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index.js
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index.js
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import jsTokens, { matchToToken } from "js-tokens";
import esutils from "esutils";
import Chalk from "chalk";
/**
* Chalk styles for token types.
*/
function getDefs(chalk) {
return {
keyword: chalk.cyan,
capitalized: chalk.yellow,
jsx_tag: chalk.yellow,
punctuator: chalk.yellow,
// bracket: intentionally omitted.
number: chalk.magenta,
string: chalk.green,
regex: chalk.magenta,
comment: chalk.grey,
invalid: chalk.white.bgRed.bold,
gutter: chalk.grey,
marker: chalk.red.bold,
};
}
/**
* RegExp to test for newlines in terminal.
*/
const NEWLINE = /\r\n|[\n\r\u2028\u2029]/;
/**
* RegExp to test for what seems to be a JSX tag name.
*/
const JSX_TAG = /^[a-z][\w-]*$/i;
/**
* RegExp to test for the three types of brackets.
*/
const BRACKET = /^[()\[\]{}]$/;
/**
* Get the type of token, specifying punctuator type.
*/
function getTokenType(match) {
const [offset, text] = match.slice(-2);
const token = matchToToken(match);
if (token.type === "name") {
if (esutils.keyword.isReservedWordES6(token.value)) {
return "keyword";
}
if (
JSX_TAG.test(token.value) &&
(text[offset - 1] === "<" || text.substr(offset - 2, 2) == "</")
) {
return "jsx_tag";
}
if (token.value[0] !== token.value[0].toLowerCase()) {
return "capitalized";
}
}
if (token.type === "punctuator" && BRACKET.test(token.value)) {
return "bracket";
}
return token.type;
}
/**
* Highlight `text`.
*/
function highlight(defs: Object, text: string) {
return text.replace(jsTokens, function (...args) {
const type = getTokenType(args);
const colorize = defs[type];
if (colorize) {
return args[0].split(NEWLINE).map((str) => colorize(str)).join("\n");
} else {
return args[0];
}
});
}
/**
* Create a code frame, adding line numbers, code highlighting, and pointing to a given position.
*/
export default function (
rawLines: string,
lineNumber: number,
colNumber: ?number,
opts: Object = {},
): string {
colNumber = Math.max(colNumber, 0);
const highlighted = (opts.highlightCode && Chalk.supportsColor) || opts.forceColor;
let chalk = Chalk;
if (opts.forceColor) {
chalk = new Chalk.constructor({ enabled: true });
}
const maybeHighlight = (chalkFn, string) => {
return highlighted ? chalkFn(string) : string;
};
const defs = getDefs(chalk);
if (highlighted) rawLines = highlight(defs, rawLines);
const linesAbove = opts.linesAbove || 2;
const linesBelow = opts.linesBelow || 3;
const lines = rawLines.split(NEWLINE);
let start = Math.max(lineNumber - (linesAbove + 1), 0);
let end = Math.min(lines.length, lineNumber + linesBelow);
if (!lineNumber && !colNumber) {
start = 0;
end = lines.length;
}
const numberMaxWidth = String(end).length;
const frame = lines.slice(start, end).map((line, index) => {
const number = start + 1 + index;
const paddedNumber = ` ${number}`.slice(-numberMaxWidth);
const gutter = ` ${paddedNumber} | `;
if (number === lineNumber) {
let markerLine = "";
if (colNumber) {
const markerSpacing = line.slice(0, colNumber - 1).replace(/[^\t]/g, " ");
markerLine = [
"\n ",
maybeHighlight(defs.gutter, gutter.replace(/\d/g, " ")),
markerSpacing,
maybeHighlight(defs.marker, "^")
].join("");
}
return [
maybeHighlight(defs.marker, ">"),
maybeHighlight(defs.gutter, gutter),
line,
markerLine
].join("");
} else {
return ` ${maybeHighlight(defs.gutter, gutter)}${line}`;
}
}).join("\n");
if (highlighted) {
return chalk.reset(frame);
} else {
return frame;
}
}