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Fixed handling of calc() function in CSS minifier #35

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Fixed handling of calc() function in CSS minifier #35

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54 changes: 47 additions & 7 deletions src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -26,18 +26,58 @@ export default (options = {}) => {
return result;
};

const findClosingParenthesis = (content, from) => {
let depth = 1;
for (let i = from; i < content.length; i += 1) {
const char = content[i];
if (char == "(") {
depth += 1;
} else if (char == ")") {
if (depth === 1) {
return i;
}

depth -= 1;
}
}

return undefined;
};

const replaceCalc = (content) => {
const calc_functions = [];
const calc_start_regex = /\bcalc\([^)]/g;
let match;
while ((match = calc_start_regex.exec(content)) !== null) {
if (match.index === calc_start_regex.lastIndex) {
break;
}

const start = match.index + 5;
const end = findClosingParenthesis(content, start);
if (end === undefined) {
throw new Error("Missing closing parenthesis in calc() function");
}

const calc_function = content.slice(start, end);
calc_functions.push(calc_function);

const before = content.slice(0, match.index);
const after = content.slice(end + 1);
content = `${before}__CALC__${after}`;
}

return { calc_functions, result: content };
};

/* minify css */
const minifyCSS = (content) => {
const calc_functions = [];
const calc_regex = /\bcalc\(([^)]+)\)/g;
const comments = /("(?:[^"\\]+|\\.)*"|'(?:[^'\\]+|\\.)*')|\/\*[\s\S]*?\*\//g;
const syntax = /("(?:[^"\\]+|\\.)*"|'(?:[^'\\]+|\\.)*')|\s*([{};,>~])\s*|\s*([*$~^|]?=)\s*|\s+([+-])(?=.*\{)|([[(:])\s+|\s+([\])])|\s+(:)(?![^}]*\{)|^\s+|\s+$|(\s)\s+(?![^(]*\))/g;

return content
.replace(calc_regex, (_, group) => {
calc_functions.push(group);
return "__CALC__";
})
const { result, calc_functions } = replaceCalc(content);

return result
.replace(comments, "$1")
.replace(syntax, "$1$2$3$4$5$6$7$8")
.replace(/__CALC__/g, () => `calc(${calc_functions.shift()})`)
Expand Down