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Improve generator behavior when comments:false #15173

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merged 2 commits into from Nov 25, 2022
Merged

Improve generator behavior when comments:false #15173

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5862a17
improve
liuxingbaoyu Nov 9, 2022
ca65490
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liuxingbaoyu Nov 14, 2022
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10 changes: 10 additions & 0 deletions packages/babel-generator/src/index.ts
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Expand Up @@ -109,6 +109,16 @@ function normalizeOptions(
format.indent.adjustMultilineComment = false;
}

const { auxiliaryCommentBefore, auxiliaryCommentAfter, shouldPrintComment } =
format;

if (auxiliaryCommentBefore && !shouldPrintComment(auxiliaryCommentBefore)) {
format.auxiliaryCommentBefore = undefined;
}
if (auxiliaryCommentAfter && !shouldPrintComment(auxiliaryCommentAfter)) {
format.auxiliaryCommentAfter = undefined;
}

Comment on lines +112 to +121
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Since shouldPrintComment does not pass any information other than the comment content, it is safe to call it only once.

return format;
}

Expand Down
82 changes: 45 additions & 37 deletions packages/babel-generator/src/printer.ts
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Expand Up @@ -35,9 +35,15 @@ const enum COMMENT_TYPE {

const enum COMMENT_SKIP_NEWLINE {
DEFAULT,
SKIP_ALL,
SKIP_LEADING,
SKIP_TRAILING,
ALL,
LEADING,
TRAILING,
}

const enum PRINT_COMMENT_HINT {
SKIP,
ALLOW,
DEFER,
}

export type Format = {
Expand Down Expand Up @@ -903,48 +909,50 @@ class Printer {
}
}

// Returns `true` if the comment cannot be printed in this position due to
// Returns `PRINT_COMMENT_HINT.DEFER` if the comment cannot be printed in this position due to
// line terminators, signaling that the print comments loop can stop and
// resume printing comments at the next posisble position. This happens when
// resume printing comments at the next possible position. This happens when
// printing inner comments, since if we have an inner comment with a multiline
// there is at least one inner position where line terminators are allowed.
_printComment(
comment: t.Comment,
skipNewLines: COMMENT_SKIP_NEWLINE,
): boolean {
_shouldPrintComment(comment: t.Comment): PRINT_COMMENT_HINT {
// Some plugins (such as flow-strip-types) use this to mark comments as removed using the AST-root 'comments' property,
// where they can't manually mutate the AST node comment lists.
if (comment.ignore) return false;

if (this._printedComments.has(comment)) return false;
if (comment.ignore) return PRINT_COMMENT_HINT.SKIP;

const noLineTerminator = this._noLineTerminator;
if (this._printedComments.has(comment)) return PRINT_COMMENT_HINT.SKIP;

if (
noLineTerminator &&
this._noLineTerminator &&
(HAS_NEWLINE.test(comment.value) ||
HAS_BlOCK_COMMENT_END.test(comment.value))
) {
return true;
return PRINT_COMMENT_HINT.DEFER;
}

if (!this.format.shouldPrintComment(comment.value)) return false;

this._printedComments.add(comment);

if (!this.format.shouldPrintComment(comment.value)) {
return PRINT_COMMENT_HINT.SKIP;
}

return PRINT_COMMENT_HINT.ALLOW;
}

_printComment(comment: t.Comment, skipNewLines: COMMENT_SKIP_NEWLINE) {
const noLineTerminator = this._noLineTerminator;
const isBlockComment = comment.type === "CommentBlock";

// Add a newline before and after a block comment, unless explicitly
// disallowed
const printNewLines =
isBlockComment &&
skipNewLines !== COMMENT_SKIP_NEWLINE.SKIP_ALL &&
skipNewLines !== COMMENT_SKIP_NEWLINE.ALL &&
!this._noLineTerminator;

if (
printNewLines &&
this._buf.hasContent() &&
skipNewLines !== COMMENT_SKIP_NEWLINE.SKIP_LEADING
skipNewLines !== COMMENT_SKIP_NEWLINE.LEADING
) {
this.newline(1);
}
Expand Down Expand Up @@ -996,11 +1004,9 @@ class Printer {
this.newline(1, true);
}

if (printNewLines && skipNewLines !== COMMENT_SKIP_NEWLINE.SKIP_TRAILING) {
if (printNewLines && skipNewLines !== COMMENT_SKIP_NEWLINE.TRAILING) {
this.newline(1);
}

return false;
}

_printComments(
Expand All @@ -1025,8 +1031,12 @@ class Printer {
for (let i = 0; i < len; i++) {
const comment = comments[i];

const printed = this._printedComments.has(comment);
if (hasLoc && comment.loc && !printed) {
const shouldPrint = this._shouldPrintComment(comment);
if (shouldPrint === PRINT_COMMENT_HINT.DEFER) {
hasLoc = false;
break;
}
if (hasLoc && comment.loc && shouldPrint === PRINT_COMMENT_HINT.ALLOW) {
const commentStartLine = comment.loc.start.line;
const commentEndLine = comment.loc.end.line;
if (type === COMMENT_TYPE.LEADING) {
Expand All @@ -1047,7 +1057,7 @@ class Printer {
lastLine = commentEndLine;

maybeNewline(offset);
this._printComment(comment, COMMENT_SKIP_NEWLINE.SKIP_ALL);
this._printComment(comment, COMMENT_SKIP_NEWLINE.ALL);

if (i + 1 === len) {
maybeNewline(
Expand All @@ -1061,7 +1071,7 @@ class Printer {
lastLine = commentEndLine;

maybeNewline(offset);
if (this._printComment(comment, COMMENT_SKIP_NEWLINE.SKIP_ALL)) break;
this._printComment(comment, COMMENT_SKIP_NEWLINE.ALL);

if (i + 1 === len) {
maybeNewline(Math.min(1, nodeEndLine - lastLine)); // TODO: Improve here when inner comments processing is stronger
Expand All @@ -1073,12 +1083,13 @@ class Printer {
lastLine = commentEndLine;

maybeNewline(offset);
this._printComment(comment, COMMENT_SKIP_NEWLINE.SKIP_ALL);
this._printComment(comment, COMMENT_SKIP_NEWLINE.ALL);
}
} else {
hasLoc = false;

if (printed) continue;
if (shouldPrint !== PRINT_COMMENT_HINT.ALLOW) {
continue;
}

if (len === 1) {
const singleLine = comment.loc
Expand All @@ -1096,13 +1107,11 @@ class Printer {
comment,
(shouldSkipNewline && node.type !== "ObjectExpression") ||
(singleLine && isFunction(parent, { body: node }))
? COMMENT_SKIP_NEWLINE.SKIP_ALL
? COMMENT_SKIP_NEWLINE.ALL
: COMMENT_SKIP_NEWLINE.DEFAULT,
);
} else if (shouldSkipNewline && type === COMMENT_TYPE.TRAILING) {
if (this._printComment(comment, COMMENT_SKIP_NEWLINE.SKIP_ALL)) {
break;
}
this._printComment(comment, COMMENT_SKIP_NEWLINE.ALL);
} else {
this._printComment(comment, COMMENT_SKIP_NEWLINE.DEFAULT);
}
Expand All @@ -1117,15 +1126,14 @@ class Printer {
// /*:: b: ?string*/
// }

const skippedDueToNewline = this._printComment(
this._printComment(
comment,
i === 0
? COMMENT_SKIP_NEWLINE.SKIP_LEADING
? COMMENT_SKIP_NEWLINE.LEADING
: i === len - 1
? COMMENT_SKIP_NEWLINE.SKIP_TRAILING
? COMMENT_SKIP_NEWLINE.TRAILING
: COMMENT_SKIP_NEWLINE.DEFAULT,
);
if (skippedDueToNewline) break;
} else {
this._printComment(comment, COMMENT_SKIP_NEWLINE.DEFAULT);
}
Expand Down
4 changes: 1 addition & 3 deletions packages/babel-generator/test/fixtures/regression/15161/output.js
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@@ -1,3 +1 @@
var test = (
) => {
};
var test = () => {};