing them down.
	undefinedFunction($name, $node)	The error for a call that resolves to nothing -- an `@fn` of another namespace, or a typo.
	useStyle($node, $scope, $frame)	`@use lib::center` / `@use size(48px, 48px)` -- expand a reusable style in place.
	variableName($path)
	variant($node, $scope, $frame)	`@variant primary { ...
	__construct($options, $context, $registry)

Constants7

CSS_FUNCTIONS

The css functions a value may call. Anything else is reported as an undefined function in strictFunctions mode (the default), which is what catches a misspelled @fn instead of emitting css no browser understands. A vendor prefixed (-webkit-...) or custom (--...) function is always allowed.

const CSS_FUNCTIONS = […114 items]

See: Parser::CSS_FUNCTIONS for the ones whose arguments are additionally kept as written.

DECLARATION_AT_RULES

at-rules whose body is a declaration block rather than a set of rules

const DECLARATION_AT_RULES = […6 items]

MAX_DEPTH

const MAX_DEPTH = 100

MAX_ITERATIONS

how many times a single @for may run, so a mistyped range cannot hang a page

const MAX_ITERATIONS = 100000

NESTED_AT_RULES

at-rules whose body holds rules that must not be prefixed by the enclosing selector

const NESTED_AT_RULES = ['@keyframes', '@-webkit-keyframes']

OPTIONS

the options a @config instruction is allowed to set

const OPTIONS = […10 items]

PAGE_MARGIN_AT_RULES

The sixteen margin boxes of @page. They hold declarations, like @page itself, but they are written *inside* it -- `@page

const PAGE_MARGIN_AT_RULES = […16 items]

{@bottom-center {content: counter(page)}}` -- so the enclosing `@page` becomes a wrapper for them rather than the rule they add to. Read as an ordinary at-rule they wrapped their own parent instead, and `@bottom-center {@page {...}}` is not css any browser or print engine reads.

Properties18

context

protected MMO\client\scs\CompilationContext $context

Type: CompilationContext

emitter

protected MMO\client\scs\Emitter $emitter

Type: Emitter

evaluator

protected MMO\client\scs\Evaluator $evaluator

Type: Evaluator

expanding

protected array $expanding = []

Type: array

files

protected array $files = []

Type: array

functions

protected array $functions = []

Type: array

global

protected MMO\client\scs\Scope $global

Type: Scope

imported

protected array $imported = []

Type: array

index

protected array $index = ['style' => [], 'function' => []]

Type: array

namespace

protected string $namespace = ''

Type: string

namespaces

protected array $namespaces = []

Type: array

options

protected array $options

Type: array

registry

protected MMO\client\scs\PhpFunctionRegistry $registry

Type: PhpFunctionRegistry

scopes

protected array $scopes = []

Type: array

sources

protected array $sources = []

Type: array

styles

protected array $styles = []

Type: array

themes

protected array $themes = []

Type: array

tokens

protected array $tokens = []

Type: array

Methods46

atRule($node, $scope, $frame)

Compiler.php:762

A css at-rule the language does not interpret: @media, @supports, @keyframes, @font-face...

protected function atRule( MMO\client\scs\nodes\AtRuleNode $node, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): void

$node	AtRuleNode
$scope	Scope
$frame	Frame
returns	void

bind($params, $args, $parent, $node, $name)

Compiler.php:1010

Bind the arguments of a @style or a @fn call to a new scope.

protected function bind( array $params, array $args, MMO\client\scs\Scope $parent, MMO\client\scs\nodes\Node $node, string $name ): MMO\client\scs\Scope

$params	array	[['name' => string, 'default' => ?Node], ...]
$args	array
$parent	Scope	the definition's scope
$node	Node	the call, for error reporting
$name	string
returns	Scope

callFunction($name, $args, $node, $namespace)

Compiler.php:945

Call an @fn.

function callFunction( string $name, array $args, MMO\client\scs\nodes\CallNode $node, ?string $namespace = null ): MMO\client\scs\Value

$name	string
$args	array
$node	CallNode
$namespace = null	null \| string	the namespace written before `::`, null for an unqualified call
returns	Value

callPhp($node, $args, $scope, $selector)

Compiler.php:978

Call an authorized php function (PhpFunctionRegistry).

function callPhp( MMO\client\scs\nodes\CallNode $node, array $args, MMO\client\scs\Scope $scope, ?string $selector = null ): MMO\client\scs\Value

$node	CallNode
$args	array
$scope	Scope
$selector = null	null \| string	the resolved selector, given to context-aware functions
returns	Value

circular($key, $node)

Compiler.php:1032

protected function circular(string $key, MMO\client\scs\nodes\Node $node): MMO\client\exceptions\eSCS

$key	string
$node	Node
returns	eSCS

compile($source, $filename)

Compiler.php:155

Compile a .scs source.

function compile(string $source, string $filename = '<scs>'): MMO\client\scs\Result

$source	string
$filename = '<scs>'	string	the source's name, used by `@import` resolution and error reporting
returns	Result
throws		on any compilation error

component($node, $scope, $frame)

Compiler.php:653

@component button { ... } -- a name becomes a selector through the componentSelector option, an explicit selector is used as written.

protected function component( MMO\client\scs\nodes\ComponentNode $node, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): void

$node	ComponentNode
$scope	Scope
$frame	Frame
returns	void

configure($node)

Compiler.php:493

Apply a @config instruction.

protected function configure(MMO\client\scs\nodes\ConfigNode $node): void

$node	ConfigNode
returns	void

context()

Compiler.php:196

function context(): MMO\client\scs\CompilationContext

returns

CompilationContext

declare($node, $scope, $frame)

Compiler.php:637

Emit a declaration into the frame's rule.

protected function declare( MMO\client\scs\nodes\DeclarationNode $node, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): void

$node	DeclarationNode
$scope	Scope
$frame	Frame
returns	void

declareNamespace($filename, $statements, $alias, $merge, $node)

Compiler.php:258

Give a file its namespace, and remember it: from @namespace, else from an as alias, else from the file name (lib.scs holds lib), else the anonymous namespace of a source with no name of its own.

protected function declareNamespace( string $filename, array $statements, ?string $alias = null, ?string $merge = null, ?MMO\client\scs\nodes\Node $node = null ): string

$filename	string
$statements	array	the file's top level statements, read for a `@namespace` instruction
$alias = null	null \| string	the name the importing file registers it under
$merge = null	null \| string	the namespace to merge it into (`@import ... as self`)
$node = null	null \| Node	the `@import` reporting the error
returns	string	the namespace

define($kind, $namespace, $node)

Compiler.php:419

protected function define(string $kind, string $namespace, MMO\client\scs\nodes\Node $node): void

$kind	string	'style' or 'function'
$namespace	string
$node	Node
returns	void

emitter()

Compiler.php:198

function emitter(): MMO\client\scs\Emitter

returns

Emitter

error($message, $context, $location, $previous)

Compiler.php:210

Build a located compilation error, with the source line it happened on.

function error( string $message, array $context = [], ?MMO\client\scs\SourceLocation $location = null, ?Throwable $previous = null ): MMO\client\exceptions\eSCS

$message	string	a `{placeholder}` message
$context = []	array
$location = null	null \| SourceLocation
$previous = null	null \| Throwable
returns	eSCS

evaluate($expression, $selector)

Compiler.php:188

Evaluate a single scs expression, without generating any css.

function evaluate(string $expression, ?string $selector = null): MMO\client\scs\Value

$expression	string	ex: `php::calculatePadding()`, `$spacing`
$selector = null	null \| string	the selector context-aware php functions should see
returns	Value

$compiler->evaluate('$spacing * 2');

exec($statements, $scope, $frame)

Compiler.php:525

Execute a list of statements.

protected function exec( array $statements, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): ?MMO\client\scs\Value

$statements	array
$scope	Scope
$frame	Frame
returns	null \| Value	the value of a `return` statement, when one was reached (inside a `@fn`)

execNode($statement, $scope, $frame)

Compiler.php:544

protected function execNode( MMO\client\scs\nodes\Node $statement, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): ?MMO\client\scs\Value

$statement	Node
$scope	Scope
$frame	Frame
returns	null \| Value

execStatement($statement, $scope, $frame)

Compiler.php:533

protected function execStatement( MMO\client\scs\nodes\Node $statement, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): ?MMO\client\scs\Value

$statement	Node
$scope	Scope
$frame	Frame
returns	null \| Value

hasFunction($name, $namespace)

Compiler.php:920

function hasFunction(string $name, ?string $namespace = null): bool

$name	string
$namespace = null	null \| string	the namespace written before `::`, null for an unqualified call
returns	bool	true when an `@fn` answers to this name here

hoist($statements)

Compiler.php:399

Step 4 of the pipeline: register @config, @theme paths, @style and @fn before anything is generated, so they can be referenced regardless of where they are declared.

protected function hoist(array $statements): void

$statements	array
returns	void

import($node, $directory, $namespace)

Compiler.php:333

Resolve, read and parse an @imported file.

protected function import( MMO\client\scs\nodes\ImportNode $node, string $directory, string $namespace = '' ): array

$node	ImportNode
$directory	string
$namespace = ''	string
returns	array	the imported statements, empty when the file was already imported

isCssFunction($name)

Compiler.php:929

function isCssFunction(string $name): bool

$name	string
returns	bool	true when an unknown function may be emitted as a plain css function

$compiler->isCssFunction('linear-gradient'); // true

Key($namespace, $name)

staticCompiler.php:323

static function Key(string $namespace, string $name): string

$namespace	string
$name	string
returns	string	the key a definition is registered under

load($source, $filename)

Compiler.php:224

Parse a source and merge everything it @imports, in place.

protected function load(string $source, string $filename): array

$source	string
$filename	string
returns	array	the flattened top level statements

lookup($kind, $namespace, $name)

Compiler.php:437

Find a @style or a @fn: qualified, in the namespace it names; unqualified, in the namespace of the file the reference is written in.

protected function lookup(string $kind, ?string $namespace, string $name): ?array

$kind	string	'style' or 'function'
$namespace	null \| string
$name	string
returns	null \| array	the registration, null when nothing declares this name here

loop($node, $scope, $frame)

Compiler.php:715

@for $i in 1..6 / @for $key:$value in $collection.

protected function loop( MMO\client\scs\nodes\ForNode $node, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): ?MMO\client\scs\Value

$node	ForNode
$scope	Scope
$frame	Frame
returns	null \| Value

merge($ast, $directory, $namespace)

Compiler.php:237

protected function merge( MMO\client\scs\nodes\StylesheetNode $ast, string $directory, string $namespace ): array

$ast	StylesheetNode
$directory	string	the directory `@import` paths are relative to
$namespace	string	the namespace of the file being merged, for its `@import ... as self`
returns	array

namespaceOf($node)

Compiler.php:314

protected function namespaceOf(MMO\client\scs\nodes\Node $node): string

$node	Node
returns	string	the namespace the node was written in

NamespaceOfFile($filename)

staticCompiler.php:287

static function NamespaceOfFile(string $filename): string

$filename	string
returns	string	the namespace a file is named after: `parts/buttons.scs` is `buttons`, a source with no usable file name (an inline stylesheet) is the anonymous namespace

namespaceScope($namespace)

Compiler.php:295

function namespaceScope(string $namespace): ?MMO\client\scs\Scope

$namespace	string
returns	null \| Scope	the top level variables of a declared namespace, null when nothing declares it

options()

Compiler.php:200

function options(): array

returns

array

query($target, $scope, $frame)

Compiler.php:873

Turn a @screen target into a media query.

protected function query( MMO\client\scs\nodes\ValueListNode $target, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): string

$target	ValueListNode	`tablet`, `455px`, `(max-width: 600px)` or `print`
$scope	Scope
$frame	Frame
returns	string

registry()

Compiler.php:197

function registry(): MMO\client\scs\PhpFunctionRegistry

returns

PhpFunctionRegistry

resolve($path, $directory, $node)

Compiler.php:374

protected function resolve(string $path, string $directory, MMO\client\scs\nodes\Node $node): string

$path	string
$directory	string
$node	Node
returns	string	the resolved, existing filename
throws		when the file cannot be found

scope()

Compiler.php:199

function scope(): MMO\client\scs\Scope

returns

Scope

scopeOf($namespace)

Compiler.php:303

protected function scopeOf(?string $namespace): MMO\client\scs\Scope

$namespace	null \| string
returns	Scope	the scope holding the top level variables of a namespace

selectors($selector, $frame)

Compiler.php:817

Resolve a (possibly nested) selector against the frame it is declared in.

protected function selectors(string $selector, MMO\client\scs\Frame $frame): array

$selector	string	the rendered selector, ex: `&:hover, .title`
$frame	Frame
returns	array

split($selector)

Compiler.php:839

Split a selector list on its top level commas (a comma inside :is(...) or [attr=","] is not one).

protected function split(string $selector): array

$selector	string
returns	array

theme($node, $scope, $frame)

Compiler.php:682

@theme { ... } -- emit the design tokens as css custom properties.

protected function theme( MMO\client\scs\nodes\ThemeNode $node, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): void

With `emitThemes` off the tokens are still registered -- `$colors.primary` keeps resolving to `var(--colors-primary)` -- but no `:root` rule is generated. That is what lets a stylesheet compiled *inside* a shadow root ([`JHSCompiler`](https://mcp.mmoframework.fr/documentation/mmo.client/php/JHSCompiler.md#jhscompiler)) reference the document's tokens without redeclaring the whole palette in every custom element.

$node	ThemeNode
$scope	Scope
$frame	Frame
returns	void

themeValue($path)

Compiler.php:899

Resolve a $path against the declared design tokens.

function themeValue(string $path): ?MMO\client\scs\Value

$path	string	ex: `colors.primary`
returns	null \| Value	`var(--colors-primary)`, or the token's value in `resolveThemeValues` mode, or null when no theme declares this path

undefined($kind, $namespace, $name, $node)

Compiler.php:451

The error for a reference that resolves to nothing -- naming the namespace the definition really lives in, which is the whole point of writing them down.

protected function undefined( string $kind, ?string $namespace, string $name, MMO\client\scs\nodes\Node $node ): MMO\client\exceptions\eSCS

$kind	string
$namespace	null \| string
$name	string
$node	Node
returns	eSCS

undefinedFunction($name, $node)

Compiler.php:488

The error for a call that resolves to nothing -- an @fn of another namespace, or a typo.

function undefinedFunction(string $name, MMO\client\scs\nodes\CallNode $node): MMO\client\exceptions\eSCS

$name	string
$node	CallNode
returns	eSCS

useStyle($node, $scope, $frame)

Compiler.php:697

@use lib::center / @use size(48px, 48px) -- expand a reusable style in place.

protected function useStyle( MMO\client\scs\nodes\UseNode $node, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): void

$node	UseNode
$scope	Scope
$frame	Frame
returns	void

variableName($path)

Compiler.php:889

protected function variableName(string $path): string

$path	string
returns	string	the css custom property a design token is emitted as

variant($node, $scope, $frame)

Compiler.php:661

@variant primary { ... } -- emitted as {selector}--{variant}.

protected function variant( MMO\client\scs\nodes\VariantNode $node, MMO\client\scs\Scope $scope, MMO\client\scs\Frame $frame ): void

$node	VariantNode
$scope	Scope
$frame	Frame
returns	void

__construct($options, $context, $registry)

Compiler.php:116

function __construct( array $options = [], ?MMO\client\scs\CompilationContext $context = null, ?MMO\client\scs\PhpFunctionRegistry $registry = null )

$options = []	array	`SCSCompiler::DefaultConfig` for the supported keys
$context = null	null \| CompilationContext	the values injected by the php application (`context::name`)
$registry = null	null \| PhpFunctionRegistry	the authorized php callables (`php::name()`)