Translator – Errors with a Range of Tokens

Currently when the Translator detects an error, the error code is returned along with the token where the error was detected. The caller uses the column and length values in the token to point to the token. (Later the token will be highlighted in a different color.)

Now it is desired that a range of tokens be highlighted to show an entire sub-expression that contains an error. While it is possible to modify all the functions within the Translator for a second return token, there is an easier solution.

The column and length members of the token are used to output the error – where the token starts and how long it is. The Translator, upon detecting an error with a range of tokens, only needs to modify the length token where the beginning of the error is detected, to include all the tokens. The Translator can do this by using the column of the first token, the column of the last token and the length of the last token. The equation would be:

first->length = last->column – first->column + last->length

So when an error is detected and a range of tokens are involved, the length of the token being returned will be set using the equation above.