All files / NCalc Expression.ts

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/* eslint-disable @typescript-eslint/no-explicit-any */
import {EvaluationException, EvaluationVisitor, LogicalExpression} from '@/NCalc/Domain/index';
import NCalcParser from '@/Grammar/NCalcParser';
import NCalcLexer from '@/Grammar/NCalcLexer';
import {EvaluateOptions} from './EvaluationOptions';
import {EvaluateFunctionHandler, EvaluateParameterHandler} from './types';
import {default as antlr4} from 'antlr4';
import { ErrorListener } from './ErrorListener';
 
export class Expression {
 
    private lexerErrors: ErrorListener;
 
    private parserErrors: ErrorListener;
 
    public Options: EvaluateOptions = EvaluateOptions.None;
 
    /**
   * Orginal strings representation of the expression
   */
    protected OriginalExpression: string;
 
    private static _cacheEnabled = true;
 
    private static _compiledExpression: {[key: string]: WeakRef<LogicalExpression>} = {};
 
    public ParsedExpression: LogicalExpression;
 
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    protected ParameterEnumerators: {[key: string]: any} = {};
 
    protected ParametersBackup: {[key: string]: object} = {};
 
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    public Parameters: {[key: string]: any} = {};
 
    public get CacheEnabled() {
        return Expression._cacheEnabled;
    }
 
    public set CacheEnabled(value: boolean) {
        Expression._cacheEnabled = value;
        Iif (value === false) {
            Expression._compiledExpression = {};
        }
    }
 
    public static get CachedExpressions() {
        return Expression._compiledExpression;
    }
 
    public constructor(expression: LogicalExpression);
    public constructor(expression: string);
    public constructor(expression: LogicalExpression, options: EvaluateOptions);
    public constructor(expression: string, options: EvaluateOptions);
    public constructor(expression: any, options: EvaluateOptions = EvaluateOptions.None) {
        Iif (expression == null || expression == '') {
            throw new Error('The expression cannot be null or empty');
        }
 
        if (typeof expression === 'string') {
            this.OriginalExpression = expression;
        } else {
            this.ParsedExpression = expression;
        }
 
        if (options) {
            this.Options = options;
        }
 
        this.lexerErrors = new ErrorListener();
        this.parserErrors = new ErrorListener();
    }
 
    public get errors() {
        return this.lexerErrors.errors.concat(this.parserErrors.errors);
    }
 
    public Compile(expression: string, nocache: boolean): LogicalExpression {
        let logicalExpression: LogicalExpression | null = null;
 
        if (this.CacheEnabled && !nocache) {
            if (Object.prototype.hasOwnProperty.call(Expression._compiledExpression, expression)) {
                const wr = Expression._compiledExpression[expression];
                const stored = wr.deref();
                if (stored && stored !== undefined) {
                    return stored;
                }
            }
        }
 
        if (logicalExpression == null) {
            // Create the lexer
            const inputStream = new antlr4.CharStream(expression);
            const lexer = new NCalcLexer(inputStream);
            lexer.addErrorListener(this.lexerErrors);
 
            // Create parser
            const tokenStream = new antlr4.CommonTokenStream(lexer);
            const parser = new NCalcParser(tokenStream);
            parser.addErrorListener(this.parserErrors);
 
            logicalExpression = (parser as any).GetExpression();
 
            if (this.CacheEnabled && !nocache) {
                Expression._compiledExpression[expression] = new WeakRef(logicalExpression);
            }
        }
 
        return logicalExpression;
    }
 
    /**
   * Detects whether the expression has errors. This will simply return a boolean value.
   * You can access the error by using the `errors` getter.
   */
    public HasErrors(): boolean {
        try {
            if (this.ParsedExpression == null) {
                this.ParsedExpression = this.Compile(
                    this.OriginalExpression,
                    (this.Options & EvaluateOptions.NoCache) == EvaluateOptions.NoCache
                );
            }
 
            if (this.errors.length > 0) {
                throw new Error();
            }
 
            // In case HasErrors() is called multiple times for the same expression
            return this.ParsedExpression === null || this.ParsedExpression === undefined;
        } catch (e) {
            return true;
        }
    }
 
    public EvaluateFunction: {[key: string]: EvaluateFunctionHandler} = {};
    public EvaluateParameter: {[key: string]: EvaluateParameterHandler} = {};
 
    public Evaluate(): any {
        Iif (this.HasErrors()) {
            throw new EvaluationException('Failed evaluating the expression. Refer to errors.');
        }
 
        Iif (this.ParsedExpression == null) {
            this.ParsedExpression = this.Compile(
                this.OriginalExpression,
                (this.Options & EvaluateOptions.NoCache) == EvaluateOptions.NoCache
            );
        }
 
        const visitor = new EvaluationVisitor(this.Options);
        visitor.EvaluateFunction = this.EvaluateFunction;
        visitor.EvaluateParameter = this.EvaluateParameter;
        visitor.Parameters = this.Parameters;
 
        // if array evaluation, execute the same expression multiple times
        if ((this.Options & EvaluateOptions.IterateParameters) == EvaluateOptions.IterateParameters) {
            let size = -1;
            this.ParametersBackup = {};
            for (const key in this.Parameters) {
                this.ParametersBackup[key] = this.Parameters[key];
            }
 
            this.ParameterEnumerators = {};
 
            for (const parameter in this.Parameters) {
                const value = this.Parameters[parameter];
                if (Array.isArray(value)) {
                    const localsize = value.length;
                    if (size == -1) {
                        size = localsize;
                    } else IEif (localsize != size) {
                        throw new EvaluationException(
                            'When IterateParameters option is used, IEnumerable parameters must have the same number of items'
                        );
                    }
                }
            }
 
            for (const key in this.Parameters) {
                const parameter = this.Parameters[key];
                if (parameter != null) {
                    this.ParameterEnumerators[key] = parameter;
                }
            }
 
            const results = [];
            for (let i = 0; i < size; i++) {
                for (const key in this.ParameterEnumerators) {
                    const enumerator = this.ParameterEnumerators[key];
                    this.Parameters[key] = enumerator[i];
                }
 
                this.ParsedExpression.Accept(visitor);
                results.push(visitor.Result);
            }
 
            return results;
        }
 
        this.ParsedExpression.Accept(visitor);
        return visitor.Result;
    }
}