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Refactor trailing comment adjustment #10380

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merged 7 commits into from Sep 3, 2019
Merged

Refactor trailing comment adjustment #10380

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cdf6dc9
Refactor trailing comment adjustment
Aug 31, 2019
f67dcbb
Fix tests
Aug 31, 2019
d50f9d6
Drop the underscore in adjustCommentsAfterTrailingComma_
Aug 31, 2019
5696c94
Handle ArrayPattern
Aug 31, 2019
10bea52
Handle ObjectPattern
Aug 31, 2019
7819484
Handle import and export declarations
Aug 31, 2019
816b1e9
Remove unnecessary check
Sep 2, 2019
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144 changes: 65 additions & 79 deletions packages/babel-parser/src/parser/comments.js
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Expand Up @@ -38,6 +38,45 @@ export default class CommentsParser extends BaseParser {
this.state.leadingComments.push(comment);
}

adjustCommentsAfterTrailingComma(node: Node, elements: Node[]) {
if (elements.length === 0) {
return;
}
if (this.state.leadingComments.length === 0) {
return;
}

const lastElement = last(elements);

for (let j = 0; j < this.state.leadingComments.length; j++) {
if (
this.state.leadingComments[j].end < this.state.commentPreviousNode.end
) {
this.state.leadingComments.splice(j, 1);
j--;
}
}

const newTrailingComments = [];
while (this.state.leadingComments.length) {
const leadingComment = this.state.leadingComments.shift();
if (leadingComment.end < node.end) {
newTrailingComments.push(leadingComment);
} else {
if (node.trailingComments === undefined) {
node.trailingComments = [];
}
node.trailingComments.push(leadingComment);
}
}

if (newTrailingComments.length > 0) {
lastElement.trailingComments = newTrailingComments;
} else if (lastElement.trailingComments !== undefined) {
lastElement.trailingComments = [];
}
}

processComment(node: Node): void {
if (node.type === "Program" && node.body.length > 0) return;

Expand Down Expand Up @@ -84,86 +123,33 @@ export default class CommentsParser extends BaseParser {

if (!lastChild && firstChild) lastChild = firstChild;

// Attach comments that follow a trailing comma on the last
// property in an object literal or a trailing comma in function arguments
// or a trailing comma in array expressions as trailing comments
if (firstChild && this.state.leadingComments.length > 0) {
const lastComment = last(this.state.leadingComments);

if (firstChild.type === "ObjectProperty") {
if (lastComment.start >= node.start && lastComment.end <= node.end) {
if (this.state.commentPreviousNode) {
for (j = 0; j < this.state.leadingComments.length; j++) {
if (
this.state.leadingComments[j].end <
this.state.commentPreviousNode.end
) {
this.state.leadingComments.splice(j, 1);
j--;
}
}

if (this.state.leadingComments.length > 0) {
firstChild.trailingComments = this.state.leadingComments;
this.state.leadingComments = [];
}
}
}
} else if (
node.type === "CallExpression" &&
node.arguments &&
node.arguments.length
) {
const lastArg = last(node.arguments);

if (
lastArg &&
lastComment.start >= lastArg.start &&
lastComment.end <= node.end
) {
if (this.state.commentPreviousNode) {
for (j = 0; j < this.state.leadingComments.length; j++) {
if (
this.state.leadingComments[j].end <
this.state.commentPreviousNode.end
) {
this.state.leadingComments.splice(j, 1);
j--;
}
}
if (this.state.leadingComments.length > 0) {
lastArg.trailingComments = this.state.leadingComments;
this.state.leadingComments = [];
}
}
}
} else if (node.type === "ArrayExpression" && node.elements.length > 0) {
if (this.state.commentPreviousNode) {
for (j = 0; j < this.state.leadingComments.length; j++) {
if (
this.state.leadingComments[j].end <
this.state.commentPreviousNode.end
) {
this.state.leadingComments.splice(j, 1);
j--;
}
}

const lastElement = last(node.elements);
lastElement.trailingComments = [];
while (this.state.leadingComments.length) {
const leadingComment = this.state.leadingComments.shift();
if (leadingComment.end < node.end) {
lastElement.trailingComments.push(leadingComment);
} else {
if (node.trailingComments === undefined) {
node.trailingComments = [];
}
node.trailingComments.push(leadingComment);
}
}
}
// Adjust comments that follow a trailing comma on the last element in a
// comma separated list of nodes to be the trailing comments on the last
// element
if (firstChild) {
switch (node.type) {
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Maybe also SequenceExpression? (I didn't check)

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I don't think SequenceExpression will allow trailing comma.

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I skimmed through https://github.com/babel/babylon/blob/master/ast/spec.md and looks like ImportDeclaration and ArrayPattern also allow trailing commas. Should I add those?

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Yeas please! And also ExportNamedDeclaration and ObjectPattern

case "ObjectExpression":
case "ObjectPattern":
this.adjustCommentsAfterTrailingComma(node, node.properties);
break;
case "CallExpression":
this.adjustCommentsAfterTrailingComma(node, node.arguments);
break;
case "ArrayExpression":
case "ArrayPattern":
this.adjustCommentsAfterTrailingComma(node, node.elements);
break;
}
} else if (
this.state.commentPreviousNode &&
((this.state.commentPreviousNode.type === "ImportSpecifier" &&
node.type !== "ImportSpecifier") ||
(this.state.commentPreviousNode.type === "ExportSpecifier" &&
node.type !== "ExportSpecifier"))
) {
this.adjustCommentsAfterTrailingComma(node, [
this.state.commentPreviousNode,
]);
}

if (lastChild) {
Expand Down
6 changes: 6 additions & 0 deletions packages/babel-parser/test/fixtures/comments/basic/array-pattern-trailing-comma/input.js
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@@ -0,0 +1,6 @@
const [
/* One */
x
/* Two */,
/* Three */
] /* Four */ = [];