Parse interpolated variables from SQL.

If you're implementing a backend that uses non-ANSI quoting or commenting rules, you'll need to implement a method for sqlParseVariables that calls sqlParseVariablesImpl with the appropriate quote and comment specifications.

sqlCommentSpec(start, end, endRequired)

sqlQuoteSpec(start, end, escape = "", doubleEscape = TRUE)

sqlParseVariablesImpl(sql, quotes, comments)

sqlParseVariables(conn, sql, ...)

Arguments

start, end: Start and end characters for quotes and comments
endRequired: Is the ending character of a comment required?
escape: What character can be used to escape quoting characters? Defaults to "", i.e. nothing.
doubleEscape: Can quoting characters be escaped by doubling them? Defaults to TRUE.
sql: SQL to parse (a character string)
quotes: A list of QuoteSpec calls defining the quoting specification.
comments: A list of CommentSpec calls defining the commenting specification.

Examples

# Use [] for quoting and no comments
sqlParseVariablesImpl("[?a]",
  list(sqlQuoteSpec("[", "]", "\\", FALSE)),
  list()
)
#> $start
#> integer(0)
#> 
#> $end
#> integer(0)
#> 

# Standard quotes, use # for commenting
sqlParseVariablesImpl("# ?a\n?b",
  list(sqlQuoteSpec("'", "'"), sqlQuoteSpec('"', '"')),
  list(sqlCommentSpec("#", "\n", FALSE))
)
#> $start
#> [1] 6
#> 
#> $end
#> [1] 7
#>