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- import nodejsCustomInspectSymbol from './nodejsCustomInspectSymbol';
- const MAX_ARRAY_LENGTH = 10;
- const MAX_RECURSIVE_DEPTH = 2;
- export default function inspect(value: mixed): string {
- return formatValue(value, []);
- }
- function formatValue(value, seenValues) {
- switch (typeof value) {
- case 'string':
- return JSON.stringify(value);
- case 'function':
- return value.name ? `[function ${value.name}]` : '[function]';
- case 'object':
- if (value === null) {
- return 'null';
- }
- return formatObjectValue(value, seenValues);
- default:
- return String(value);
- }
- }
- function formatObjectValue(value, previouslySeenValues) {
- if (previouslySeenValues.indexOf(value) !== -1) {
- return '[Circular]';
- }
- const seenValues = [...previouslySeenValues, value];
- const customInspectFn = getCustomFn(value);
- if (customInspectFn !== undefined) {
-
- const customValue = customInspectFn.call(value);
-
- if (customValue !== value) {
- return typeof customValue === 'string'
- ? customValue
- : formatValue(customValue, seenValues);
- }
- } else if (Array.isArray(value)) {
- return formatArray(value, seenValues);
- }
- return formatObject(value, seenValues);
- }
- function formatObject(object, seenValues) {
- const keys = Object.keys(object);
- if (keys.length === 0) {
- return '{}';
- }
- if (seenValues.length > MAX_RECURSIVE_DEPTH) {
- return '[' + getObjectTag(object) + ']';
- }
- const properties = keys.map(key => {
- const value = formatValue(object[key], seenValues);
- return key + ': ' + value;
- });
- return '{ ' + properties.join(', ') + ' }';
- }
- function formatArray(array, seenValues) {
- if (array.length === 0) {
- return '[]';
- }
- if (seenValues.length > MAX_RECURSIVE_DEPTH) {
- return '[Array]';
- }
- const len = Math.min(MAX_ARRAY_LENGTH, array.length);
- const remaining = array.length - len;
- const items = [];
- for (let i = 0; i < len; ++i) {
- items.push(formatValue(array[i], seenValues));
- }
- if (remaining === 1) {
- items.push('... 1 more item');
- } else if (remaining > 1) {
- items.push(`... ${remaining} more items`);
- }
- return '[' + items.join(', ') + ']';
- }
- function getCustomFn(object) {
- const customInspectFn = object[String(nodejsCustomInspectSymbol)];
- if (typeof customInspectFn === 'function') {
- return customInspectFn;
- }
- if (typeof object.inspect === 'function') {
- return object.inspect;
- }
- }
- function getObjectTag(object) {
- const tag = Object.prototype.toString
- .call(object)
- .replace(/^\[object /, '')
- .replace(/]$/, '');
- if (tag === 'Object' && typeof object.constructor === 'function') {
- const name = object.constructor.name;
- if (typeof name === 'string' && name !== '') {
- return name;
- }
- }
- return tag;
- }
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