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import {assert} from './common.js';import * as errors from './errors.js';import * as util from './util.js';
// --------------------------------------------------------------------// Private stuff// --------------------------------------------------------------------
export class Interval {  constructor(sourceString, startIdx, endIdx) {    this.sourceString = sourceString;    this.startIdx = startIdx;    this.endIdx = endIdx;  }
  get contents() {    if (this._contents === undefined) {      this._contents = this.sourceString.slice(this.startIdx, this.endIdx);    }    return this._contents;  }
  get length() {    return this.endIdx - this.startIdx;  }
  coverageWith(...intervals) {    return Interval.coverage(...intervals, this);  }
  collapsedLeft() {    return new Interval(this.sourceString, this.startIdx, this.startIdx);  }
  collapsedRight() {    return new Interval(this.sourceString, this.endIdx, this.endIdx);  }
  getLineAndColumn() {    return util.getLineAndColumn(this.sourceString, this.startIdx);  }
  getLineAndColumnMessage() {    const range = [this.startIdx, this.endIdx];    return util.getLineAndColumnMessage(this.sourceString, this.startIdx, range);  }
  // Returns an array of 0, 1, or 2 intervals that represents the result of the  // interval difference operation.  minus(that) {    if (this.sourceString !== that.sourceString) {      throw errors.intervalSourcesDontMatch();    } else if (this.startIdx === that.startIdx && this.endIdx === that.endIdx) {      // `this` and `that` are the same interval!      return [];    } else if (this.startIdx < that.startIdx && that.endIdx < this.endIdx) {      // `that` splits `this` into two intervals      return [        new Interval(this.sourceString, this.startIdx, that.startIdx),        new Interval(this.sourceString, that.endIdx, this.endIdx),      ];    } else if (this.startIdx < that.endIdx && that.endIdx < this.endIdx) {      // `that` contains a prefix of `this`      return [new Interval(this.sourceString, that.endIdx, this.endIdx)];    } else if (this.startIdx < that.startIdx && that.startIdx < this.endIdx) {      // `that` contains a suffix of `this`      return [new Interval(this.sourceString, this.startIdx, that.startIdx)];    } else {      // `that` and `this` do not overlap      return [this];    }  }
  // Returns a new Interval that has the same extent as this one, but which is relative  // to `that`, an Interval that fully covers this one.  relativeTo(that) {    if (this.sourceString !== that.sourceString) {      throw errors.intervalSourcesDontMatch();    }    assert(        this.startIdx >= that.startIdx && this.endIdx <= that.endIdx,        'other interval does not cover this one',    );    return new Interval(        this.sourceString,        this.startIdx - that.startIdx,        this.endIdx - that.startIdx,    );  }
  // Returns a new Interval which contains the same contents as this one,  // but with whitespace trimmed from both ends.  trimmed() {    const {contents} = this;    const startIdx = this.startIdx + contents.match(/^\s*/)[0].length;    const endIdx = this.endIdx - contents.match(/\s*$/)[0].length;    return new Interval(this.sourceString, startIdx, endIdx);  }
  subInterval(offset, len) {    const newStartIdx = this.startIdx + offset;    return new Interval(this.sourceString, newStartIdx, newStartIdx + len);  }}
Interval.coverage = function(firstInterval, ...intervals) {  let {startIdx, endIdx} = firstInterval;  for (const interval of intervals) {    if (interval.sourceString !== firstInterval.sourceString) {      throw errors.intervalSourcesDontMatch();    } else {      startIdx = Math.min(startIdx, interval.startIdx);      endIdx = Math.max(endIdx, interval.endIdx);    }  }  return new Interval(firstInterval.sourceString, startIdx, endIdx);};