R/history.r

In ProvTools/provR: Provenance Capture Package

# Copyright (C) 2017 Harvard University, Mount Holyoke College
#
# This file is part of ProvR.
#
# ProvR is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# ProvR is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with ProvR; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
# This package was forked from <https://github.com/End-to-end-provenance/RDataTracker>
#
# Contact: Matthew Lau <matthewklau@fas.harvard.edu>

# .ddg.load.history takes in the name of a history file, opens it, scans it for
# the last occurrence of the string specified by timestamp, and returns the lines
# from that point forward.
# hist.file - name of history file.  timestamp - timestamp string.
.ddg.load.history <- function(hist.file, timestamp) {
    # Read from specified file.
    history <- readLines(hist.file)
    history.lines <- length(history)
    # Find the timestamp specified in the history.  There may be more than one with
    # the same timestamp, so pick the last of these.
    history.timestamp.line <- tail(which(history == timestamp), 1)
    if (length(history.timestamp.line) == 0) {
        error.msg <- paste("Part of history is missing. DDG may be incomplete! Tried reading from",
            hist.file, "but could not find timestamp:", timestamp)

        .ddg.insert.error.message(error.msg)
        history.timestamp.line <- 0
    }
    # Need to check if the timestamp line is the last line in the file explicitly.
    # If we don't do that and take the vector, we will get the last line in the file
    # since R will create a descending sequence for the vector.
    if (history.timestamp.line == history.lines)
        return(vector())
    # NEED the paren around sum.
    return(history[(history.timestamp.line + 1):history.lines])
}

# .ddg.save.history saves the current and unsaved R command history to the
# specified file if that file matches the DDG history file.  Note: the commented
# section of code appends the information to this file.

# savehistory is not supported on all R platforms.  If it is not supported, this
# will fail silently.

# hist.file - name of history file.

.ddg.save.history <- function(hist.file) {
    # USED TO STORE ENTIRE HISTORY IN SEP. FILE.  Write history out to temporary file
    if (.ddg.is.set(".ddg.history.file") && is.character(.ddg.get(".ddg.history.file")) &&
        .ddg.get(".ddg.history.file") == hist.file) {
        savehistory(hist.file)
    }
}