JSPM

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  • License MIT

Scanner and parser for JSON with comments.

Package Exports

  • jsonc-parser

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (jsonc-parser) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

jsonc-parser

Scanner and parser for JSON with comments.

npm Package NPM Downloads

Why?

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.

  • the scanner tokenizes the input string into tokens and token offsets
  • the parse function evaluates the JavaScipt object represented by JSON string in a fault tolerant fashion.
  • the visit function implements a 'SAX' style parser with callbacks for the encountered properties and values

Installation

npm install --save jsonc-parser

API

Scanner:

/**
 * Creates a JSON scanner on the given text.
 * If ignoreTrivia is set, whitespaces or comments are ignored.
 */
export function createScanner(text:string, ignoreTrivia:boolean = false):JSONScanner;
    
/**
 * The scanner object, representing a JSON scanner at a position in the input string.
 */
export interface JSONScanner {
    /**
     * Sets the scan position to a new offset. A call to 'scan' is needed to get the first token.
     */
    setPosition(pos: number): any;
    /**
     * Read the next token. Returns the tolen code.
     */
    scan(): SyntaxKind;
    /**
     * Returns the current scan position, which is after the last read token.
     */
    getPosition(): number;
    /**
     * Returns the last read token.
     */
    getToken(): SyntaxKind;
    /**
     * Returns the last read token value. The value for strings is the decoded string content. For numbers its of type number, for boolean it's true or false.
     */
    getTokenValue(): string;
    /**
     * The start offset of the last read token.
     */
    getTokenOffset(): number;
    /**
     * The length of the last read token.
     */
    getTokenLength(): number;
    /**
     * An error code of the last scan.
     */
    getTokenError(): ScanError;
}

Parser:

export interface ParseOptions {
    disallowComments?: boolean;
}
/**
 * Parses the given text and returns the object the JSON content represents. On invalid input, the parser tries to be as fault lolerant as possible, but still return a result.
 * Therefore always check the errors list to find out if the input was valid.
 */
export declare function parse(text: string, errors?: {error: ParseErrorCode;}[], options?: ParseOptions): any;

/**
 * Parses the given text and invokes the visitor functions for each object, array and literal reached.
 */
export declare function visit(text: string, visitor: JSONVisitor, options?: ParseOptions): any;

export interface JSONVisitor {
    /**
     * Invoked when an open brace is encountered and an object is started. The offset and length represent the location of the open brace.
     */
    onObjectBegin?: (offset: number, length: number) => void;
    /**
     * Invoked when a property is encountered. The offset and length represent the location of the property name.
     */
    onObjectProperty?: (property: string, offset: number, length: number) => void;
    /**
     * Invoked when a closing brace is encountered and an object is completed. The offset and length represent the location of the closing brace.
     */
    onObjectEnd?: (offset: number, length: number) => void;
    /**
     * Invoked when an open bracket is encountered. The offset and length represent the location of the open bracket.
     */
    onArrayBegin?: (offset: number, length: number) => void;
    /**
     * Invoked when a closing bracket is encountered. The offset and length represent the location of the closing bracket.
     */
    onArrayEnd?: (offset: number, length: number) => void;
    /**
     * Invoked when a literal value is encountered. The offset and length represent the location of the literal value.
     */
    onLiteralValue?: (value: any, offset: number, length: number) => void;
    /**
     * Invoked when a comma or colon separator is encountered. The offset and length represent the location of the separator.
     */
    onSeparator?: (charcter: string, offset: number, length: number) => void;
    /**
     * Invoked on an error.
     */
    onError?: (error: ParseErrorCode, offset: number, length: number) => void;
}

/**
 * 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.
 */
export declare function parseTree(text: string, errors?: ParseError[], options?: ParseOptions): Node;

export declare type NodeType = "object" | "array" | "property" | "string" | "number" | "boolean" | "null";
export interface Node {
    type: NodeType;
    value?: any;
    offset: number;
    length: number;
    columnOffset?: number;
    parent?: Node;
    children?: Node[];
}

Utilities:

/**
 * Takes JSON with JavaScript-style comments and remove
 * them. Optionally replaces every none-newline character
 * of comments with a replaceCharacter
 */
export declare function stripComments(text: string, replaceCh?: string): string;

/**
 * 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.
 */
export declare function getLocation(text: string, position: number): Location;

export declare type Segment = string | number;
export interface Location {
    /**
     * The previous property key or literal value (string, number, boolean or null) or undefined.
     */
    previousNode?: Node;
    /**
     * The path describing the location in the JSON document. The path consists of a sequence strings
     * representing an object property or numbers for array indices.
     */
    path: Segment[];
    /**
     * Matches the locations path against a pattern consisting of strings (for properties) and numbers (for array indices).
     * '*' will match a single segment, of any property name or index.
     * '**' will match a sequece of segments or no segment, of any property name or index.
     */
    matches: (patterns: Segment[]) => boolean;
    /**
     * If set, the location's offset is at a property key.
     */
    isAtPropertyKey: boolean;
}


License

(MIT License)

Copyright 2016, Microsoft