I'm using fsyacc/fslex from F# Power Pack to parse some source code.
To detect errors I use the following code:
use inputChannel = new StreamReader(File.OpenRead tempFileName)
let lexbuf = Lexing.LexBuffer<_>.FromTextReader inputChannel
let ast = try
Parser.start Lexer.tokenize lexbuf
with e ->
let pos = lexbuf.EndPos
let line = pos.Line
let column = pos.Column
let message = e.Message
let lastToken = new System.String(lexbuf.Lexeme)
printf "Parse failed at line %d, column %d:\n" line column
printf "Last loken: %s" lastToken
printf "\n"
exit 1
But when this code throws the error message on parsing multi-line source file, I'm getting wrong line and column position:
Parse failed at line 0, column 10899:
How can I get line number correctly on which error has been occurred?
During lexing, you need to manually increment the line number with a rule like
...
let newline = ('\n' | '\r' '\n')
rule tokenize = parse
| newline { lexbuf.EndPos <- lexbuf.EndPos.NextLine; tokenize lexbuf }
...
来源:https://stackoverflow.com/questions/7928438/meaningful-errors-during-parsing-with-fsyacc