flow-build/src/utils/formatWebpackMessages.js

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/**
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

"use strict";

// WARNING: this code is untranspiled and is used in browser too.
// Please make sure any changes are in ES5 or contribute a Babel compile step.

// Some custom utilities to prettify Webpack output.
// This is quite hacky and hopefully won't be needed when Webpack fixes this.
// https://github.com/webpack/webpack/issues/2878

var chalk = require("chalk");
var friendlySyntaxErrorLabel = "Syntax error:";
/**
 * 
 */
function isLikelyASyntaxError(message) {
    return message.indexOf(friendlySyntaxErrorLabel) !== -1;
}
/**
 * Cleans up webpack error messages.
 * eslint-disable-next-line no-unused-vars
 */
function formatMessage(message, isError) {
    var lines = message.split("\n");

    if (lines.length > 2 && lines[1] === "") {
        // Remove extra newline.
        lines.splice(1, 1);
    }

    // Remove webpack-specific loader notation from filename.
    // Before:
    // ./~/css-loader!./~/postcss-loader!./src/App.css
    // After:
    // ./src/App.css
    if (lines[0].lastIndexOf("!") !== -1) {
        lines[0] = lines[0].substr(lines[0].lastIndexOf("!") + 1);
    }

    lines = lines.filter(function(line) {
        // Webpack adds a list of entry points to warning messages:
        //  @ ./src/index.js
        //  @ multi react-scripts/~/react-dev-utils/webpackHotDevClient.js ...
        // It is misleading (and unrelated to the warnings) so we clean it up.
        // It is only useful for syntax errors but we have beautiful frames for them.
        return line.indexOf(" @ ") !== 0;
    });

    // line #0 is filename
    // line #1 is the main error message
    if (!lines[0] || !lines[1]) {
        return lines.join("\n");
    }

    // Cleans up verbose "module not found" messages for files and packages.
    if (lines[1].indexOf("Module not found: ") === 0) {
        lines = [
            lines[0],
            // Clean up message because "Module not found: " is descriptive enough.
            lines[1]
                .replace("Cannot resolve 'file' or 'directory' ", "")
                .replace("Cannot resolve module ", "")
                .replace("Error: ", "")
                .replace("[CaseSensitivePathsPlugin] ", "")
        ];
    }

    // Cleans up syntax error messages.
    if (lines[1].indexOf("Module build failed: ") === 0) {
        lines[1] = lines[1].replace(
            "Module build failed: SyntaxError:",
            friendlySyntaxErrorLabel
        );
    }

    // Clean up export errors.
    // TODO: we should really send a PR to Webpack for this.
    var exportError = /\s*(.+?)\s*(")?export '(.+?)' was not found in '(.+?)'/;
    if (lines[1].match(exportError)) {
        lines[1] = lines[1].replace(
            exportError,
            "$1 '$4' does not contain an export named '$3'."
        );
    }

    lines[0] = chalk.inverse(lines[0]);

    // Reassemble the message.
    message = lines.join("\n");
    // Internal stacks are generally useless so we strip them... with the
    // exception of stacks containing `webpack:` because they're normally
    // from user code generated by WebPack. For more information see
    // https://github.com/facebookincubator/create-react-app/pull/1050
    message = message.replace(
        /^\s*at\s((?!webpack:).)*:\d+:\d+[\s)]*(\n|$)/gm,
        ""
    ); // at ... ...:x:y

    return message.trim();
}

/**
 * 
 */
function formatWebpackMessages(json) {
    var formattedErrors = json.errors.map(function(message) {
        return formatMessage(message, true);
    });
    var formattedWarnings = json.warnings.map(function(message) {
        return formatMessage(message, false);
    });
    var result = {
        errors: formattedErrors,
        warnings: formattedWarnings
    };
    if (result.errors.some(isLikelyASyntaxError)) {
        // If there are any syntax errors, show just them.
        // This prevents a confusing ESLint parsing error
        // preceding a much more useful Babel syntax error.
        result.errors = result.errors.filter(isLikelyASyntaxError);
    }
    return result;
}

module.exports = formatWebpackMessages;