365 lines
14 KiB
Markdown
365 lines
14 KiB
Markdown
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# jsonc-parser
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Scanner and parser for JSON with comments.
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[](https://www.npmjs.org/package/jsonc-parser)
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[](https://npmjs.org/package/jsonc-parser)
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[](https://github.com/microsoft/node-jsonc-parser/workflows/Tests)
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[](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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* When `false` is returned, the array items will not be visited.
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*/
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onObjectBegin?: (offset: number, length: number, startLine: number, startCharacter: number, pathSupplier: () => JSONPath) => void | boolean;
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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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* When `false` is returned, the array items will not be visited.*
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*/
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onArrayBegin?: (offset: number, length: number, startLine: number, startCharacter: number, pathSupplier: () => JSONPath) => void | boolean;
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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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