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Truncating lineText in references #51137

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Truncating lineText in references #51137

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21 changes: 20 additions & 1 deletion src/server/session.ts
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Expand Up @@ -3522,7 +3522,26 @@ namespace ts.server {
const scriptInfo = Debug.checkDefined(projectService.getScriptInfo(fileName));
const span = toProtocolTextSpanWithContext(textSpan, contextSpan, scriptInfo);
const lineSpan = scriptInfo.lineToTextSpan(span.start.line - 1);
const lineText = scriptInfo.getSnapshot().getText(lineSpan.start, textSpanEnd(lineSpan)).replace(/\r|\n/g, "");
if (lineSpan.length > 1024) {
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Since 1024 is just a number I made up, it may need to be tuned. That would be easier if it were a constant.

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To avoid using a magic number, it would be better to create a new variable with a proper name and store 1024 into it.

var start = (span.start.offset > 500) ? (span.start.offset - 501 + lineSpan.start) : lineSpan.start;
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We never use var because it has weird scoping (e.g. lineText below is visible outside the if block).

var end = (lineSpan.length -2 - span.end.offset > 500) ? (span.end.offset + 499 + lineSpan.start) : ts.textSpanEnd(lineSpan)-2; // need to ask why length is 2 more
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I probably said "500", but I meant "half of the max length" (easy, if you have a constant for the max length). Also, you may discover after playing with it, that you want less text before and more text after the reference.

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Usually when we subtract two from the length of a line, it's for \r and \n, but line endings vary by platform, so it's usually necessary to use a helper (we probably have one in core.ts or utilities.ts.

var lineText;
const sourceFile = scriptInfo.getDefaultProject().getLanguageService().getProgram()!.getSourceFile(fileName)!;
let tokenAtPosition = getTokenAtPosition(sourceFile, start);
let tokenAtPositionEnd = getTokenAtPosition(sourceFile, end - 1);
if (tokenAtPosition.getStart() < start) {
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feed in the optional sourceFile parameter to getStart.

const nextToken = findNextToken(tokenAtPosition, tokenAtPosition.parent, sourceFile)?.getStart()!;
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I might call this "nextTokenStart", to make it clearer that it's not a token.

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Does getStart return the position before or after the leading trivia?

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In here, getStart returns the start position of the token that was a result of findNextToken

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But if the token looks like /*comment*/identifier, is getStart before or after the comment?

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Also, the ?. followed by the ! is very questionable. Please handle the undefined explicitly.

Also, if you are calling getStart, feed in the optional sourceFile parameter.

start = (nextToken - start) > 10 ? start : nextToken;
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As this gets more polished, it might help to add comments.

}
if (tokenAtPositionEnd.getEnd() > end) {
const precedingToken = findPrecedingToken(end, sourceFile, tokenAtPositionEnd)?.getStart()!;
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Same comment with ?./! and the sourceFile argument to getStart

end = (end - precedingToken) > 10 ? end: precedingToken;
}
lineText = scriptInfo.getSnapshot().getText(start, end).replace(/\r|\n/g, "")!;
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I wonder if we want to add "..." or something when we truncate?

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Aside from the ... issue, we have a trimString (or possibly trimStringEnd) helper which you should probably use instead.

}
else {
lineText = scriptInfo.getSnapshot().getText(lineSpan.start, textSpanEnd(lineSpan)).replace(/\r|\n/g, "");
}
return {
file: fileName,
...span,
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