CssValue

#include <Ultralight/dom/StyleValue.h>

Overview

Compile-time wrapper for CSS string literals assigned to element styles.

CssValue wraps CSS string literals assigned to inline styles, which the library parses when written. It checks the literal at compile time to catch mistyped numbers and units before your code runs.

String literals convert to CssValue on their own when assigned to style properties:

hud.style.width = "50%";       // a number: checked when you compile
hud.style.margin = "0 auto";   // other CSS: parsed when it's written
hud.style.fontSize = "12pt";   // a unit StyleValue doesn't have: parsed when it's written
// hud.style.width = "50pxx";  // a typo: compile error

Strings Built at Run Time

Style properties provide a separate overload for dynamic values, parsing the CSS text when it's written.

Wrap a char array filled at run time in std::string_view so the compiler doesn't treat the buffer as a string literal and fail to compile:

char text[16];
std::snprintf(text, sizeof(text), "%dpx", bar_width);
hud.style.width = std::string_view(text);

Note

On older MSVC toolsets (before Visual Studio 2026), a mistyped literal causes a compile error only in a constant expression. In ordinary style writes, it's ignored when written.

See also

dom::StyleValue, dom::Element::style

Public Types
enum class	Kind : uint8_t { Passthrough = 0 , Numeric }
	How the literal is written– either parsed as a number at compile time (Numeric) or passed to the library's CSS parser as text (Passthrough). More...

Public Member Functions
template<size_t N>
UL_CSS_CONSTEVAL	CssValue (const char(&s)[N])
	Capture a string literal and parse it at compile time.
constexpr Kind	kind () const
	Get how the literal is written (see Kind).
constexpr double	value () const
	Get the parsed number (only meaningful when kind() is Kind::Numeric).
constexpr StyleUnit	unit () const
	Get the parsed unit (only meaningful when kind() is Kind::Numeric).
constexpr const char *	text () const
	Get the literal's text as written (null-terminated).
constexpr size_t	length () const
	Get the literal's length in bytes.

Member Enumeration Documentation

Kind

enum class Kind : uint8_t

strong

How the literal is written– either parsed as a number at compile time (Numeric) or passed to the library's CSS parser as text (Passthrough).

Enumerator
Passthrough
Numeric

Constructor & Destructor Documentation

CssValue()

template<size_t N>

UL_CSS_CONSTEVAL CssValue ( const char(&) s[N] )

inline

Capture a string literal and parse it at compile time.

Parameters

s	The string literal.

Member Function Documentation

kind()

Kind kind ( ) const

inlineconstexpr

Get how the literal is written (see Kind).

length()

size_t length ( ) const

inlineconstexpr

Get the literal's length in bytes.

text()

const char * text ( ) const

inlineconstexpr

Get the literal's text as written (null-terminated).

unit()

StyleUnit unit ( ) const

inlineconstexpr

Get the parsed unit (only meaningful when kind() is Kind::Numeric).

value()

double value ( ) const

inlineconstexpr

Get the parsed number (only meaningful when kind() is Kind::Numeric).

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The documentation for this class was generated from the following file:

• Ultralight/dom/StyleValue.h