Merge "YANG Model update for A1 Adapter"

[ccsdk/features.git] / sdnr / wt / odlux / apps / configurationApp / src / yang / yangParser.ts

import { Token, Statement, Module, Identity } from "../models/yang";
import { ViewSpecification, ViewElement, isViewElementObjectOrList, ViewElementBase, isViewElementReference } from "../models/uiModels";
import { yangService } from "../services/yangService";

export const splitVPath = (vPath: string, vPathParser: RegExp): RegExpMatchArray[] => {
  const pathParts: RegExpMatchArray[] = [];
  let partMatch: RegExpExecArray | null;
  if (vPath) do {
    partMatch = vPathParser.exec(vPath);
    if (partMatch) {
      pathParts.push(partMatch);
    }
  } while (partMatch)
  return pathParts;
}

class YangLexer {

  private pos: number = 0;
  private buf: string = "";

  constructor(input: string) {
    this.pos = 0;
    this.buf = input;
  }

  private _optable: { [key: string]: string } = {
    ';': 'SEMI',
    '{': 'L_BRACE',
    '}': 'R_BRACE',
  };

  private _isNewline(char: string): boolean {
    return char === '\r' || char === '\n';
  }

  private _isWhitespace(char: string): boolean {
    return char === ' ' || char === '\t' || this._isNewline(char);
  }

  private _isDigit(char: string): boolean {
    return char >= '0' && char <= '9';
  }

  private _isAlpha(char: string): boolean {
    return (char >= 'a' && char <= 'z') ||
      (char >= 'A' && char <= 'Z')
  }

  private _isAlphanum(char: string): boolean {
    return this._isAlpha(char) || this._isDigit(char) ||
      char === '_' || char === '-' || char === '.';
  }

  private _skipNontokens() {
    while (this.pos < this.buf.length) {
      const char = this.buf.charAt(this.pos);
      if (this._isWhitespace(char)) {
        this.pos++;
      } else {
        break;
      }
    }
  }

  private _processString(terminator: string | null): Token {
    // this.pos points at the opening quote. Find the ending quote.
    let end_index = this.pos + 1;
    while (end_index < this.buf.length) {
      const char = this.buf.charAt(end_index);
      if (char === "\\") {
        end_index += 2;
        continue;
      };
      if (terminator === null && (this._isWhitespace(char) || this._optable[char] !== undefined) || char === terminator) {
        break;
      }
      end_index++;
    }

    if (end_index >= this.buf.length) {
      throw Error('Unterminated quote at ' + this.pos);
    } else {
      const start = this.pos + (terminator ? 1 : 0);
      const end = end_index;
      const tok = {
        name: 'STRING',
        value: this.buf.substring(start, end),
        start,
        end
      };
      this.pos = terminator ? end + 1 : end;
      return tok;
    }
  }

  private _processIdentifier(): Token {
    let endpos = this.pos + 1;
    while (endpos < this.buf.length &&
      this._isAlphanum(this.buf.charAt(endpos))) {
      endpos++;
    }

    const tok = {
      name: 'IDENTIFIER',
      value: this.buf.substring(this.pos, endpos),
      start: this.pos,
      end: endpos
    };
    this.pos = endpos;
    return tok;
  }

  private _processNumber(): Token {
    let endpos = this.pos + 1;
    while (endpos < this.buf.length &&
      this._isDigit(this.buf.charAt(endpos))) {
      endpos++;
    }

    const tok = {
      name: 'NUMBER',
      value: this.buf.substring(this.pos, endpos),
      start: this.pos,
      end: endpos
    };
    this.pos = endpos;
    return tok;
  }

  private _processLineComment() {
    var endpos = this.pos + 2;
    // Skip until the end of the line
    while (endpos < this.buf.length && !this._isNewline(this.buf.charAt(endpos))) {
      endpos++;
    }
    this.pos = endpos + 1;
  }

  private _processBlockComment() {
    var endpos = this.pos + 2;
    // Skip until the end of the line
    while (endpos < this.buf.length && !((this.buf.charAt(endpos) === "/" && this.buf.charAt(endpos - 1) === "*"))) {
      endpos++;
    }
    this.pos = endpos + 1;
  }

  public tokenize(): Token[] {
    const result: Token[] = [];
    this._skipNontokens();
    while (this.pos < this.buf.length) {

      const char = this.buf.charAt(this.pos);
      const op = this._optable[char];

      if (op !== undefined) {
        result.push({ name: op, value: char, start: this.pos, end: ++this.pos });
      } else if (this._isAlpha(char)) {
        result.push(this._processIdentifier());
        this._skipNontokens();
        const peekChar = this.buf.charAt(this.pos);
        if (this._optable[peekChar] === undefined) {
          result.push((peekChar !== "'" && peekChar !== '"')
            ? this._processString(null)
            : this._processString(peekChar));
        }
      } else if (char === '/' && this.buf.charAt(this.pos + 1) === "/") {
        this._processLineComment();
      } else if (char === '/' && this.buf.charAt(this.pos + 1) === "*") {
        this._processBlockComment();
      } else {
        throw Error('Token error at ' + this.pos + " " + this.buf[this.pos]);
      }
      this._skipNontokens();
    }
    return result;
  }

  public tokenize2(): Statement {
    let stack: Statement[] = [{ key: "ROOT", sub: [] }];
    let current: Statement | null = null;

    this._skipNontokens();
    while (this.pos < this.buf.length) {

      const char = this.buf.charAt(this.pos);
      const op = this._optable[char];

      if (op !== undefined) {
        if (op === "L_BRACE") {
          current && stack.unshift(current);
          current = null;
        } else if (op === "R_BRACE") {
          current = stack.shift() || null;
        }
        this.pos++;
      } else if (this._isAlpha(char)) {
        const key = this._processIdentifier().value;
        this._skipNontokens();
        let peekChar = this.buf.charAt(this.pos);
        let arg = undefined;
        if (this._optable[peekChar] === undefined) {
          arg = (peekChar === '"' || peekChar === "'")
            ? this._processString(peekChar).value
            : this._processString(null).value;
        }
        do {
          this._skipNontokens();
          peekChar = this.buf.charAt(this.pos);
          if (peekChar !== "+") break;
          this.pos++;
          this._skipNontokens();
          peekChar = this.buf.charAt(this.pos);
          arg += (peekChar === '"' || peekChar === "'")
            ? this._processString(peekChar).value
            : this._processString(null).value;
        } while (true);
        current = { key, arg, sub: [] };
        stack[0].sub!.push(current);
      } else if (char === '/' && this.buf.charAt(this.pos + 1) === "/") {
        this._processLineComment();
      } else if (char === '/' && this.buf.charAt(this.pos + 1) === "*") {
        this._processBlockComment();
      } else {
        throw Error('Token error at ' + this.pos + " " + this.buf.slice(this.pos - 10, this.pos + 10));
      }
      this._skipNontokens();
    }
    if (stack[0].key !== "ROOT" || !stack[0].sub![0]) {
      throw new Error("Internal Perser Error");
    }
    return stack[0].sub![0];
  }
}

export class YangParser {
  private _groupingsToResolve: (() => void)[] = [];
  private _identityToResolve: (() => void)[] = [];

  private _modules: { [name: string]: Module } = {};
  private _views: ViewSpecification[] = [{
    id: "0",
    name: "root",
    language: "en-US",
    canEdit: false,
    parentView: "0",
    title: "root",
    elements: {},
   }];

  constructor() {

  }

  public get modules() {
    return this._modules;
  }

  public get views() {
    return this._views;
  }

  public async addCapability(capability: string, version?: string) {
    // do not add twice
    if (this._modules[capability]) {
      return;
    }

    const data = await yangService.getCapability(capability, version);
    if (!data) {
      throw new Error(`Could not load yang file for ${capability}.`);
    }

    const rootStatement = new YangLexer(data).tokenize2();

    if (rootStatement.key !== "module") {
      throw new Error(`Root element of ${capability} is not a module.`);
    }
    if (rootStatement.arg !== capability) {
      throw new Error(`Root element capability ${rootStatement.arg} does not requested ${capability}.`);
    }

    const module = this._modules[capability] = {
      name: rootStatement.arg,
      revisions: {},
      imports: {},
      features: {},
      identities: {},
      augments: {},
      groupings: {},
      typedefs: {},
      views: {},
      elements: {}
    };

    await this.handleModule(module, rootStatement, capability);
  }

  private async handleModule(module: Module, rootStatement: Statement, capability: string) {

    // extract namespace && prefix
    module.namespace = this.extractValue(rootStatement, "namespace");
    module.prefix = this.extractValue(rootStatement, "prefix");
    if (module.prefix) {
      module.imports[module.prefix] = capability;
    }

    // extract revisions
    const revisions = this.extractNodes(rootStatement, "revision");
    module.revisions = {
      ...module.revisions,
      ...revisions.reduce<{ [version: string]: { }}>((acc, version) => {
        if (!version.arg) {
          throw new Error(`Module [${module.name}] has a version w/o version number.`);
        }
        const description = this.extractValue(version, "description");
        const reference = this.extractValue(version,"reference");
        acc[version.arg] = {
          description,
          reference,
        };
        return acc;
      }, {})
    };

    // extract features
    const features = this.extractNodes(rootStatement, "feature");
    module.features = {
      ...module.features,
      ...features.reduce<{ [version: string]: {} }>((acc, feature) => {
        if (!feature.arg) {
          throw new Error(`Module [${module.name}] has a feature w/o name.`);
        }
        const description = this.extractValue(feature, "description");
        acc[feature.arg] = {
          description,
        };
        return acc;
      }, {})
    };

    // extract imports
    const imports = this.extractNodes(rootStatement, "import");
    module.imports = {
      ...module.imports,
      ...imports.reduce < { [key: string]: string }>((acc, imp) => {
        const prefix = imp.sub && imp.sub.filter(s => s.key === "prefix");
        if (!imp.arg) {
           throw new Error(`Module [${module.name}] has an import with neither name nor prefix.`);
        }
        acc[prefix && prefix.length === 1 && prefix[0].arg || imp.arg] = imp.arg;
        return acc;
      }, {})
    };

    // import all required files
    if (imports) for (let ind = 0; ind < imports.length; ++ind) {
      await this.addCapability(imports[ind].arg!);
    }

    this.extractTypeDefinitions(rootStatement, module, "");

    this.extractIdentites(rootStatement, 0, module, "");

    const groupings = this.extractGroupings(rootStatement, 0, module, "");
    this._views.push(...groupings);

    const augments = this.extractAugments(rootStatement, 0, module, "");
    this._views.push(...augments);

    // the default for config on module level is config = true;
    const [currentView, subViews] = this.extractSubViews(rootStatement, 0, module, "");
    this._views.push(currentView, ...subViews);

    // create the root elements for this module
    module.elements = currentView.elements;
    Object.keys(module.elements).forEach(key => {
      const viewElement = module.elements[key];
      if (!isViewElementObjectOrList(viewElement)) {
        throw new Error(`Module: [${module}]. Only List or Object allowed on root level.`);
      }
      const viewIdIndex = Number(viewElement.viewId);
      module.views[key] = this._views[viewIdIndex];
      this._views[0].elements[key] = module.elements[key];
    });
    return module;
  }

  public postProcess() {
    // process all groupings
    // execute all post processes like resolving in propper order
    this._groupingsToResolve.forEach(cb => {
      try { cb(); } catch (error) {
        console.warn(`Error resolving: [${error.message}]`);
      }
    });

    // process all augmentations
    Object.keys(this.modules).forEach(modKey => {
      const module = this.modules[modKey];
      Object.keys(module.augments).forEach(augKey => {
        const augments = module.augments[augKey];
        const viewSpec = this.resolveView(augKey);
        if (!viewSpec) console.warn(`Could not find view to augment [${augKey}] in [${module.name}].`);
        if (augments && viewSpec) {
          augments.forEach(augment => Object.keys(augment.elements).forEach(key => {
            const elm = augment.elements[key];
            viewSpec.elements[key] = {
              ...augment.elements[key],
              when: elm.when ? `(${augment.when}) and (${elm.when})` : augment.when,
              ifFeature: elm.ifFeature ? `(${augment.ifFeature}) and (${elm.ifFeature})` : augment.ifFeature,
            };
          }));
        }
      });
    });

    // process Identities
    const traverseIdentity = (identities : Identity[]) => {
      const result: Identity[] = [];
      for (let identity of identities) {
        if (identity.children && identity.children.length > 0) {
          result.push(...traverseIdentity(identity.children));
        } else {
          result.push(identity);
        }
      }
      return result;
    }


    const baseIdentites: Identity[] = [];
    Object.keys(this.modules).forEach(modKey => {
      const module = this.modules[modKey];
      Object.keys(module.identities).forEach(idKey => {
        const identity = module.identities[idKey];
        if (identity.base != null) {
          const base = this.resolveIdentity(identity.base, module);
          base.children?.push(identity);
        } else {
          baseIdentites.push(identity);
        }
      });
    });
    baseIdentites.forEach(identity => {
      identity.values = identity.children && traverseIdentity(identity.children) || [];
    });

    this._identityToResolve.forEach(cb => {
      try { cb(); } catch (error) {
        console.warn(error.message);
      }
    });
  };


  private _nextId = 1;
  private get nextId() {
    return this._nextId++;
  }

  private extractNodes(statement: Statement, key: string): Statement[] {
    return statement.sub && statement.sub.filter(s => s.key === key) || [];
  }

  private extractValue(statement: Statement, key: string): string | undefined;
  private extractValue(statement: Statement, key: string, parser: RegExp): RegExpExecArray | undefined;
  private extractValue(statement: Statement, key: string, parser?: RegExp): string | RegExpExecArray | undefined {
    const typeNodes = this.extractNodes(statement, key);
    const rawValue = typeNodes.length > 0 && typeNodes[0].arg || undefined;
    return parser
      ? rawValue && parser.exec(rawValue) || undefined
      : rawValue;
  }

  private extractTypeDefinitions(statement: Statement, module: Module, currentPath: string): void {
    const typedefs = this.extractNodes(statement, "typedef");
    typedefs && typedefs.forEach(def => {
      if (! def.arg) {
        throw new Error(`Module: [${module.name}]. Found typefed without name.`);
      }
      module.typedefs[def.arg] = this.getViewElement(def, module, 0, currentPath, false);
    });
  }

  /** Handles Goupings like named Container */
  private extractGroupings(statement: Statement, parentId: number, module: Module, currentPath: string): ViewSpecification[] {
    const subViews: ViewSpecification[] = [];
    const groupings = this.extractNodes(statement, "grouping");
    if (groupings && groupings.length > 0) {
      subViews.push(...groupings.reduce<ViewSpecification[]>((acc, cur) => {
        if (!cur.arg) {
          throw new Error(`Module: [${module.name}][${currentPath}]. Found grouping without name.`);
        }
        const grouping = cur.arg;

        // the default for config on module level is config = true;
        const [currentView, subViews] = this.extractSubViews(cur, parentId, module, currentPath);
        grouping && (module.groupings[grouping] = currentView);
        acc.push(currentView, ...subViews);
        return acc;
      }, []));
    }

    return subViews;
  }

  /** Handles Augmants also like named Container */
  private extractAugments(statement: Statement, parentId: number, module: Module, currentPath: string): ViewSpecification[] {
    const subViews: ViewSpecification[] = [];
    const augments = this.extractNodes(statement, "augment");
    if (augments && augments.length > 0) {
      subViews.push(...augments.reduce<ViewSpecification[]>((acc, cur) => {
        if (!cur.arg) {
          throw new Error(`Module: [${module.name}][${currentPath}]. Found augment without path.`);
        }
        const augment = this.resolveReferencePath(cur.arg, module);

        // the default for config on module level is config = true;
        const [currentView, subViews] = this.extractSubViews(cur, parentId, module, currentPath);
        if (augment) {
          module.augments[augment] = module.augments[augment] || [];
          module.augments[augment].push(currentView);
        }
        acc.push(currentView, ...subViews);
        return acc;
      }, []));
    }

    return subViews;
  }

  /** Handles Identities  */
  private extractIdentites(statement: Statement, parentId: number, module: Module, currentPath: string) {
    const identities = this.extractNodes(statement, "identity");
    module.identities = identities.reduce<{ [name: string]: Identity }>((acc, cur) => {
      if (!cur.arg) {
        throw new Error(`Module: [${module.name}][${currentPath}]. Found identiy without name.`);
      }
      acc[cur.arg] = {
        id: `${module.name}:${cur.arg}`,
        label: cur.arg,
        base: this.extractValue(cur, "base"),
        description: this.extractValue(cur, "description"),
        reference: this.extractValue(cur, "reference"),
        children: []
      }
      return acc;
    }, {});
  }

  private extractSubViews(statement: Statement, parentId: number, module: Module, currentPath: string): [ViewSpecification, ViewSpecification[]] {
    const subViews: ViewSpecification[] = [];
    const currentId = this.nextId;
    let elements: ViewElement[] = [];

    const configValue = this.extractValue(statement, "config");
    const config = configValue == null ? true : configValue.toLocaleLowerCase() !== "false";

    // extract conditions
    const ifFeature = this.extractValue(statement, "if-feature");
    const whenCondition = this.extractValue(statement, "when");

    // extract all container
    const container = this.extractNodes(statement, "container");
    if (container && container.length > 0) {
      subViews.push(...container.reduce<ViewSpecification[]>((acc, cur) => {
        if (!cur.arg) {
          throw new Error(`Module: [${module.name}]. Found container without name.`);
        }
        const [currentView, subViews] = this.extractSubViews(cur, currentId, module, `${currentPath}/${module.name}:${cur.arg}`);
        elements.push({
          id: parentId === 0 ? `${module.name}:${cur.arg}` : cur.arg,
          label: cur.arg,
          uiType: "object",
          viewId: currentView.id,
          config: config
        });
        acc.push(currentView, ...subViews);
        return acc;
      }, []));
    }

    // process all lists
    // a list is a list of containers with the leafs contained in the list
    const lists = this.extractNodes(statement, "list");
    if (lists && lists.length > 0) {
      subViews.push(...lists.reduce<ViewSpecification[]>((acc, cur) => {
        if (!cur.arg) {
          throw new Error(`Module: [${module.name}]. Found list without name.`);
        }
        const key = this.extractValue(cur, "key") || undefined;
        if (config && !key) {
          throw new Error(`Module: [${module.name}]. Found configurable list without key.`);
        }
        const [currentView, subViews] = this.extractSubViews(cur, currentId, module, `${currentPath}/${module.name}:${cur.arg}`);
        elements.push({
          id: parentId === 0 ? `${module.name}:${cur.arg}` : cur.arg,
          label: cur.arg,
          isList: true,
          uiType: "object",
          viewId: currentView.id,
          key: key,
          config: config
        });
        acc.push(currentView, ...subViews);
        return acc;
      }, []));
    }

    // process all leaf-lists
    // a leaf-list is a list of some type
    const leafLists = this.extractNodes(statement, "leaf-list");
    if (leafLists && leafLists.length > 0) {
      elements.push(...leafLists.reduce<ViewElement[]>((acc, cur) => {
        const element = this.getViewElement(cur, module, parentId, currentPath, true);
        element && acc.push(element);
        return acc;
      }, []));
    }

    // process all leafs
    // a leaf is mainly a property of an object
    const leafs = this.extractNodes(statement, "leaf");
    if (leafs && leafs.length > 0) {
      elements.push(...leafs.reduce<ViewElement[]>((acc, cur) => {
        const element = this.getViewElement(cur, module, parentId, currentPath, false);
        element && acc.push(element);
        return acc;
      }, []));
    }


    const choiceStms = this.extractNodes(statement, "choice");
    if (choiceStms && choiceStms.length > 0) {
      for (let i = 0; i < choiceStms.length; ++i) {
        const cases = this.extractNodes(choiceStms[i], "case");
        console.warn(`Choice found ${choiceStms[i].arg}::${cases.map(c => c.arg).join(";")}`, choiceStms[i]);
      }
    }

    const rpcs = this.extractNodes(statement, "rpc");
    if (rpcs && rpcs.length > 0) {
      // todo:
    }

    if (!statement.arg) {
      throw new Error(`Module: [${module.name}]. Found statement without name.`);
    }

    const viewSpec: ViewSpecification = {
      id: String(currentId),
      parentView: String(parentId),
      name: statement.arg,
      title: statement.arg,
      language: "en-us",
      canEdit: false,
      ifFeature: ifFeature,
      when: whenCondition,
      elements: elements.reduce<{ [name: string]: ViewElement }>((acc, cur) => {
        acc[cur.id] = cur;
        return acc;
      }, {}),
    };

    // evaluate canEdit depending on all conditions
    Object.defineProperty(viewSpec, "canEdit", {
      get: () => {
        return Object.keys(viewSpec.elements).some(key => {
          const elm = viewSpec.elements[key];
          return (!isViewElementObjectOrList(elm) && elm.config);
        });
      }
    });

    // merge in all uses references and resolve groupings
    const usesRefs = this.extractNodes(statement, "uses");
    if (usesRefs && usesRefs.length > 0) {

      viewSpec.uses = (viewSpec.uses || []);
      for (let i = 0; i < usesRefs.length; ++i) {
        const groupingName = usesRefs[i].arg;
        if (!groupingName) {
          throw new Error(`Module: [${module.name}]. Found an uses statement without a grouping name.`);
        }

        viewSpec.uses.push(this.resolveReferencePath(groupingName, module));

        this._groupingsToResolve.push(() => {
          const groupingViewSpec = this.resolveGrouping(groupingName, module);
          if (groupingViewSpec) {
            Object.keys(groupingViewSpec.elements).forEach(key => {
              const elm = groupingViewSpec.elements[key];
              viewSpec.elements[key] = {
                ...groupingViewSpec.elements[key],
                when: elm.when ? `(${groupingViewSpec.when}) and (${elm.when})` : groupingViewSpec.when,
                ifFeature: elm.ifFeature ? `(${groupingViewSpec.ifFeature}) and (${elm.ifFeature})` : groupingViewSpec.ifFeature,
              };
            });
          }
        });
      }
    }

    return [viewSpec, subViews];
  }

  /** Extracts the UI View from the type in the cur statement. */
  private getViewElement(cur: Statement, module: Module, parentId: number, currentPath: string, isList: boolean): ViewElement {

    const type = this.extractValue(cur, "type");
    const defaultVal = this.extractValue(cur, "default") || undefined;
    const description = this.extractValue(cur, "description") || undefined;
    const rangeMatch = this.extractValue(cur, "range", /^(\d+)\.\.(\d+)/) || undefined;

    const configValue = this.extractValue(cur, "config");
    const config = configValue == null ? true : configValue.toLocaleLowerCase() !== "false";

    const mandatory = this.extractValue(cur, "mandatory") === "true" || false;

    if (!cur.arg) {
      throw new Error(`Module: [${module.name}]. Found element without name.`);
    }

    if (!type) {
      throw new Error(`Module: [${module.name}].[${cur.arg}]. Found element without type.`);
    }

    const element: ViewElementBase = {
      id: parentId === 0 ? `${module.name}:${cur.arg}`: cur.arg,
      label: cur.arg,
      config: config,
      mandatory: mandatory,
      isList: isList,
      default: defaultVal,
      description: description
    };

    if (type === "string") {
      return ({
        ...element,
        uiType: "string",
        pattern: this.extractNodes(this.extractNodes(cur, "type")[0]!, "pattern").map(p => p.arg!).filter(p => !!p),
      });
    } else if (type === "boolean") {
      return ({
        ...element,
        uiType: "boolean"
      });
    } else if (type === "uint8") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +255,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "uint16") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +65535,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "uint32") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +4294967295,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "uint64") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +18446744073709551615,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "int8") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : -128,
        max: rangeMatch ? Number(rangeMatch[1]) : +127,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "int16") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : -32768,
        max: rangeMatch ? Number(rangeMatch[1]) : +32767,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "int32") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : -2147483648,
        max: rangeMatch ? Number(rangeMatch[1]) : +2147483647,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "int64") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +18446744073709551615,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
      });
    } else if (type === "decimal16") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +18446744073709551615,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
        fDigits: Number(this.extractValue(this.extractNodes(cur, "type")[0]!, "fraction-digits")) || -1
      });
    } else if (type === "decimal32") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +18446744073709551615,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
        fDigits: Number(this.extractValue(this.extractNodes(cur, "type")[0]!, "fraction-digits")) || -1
      });
    } else if (type === "decimal64") {
      return ({
        ...element,
        uiType: "number",
        min: rangeMatch ? Number(rangeMatch[0]) : 0,
        max: rangeMatch ? Number(rangeMatch[1]) : +18446744073709551615,
        units: this.extractValue(cur, "units") || undefined,
        format: this.extractValue(cur, "format") || undefined,
        fDigits: Number(this.extractValue(this.extractNodes(cur, "type")[0]!, "fraction-digits")) || -1
      });
    } else if (type === "enumeration") {
      const typeNode = this.extractNodes(cur, "type")[0]!;
      const enumNodes = this.extractNodes(typeNode, "enum");
      return ({
        ...element,
        uiType: "selection",
        options: enumNodes.reduce<{ key: string; value: string; description?: string }[]>((acc, enumNode) => {
          if (!enumNode.arg) {
            throw new Error(`Module: [${module.name}][${currentPath}][${cur.arg}]. Found option without name.`);
          }
          const ifClause = this.extractValue(enumNode, "if-feature");
          const value = this.extractValue(enumNode, "value");
          const enumOption = {
            key: enumNode.arg,
            value: value != null ? value : enumNode.arg,
            description: this.extractValue(enumNode, "description") || undefined
          };
          // todo: ❗ handle the if clause ⚡
          acc.push(enumOption);
          return acc;
        }, [])
      });
    } else if (type === "leafref") {
      const typeNode = this.extractNodes(cur, "type")[0]!;
      const vPath = this.extractValue(typeNode, "path");
      if (!vPath) {
        throw new Error(`Module: [${module.name}][${currentPath}][${cur.arg}]. Found leafref without path.`);
      }
      const refPath = this.resolveReferencePath(vPath, module);
      const resolve = this.resolveReference.bind(this);
      const res : ViewElement = {
        ...element,
        uiType: "reference",
        referencePath: refPath,
        ref(this: ViewElement, currentPath: string) {
          const resolved = resolve(refPath, currentPath);
          return resolved && {
            ...resolved,
            id: this.id,
            label: this.label,
            config: this.config,
            mandatory: this.mandatory,
            isList: this.isList,
            default: this.default,
            description: this.description,
          } as ViewElement;
        }
      };
      return res;
    } else if (type === "identityref") {
      const typeNode = this.extractNodes(cur, "type")[0]!;
      const base = this.extractValue(typeNode, "base");
      if (!base) {
        throw new Error(`Module: [${module.name}][${currentPath}][${cur.arg}]. Found identityref without base.`);
      }
      const res: ViewElement = {
        ...element,
        uiType: "selection",
        options: []
      };
      this._identityToResolve.push(() => {
        const identity : Identity = this.resolveIdentity(base, module);
        if (!identity) {
          throw new Error(`Module: [${module.name}][${currentPath}][${cur.arg}]. Could not resolve identity [${base}].`);
        }
        if (!identity.values || identity.values.length === 0) {
          throw new Error(`Identity: [${base}] has no values.`);
        }
        res.options = identity.values.map(val => ({
          key: val.id,
          value: val.id,
          description: val.description
        }));
      });
      return res ;
    } else if (type === "empty") {
      // todo: ❗ handle empty ⚡
      /*  9.11.  The empty Built-In Type
          The empty built-in type represents a leaf that does not have any
          value, it conveys information by its presence or absence. */
      console.warn(`found type: empty in [${module.name}][${currentPath}][${element.label}]`);
      return {
        ...element,
        uiType: "string",
      };
    } else if (type === "union") {
      // todo: ❗ handle union ⚡
      /* 9.12.  The union Built-In Type */
      console.warn(`found type: union in [${module.name}][${currentPath}][${element.label}]`);
      return {
        ...element,
        uiType: "string",
      };
    } else if (type === "bits") {
      const typeNode = this.extractNodes(cur, "type")[0]!;
      const bitNodes = this.extractNodes(typeNode, "bit");
      return {
        ...element,
        uiType: "bits",
        flags: bitNodes.reduce<{[name: string]: number | undefined; }>((acc, bitNode) => {
          if (!bitNode.arg) {
            throw new Error(`Module: [${module.name}][${currentPath}][${cur.arg}]. Found bit without name.`);
          }
          const ifClause = this.extractValue(bitNode, "if-feature");
          const pos = Number(this.extractValue(bitNode, "position"));
          acc[bitNode.arg] = pos === pos ? pos : undefined;
          return acc;
        }, {})
      };
    } else if (type === "binary") {
      const typeNode = this.extractNodes(cur, "type")[0]!;
      const length = Number(this.extractValue(typeNode, "length"));
      return {
        ...element,
        uiType: "binary",
        length: length === length ? length : undefined
      };
    } else {
      // not a build in type, have to resolve type
      const typeRef = this.resolveType(type, module);
      if (typeRef == null) console.error(new Error(`Could not resolve type ${type} in [${module.name}][${currentPath}].`));
      return ({
        ...typeRef,
        ...element,
        description: description
      }) as ViewElement;
    }
  }

  private resolveReferencePath(vPath: string, module: Module) {
    const vPathParser = /(?:(?:([^\/\:]+):)?([^\/]+))/g // 1 = opt: namespace / 2 = property
    return vPath.replace(vPathParser, (_, ns, property) => {
      const nameSpace = ns && module.imports[ns] || module.name;
      return `${nameSpace}:${property}`;
    });
  }


  private resolveReference(vPath: string, currentPath: string) {
    const vPathParser = /(?:(?:([^\/\[\]\:]+):)?([^\/\[\]]+)(\[[^\]]+\])?)/g // 1 = opt: namespace / 2 = property / 3 = opt: indexPath
    let element : ViewElement | null = null;
    let moduleName = "";

    const vPathParts = splitVPath(vPath, vPathParser).map(p => ({ ns: p[1], property: p[2], ind: p[3] }));
    const resultPathParts = !vPath.startsWith("/")
      ? splitVPath(currentPath, vPathParser).map(p => ({ ns: p[1], property: p[2], ind: p[3] }))
      : [];

    for (let i = 0; i < vPathParts.length; ++i){
      const vPathPart = vPathParts[i];
      if (vPathPart.property === "..") {
        resultPathParts.pop();
      } else if (vPathPart.property !== ".") {
        resultPathParts.push(vPathPart);
      }
    }

    // resolve element by path
    for (let j = 0; j < resultPathParts.length;++j){
      const pathPart = resultPathParts[j];
        if (j===0) {
          moduleName = pathPart.ns;
          const rootModule = this._modules[moduleName];
          if (!rootModule) throw new Error("Could not resolve module [" + moduleName +"].\r\n" + vPath);
          element = rootModule.elements[`${pathPart.ns}:${pathPart.property}`];
        } else if (element && isViewElementObjectOrList(element)) {
          const view: ViewSpecification = this._views[+element.viewId];
          if (moduleName !== pathPart.ns) {
            moduleName = pathPart.ns;
            element = view.elements[`${moduleName}:${pathPart.property}`];
          } else {
            element = view.elements[pathPart.property] || view.elements[`${moduleName}:${pathPart.property}`];
          }
        } else {
          throw new Error("Could not resolve reference.\r\n" + vPath);
        }
        if (!element) throw new Error("Could not resolve path [" + pathPart.property + "] in ["+ currentPath +"] \r\n" + vPath);
      }

    return element;
  }

  private resolveView(vPath: string) {
    const vPathParser = /(?:(?:([^\/\[\]\:]+):)?([^\/\[\]]+)(\[[^\]]+\])?)/g // 1 = opt: namespace / 2 = property / 3 = opt: indexPath
    let element: ViewElement | null = null;
    let partMatch: RegExpExecArray | null;
    let view: ViewSpecification | null = null;
    let moduleName = "";
    if (vPath) do {
      partMatch = vPathParser.exec(vPath);
      if (partMatch) {
        if (element === null) {
          moduleName = partMatch[1]!;
          const rootModule = this._modules[moduleName];
          if (!rootModule) return null;
          element = rootModule.elements[`${moduleName}:${partMatch[2]!}`];
        } else if (isViewElementObjectOrList(element)) {
          view = this._views[+element.viewId];
          if (moduleName !== partMatch[1]) {
            moduleName = partMatch[1];
            element = view.elements[`${moduleName}:${partMatch[2]}`];
          } else {
            element = view.elements[partMatch[2]];
          }
        } else {
          return null;
        }
        if (!element) return null;
      }
    } while (partMatch)
    return element && isViewElementObjectOrList(element) && this._views[+element.viewId] || null;
  }

  private resolveType(type: string, module: Module) {
    const collonInd = type.indexOf(":");
    const preFix = collonInd > -1 ? type.slice(0, collonInd) : "";
    const typeName = collonInd > -1 ? type.slice(collonInd + 1) : type;

    const res = preFix
      ? this._modules[module.imports[preFix]].typedefs[typeName]
      : module.typedefs[typeName];
    return res;
  }

  private resolveGrouping(grouping: string, module: Module) {
    const collonInd = grouping.indexOf(":");
    const preFix = collonInd > -1 ? grouping.slice(0, collonInd) : "";
    const groupingName = collonInd > -1 ? grouping.slice(collonInd + 1) : grouping;

    return preFix
      ? this._modules[module.imports[preFix]].groupings[groupingName]
      : module.groupings[groupingName];

  }

  private resolveIdentity(identity: string, module: Module) {
    const collonInd = identity.indexOf(":");
    const preFix = collonInd > -1 ? identity.slice(0, collonInd) : "";
    const identityName = collonInd > -1 ? identity.slice(collonInd + 1) : identity;

    return preFix
      ? this._modules[module.imports[preFix]].identities[identityName]
      : module.identities[identityName];

  }
}