GDevelop/GDJS/Runtime/variablescontainer.ts

/*
 * GDevelop JS Platform
 * Copyright 2013-2016 Florian Rival (Florian.Rival@gmail.com). All rights reserved.
 * This project is released under the MIT License.
 */
namespace gdjs {
  /**
   * VariablesContainer stores variables, usually for a a RuntimeGame, a RuntimeScene
   * or a RuntimeObject.
   */
  export class VariablesContainer {
    _variables: Hashtable<gdjs.Variable>;
    _variablesArray: gdjs.Variable[] = [];

    /**
     * @param [initialVariablesData] Optional array containing representations of the base variables.
     */
    constructor(initialVariablesData?: VariableData[]) {
      this._variables = new Hashtable();

      if (initialVariablesData !== undefined) {
        this.initFrom(initialVariablesData);
      }
    }

    /**
     * Initialize variables from a container data.<br>
     * If `keepOldVariables` is set to false (by default), all already existing variables will be
     * erased, but the new variables will be accessible thanks to getFromIndex. <br>
     * if `keepOldVariables` is set to true, already existing variables won't be erased and will be
     * still accessible thanks to getFromIndex.
     *
     * @param data The array containing data used to initialize variables.
     * @param [keepOldVariables] If set to true, already existing variables won't be erased.
     */
    initFrom(data: VariableData[], keepOldVariables?: Boolean) {
      if (keepOldVariables === undefined) {
        keepOldVariables = false;
      }
      if (!keepOldVariables) {
        VariablesContainer._deletedVars = VariablesContainer._deletedVars || [];
        // @ts-ignore
        this._variables.keys(VariablesContainer._deletedVars);
      }
      const that = this;
      let i = 0;
      for (let j = 0; j < data.length; ++j) {
        const varData = data[j];
        if (!varData.name) continue;

        //Get the variable:
        const variable = that.get(varData.name);
        variable.reinitialize(varData);
        if (!keepOldVariables) {
          //Register the variable in the extra array to ensure a fast lookup using getFromIndex.
          if (i < that._variablesArray.length) {
            that._variablesArray[i] = variable;
          } else {
            that._variablesArray.push(variable);
          }
          ++i;

          //Remove the variable from the list of variables to be deleted.
          const idx = VariablesContainer._deletedVars.indexOf(varData.name);
          if (idx !== -1) {
            VariablesContainer._deletedVars[idx] = undefined;
          }
        }
      }
      if (!keepOldVariables) {
        this._variablesArray.length = i;

        //If we do not want to keep the already existing variables,
        //remove all the variables not assigned above.
        //(Here, remove means flag the variable as not existing, to avoid garbage creation ).
        for (
          let i = 0, len = VariablesContainer._deletedVars.length;
          i < len;
          ++i
        ) {
          const variableName = VariablesContainer._deletedVars[i];
          if (variableName !== undefined) {
            this._variables.get(variableName).setUndefinedInContainer();
          }
        }
      }
    }

    /**
     * Add a new variable.
     * This can be costly, don't use in performance sensitive paths.
     *
     * @param name Variable name
     * @param newVariable The variable to be added
     */
    add(name: string, newVariable: gdjs.Variable) {
      const oldVariable = this._variables.get(name);

      // Variable is either already defined, considered as undefined
      // in the container or missing in the container.
      // Whatever the case, replace it by the new.
      this._variables.put(name, newVariable);
      if (oldVariable) {
        // If variable is indexed, ensure that the variable as the index
        // is replaced too. This can be costly (indexOf) but we assume `add` is not
        // used in performance sensitive code.
        const variableIndex = this._variablesArray.indexOf(oldVariable);
        if (variableIndex !== -1) {
          this._variablesArray[variableIndex] = newVariable;
        }
      }
    }

    /**
     * Remove a variable.
     * (the variable is not really removed from the container to avoid creating garbage, but marked as undefined)
     * @param name Variable to be removed
     */
    remove(name: string) {
      const variable = this._variables.get(name);
      if (variable) {
        variable.setUndefinedInContainer();
      }
    }

    /**
     * Get a variable.
     * @param name The variable's name
     * @return The specified variable. If not found, an empty variable is added to the container.
     */
    get(name: string): gdjs.Variable {
      let variable = this._variables.get(name);
      if (!variable) {
        //Add automatically inexisting variables.
        variable = new gdjs.Variable();
        this._variables.put(name, variable);
      } else {
        if (
          //Reuse variables removed before.
          variable.isUndefinedInContainer()
        ) {
          variable.reinitialize();
        }
      }
      return variable;
    }

    /**
     * Get a variable using its index. If you're unsure about how to use this method, prefer to use `get`.
     * The index of a variable is its index in the data passed to initFrom.
     *
     * This method is generally used by events generated code to increase lookup speed for variables.
     *
     * @param id The variable index
     * @return The specified variable. If not found, an empty variable is added to the container, but it
     * should not happen.
     */
    getFromIndex(id: number): gdjs.Variable {
      if (id >= this._variablesArray.length) {
        //Add automatically non-existing variables.
        let variable = new gdjs.Variable();
        this._variables.put('', variable);
        return variable;
      } else {
        let variable: gdjs.Variable = this._variablesArray[id];
        //Reuse variables removed before.
        if (variable.isUndefinedInContainer()) {
          variable.reinitialize();
        }
        return variable;
      }
    }

    /**
     * Check if a variable exists in the container.
     * @param name The variable's name
     * @return true if the variable exists.
     */
    has(name: string): boolean {
      const variable = this._variables.get(name);
      return variable && !variable.isUndefinedInContainer();
    }
    static _deletedVars: Array<string | undefined> = [];

    /**
     * "Bad" variable container, used by events when no other valid container can be found.
     * This container has no state and always returns the bad variable ( see VariablesContainer.badVariable ).
     * @static
     */
    static badVariablesContainer: VariablesContainer = {
      _variables: new Hashtable(),
      _variablesArray: [],
      has: function () {
        return false;
      },
      getFromIndex: function () {
        return VariablesContainer.badVariable;
      },
      get: function () {
        return VariablesContainer.badVariable;
      },
      remove: function () {
        return;
      },
      add: function () {
        return;
      },
      initFrom: function () {
        return;
      },
    };

    /**
     * "Bad" variable, used by events when no other valid variable can be found.
     * This variable has no state and always return 0 or the empty string.
     * @static
     */
    static badVariable: Variable = {
      _type: 'number',
      _bool: false,
      _children: {},
      _childrenArray: [],
      _str: '',
      _undefinedInContainer: true,
      _value: 0,
      fromJSON: () => gdjs.VariablesContainer.badVariable,
      toJSObject: () => 0,
      fromJSObject: () => gdjs.VariablesContainer.badVariable,
      reinitialize: () => {},
      addChild: () => gdjs.VariablesContainer.badVariable,
      castTo: () => {},
      clearChildren: () => {},
      clone: () => gdjs.VariablesContainer.badVariable,
      getChildrenCount: () => 0,
      replaceChildren: () => {},
      replaceChildrenArray: () => {},
      getType: function () {
        return 'number';
      },
      isPrimitive: function () {
        return true;
      },
      setValue: () => {},
      getValue: () => 0,
      getChild: () => gdjs.VariablesContainer.badVariable,
      getChildAt: () => gdjs.VariablesContainer.badVariable,
      hasChild: function () {
        return false;
      },
      isStructure: function () {
        return false;
      },
      isNumber: function () {
        return true;
      },
      removeChild: function () {
        return;
      },
      setNumber: function () {
        return;
      },
      setString: function () {
        return;
      },
      setBoolean: function () {
        return;
      },
      getAsString: function () {
        return '0';
      },
      getAsNumber: function () {
        return 0;
      },
      getAsBoolean: function () {
        return false;
      },
      getAllChildren: function () {
        return {};
      },
      getAllChildrenArray: function () {
        return [];
      },
      pushVariableCopy: () => {},
      pushValue: () => {},
      removeAtIndex: function () {
        return;
      },
      add: function () {
        return;
      },
      sub: function () {
        return;
      },
      mul: function () {
        return;
      },
      div: function () {
        return;
      },
      concatenate: function () {
        return;
      },
      concatenateString: function () {
        return;
      },
      setUndefinedInContainer: function () {
        return;
      },
      isUndefinedInContainer: function () {
        return true;
      },
    };
  }
}