es-feature-detection/lib/featureTestParser.js

'use strict';

var fs = require('fs');
var nPath = require('path');
var readline = require('readline');
var mkdirp = require('mkdirp');

function readFeatureTestLines(output) {
  return readline.createInterface({
    input: fs.createReadStream(nPath.join(__dirname, '../browser/features.js')),
    historySize: 0
  });
}

function lineParser() {
  var currObj = void 0;
  return function (line) {
    var m = /^\s+'([^']+)':\s+(.)/.exec(line);

    if (!m) {
      var res = currObj ? { closing: true, object: currObj } : null;
      currObj = null;
      return res;
    }

    var name = m[1];

    if (m[2] === '{') {
      currObj = name;
      return { opening: true, object: name };
    }

    if (!currObj) {
      return { object: name };
    }

    return { object: currObj, method: name };
  };
}

function composeFeatures(features) {
  return new Promise(function (resolve) {
    var lines = [];
    var liner = readFeatureTestLines();
    var parseLine = lineParser();

    var methods = new Set();
    var objects = features.reduce(function (set, feature) {
      var parts = feature.split('.');
      set.add(parts[0]);
      if (parts[1]) {
        methods.add(feature);
      }
      return set;
    }, new Set());

    liner.on('line', function (line) {
      var res = parseLine(line);

      if ((res && objects.has(res.object) && (res.method && methods.has(res.object + '.' + res.method) || !res.method) || !res) && !/^\s*$/.test(line)) {
        lines.push(line);
      }
    });

    liner.on('close', function () {
      return resolve({ features: features, lines: lines });
    });
  });
}

function composeFeatureFile(features, filePath) {
  if (!filePath) {
    filePath = 'featuretest.js';
  }

  return composeFeatures(features).then(function (composedScript) {
    return new Promise(function (resolve, reject) {
      mkdirp(nPath.dirname(filePath), function (err) {
        if (err) {
          reject(err);
        }

        var writeStream = fs.createWriteStream(filePath);
        writeStream.write('const features = [\'' + composedScript.features.join("','") + '\'];\n');
        composedScript.lines[0] = composedScript.lines[0].replace('export default ', '');
        writeStream.write(composedScript.lines.join('\n'));

        resolve(writeStream);
      });
    });
  });
}

function readFeatures() {
  return new Promise(function (resolve) {
    var objects = new Set();
    var methods = new Map();

    var liner = readFeatureTestLines();
    var parseLine = lineParser();

    var waitForClosing = void 0;

    liner.on('line', function (line) {
      var res = parseLine(line);

      if (!res) {
        return;
      }

      if (res.opening) {
        waitForClosing = true;
      } else if (res.closing) {
        waitForClosing = false;
      } else if (waitForClosing && res.object === res.method) {
        objects.add(res.object);
      } else if (res.method) {
        var objList = methods.get(res.method) || [];
        objList.push(res.object);
        methods.set(res.method, objList);
      } else if (res.object) {
        objects.add(res.object);
      }
    });

    liner.on('close', function () {
      return resolve({ objects: objects, methods: methods });
    });
  });
}

module.exports.compose = composeFeatures;
module.exports.write = composeFeatureFile;
module.exports.read = readFeatures;