Method buildSourceMap

src/LuaPrinter.ts:888–947

(sourceRoot: string, rootSourceNode: SourceNode)

    // The key difference between this and SourceNode.toStringWithSourceMap() is that SourceNodes with null line/column
    // will not generate 'empty' mappings in the source map that point to nothing in the original TS.
    private buildSourceMap(sourceRoot: string, rootSourceNode: SourceNode): SourceMapGenerator {
        const map = new SourceMapGenerator({
            file: path.basename(this.luaFile),
            sourceRoot,
        });

        let generatedLine = 1;
        let generatedColumn = 0;
        let currentMapping: Mapping | undefined;

        const isNewMapping = (sourceNode: SourceNode) => {
            if (sourceNode.line === null) {
                return false;
            }
            if (currentMapping === undefined) {
                return true;
            }
            if (
                currentMapping.generated.line === generatedLine &&
                currentMapping.generated.column === generatedColumn &&
                currentMapping.name === sourceNode.name
            ) {
                return false;
            }
            return (
                currentMapping.original.line !== sourceNode.line ||
                currentMapping.original.column !== sourceNode.column ||
                currentMapping.name !== sourceNode.name
            );
        };

        const build = (sourceNode: SourceNode) => {
            if (isNewMapping(sourceNode)) {
                currentMapping = {
                    source: sourceNode.source,
                    original: { line: sourceNode.line, column: sourceNode.column },
                    generated: { line: generatedLine, column: generatedColumn },
                    name: sourceNode.name,
                };
                map.addMapping(currentMapping);
            }

            for (const chunk of sourceNode.children as SourceChunk[]) {
                if (typeof chunk === "string") {
                    const lines = chunk.split("\n");
                    if (lines.length > 1) {
                        generatedLine += lines.length - 1;
                        generatedColumn = 0;
                        currentMapping = undefined; // Mappings end at newlines
                    }
                    generatedColumn += lines[lines.length - 1].length;
                } else {
                    build(chunk);
                }
            }
        };
        build(rootSourceNode);