index.js
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import postcss from 'postcss'
import replaceSymbols, {replaceAll} from 'icss-replace-symbols'
const matchImports = /^(.+?|\([\s\S]+?\))\s+from\s+("[^"]*"|'[^']*'|[\w-]+)$/
const matchValueDefinition = /(?:\s+|^)([\w-]+):?\s+(.+?)\s*$/g
const matchImport = /^([\w-]+)(?:\s+as\s+([\w-]+))?/
let options = {}
let importIndex = 0
let createImportedName = options && options.createImportedName || ((importName/*, path*/) => `i__const_${importName.replace(/\W/g, '_')}_${importIndex++}`)
export default postcss.plugin('postcss-modules-values', () => (css, result) => {
let importAliases = []
let definitions = {}
const addDefinition = atRule => {
let matches
while (matches = matchValueDefinition.exec(atRule.params)) {
let [/*match*/, key, value] = matches
// Add to the definitions, knowing that values can refer to each other
definitions[key] = replaceAll(definitions, value)
atRule.remove()
}
}
const addImport = atRule => {
let matches = matchImports.exec(atRule.params)
if (matches) {
let [/*match*/, aliases, path] = matches
// We can use constants for path names
if (definitions[path]) path = definitions[path]
let imports = aliases.replace(/^\(\s*([\s\S]+)\s*\)$/, '$1').split(/\s*,\s*/).map(alias => {
let tokens = matchImport.exec(alias)
if (tokens) {
let [/*match*/, theirName, myName = theirName] = tokens
let importedName = createImportedName(myName)
definitions[myName] = importedName
return { theirName, importedName }
} else {
throw new Error(`@import statement "${alias}" is invalid!`)
}
})
importAliases.push({ path, imports })
atRule.remove()
}
}
/* Look at all the @value statements and treat them as locals or as imports */
css.walkAtRules('value', atRule => {
if (matchImports.exec(atRule.params)) {
addImport(atRule)
} else {
if (atRule.params.indexOf('@value') !== -1) {
result.warn('Invalid value definition: ' + atRule.params)
}
addDefinition(atRule)
}
})
/* We want to export anything defined by now, but don't add it to the CSS yet or
it well get picked up by the replacement stuff */
let exportDeclarations = Object.keys(definitions).map(key => postcss.decl({
value: definitions[key],
prop: key,
raws: { before: "\n " }
}))
/* If we have no definitions, don't continue */
if (!Object.keys(definitions).length) return
/* Perform replacements */
replaceSymbols(css, definitions)
/* Add export rules if any */
if (exportDeclarations.length > 0) {
let exportRule = postcss.rule({
selector: `:export`,
raws: { after: "\n" }
})
exportRule.append(exportDeclarations)
css.prepend(exportRule)
}
/* Add import rules */
importAliases.reverse().forEach(({ path, imports }) => {
let importRule = postcss.rule({
selector: `:import(${path})`,
raws: { after: "\n" }
})
imports.forEach(({ theirName, importedName }) => {
importRule.append({
value: theirName,
prop: importedName,
raws: { before: "\n " }
})
})
css.prepend(importRule)
})
})