90 lines
2.4 KiB
JavaScript
90 lines
2.4 KiB
JavaScript
import {GenMapping, maybeAddSegment, toEncodedMap} from "@jridgewell/gen-mapping";
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import {charCodes} from "./parser/util/charcodes";
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/**
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* Generate a source map indicating that each line maps directly to the original line,
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* with the tokens in their new positions.
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*/
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export default function computeSourceMap(
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{code: generatedCode, mappings: rawMappings},
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filePath,
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options,
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source,
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tokens,
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) {
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const sourceColumns = computeSourceColumns(source, tokens);
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const map = new GenMapping({file: options.compiledFilename});
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let tokenIndex = 0;
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// currentMapping is the output source index for the current input token being
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// considered.
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let currentMapping = rawMappings[0];
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while (currentMapping === undefined && tokenIndex < rawMappings.length - 1) {
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tokenIndex++;
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currentMapping = rawMappings[tokenIndex];
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}
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let line = 0;
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let lineStart = 0;
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if (currentMapping !== lineStart) {
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maybeAddSegment(map, line, 0, filePath, line, 0);
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}
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for (let i = 0; i < generatedCode.length; i++) {
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if (i === currentMapping) {
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const genColumn = currentMapping - lineStart;
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const sourceColumn = sourceColumns[tokenIndex];
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maybeAddSegment(map, line, genColumn, filePath, line, sourceColumn);
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while (
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(currentMapping === i || currentMapping === undefined) &&
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tokenIndex < rawMappings.length - 1
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) {
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tokenIndex++;
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currentMapping = rawMappings[tokenIndex];
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}
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}
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if (generatedCode.charCodeAt(i) === charCodes.lineFeed) {
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line++;
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lineStart = i + 1;
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if (currentMapping !== lineStart) {
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maybeAddSegment(map, line, 0, filePath, line, 0);
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}
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}
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}
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const {sourceRoot, sourcesContent, ...sourceMap} = toEncodedMap(map);
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return sourceMap ;
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}
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/**
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* Create an array mapping each token index to the 0-based column of the start
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* position of the token.
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*/
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function computeSourceColumns(code, tokens) {
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const sourceColumns = new Array(tokens.length);
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let tokenIndex = 0;
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let currentMapping = tokens[tokenIndex].start;
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let lineStart = 0;
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for (let i = 0; i < code.length; i++) {
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if (i === currentMapping) {
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sourceColumns[tokenIndex] = currentMapping - lineStart;
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tokenIndex++;
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currentMapping = tokens[tokenIndex].start;
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}
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if (code.charCodeAt(i) === charCodes.lineFeed) {
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lineStart = i + 1;
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}
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}
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return sourceColumns;
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}
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