ngx-i18nsupport/src/xliffmerge/ngx-translate-extraction-pattern.ts

Some tooling to be used with the Angular 2 i18n workflow

/**
 * Helper class to parse ngx translate extraction pattern
 * and to decide wether a given message matches the pattern.
 */
export class NgxTranslateExtractionPattern {

    private _matchExplicitId: boolean;
    private _descriptionPatterns: string[];

    /**
     * Construct the pattern from given description string
     * @param extractionPatternString
     * @throws an error, if there is a syntax error
     */
    constructor(private extractionPatternString) {
        const parts = extractionPatternString.split('|');
        this._matchExplicitId = false;
        this._descriptionPatterns = [];
        for (let i = 0; i < parts.length; i++) {
            const part = parts[i];
            if (part === '@@') {
                if (this._matchExplicitId) {
                    throw new Error('extraction pattern must not contain @@ twice');
                }
                this._matchExplicitId = true;
            } else {
                const errorString = this.checkValidDescriptionPattern(part);
                if (errorString) {
                    throw new Error(errorString);
                }
                this._descriptionPatterns.push(part);
            }
        }
    }

    /**
     * Check, wether an explicitly set id matches the pattern.
     * @param {string} id
     * @return {boolean}
     */
    public isExplicitIdMatched(id: string): boolean {
        return id && this._matchExplicitId;
    }

    /**
     * Check, wether a given description matches the pattern.
     * @param {string} description
     * @return {boolean}
     */
    public isDescriptionMatched(description: string): boolean {
        return this._descriptionPatterns.indexOf(description) >= 0;
    }

    private checkValidDescriptionPattern(descriptionPattern: string): string {
        if (!descriptionPattern) {
            return 'empty value not allowed';
        }
        if (/^[a-zA-Z_][a-zA-Z_-]*$/.test(descriptionPattern)) {
            return null; // it is ok
        } else {
            return 'description pattern must be an identifier containing only letters, digits, _ or -'
        }
    }
}