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# jsonc-parser |
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Scanner and parser for JSON with comments. |
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[![npm Package](https://img.shields.io/npm/v/jsonc-parser.svg?style=flat-square)](https://www.npmjs.org/package/jsonc-parser) |
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[![NPM Downloads](https://img.shields.io/npm/dm/jsonc-parser.svg)](https://npmjs.org/package/jsonc-parser) |
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[![Build Status](https://github.com/microsoft/node-jsonc-parser/workflows/Tests/badge.svg)](https://github.com/microsoft/node-jsonc-parser/workflows/Tests) |
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[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT) |
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Why? |
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---- |
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JSONC is JSON with JavaScript style comments. This node module provides a scanner and fault tolerant parser that can process JSONC but is also useful for standard JSON. |
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- the *scanner* tokenizes the input string into tokens and token offsets |
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- the *visit* function implements a 'SAX' style parser with callbacks for the encountered properties and values. |
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- the *parseTree* function computes a hierarchical DOM with offsets representing the encountered properties and values. |
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- the *parse* function evaluates the JavaScript object represented by JSON string in a fault tolerant fashion. |
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- the *getLocation* API returns a location object that describes the property or value located at a given offset in a JSON document. |
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- the *findNodeAtLocation* API finds the node at a given location path in a JSON DOM. |
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- the *format* API computes edits to format a JSON document. |
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- the *modify* API computes edits to insert, remove or replace a property or value in a JSON document. |
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- the *applyEdits* API applies edits to a document. |
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Installation |
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------------ |
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``` |
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npm install --save jsonc-parser |
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``` |
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API |
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--- |
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### Scanner: |
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```typescript |
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/** |
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* Creates a JSON scanner on the given text. |
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* If ignoreTrivia is set, whitespaces or comments are ignored. |
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*/ |
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export function createScanner(text: string, ignoreTrivia: boolean = false): JSONScanner; |
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/** |
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* The scanner object, representing a JSON scanner at a position in the input string. |
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*/ |
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export interface JSONScanner { |
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/** |
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* Sets the scan position to a new offset. A call to 'scan' is needed to get the first token. |
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*/ |
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setPosition(pos: number): any; |
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/** |
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* Read the next token. Returns the token code. |
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*/ |
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scan(): SyntaxKind; |
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/** |
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* Returns the zero-based current scan position, which is after the last read token. |
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*/ |
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getPosition(): number; |
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/** |
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* Returns the last read token. |
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*/ |
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getToken(): SyntaxKind; |
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/** |
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* Returns the last read token value. The value for strings is the decoded string content. For numbers it's of type number, for boolean it's true or false. |
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*/ |
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getTokenValue(): string; |
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/** |
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* The zero-based start offset of the last read token. |
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*/ |
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getTokenOffset(): number; |
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/** |
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* The length of the last read token. |
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*/ |
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getTokenLength(): number; |
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/** |
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* The zero-based start line number of the last read token. |
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*/ |
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getTokenStartLine(): number; |
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/** |
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* The zero-based start character (column) of the last read token. |
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*/ |
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getTokenStartCharacter(): number; |
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/** |
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* An error code of the last scan. |
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*/ |
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getTokenError(): ScanError; |
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} |
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``` |
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### Parser: |
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```typescript |
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export interface ParseOptions { |
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disallowComments?: boolean; |
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allowTrailingComma?: boolean; |
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allowEmptyContent?: boolean; |
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} |
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/** |
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* Parses the given text and returns the object the JSON content represents. On invalid input, the parser tries to be as fault tolerant as possible, but still return a result. |
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* Therefore always check the errors list to find out if the input was valid. |
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*/ |
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export declare function parse(text: string, errors?: {error: ParseErrorCode;}[], options?: ParseOptions): any; |
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/** |
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* Parses the given text and invokes the visitor functions for each object, array and literal reached. |
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*/ |
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export declare function visit(text: string, visitor: JSONVisitor, options?: ParseOptions): any; |
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/** |
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* Visitor called by {@linkcode visit} when parsing JSON. |
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* |
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* The visitor functions have the following common parameters: |
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* - `offset`: Global offset within the JSON document, starting at 0 |
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* - `startLine`: Line number, starting at 0 |
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* - `startCharacter`: Start character (column) within the current line, starting at 0 |
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* |
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* Additionally some functions have a `pathSupplier` parameter which can be used to obtain the |
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* current `JSONPath` within the document. |
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*/ |
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export interface JSONVisitor { |
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/** |
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* Invoked when an open brace is encountered and an object is started. The offset and length represent the location of the open brace. |
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*/ |
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onObjectBegin?: (offset: number, length: number, startLine: number, startCharacter: number, pathSupplier: () => JSONPath) => void; |
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/** |
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* Invoked when a property is encountered. The offset and length represent the location of the property name. |
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* The `JSONPath` created by the `pathSupplier` refers to the enclosing JSON object, it does not include the |
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* property name yet. |
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*/ |
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onObjectProperty?: (property: string, offset: number, length: number, startLine: number, startCharacter: number, pathSupplier: () => JSONPath) => void; |
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/** |
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* Invoked when a closing brace is encountered and an object is completed. The offset and length represent the location of the closing brace. |
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*/ |
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onObjectEnd?: (offset: number, length: number, startLine: number, startCharacter: number) => void; |
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/** |
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* Invoked when an open bracket is encountered. The offset and length represent the location of the open bracket. |
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*/ |
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onArrayBegin?: (offset: number, length: number, startLine: number, startCharacter: number, pathSupplier: () => JSONPath) => void; |
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/** |
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* Invoked when a closing bracket is encountered. The offset and length represent the location of the closing bracket. |
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*/ |
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onArrayEnd?: (offset: number, length: number, startLine: number, startCharacter: number) => void; |
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/** |
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* Invoked when a literal value is encountered. The offset and length represent the location of the literal value. |
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*/ |
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onLiteralValue?: (value: any, offset: number, length: number, startLine: number, startCharacter: number, pathSupplier: () => JSONPath) => void; |
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/** |
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* Invoked when a comma or colon separator is encountered. The offset and length represent the location of the separator. |
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*/ |
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onSeparator?: (character: string, offset: number, length: number, startLine: number, startCharacter: number) => void; |
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/** |
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* When comments are allowed, invoked when a line or block comment is encountered. The offset and length represent the location of the comment. |
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*/ |
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onComment?: (offset: number, length: number, startLine: number, startCharacter: number) => void; |
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/** |
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* Invoked on an error. |
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*/ |
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onError?: (error: ParseErrorCode, offset: number, length: number, startLine: number, startCharacter: number) => void; |
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} |
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/** |
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* Parses the given text and returns a tree representation the JSON content. On invalid input, the parser tries to be as fault tolerant as possible, but still return a result. |
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*/ |
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export declare function parseTree(text: string, errors?: ParseError[], options?: ParseOptions): Node | undefined; |
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export declare type NodeType = "object" | "array" | "property" | "string" | "number" | "boolean" | "null"; |
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export interface Node { |
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type: NodeType; |
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value?: any; |
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offset: number; |
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length: number; |
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colonOffset?: number; |
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parent?: Node; |
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children?: Node[]; |
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} |
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``` |
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### Utilities: |
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```typescript |
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/** |
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* Takes JSON with JavaScript-style comments and remove |
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* them. Optionally replaces every none-newline character |
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* of comments with a replaceCharacter |
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*/ |
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export declare function stripComments(text: string, replaceCh?: string): string; |
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/** |
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* For a given offset, evaluate the location in the JSON document. Each segment in the location path is either a property name or an array index. |
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*/ |
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export declare function getLocation(text: string, position: number): Location; |
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/** |
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* A {@linkcode JSONPath} segment. Either a string representing an object property name |
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* or a number (starting at 0) for array indices. |
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*/ |
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export declare type Segment = string | number; |
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export declare type JSONPath = Segment[]; |
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export interface Location { |
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/** |
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* The previous property key or literal value (string, number, boolean or null) or undefined. |
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*/ |
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previousNode?: Node; |
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/** |
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* The path describing the location in the JSON document. The path consists of a sequence strings |
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* representing an object property or numbers for array indices. |
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*/ |
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path: JSONPath; |
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/** |
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* Matches the locations path against a pattern consisting of strings (for properties) and numbers (for array indices). |
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* '*' will match a single segment, of any property name or index. |
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* '**' will match a sequence of segments or no segment, of any property name or index. |
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*/ |
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matches: (patterns: JSONPath) => boolean; |
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/** |
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* If set, the location's offset is at a property key. |
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*/ |
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isAtPropertyKey: boolean; |
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} |
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/** |
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* Finds the node at the given path in a JSON DOM. |
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*/ |
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export function findNodeAtLocation(root: Node, path: JSONPath): Node | undefined; |
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/** |
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* Finds the most inner node at the given offset. If includeRightBound is set, also finds nodes that end at the given offset. |
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*/ |
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export function findNodeAtOffset(root: Node, offset: number, includeRightBound?: boolean) : Node | undefined; |
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/** |
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* Gets the JSON path of the given JSON DOM node |
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*/ |
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export function getNodePath(node: Node): JSONPath; |
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/** |
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* Evaluates the JavaScript object of the given JSON DOM node |
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*/ |
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export function getNodeValue(node: Node): any; |
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/** |
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* Computes the edit operations needed to format a JSON document. |
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* |
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* @param documentText The input text |
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* @param range The range to format or `undefined` to format the full content |
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* @param options The formatting options |
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* @returns The edit operations describing the formatting changes to the original document following the format described in {@linkcode EditResult}. |
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* To apply the edit operations to the input, use {@linkcode applyEdits}. |
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*/ |
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export function format(documentText: string, range: Range, options: FormattingOptions): EditResult; |
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/** |
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* Computes the edit operations needed to modify a value in the JSON document. |
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* |
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* @param documentText The input text |
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* @param path The path of the value to change. The path represents either to the document root, a property or an array item. |
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* If the path points to an non-existing property or item, it will be created. |
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* @param value The new value for the specified property or item. If the value is undefined, |
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* the property or item will be removed. |
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* @param options Options |
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* @returns The edit operations describing the changes to the original document, following the format described in {@linkcode EditResult}. |
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* To apply the edit operations to the input, use {@linkcode applyEdits}. |
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*/ |
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export function modify(text: string, path: JSONPath, value: any, options: ModificationOptions): EditResult; |
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/** |
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* Applies edits to an input string. |
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* @param text The input text |
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* @param edits Edit operations following the format described in {@linkcode EditResult}. |
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* @returns The text with the applied edits. |
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* @throws An error if the edit operations are not well-formed as described in {@linkcode EditResult}. |
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*/ |
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export function applyEdits(text: string, edits: EditResult): string; |
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/** |
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* An edit result describes a textual edit operation. It is the result of a {@linkcode format} and {@linkcode modify} operation. |
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* It consist of one or more edits describing insertions, replacements or removals of text segments. |
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* * The offsets of the edits refer to the original state of the document. |
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* * No two edits change or remove the same range of text in the original document. |
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* * Multiple edits can have the same offset if they are multiple inserts, or an insert followed by a remove or replace. |
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* * The order in the array defines which edit is applied first. |
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* To apply an edit result use {@linkcode applyEdits}. |
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* In general multiple EditResults must not be concatenated because they might impact each other, producing incorrect or malformed JSON data. |
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*/ |
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export type EditResult = Edit[]; |
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/** |
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* Represents a text modification |
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*/ |
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export interface Edit { |
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/** |
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* The start offset of the modification. |
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*/ |
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offset: number; |
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/** |
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* The length of the modification. Must not be negative. Empty length represents an *insert*. |
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*/ |
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length: number; |
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/** |
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* The new content. Empty content represents a *remove*. |
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*/ |
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content: string; |
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} |
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/** |
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* A text range in the document |
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*/ |
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export interface Range { |
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/** |
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* The start offset of the range. |
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*/ |
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offset: number; |
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/** |
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* The length of the range. Must not be negative. |
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*/ |
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length: number; |
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} |
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/** |
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* Options used by {@linkcode format} when computing the formatting edit operations |
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*/ |
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export interface FormattingOptions { |
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/** |
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* If indentation is based on spaces (`insertSpaces` = true), then what is the number of spaces that make an indent? |
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*/ |
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tabSize: number; |
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/** |
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* Is indentation based on spaces? |
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*/ |
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insertSpaces: boolean; |
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/** |
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* The default 'end of line' character |
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*/ |
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eol: string; |
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} |
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/** |
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* Options used by {@linkcode modify} when computing the modification edit operations |
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*/ |
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export interface ModificationOptions { |
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/** |
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* Formatting options. If undefined, the newly inserted code will be inserted unformatted. |
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*/ |
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formattingOptions?: FormattingOptions; |
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/** |
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* Default false. If `JSONPath` refers to an index of an array and `isArrayInsertion` is `true`, then |
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* {@linkcode modify} will insert a new item at that location instead of overwriting its contents. |
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*/ |
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isArrayInsertion?: boolean; |
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/** |
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* Optional function to define the insertion index given an existing list of properties. |
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*/ |
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getInsertionIndex?: (properties: string[]) => number; |
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} |
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``` |
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License |
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------- |
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(MIT License) |
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Copyright 2018, Microsoft |
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