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Improve error position reported by the lexer #186

Merged
merged 1 commit into from
Oct 29, 2024
Merged

Improve error position reported by the lexer #186

merged 1 commit into from
Oct 29, 2024

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makenowjust
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@makenowjust makenowjust commented Oct 28, 2024 •
edited
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This introduces two helper methods, errorfAtPosition and panicfAtPosition, and uses them to report errors caused by tokenizing string-like literals and skipping comments.

This fix improves error positions of unclosed string/comment and invalid escape sequences.

Before:

$ go run ./tools/parse/main.go 'SELECT "foo'
syntax error: :1:8: unclosed string literal

  1:  SELECT "foo
             ^
exit status 1
$ go run ./tools/parse/main.go 'SELECT "foo\UFFFFFFFF'
syntax error: :1:8: invalid escape sequence: invalid code point: U+FFFFFFFF

  1:  SELECT "foo\UFFFFFFFF
             ^
exit status 1
$ go run ./tools/parse/main.go '/* comment'
syntax error: :1:11: unclosed comment

  1:  /* comment
                ^
exit status 1

After:

$ go run ./tools/parse/main.go 'SELECT "foo'
syntax error: :1:8: unclosed string literal

  1:  SELECT "foo
             ^~~~
exit status 1
$ go run ./tools/parse/main.go 'SELECT "foo\UFFFFFFFF'
syntax error: :1:12: invalid escape sequence: invalid code point: U+FFFFFFFF

  1:  SELECT "foo\UFFFFFFFF
                 ^~~~~~~~~~
exit status 1
$ go run ./tools/parse/main.go '/* comment'
syntax error: :1:1: unclosed comment

  1:  /* comment
      ^~~~~~~~~~
exit status 1

@apstndb
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apstndb commented Oct 28, 2024

LGTM!

Out of curiosity, I checked to see if there was an error with the multi-line comment.

$ go run ./tools/parse/main.go "SELECT
/*
one
two
three"
2024/10/28 21:52:13 syntax error: :2:1: unclosed comment

  2:  /*
  3:  one
  4:  two
  5:  three
exit status 1

There doesn't seem to be anything strange.

@makenowjust
Improve error position reported by the lexer
957fd8c 
This introduces two helper method `errorfAtPosition` and
`panicfAtPosition`, and uses them for reporting errors caused by
tokenizing string-like literals and skipping comments.
@makenowjust makenowjust merged commit e50eded into main Oct 29, 2024
4 checks passed
@makenowjust makenowjust deleted the improve-lex-error branch October 29, 2024 13:14
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2 participants
@makenowjust @apstndb