Mapped Source

Tools for reading and editing source mapped files

Installation

npm install --save toptensoftware/mapped-source

Usage

Load a file

let ms = MappedSource.fromFile("file.js");

Reading

• filename - name of the loaded file
• code - content of the file
• lineMap - a line mapping of offet to line/column position - see here
• sourceMap - source map consume - see here
• fromOffset - given a file offset returns the original position (if mapped by source map file, otherwise position in this file).

// File name
let filename = ms.filename;

// Code
let code = ms.code;

// LineMapping
let offset = ms.lineMap.toOffset({line: 10, column: 20});
let pos = ms.lineMap.fromOffset(1000);

// Returns source:null, line: null, column: null if not mapped
let originalPos = ms.sourceMap.originalPositionFor({line: 10, column: 20});

// Returns position in this file if not mapped
let originalPos = ms.originalPositionFor({line: 10, column: 20});
let originalPos = ms.fromOffset(1000);

Editing

To edit a source mapped file, first load it as described above then call createEditable() to get an EditableMappedSource

let ems = MappedSource.fromFile("test.js").createEditable();

EditableMappedSource supports:

• code - the current code content
• substring(start, end) - returns a new EditableMappedSource with a subsection of the original string and cropped mapped points
• splice(offset, length, str) - replaces length characters at offset with str.
• insert(offset, str) - inserts str at offset.
• delete(offset, length) - deletes length characters at offset.
• append(str) - appends str.
• createSourceMap() - create a JSON serializable source map object
• save(filename) - saves the file and updated source map

All edit operations update both the original code string and any affected mapped points.

Note that splice, insert and append can accept either a string or another EditableMappedSource as the string content parameter. If another EditableMappedSource is used, the source map is updated to include the new mapped points.