| // Copyright 2023 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| //go:build goexperiment.jsonv2 |
| |
| // Package jsontext implements syntactic processing of JSON |
| // as specified in RFC 4627, RFC 7159, RFC 7493, RFC 8259, and RFC 8785. |
| // JSON is a simple data interchange format that can represent |
| // primitive data types such as booleans, strings, and numbers, |
| // in addition to structured data types such as objects and arrays. |
| // |
| // This package (encoding/json/jsontext) is experimental, |
| // and not subject to the Go 1 compatibility promise. |
| // It only exists when building with the GOEXPERIMENT=jsonv2 environment variable set. |
| // Most users should use [encoding/json]. |
| // |
| // The [Encoder] and [Decoder] types are used to encode or decode |
| // a stream of JSON tokens or values. |
| // |
| // # Tokens and Values |
| // |
| // A JSON token refers to the basic structural elements of JSON: |
| // |
| // - a JSON literal (i.e., null, true, or false) |
| // - a JSON string (e.g., "hello, world!") |
| // - a JSON number (e.g., 123.456) |
| // - a begin or end delimiter for a JSON object (i.e., '{' or '}') |
| // - a begin or end delimiter for a JSON array (i.e., '[' or ']') |
| // |
| // A JSON token is represented by the [Token] type in Go. Technically, |
| // there are two additional structural characters (i.e., ':' and ','), |
| // but there is no [Token] representation for them since their presence |
| // can be inferred by the structure of the JSON grammar itself. |
| // For example, there must always be an implicit colon between |
| // the name and value of a JSON object member. |
| // |
| // A JSON value refers to a complete unit of JSON data: |
| // |
| // - a JSON literal, string, or number |
| // - a JSON object (e.g., `{"name":"value"}`) |
| // - a JSON array (e.g., `[1,2,3,]`) |
| // |
| // A JSON value is represented by the [Value] type in Go and is a []byte |
| // containing the raw textual representation of the value. There is some overlap |
| // between tokens and values as both contain literals, strings, and numbers. |
| // However, only a value can represent the entirety of a JSON object or array. |
| // |
| // The [Encoder] and [Decoder] types contain methods to read or write the next |
| // [Token] or [Value] in a sequence. They maintain a state machine to validate |
| // whether the sequence of JSON tokens and/or values produces a valid JSON. |
| // [Options] may be passed to the [NewEncoder] or [NewDecoder] constructors |
| // to configure the syntactic behavior of encoding and decoding. |
| // |
| // # Terminology |
| // |
| // The terms "encode" and "decode" are used for syntactic functionality |
| // that is concerned with processing JSON based on its grammar, and |
| // the terms "marshal" and "unmarshal" are used for semantic functionality |
| // that determines the meaning of JSON values as Go values and vice-versa. |
| // This package (i.e., [jsontext]) deals with JSON at a syntactic layer, |
| // while [encoding/json/v2] deals with JSON at a semantic layer. |
| // The goal is to provide a clear distinction between functionality that |
| // is purely concerned with encoding versus that of marshaling. |
| // For example, one can directly encode a stream of JSON tokens without |
| // needing to marshal a concrete Go value representing them. |
| // Similarly, one can decode a stream of JSON tokens without |
| // needing to unmarshal them into a concrete Go value. |
| // |
| // This package uses JSON terminology when discussing JSON, which may differ |
| // from related concepts in Go or elsewhere in computing literature. |
| // |
| // - a JSON "object" refers to an unordered collection of name/value members. |
| // - a JSON "array" refers to an ordered sequence of elements. |
| // - a JSON "value" refers to either a literal (i.e., null, false, or true), |
| // string, number, object, or array. |
| // |
| // See RFC 8259 for more information. |
| // |
| // # Specifications |
| // |
| // Relevant specifications include RFC 4627, RFC 7159, RFC 7493, RFC 8259, |
| // and RFC 8785. Each RFC is generally a stricter subset of another RFC. |
| // In increasing order of strictness: |
| // |
| // - RFC 4627 and RFC 7159 do not require (but recommend) the use of UTF-8 |
| // and also do not require (but recommend) that object names be unique. |
| // - RFC 8259 requires the use of UTF-8, |
| // but does not require (but recommends) that object names be unique. |
| // - RFC 7493 requires the use of UTF-8 |
| // and also requires that object names be unique. |
| // - RFC 8785 defines a canonical representation. It requires the use of UTF-8 |
| // and also requires that object names be unique and in a specific ordering. |
| // It specifies exactly how strings and numbers must be formatted. |
| // |
| // The primary difference between RFC 4627 and RFC 7159 is that the former |
| // restricted top-level values to only JSON objects and arrays, while |
| // RFC 7159 and subsequent RFCs permit top-level values to additionally be |
| // JSON nulls, booleans, strings, or numbers. |
| // |
| // By default, this package operates on RFC 7493, but can be configured |
| // to operate according to the other RFC specifications. |
| // RFC 7493 is a stricter subset of RFC 8259 and fully compliant with it. |
| // In particular, it makes specific choices about behavior that RFC 8259 |
| // leaves as undefined in order to ensure greater interoperability. |
| // |
| // # Security Considerations |
| // |
| // See the "Security Considerations" section in [encoding/json/v2]. |
| package jsontext |
| |
| // requireKeyedLiterals can be embedded in a struct to require keyed literals. |
| type requireKeyedLiterals struct{} |
| |
| // nonComparable can be embedded in a struct to prevent comparability. |
| type nonComparable [0]func() |
