in src/lib/CodeMirror/indentationMarkers.ts [126:139]
constructor(lines: Set<Line>, state: EditorState, unitWidth: number) {
this.lines = lines;
this.state = state;
this.map = new Map();
this.unitWidth = unitWidth;
for (const line of this.lines) {
this.add(line);
}
if (this.state.facet(indentationMarkerConfig).highlightActiveBlock) {
this.findAndSetActiveLines();
}
}