@wix/css-property-parser/dist/evaluators/z-index.js

A comprehensive TypeScript library for parsing and serializing CSS property values with full MDN specification compliance

// CSS z-index property evaluator
// Handles CSS z-index property values according to MDN specification
// https://developer.mozilla.org/en-US/docs/Web/CSS/z-index
import { isCssVariable, isGlobalKeyword, getValidKeyword } from '../utils/shared-utils.js';
import { parse as parseCSSVariable, toCSSValue as cssVariableToCSSValue } from './css-variable.js';
import { parse as parseNumber, toCSSValue as numberToCSSValue } from './number.js';
import { parseCalcFunction } from '../utils/css-function-parser.js';
import { Z_INDEX_KEYWORDS } from '../types.js';
/**
 * Check if a string represents a valid integer for z-index
 * We need to validate the string form to reject decimal representations like "10.0"
 */
function isValidZIndexInteger(value) {
    // Must match integer pattern exactly (no decimals, no scientific notation)
    const integerPattern = /^[+-]?\d+$/;
    return integerPattern.test(value);
}
/**
 * Check if a number value is a valid integer for z-index
 */
function isValidZIndexNumber(numberValue) {
    // CSS variables can't be validated at parse time
    if ('CSSvariable' in numberValue) {
        return true;
    }
    if ('expression' in numberValue) {
        // Allow calc expressions (can't validate at parse time)
        return true;
    }
    if ('keyword' in numberValue) {
        // Allow keywords (inherit, initial, etc.)
        return true;
    }
    // Check if it's an integer (z-index doesn't accept decimals)
    return Number.isInteger(numberValue.value);
}
/**
 * Parses a CSS z-index property value according to MDN specification
 *
 * Supports:
 * - auto: Stack level equals parent element (default)
 * - Integer values: Positive, zero, or negative integers
 * - Global keywords: inherit, initial, unset, revert, revert-layer
 * - CSS variables: var(--custom-z-index)
 *
 * @param value - The CSS value to parse
 * @returns Parsed ZIndexValue or null if invalid
 */
export function parse(value) {
    if (!value || typeof value !== 'string')
        return null;
    const trimmed = value.trim();
    if (trimmed === '')
        return null;
    // CSS variables - parse and return directly
    if (isCssVariable(trimmed)) {
        return parseCSSVariable(trimmed);
    }
    // Global keywords
    if (isGlobalKeyword(trimmed)) {
        return { type: 'keyword', keyword: trimmed.toLowerCase() };
    }
    // Z-index-specific keywords (auto)
    const zIndexKeyword = getValidKeyword(trimmed, Z_INDEX_KEYWORDS);
    if (zIndexKeyword) {
        return { type: 'keyword', keyword: zIndexKeyword };
    }
    // Handle calc() expressions (they can contain any expression, can't validate at parse time)
    const calcResult = parseCalcFunction(trimmed);
    if (calcResult) {
        return calcResult;
    }
    // Try parsing as number (integers only)
    // First validate that the string represents a valid integer
    if (isValidZIndexInteger(trimmed)) {
        const numberResult = parseNumber(trimmed);
        if (numberResult && isValidZIndexNumber(numberResult)) {
            return numberResult;
        }
    }
    return null;
}
/**
 * Converts a parsed ZIndexValue back to CSS string representation
 *
 * @param parsed - The parsed z-index value
 * @returns CSS string or null if invalid
 */
export function toCSSValue(parsed) {
    if (!parsed)
        return null;
    if (parsed.type === 'variable') {
        return cssVariableToCSSValue(parsed);
    }
    if (parsed.type === 'keyword') {
        return parsed.keyword;
    }
    if (parsed.type === 'number') {
        return numberToCSSValue(parsed);
    }
    return null;
}