Method add

packages/less/lib/less/source-map-output.js:48–108

(chunk, fileInfo, index, mapLines)

        }

        add(chunk, fileInfo, index, mapLines) {

            // ignore adding empty strings
            if (!chunk) {
                return;
            }

            let lines, sourceLines, columns, sourceColumns, i;

            if (fileInfo && fileInfo.filename) {
                let inputSource = this._contentsMap[fileInfo.filename];

                // remove vars/banner added to the top of the file
                if (this._contentsIgnoredCharsMap[fileInfo.filename]) {
                    // adjust the index
                    index -= this._contentsIgnoredCharsMap[fileInfo.filename];
                    if (index < 0) { index = 0; }
                    // adjust the source
                    inputSource = inputSource.slice(this._contentsIgnoredCharsMap[fileInfo.filename]);
                }

                /** 
                 * ignore empty content, or failsafe
                 * if contents map is incorrect
                 */
                if (inputSource === undefined) {
                    this._css.push(chunk);
                    return;
                }

                inputSource = inputSource.substring(0, index);
                sourceLines = inputSource.split('\n');
                sourceColumns = sourceLines[sourceLines.length - 1];
            }

            lines = chunk.split('\n');
            columns = lines[lines.length - 1];

            if (fileInfo && fileInfo.filename) {
                if (!mapLines) {
                    this._sourceMapGenerator.addMapping({ generated: { line: this._lineNumber + 1, column: this._column},
                        original: { line: sourceLines.length, column: sourceColumns.length},
                        source: this.normalizeFilename(fileInfo.filename)});
                } else {
                    for (i = 0; i < lines.length; i++) {
                        this._sourceMapGenerator.addMapping({ generated: { line: this._lineNumber + i + 1, column: i === 0 ? this._column : 0},
                            original: { line: sourceLines.length + i, column: i === 0 ? sourceColumns.length : 0},
                            source: this.normalizeFilename(fileInfo.filename)});
                    }
                }
            }

            if (lines.length === 1) {
                this._column += columns.length;
            } else {
                this._lineNumber += lines.length - 1;
                this._column = columns.length;
            }