Add experimental/ast/printer package#657
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doriable
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The API looks very reasonable to me, I just had a few nitpicks/discussion points for clarifying a few things. Thank you!
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experimental/printer packageexperimental/ast/printer package
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| // PrintFile renders an AST file to protobuf source text. | ||
| func PrintFile(file *ast.File, opts Options) string { |
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You want this to take function options right?
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Do you mean type Option func(...)? Was following dom and report options
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| // the pending buffer so that adjacent pure-newline runs are combined into a | ||
| // single kindBreak dom tag, preventing the dom from merging them and |
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Could this be dealt with by making kindBreak a bit more sophisticated?
Add TestBufFormat that reads buf's bufformat testdata (54 test cases) and compares printer output against golden files. Currently 35/54 pass. Fixes: - Empty files produce empty output instead of trailing newline - New gapInline style keeps punctuation on same line as preceding comments: `value /* comment */;` instead of breaking to new line - New gapGlue style for path separators glues comments without spaces: `header/*comment*/.v1` - Preserve source blank lines after detached comments using actual newline count from pending trivia tokens - Body declarations at file level only get blank lines when source had them, instead of unconditionally - Compound string first element on new indented line after `=` - Strip trailing whitespace from comments in format mode
Add test cases documenting 8 remaining formatting issues: - Issue 1: trailing // before ] should become /* */ on single-line - Issue 2: trailing comment after , should stay inline - Issue 3: comment after [ opener should expand to multi-line - Issue 5: comment before } in enum (already passes) - Issue 6: EOF comment after blank line should preserve blank line - Issue 7: block comments in RPC parens should not add extra spaces - Issue 8: extension path comments should preserve spaces - Issue 9: message literal with block comments should expand
Two formatting fixes: - Extract inline trailing comments after commas in walkDecl so they stay on the same line as the comma instead of becoming leading trivia on the next token - Preserve blank lines before EOF comments by checking trivia.blankBeforeClose in printFile
…on trailing line to block comments
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This adds
experimental/ast/printer, an AST printer for protobuf files. The printer has two entrypoints,PrintFile(for printing an entireast.File) andPrint(for printing individual decls). Both take a set of printer options, which includes whether or not to format the printed output and/or apply any AST edits prior to printing.The printer preserves comments and whitespace using a trivia index. Each comment is classified as either attached (bound to a specific token) or detached (bound to a positional slot between declarations). Attached comments travel with their token when declarations are moved; detached comments stay in place. At print time, the printer zips slot trivia with children within each scope, and looks up attached trivia when emitting individual tokens. This works identically for natural and synthetic tokens (no special-casing needed). Synthetic tokens won't have a trivia and fallback to the declared gap. This gap is also what will be used to inform how to format the trivia between tokens when formatting.
A set of formatting options have been pre-configured to match the behaviour of the legacy protobuf formatter, and this has been confirmed through conformance tests with legacy formatter goldens. To ensure conformance and for regression testing, goldens to verify the legacy configurations have been included in the formatter tests (and verified against the current legacy formatter) and the legacy formatter behaviour tests have been vendored locally as a regression test.