pushBack {base} | R Documentation |
Functions to push back text lines onto a connection, and to enquire how many lines are currently pushed back.
pushBack(data, connection, newLine = TRUE) pushBackLength(connection)
data |
a character vector. |
connection |
A connection. |
newLine |
logical. If true, a newline is appended to each string pushed back. |
Several character strings can be pushed back on one or more occasions.
The occasions form a stack, so the first line to be retrieved will be
the first string from the last call to pushBack
. Lines which
are pushed back are read prior to the normal input from the
connection, by the normal text-reading functions such as
readLines
and scan
.
Pushback is only allowed for readable connections.
pushBack
returns nothing.
pushBackLength
returns number of lines currently pushed back.
zz <- textConnection(LETTERS) readLines(zz, 2) pushBack(c("aa", "bb"), zz) pushBackLength(zz) readLines(zz, 1) pushBackLength(zz) readLines(zz, 1) readLines(zz, 1) close(zz)