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| /*
* Copyright (c) AXA Shared Services Spain S.A.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
const { generate: unparse } = require('escodegen');
const { parse } = require('esprima');
/**
* Class for evaluating javascript expressions.
*/
class Evaluator {
/**
* Constructor of the class.
* @param {Object} context Default context.
*/
constructor(context) {
this.defaultContext = context || {};
this.failResult = {};
}
/**
* Iterates a literal node.
* @param {Object} node Node to be iterated.
*/
walkLiteral(node) {
return node.value;
}
/**
* Iterates an unary operator node.
* @param {Object} node Node to be iterated.
*/
walkUnary(node, context) {
switch (node.operator) {
case '+':
return +this.walk(node.argument, context);
case '-':
return -this.walk(node.argument, context);
case '~':
/* eslint-disable no-bitwise */
return ~this.walk(node.argument, context);
case '!':
return !this.walk(node.argument, context);
default:
return this.failResult;
}
}
/**
* Iterates an array expression node.
* @param {Object} node Node to iterate.
* @param {Object} context Context of execution.
*/
walkArray(node, context) {
const result = [];
for (let i = 0, l = node.elements.length; i < l; i += 1) {
const x = this.walk(node.elements[i], context);
if (x === this.failResult) {
return this.failResult;
}
result.push(x);
}
return result;
}
/**
* Iterate an object expression node.
* @param {Object} node Node to iterate.
* @param {Object} context Context of execution.
*/
walkObject(node, context) {
const result = {};
for (let i = 0, l = node.properties.length; i < l; i += 1) {
const prop = node.properties[i];
const value = this.walk(prop.value, context);
if (value === this.failResult) {
return this.failResult;
}
result[prop.key.value || prop.key.name] = value;
}
return result;
}
walkBinary(node, context) {
const left = this.walk(node.left, context);
if (left === this.failResult) {
return this.failResult;
}
const right = this.walk(node.right, context);
if (right === this.failResult) {
return this.failResult;
}
switch (node.operator) {
case '==':
/* eslint-disable eqeqeq */
return left == right;
case '===':
return left === right;
case '!=':
/* eslint-disable eqeqeq */
return left != right;
case '!==':
return left !== right;
case '+':
return left + right;
case '-':
return left - right;
case '*':
return left * right;
case '/':
return left / right;
case '%':
return left % right;
case '<':
return left < right;
case '<=':
return left <= right;
case '>':
return left > right;
case '>=':
return left >= right;
case '|':
/* eslint-disable no-bitwise */
return left | right;
case '&':
/* eslint-disable no-bitwise */
return left & right;
case '^':
/* eslint-disable no-bitwise */
return left ^ right;
case '||':
return left || right;
case '&&':
return left && right;
default:
return this.failResult;
}
}
walkIdentifier(node, context) {
if ({}.hasOwnProperty.call(context, node.name)) {
return context[node.name];
}
return this.failResult;
}
walkThis(node, context) {
if ({}.hasOwnProperty.call(context, 'this')) {
// eslint-disable-next-line
return context["this"];
}
return this.failResult;
}
walkCall(node, context) {
const callee = this.walk(node.callee, context);
if (callee === this.failResult || typeof callee !== 'function') {
return this.failResult;
}
let ctx = node.callee.object
? this.walk(node.callee.object, context)
: this.failResult;
if (ctx === this.failResult) {
ctx = null;
}
const args = [];
for (let i = 0, l = node.arguments.length; i < l; i += 1) {
const x = this.walk(node.arguments[i], context);
if (x === this.failResult) {
return this.failResult;
}
args.push(x);
}
return callee.apply(ctx, args);
}
walkMember(node, context) {
const obj = this.walk(node.object, context);
if (obj === this.failResult || typeof obj === 'function') {
return this.failResult;
}
if (node.property.type === 'Identifier') {
return obj[node.property.name];
}
const prop = this.walk(node.property, context);
Iif (prop === this.failResult) {
return this.failResult;
}
return obj[prop];
}
walkConditional(node, context) {
const value = this.walk(node.test, context);
if (value === this.failResult) {
return this.failResult;
}
if (value) {
return this.walk(node.consequent, context);
}
if (!node.alternate) {
return undefined;
}
return this.walk(node.alternate, context);
}
walkExpression(node, context) {
const value = this.walk(node.expression, context);
Iif (value === this.failResult) {
return this.failResult;
}
return value;
}
walkReturn(node, context) {
return this.walk(node.argument, context);
}
walkFunction(node, context) {
const newContext = {};
const keys = Object.keys(context);
keys.forEach(element => {
newContext[element] = context[element];
});
node.params.forEach(key => {
Eif (key.type === 'Identifier') {
newContext[key.name] = null;
}
});
const bodies = node.body.body;
for (let i = 0, l = bodies.length; i < l; i += 1) {
Iif (this.walk(bodies[i], newContext) === this.failResult) {
return this.failResult;
}
}
const vals = keys.map(key => context[key]);
// eslint-disable-next-line
return Function(keys.join(', '), 'return ' + unparse(node)).apply(
null,
vals
);
}
walkTemplateLiteral(node, context) {
let str = '';
for (let i = 0; i < node.expressions.length; i += 1) {
str += this.walk(node.quasis[i], context);
str += this.walk(node.expressions[i], context);
}
return str;
}
walkTemplateElement(node) {
return node.value.cooked;
}
walkTaggedTemplate(node, context) {
const tag = this.walk(node.tag, context);
const { quasi } = node;
const strings = [];
const values = [];
for (let i = 0; i < quasi.quasis.length; i += 1) {
strings.push(this.walk(quasi.quasis[i], context));
}
for (let i = 0; i < quasi.expressions.length; i += 1) {
values.push(this.walk(quasi.expressions[i], context));
}
// eslint-disable-next-line
return tag.apply(null, [strings].concat(values));
}
walkUpdateExpression(node, context) {
let value = this.walk(node.argument, context);
Iif (value === this.failResult) {
return this.failResult;
}
switch (node.operator) {
case '++':
value += 1;
return this.walkSet(node.argument, context, value);
case '--':
value -= 1;
return this.walkSet(node.argument, context, value);
default:
return this.failResult;
}
}
walkAssignmentExpression(node, context) {
const value = this.walk(node.right, context);
if (value === this.failResult) {
return this.failResult;
}
let leftValue = this.walk(node.left, context);
if (leftValue === this.failResult) {
leftValue = 0;
}
switch (node.operator) {
case '=':
this.walkSet(node.left, context, value);
return value;
case '+=':
leftValue += value;
this.walkSet(node.left, context, leftValue);
return leftValue;
case '-=':
leftValue -= value;
this.walkSet(node.left, context, leftValue);
return leftValue;
case '*=':
leftValue *= value;
this.walkSet(node.left, context, leftValue);
return leftValue;
case '/=':
leftValue /= value;
this.walkSet(node.left, context, leftValue);
return leftValue;
case '%=':
leftValue %= value;
this.walkSet(node.left, context, leftValue);
return leftValue;
case '|=':
// eslint-disable-next-line
leftValue |= value;
this.walkSet(node.left, context, leftValue);
return leftValue;
case '&=':
// eslint-disable-next-line
leftValue &= value;
this.walkSet(node.left, context, leftValue);
return leftValue;
case '^=':
// eslint-disable-next-line
leftValue ^= value;
this.walkSet(node.left, context, leftValue);
return leftValue;
default:
return this.failResult;
}
}
walkBlock(node, context) {
Eif (Array.isArray(node.body)) {
let result;
for (let i = 0; i < node.body.length; i += 1) {
result = this.walk(node.body[i], context);
}
return result;
}
return this.walk(node.body, context);
}
walk(node, context) {
switch (node.type) {
case 'Literal':
return this.walkLiteral(node, context);
case 'UnaryExpression':
return this.walkUnary(node, context);
case 'ArrayExpression':
return this.walkArray(node, context);
case 'ObjectExpression':
return this.walkObject(node, context);
case 'BinaryExpression':
case 'LogicalExpression':
return this.walkBinary(node, context);
case 'Identifier':
return this.walkIdentifier(node, context);
case 'ThisExpression':
return this.walkThis(node, context);
case 'CallExpression':
return this.walkCall(node, context);
case 'MemberExpression':
return this.walkMember(node, context);
case 'ConditionalExpression':
return this.walkConditional(node, context);
case 'ExpressionStatement':
return this.walkExpression(node, context);
case 'ReturnStatement':
return this.walkReturn(node, context);
case 'FunctionExpression':
return this.walkFunction(node, context);
case 'TemplateLiteral':
return this.walkTemplateLiteral(node, context);
case 'TemplateElement':
return this.walkTemplateElement(node, context);
case 'TaggedTemplateExpression':
return this.walkTaggedTemplate(node, context);
case 'UpdateExpression':
return this.walkUpdateExpression(node, context);
case 'AssignmentExpression':
return this.walkAssignmentExpression(node, context);
case 'IfStatement':
return this.walkConditional(node, context);
case 'BlockStatement':
return this.walkBlock(node, context);
default:
return this.failResult;
}
}
walkSetIdentifier(node, context, value) {
const newContext = context;
newContext[node.name] = value;
return value;
}
walkSetMember(node, context, value) {
const obj = this.walk(node.object, context);
if (obj === this.failResult || typeof obj === 'function') {
return this.failResult;
}
if (node.property.type === 'Identifier') {
obj[node.property.name] = value;
return value;
}
const prop = this.walk(node.property, context);
Iif (prop === this.failResult) {
return this.failResult;
}
obj[prop] = value;
return value;
}
walkSet(node, context, value) {
switch (node.type) {
case 'Identifier':
return this.walkSetIdentifier(node, context, value);
case 'MemberExpression':
return this.walkSetMember(node, context, value);
default:
return this.failResult;
}
}
evaluateAll(str, context) {
const result = [];
const newContext = context || this.context;
const compiled = parse(str);
for (let i = 0; i < compiled.body.length; i += 1) {
const expression = compiled.body[i].expression
? compiled.body[i].expression
: compiled.body[i];
const value = this.walk(expression, newContext);
result.push(value === this.failResult ? undefined : value);
}
return result;
}
evaluate(str, context) {
const result = this.evaluateAll(str, context);
if (!result || result.length === 0) {
return undefined;
}
return result[result.length - 1];
}
}
module.exports = Evaluator;
|