289 lines
10 KiB
JavaScript
289 lines
10 KiB
JavaScript
// @flow
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/**
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* Based on the comment attachment algorithm used in espree and estraverse.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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import BaseParser from "./base";
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import type { Comment, Node } from "../types";
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function last<T>(stack: $ReadOnlyArray<T>): T {
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return stack[stack.length - 1];
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}
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export default class CommentsParser extends BaseParser {
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addComment(comment: Comment): void {
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if (this.filename) comment.loc.filename = this.filename;
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this.state.trailingComments.push(comment);
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this.state.leadingComments.push(comment);
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}
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adjustCommentsAfterTrailingComma(
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node: Node,
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elements: (Node | null)[],
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// When the current node is followed by a token which hasn't a respective AST node, we
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// need to take all the trailing comments to prevent them from being attached to an
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// unrelated node. e.g. in
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// var { x } /* cmt */ = { y }
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// we don't want /* cmt */ to be attached to { y }.
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// On the other hand, in
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// fn(x) [new line] /* cmt */ [new line] y
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// /* cmt */ is both a trailing comment of fn(x) and a leading comment of y
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takeAllComments?: boolean,
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) {
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if (this.state.leadingComments.length === 0) {
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return;
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}
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let lastElement = null;
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let i = elements.length;
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while (lastElement === null && i > 0) {
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lastElement = elements[--i];
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}
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if (lastElement === null) {
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return;
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}
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for (let j = 0; j < this.state.leadingComments.length; j++) {
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if (
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this.state.leadingComments[j].end < this.state.commentPreviousNode.end
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) {
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this.state.leadingComments.splice(j, 1);
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j--;
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}
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}
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const newTrailingComments = [];
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for (let i = 0; i < this.state.leadingComments.length; i++) {
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const leadingComment = this.state.leadingComments[i];
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if (leadingComment.end < node.end) {
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newTrailingComments.push(leadingComment);
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// Perf: we don't need to splice if we are going to reset the array anyway
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if (!takeAllComments) {
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this.state.leadingComments.splice(i, 1);
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i--;
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}
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} else {
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if (node.trailingComments === undefined) {
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node.trailingComments = [];
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}
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node.trailingComments.push(leadingComment);
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}
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}
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if (takeAllComments) this.state.leadingComments = [];
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if (newTrailingComments.length > 0) {
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lastElement.trailingComments = newTrailingComments;
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} else if (lastElement.trailingComments !== undefined) {
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lastElement.trailingComments = [];
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}
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}
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processComment(node: Node): void {
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if (node.type === "Program" && node.body.length > 0) return;
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const stack = this.state.commentStack;
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let firstChild, lastChild, trailingComments, i, j;
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if (this.state.trailingComments.length > 0) {
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// If the first comment in trailingComments comes after the
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// current node, then we're good - all comments in the array will
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// come after the node and so it's safe to add them as official
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// trailingComments.
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if (this.state.trailingComments[0].start >= node.end) {
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trailingComments = this.state.trailingComments;
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this.state.trailingComments = [];
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} else {
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// Otherwise, if the first comment doesn't come after the
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// current node, that means we have a mix of leading and trailing
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// comments in the array and that leadingComments contains the
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// same items as trailingComments. Reset trailingComments to
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// zero items and we'll handle this by evaluating leadingComments
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// later.
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this.state.trailingComments.length = 0;
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}
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} else if (stack.length > 0) {
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const lastInStack = last(stack);
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if (
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lastInStack.trailingComments &&
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lastInStack.trailingComments[0].start >= node.end
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) {
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trailingComments = lastInStack.trailingComments;
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delete lastInStack.trailingComments;
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}
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}
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// Eating the stack.
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if (stack.length > 0 && last(stack).start >= node.start) {
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firstChild = stack.pop();
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}
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while (stack.length > 0 && last(stack).start >= node.start) {
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lastChild = stack.pop();
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}
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if (!lastChild && firstChild) lastChild = firstChild;
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// Adjust comments that follow a trailing comma on the last element in a
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// comma separated list of nodes to be the trailing comments on the last
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// element
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if (firstChild) {
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switch (node.type) {
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case "ObjectExpression":
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this.adjustCommentsAfterTrailingComma(node, node.properties);
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break;
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case "ObjectPattern":
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this.adjustCommentsAfterTrailingComma(node, node.properties, true);
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break;
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case "CallExpression":
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this.adjustCommentsAfterTrailingComma(node, node.arguments);
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break;
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case "ArrayExpression":
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this.adjustCommentsAfterTrailingComma(node, node.elements);
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break;
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case "ArrayPattern":
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this.adjustCommentsAfterTrailingComma(node, node.elements, true);
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break;
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}
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} else if (
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this.state.commentPreviousNode &&
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((this.state.commentPreviousNode.type === "ImportSpecifier" &&
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node.type !== "ImportSpecifier") ||
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(this.state.commentPreviousNode.type === "ExportSpecifier" &&
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node.type !== "ExportSpecifier"))
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) {
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this.adjustCommentsAfterTrailingComma(node, [
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this.state.commentPreviousNode,
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]);
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}
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if (lastChild) {
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if (lastChild.leadingComments) {
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if (
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lastChild !== node &&
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lastChild.leadingComments.length > 0 &&
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last(lastChild.leadingComments).end <= node.start
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) {
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node.leadingComments = lastChild.leadingComments;
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delete lastChild.leadingComments;
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} else {
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// A leading comment for an anonymous class had been stolen by its first ClassMethod,
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// so this takes back the leading comment.
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// See also: https://github.com/eslint/espree/issues/158
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for (i = lastChild.leadingComments.length - 2; i >= 0; --i) {
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if (lastChild.leadingComments[i].end <= node.start) {
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node.leadingComments = lastChild.leadingComments.splice(0, i + 1);
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break;
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}
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}
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}
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}
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} else if (this.state.leadingComments.length > 0) {
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if (last(this.state.leadingComments).end <= node.start) {
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if (this.state.commentPreviousNode) {
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for (j = 0; j < this.state.leadingComments.length; j++) {
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if (
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this.state.leadingComments[j].end <
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this.state.commentPreviousNode.end
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) {
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this.state.leadingComments.splice(j, 1);
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j--;
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}
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}
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}
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if (this.state.leadingComments.length > 0) {
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node.leadingComments = this.state.leadingComments;
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this.state.leadingComments = [];
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}
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} else {
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// https://github.com/eslint/espree/issues/2
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//
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// In special cases, such as return (without a value) and
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// debugger, all comments will end up as leadingComments and
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// will otherwise be eliminated. This step runs when the
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// commentStack is empty and there are comments left
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// in leadingComments.
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//
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// This loop figures out the stopping point between the actual
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// leading and trailing comments by finding the location of the
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// first comment that comes after the given node.
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for (i = 0; i < this.state.leadingComments.length; i++) {
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if (this.state.leadingComments[i].end > node.start) {
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break;
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}
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}
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// Split the array based on the location of the first comment
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// that comes after the node. Keep in mind that this could
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// result in an empty array, and if so, the array must be
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// deleted.
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const leadingComments = this.state.leadingComments.slice(0, i);
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if (leadingComments.length) {
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node.leadingComments = leadingComments;
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}
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// Similarly, trailing comments are attached later. The variable
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// must be reset to null if there are no trailing comments.
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trailingComments = this.state.leadingComments.slice(i);
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if (trailingComments.length === 0) {
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trailingComments = null;
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}
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}
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}
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this.state.commentPreviousNode = node;
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if (trailingComments) {
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if (
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trailingComments.length &&
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trailingComments[0].start >= node.start &&
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last(trailingComments).end <= node.end
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) {
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node.innerComments = trailingComments;
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} else {
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// TrailingComments maybe contain innerComments
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const firstTrailingCommentIndex = trailingComments.findIndex(
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comment => comment.end >= node.end,
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);
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if (firstTrailingCommentIndex > 0) {
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node.innerComments = trailingComments.slice(
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0,
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firstTrailingCommentIndex,
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);
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node.trailingComments = trailingComments.slice(
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firstTrailingCommentIndex,
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);
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} else {
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node.trailingComments = trailingComments;
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}
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}
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}
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stack.push(node);
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}
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}
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