fix: allow a comment between a trailing comma and ']' (#1500)#1696
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Trailing commas and comments are both allowed by default, but they did not compose inside arrays: readArray detected a trailing-comma ']' with a raw `*current_ == ']'` peek that skipped only whitespace, not comments. So `[1, 2, /* c */]` left current_ at the comment, the peek failed, and the parser tried to read another value -- which hit ']' and reported "value, object or array expected". readObject already handled this via readTokenSkippingComments. Add skipCommentTokens() (skip whitespace and comments, leaving current_ at the next significant character) and use it in readArray before the ']' check. Consumed comments stay in commentsBefore_, so a comment before a real element is still attached to it; if the array ends, they are simply not attached -- matching object behavior. Adds CharReaderTest/parseTrailingCommaWithComment covering line/block comments after a trailing comma, an empty array containing only a comment, the object form, and that a comment before a real element is still attached.
Coverage Report for CI Build 27673874228Coverage decreased (-0.06%) to 89.903%Details
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Fixes #1500.
Problem
Trailing commas and comments are both allowed by default, but they didn't compose inside arrays:
[1,2,][1,2 /* c */][1,2, /* c */][{}, // c\n]readArraydetected a trailing-comma]with a raw*current_ == ']'peek that skipped only whitespace, not comments. So after a trailing comma a following comment leftcurrent_on/, the peek failed, and the parser tried to read another value — which immediately hit].readObjectalready handled this (it usesreadTokenSkippingComments).Fix
Add
skipCommentTokens()— skip whitespace and comments, leavingcurrent_at the next significant character — and use it inreadArraybefore the]check. Consumed comments stay incommentsBefore_, so:This also makes an otherwise-empty array containing only a comment (
[ /* c */ ]) parse as an empty array.Tests
CharReaderTest/parseTrailingCommaWithCommentcovers line/block comments after a trailing comma, a nested value before the trailing comma, an empty array containing only a comment, the object form, and that a comment before a real element is still attached (hasComment(commentBefore)). All 128 unit tests pass, JSON conformance suite passes (96/96), clang-format clean. Targets 1.10.0.