parser: record scanned comments and stamp table/column positions - #46
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kyleconroy merged 1 commit intoAug 27, 2026
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Record the comments the lexer skips — '-- ' and '#' line comments and '/* */' block comments — as byte-offset spans on the Scanner, exposed through Scanner.Comments and Parser.Comments. Executable comments and optimizer hints are lexed as SQL, so they are not recorded, and recording is gated on strictly increasing positions because the scanner's lookaheads re-read source text. Stamp OriginTextPosition on FROM-clause table factors, INSERT/REPLACE table references and INSERT column lists, which goyacc left unstamped (it stamped only <expr> symbols). Consumers placing comments or errors need these positions; only Accept-reachable nodes are stamped so the restore round-trip tests can keep resetting them. This gives sqlc's MySQL engine what its ParseFile needs to power sqlc fmt: statements and comments from one lexer pass, with enough positions to anchor comments and the author's line breaks. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01C48orUYrL7xE989UGLTVqi
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This gives sqlc's MySQL engine what its ParseFile needs to power sqlc fmt: statements and comments from one lexer pass, with enough positions to anchor comments and the author's line breaks.
Comment recording
The lexer now records every comment it skips — -- and # line comments (span excludes the terminating newline) and /* */ block comments (span includes the closing */) — as byte-offset spans on the Scanner, exposed through Scanner.Comments() and a new Parser.Comments() that returns the comments from the most recent parse.
Position stamping
OriginTextPosition is now stamped on FROM-clause table factors, INSERT/REPLACE table references, and INSERT column lists, which goyacc left unstamped (it stamped only <expr> symbols). Consumers placing comments or preserving author line breaks need these positions, and 0 (the unstamped value) is indistinguishable from the start of the input.
Only Accept-reachable nodes are stamped, so the restore round-trip tests can keep resetting positions; parseTableName and parseColumnNameList themselves stay unstamped because other call sites hang their nodes off structures Accept skips (ALTER…UNION options, FOR UPDATE OF lists, procedure names).
Both changes are additive: no existing node, field, or Restore output changes, and stamping respects SkipPositionRecording.
Testing
New parser/comments_test.go covers every comment syntax, the lookahead-dedup case, the not-a-comment cases (--x, executable comments, hints), and per-parse reset. go test ./... -count=1 -timeout 120s is green, and the sqlc side (sqlc-dev/sqlc branch claude/parsefile-sqlc-fmt-marino-x6v056) passes sqlc's full --tags=examples suite against this commit.
🤖 Generated with Claude Code
https://claude.ai/code/session_01C48orUYrL7xE989UGLTVqi
Generated by Claude Code