srcfile(filename, encoding = getOption("encoding"), Enc = "unknown")
srcfilecopy(filename, lines, timestamp = Sys.time(), isFile = FALSE)
srcfilealias(filename, srcfile)
getSrcLines(srcfile, first, last)
srcref(srcfile, lloc)
"print"(x, ...)
"summary"(object, ...)
"open"(con, line, ...)
"close"(con, ...)
"print"(x, useSource = TRUE, ...)
"summary"(object, useSource = FALSE, ...)
"as.character"(x, useSource = TRUE, to = x, ...)
.isOpen(srcfile)
encoding
argument of parse
.srcfilecopy
known to come from a file system file? srcfile
object. srcfile
to obtain the
text of a srcref
. srcref
object to mark the end
of the character range. The srcfile
function produces an object of class
srcfile
, which contains the name and directory of a source code
file, along with its timestamp, for use in source level debugging (not
yet implemented) and source echoing. The encoding of the file is
saved; see file
for a discussion of encodings, and
iconvlist
for a list of allowable encodings on your platform.
The srcfilecopy
function produces an object of the descendant
class srcfilecopy
, which saves the source lines in a character
vector. It copies the value of the isFile
argument, to help
debuggers identify whether this text comes from a real file in the
file system.
The srcfilealias
function produces an object of the descendant
class srcfilealias
, which gives an alternate name to another
srcfile. This is produced by the parser when a #line
directive
is used.
The getSrcLines
function reads the specified lines from
srcfile
.
The srcref
function produces an object of class
srcref
, which describes a range of characters in a
srcfile
.
The lloc
value gives the following values:
c(first_line, first_byte, last_line, last_byte, first_column, last_column, first_parsed, last_parsed)Bytes (elements 2, 4) and columns (elements 5, 6) may be different due to multibyte characters. If only four values are given, the columns and bytes are assumed to match. Lines (elements 1, 3) and parsed lines ( elements 7, 8) may differ if a
#line
directive is used in
code: the former will respect the directive, the latter will just
count lines. If only 4 or 6 elements are given, the parsed lines
will be assumed to match the lines. Methods are defined for print
, summary
, open
,
and close
for classes srcfile
and srcfilecopy
.
The open
method opens its internal file
connection at
a particular line; if it was already open, it will be repositioned
to that line.
Methods are defined for print
, summary
and
as.character
for class srcref
. The as.character
method will read the associated source file to obtain the text
corresponding to the reference. If the to
argument is given,
it should be a second srcref
that follows the first, in the
same file; they will be treated as one reference to the whole
range. The exact behaviour depends on the
class of the source file. If the source file inherits from
class srcfilecopy
, the lines are taken from the saved copy
using the parsed line counts. If not, an attempt
is made to read the file, and the original line numbers of the
srcref
record (i.e., elements 1 and 3) are used. If an error
occurs (e.g., the file no longer exists), text like
will be returned instead,
indicating the line:column
ranges of the first and last
character. The summary
method defaults to this type of
display.
Lists of srcref
objects may be attached to expressions as the
"srcref"
attribute. (The list of srcref
objects should be the same
length as the expression.) By default, expressions are printed by
print.default
using the associated srcref
. To
see deparsed code instead, call print
with argument
useSource = FALSE
. If a srcref
object
is printed with useSource = FALSE
, the
record will be printed.
.isOpen
is intended for internal use: it checks whether the
connection associated with a srcfile
object is open.
getSrcFilename
for extracting information from a source reference.