tjson-js
Version:
Tagged JSON (TJSON): a JSON-based microformat with rich type annotations
151 lines (150 loc) • 5.82 kB
JavaScript
;
// TJSON: Tagged JSON with Rich Types
Object.defineProperty(exports, "__esModule", { value: true });
const utf8 = require("utf8");
const datatype_1 = require("./datatype");
const array_1 = require("./datatype/array");
const set_1 = require("./datatype/set");
const binary_1 = require("./datatype/binary");
const boolean_1 = require("./datatype/boolean");
const float_1 = require("./datatype/float");
const integer_1 = require("./datatype/integer");
const object_1 = require("./datatype/object");
const string_1 = require("./datatype/string");
const timestamp_1 = require("./datatype/timestamp");
datatype_1.DataType.register(new binary_1.Binary16Type);
datatype_1.DataType.register(new binary_1.Binary32Type);
datatype_1.DataType.register(new binary_1.Binary64Type);
datatype_1.DataType.register(new binary_1.Binary64Type, "d64");
datatype_1.DataType.register(new boolean_1.BooleanType);
datatype_1.DataType.register(new float_1.FloatType);
datatype_1.DataType.register(new integer_1.IntType);
datatype_1.DataType.register(new integer_1.UintType);
datatype_1.DataType.register(new object_1.ObjectType);
datatype_1.DataType.register(new string_1.StringType);
datatype_1.DataType.register(new timestamp_1.TimestampType);
class TJSON {
// Parse a UTF-8 encoded TJSON string
static parse(tjsonString, decodeUTF8 = true) {
let decodedString = decodeUTF8 ? utf8.decode(tjsonString) : tjsonString;
let result = JSON.parse(decodedString, TJSON.reviver);
if (Array.isArray(result)) {
throw new Error("toplevel arrays are not allowed in TJSON");
}
return result;
}
// Convert a value to TJSON
static stringify(value, space = 0, encodeUTF8 = true) {
let result = JSON.stringify(value, TJSON.replacer, space);
return encodeUTF8 ? utf8.encode(result) : result;
}
// Parse a TJSON type signature into the corresponding DataType object
static parseType(tag) {
// Object
if (tag == "O") {
return datatype_1.DataType.get("O");
}
// Non-Scalar
let result = tag.match(/^([A-Z][a-z0-9]*)<(.*)>$/);
if (result !== null) {
let prefix = result[1];
let inner = result[2];
switch (prefix) {
case "A":
if (inner == "") {
return new array_1.ArrayType(null);
}
else {
return new array_1.ArrayType(TJSON.parseType(inner));
}
case "S":
if (inner == "") {
return new set_1.SetType(null);
}
else {
return new set_1.SetType(TJSON.parseType(inner));
}
case "O":
return datatype_1.DataType.get(tag);
default:
throw new Error(`invalid non-scalar type: ${tag}`);
}
}
// Scalar
if (/^[a-z][a-z0-9]*$/.test(tag)) {
return datatype_1.DataType.get(tag);
}
else {
throw new Error(`invalid tag: "${tag}"`);
}
}
// Identify the TJSON DataType for a given value
static identifyType(value) {
if (typeof value === "object") {
if (Array.isArray(value)) {
return array_1.ArrayType.identifyType(value);
}
else if (value instanceof Uint8Array) {
return datatype_1.DataType.get("d");
}
else if (value instanceof Set) {
return set_1.SetType.identifyType(value);
}
else if (value instanceof Date) {
return datatype_1.DataType.get("t");
}
else {
return datatype_1.DataType.get("O");
}
}
else if (typeof value === "string") {
return datatype_1.DataType.get("s");
}
else if (typeof value === "number") {
return datatype_1.DataType.get("f");
}
else if (typeof value === "boolean") {
return datatype_1.DataType.get("b");
}
else {
throw new Error(`unsupported TJSON value: ${value}`);
}
}
// Look for objects in parsed JSON, extract their types, and decode their values
static reviver(_key, value) {
// Ignore non-objects (including arrays). Transform them on the next pass
if (typeof value !== "object" || Array.isArray(value)) {
return value;
}
let result = {};
Object.keys(value).forEach(key => {
let tagResult = key.match(/^(.*):([A-Za-z0-9\<]+[\>]*)$/);
if (tagResult === null) {
throw new Error(`failed to parse tag: ${key}`);
}
let untaggedKey = tagResult[1];
let tag = tagResult[2];
let childValue = value[key];
let type = TJSON.parseType(tag);
result[untaggedKey] = type.decode(childValue);
});
return result;
}
// Serializer for TJSON objects when building JSON strings
static replacer(_key, value) {
// Ignore non-objects (including arrays). They'll already by transformed
// at this point (by the code below)
if (typeof value !== "object" || Array.isArray(value)) {
return value;
}
let result = {};
Object.keys(value).forEach(key => {
let childValue = value[key];
let type = TJSON.identifyType(childValue);
// Add tag to resulting field
result[key + ":" + type.tag()] = type.encode(childValue);
});
return result;
}
}
exports.default = TJSON;