NativeScript/nativescript-core/ui/builder/binding-builder.ts

// regex that contains all symbols applicable for expression used to AI detect an expression.
const expressionSymbolsRegex = /[\+\-\*\/%\?:<>=!\|&\(\)^~]/;

export module bindingConstants {
    export const sourceProperty = "sourceProperty";
    export const targetProperty = "targetProperty";
    export const expression = "expression";
    export const twoWay = "twoWay";
    export const source = "source";
    export const bindingValueKey = "$value";
    export const parentValueKey = "$parent";
    export const parentsValueKey = "$parents";
    export const newPropertyValueKey = "$newPropertyValue";
}

const hasEqualSignRegex = /=+/;
const equalSignComparisionOperatorsRegex = /(==|===|>=|<=|!=|!==)/;

// this regex is used to search for all instaces of '$parents[]' within an expression
export const parentsRegex = /\$parents\s*\[\s*(['"]*)\w*\1\s*\]/g;

function isNamedParam(value) {
    const equalSignIndex = value.search(hasEqualSignRegex);
    if (equalSignIndex > -1) {
        const equalSignSurround = value.substr(equalSignIndex > 0 ? equalSignIndex - 1 : 0, 3);
        if (equalSignSurround.search(equalSignComparisionOperatorsRegex) === -1) {
            return true;
        }
    }

    return false;
}

function areNamedParams(params: Array<any>) {
    for (let i = 0; i < params.length; i++) {
        if (isNamedParam(params[i])) {
            return true;
        }
    }

    return false;
}

const namedParamConstants = {
    propName: "propName",
    propValue: "propValue"
};

function getPropertyNameValuePair(param, knownOptions, callback) {
    let nameValuePair = {};
    let propertyName = param.substr(0, param.indexOf("=")).trim();
    const propertyValue = param.substr(param.indexOf("=") + 1).trim();
    if (knownOptions) {
        if (!propertyName) {
            propertyName = knownOptions.defaultProperty;
        }
        else {
            propertyName = propertyName in knownOptions ? propertyName : null;
        }
    }

    if (propertyName) {
        if (callback) {
            nameValuePair = callback(propertyName, propertyValue);
        }
        else {
            nameValuePair[namedParamConstants.propName] = propertyName;
            nameValuePair[namedParamConstants.propValue] = propertyValue;
        }

        return nameValuePair;
    }

    return null;
}

function parseNamedProperties(parameterList, knownOptions, callback) {
    const result = {};
    let nameValuePair;
    for (let i = 0; i < parameterList.length; i++) {
        nameValuePair = getPropertyNameValuePair(parameterList[i], knownOptions, callback);
        if (nameValuePair) {
            result[nameValuePair[namedParamConstants.propName]] = nameValuePair[namedParamConstants.propValue];
        }
    }

    return result;
}

function getParamsArray(value: string) {
    const result = [];
    let skipComma = 0;
    let indexReached = 0;
    let singleQuoteBlock = false;
    let doubleQuoteBlock = false;

    for (let i = 0; i < value.length; i++) {
        if (value[i] === "\"") {
            doubleQuoteBlock = !doubleQuoteBlock;
        }

        if (value[i] === "'") {
            singleQuoteBlock = !singleQuoteBlock;
        }

        if (value[i] === "(" || value[i] === "[") {
            skipComma++;
        }

        if (value[i] === ")" || value[i] === "]") {
            skipComma--;
        }

        if (value[i] === "," && skipComma === 0 && !(singleQuoteBlock || doubleQuoteBlock)) {
            result.push(value.substr(indexReached, i - indexReached));
            indexReached = i + 1;
        }
    }

    result.push(value.substr(indexReached));

    return result;
}

function isExpression(expression: string): boolean {
    if (expression.search(expressionSymbolsRegex) > -1) {
        const parentsMatches = expression.match(parentsRegex);
        if (parentsMatches) {
            const restOfExpression = expression.substr(expression.indexOf(parentsMatches[0]) + parentsMatches[0].length);
            // no more expression regognition symbols so it is safe for sourceProperty
            if (!(restOfExpression.search(expressionSymbolsRegex) > -1)) {
                return false;
            }
        }

        return true;
    }

    return false;
}

export function getBindingOptions(name: string, value: string): any {
    let namedParams = [];
    const params = getParamsArray(value);
    if (!areNamedParams(params)) {
        if (params.length === 1) {
            const trimmedValue = params[0].trim();
            let sourceProp;
            if (isExpression(trimmedValue)) {
                sourceProp = bindingConstants.bindingValueKey;
                namedParams.push(bindingConstants.expression + " = " + trimmedValue);
            }
            else {
                sourceProp = trimmedValue;
            }
            namedParams.push(bindingConstants.sourceProperty + " = " + sourceProp);

            namedParams.push(bindingConstants.twoWay + " = true");
        }
        else {
            namedParams.push(bindingConstants.sourceProperty + " = " + params[0].trim());
            namedParams.push(bindingConstants.expression + " = " + params[1].trim());
            const twoWay = params[2] ? params[2].toLowerCase().trim() === "true" : true;
            namedParams.push(bindingConstants.twoWay + " = " + twoWay);
        }
    }
    else {
        namedParams = params;
    }

    const bindingPropertyHandler = function (prop, value) {
        const result = {};
        result[namedParamConstants.propName] = prop;
        if (prop === bindingConstants.twoWay) {
            // create a real boolean value
            if (value === "true") {
                result[namedParamConstants.propValue] = true;
            }
            else {
                result[namedParamConstants.propValue] = false;
            }
        }
        else {
            result[namedParamConstants.propValue] = value;
        }

        return result;
    };

    const bindingOptionsParameters = parseNamedProperties(namedParams, xmlBindingProperties, bindingPropertyHandler);
    const bindOptions = {
        targetProperty: name
    };

    for (let prop in bindingOptionsParameters) {
        if (bindingOptionsParameters.hasOwnProperty(prop)) {
            bindOptions[prop] = bindingOptionsParameters[prop];
        }
    }

    if (bindOptions[bindingConstants.twoWay] === undefined) {
        bindOptions[bindingConstants.twoWay] = true;
    }

    return bindOptions;
}

const xmlBindingProperties = {
    sourceProperty: true,
    expression: true,
    twoWay: true,
    source: true,
    defaultProperty: bindingConstants.sourceProperty
};