spiegel-keyman/web/source/utils/version.ts

// Ensure that this class contains no reference into core KMW code - it is referenced
// by components intended to be modular and possible to separate from core KMW.

namespace com.keyman.utils {
  // Dotted-decimal version
  export class Version {
    // Represents a default version value for keyboards compiled before this was compiled into keyboards.
    // The exact version is unknown at this point, but the value is "good enough" for what we need.
    public static readonly DEVELOPER_VERSION_FALLBACK = new Version([9, 0, 0]);

    // For 12.0, the old default behavior of adding missing keycaps to the default layers was removed,
    // as it results in unexpected, bug-like behavior for keyboard designers when it is unwanted.
    public static readonly NO_DEFAULT_KEYCAPS = new Version([12, 0]);

    public static readonly MAC_POSSIBLE_IPAD_ALIAS = new Version([10, 15]);

    private readonly components: number[]

    /**
     * Parses version information, preparing it for use in comparisons.
     * @param text Either a string representing a version number (ex: "9.0.0") or an array representing
     *             its components (ex: [9, 0, 0]).
     */
    constructor(text: String | number[]) {
      // If a keyboard doesn't specify a version, use the DEVELOPER_VERSION_FALLBACK values.
      if(text === undefined || text === null) {
        this.components = [].concat(Version.DEVELOPER_VERSION_FALLBACK.components);
        return;
      }

      if(Array.isArray(text)) {
        let components = text as number[];
        if(components.length < 2) {
          throw new Error("Version string must have at least a major and minor component!");
        } else {
          this.components = [].concat(components);
          return;
        }
      }

      // else, standard constructor path.
      let parts = text.split('.');
      let componentArray: number[] = [];

      if(parts.length < 2) {
        throw new Error("Version string must have at least a major and minor component!");
      }

      for(let i=0; i < parts.length; i++) {
        let value = parseInt(parts[i], 10);
        if(isNaN(value)) {
          throw new Error("Version string components must be numerical!");
        }

        componentArray.push(value);
      }

      this.components = componentArray;
    }

    get major(): number {
      return this.components[0];
    }

    get minor(): number {
      return this.components[1];
    }

    toString(): string {
      return this.components.join('.');
    }

    equals(other: Version): boolean {
      return this.compareTo(other) == 0;
    }

    precedes(other: Version): boolean {
      return this.compareTo(other) < 0;
    }

    compareTo(other: Version): number {
      // If the version info depth differs, we need a flag to indicate which instance is shorter.
      var isShorter: boolean = this.components.length < other.components.length;
      var maxDepth: number = (this.components.length < other.components.length) ? this.components.length : other.components.length;

      var i: number;
      for(i = 0; i < maxDepth; i++) {
        let delta = this.components[i] - other.components[i];
        if(delta != 0) {
          return delta;
        }
      }

      var longList = isShorter ? other.components : this.components;
      do {
        if(longList[i] > 0) {
          return isShorter ? -1 : 1;
        }
        i++;
      } while (i < longList.length);

      // Equal.
      return 0;
    }
  }
}