src/vs/workbench/api/common/extHostTypes.ts/SemanticTokensBuilder/constructor
class SemanticTokensBuilder:	constructor(legend?: vscode.SemanticTokensLegend) {
		this._prevLine = 0;
		this._prevChar = 0;
		this._dataIsSortedAndDeltaEncoded = true;
		this._data = [];
		this._dataLen = 0;
		this._tokenTypeStrToInt = new Map<string, number>();
		this._tokenModifierStrToInt = new Map<string, number>();
		this._hasLegend = false;
		if (legend) {
			this._hasLegend = true;
			for (let i = 0, len = legend.tokenTypes.length; i < len; i++) {
				this._tokenTypeStrToInt.set(legend.tokenTypes[i], i);
			}
			for (let i = 0, len = legend.tokenModifiers.length; i < len; i++) {
				this._tokenModifierStrToInt.set(legend.tokenModifiers[i], i);
			}
		}
	}