UrnPolicyFile.cc

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/* 
 * LSST Data Management System
 * Copyright 2008, 2009, 2010 LSST Corporation.
 * 
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * This program 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 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 LSST License Statement and 
 * the GNU General Public License along with this program.  If not, 
 * see <http://www.lsstcorp.org/LegalNotices/>.
 */
 
/*
 * UrnPolicyFile
 */
#include "lsst/pex/policy/UrnPolicyFile.h"
#include "lsst/pex/exceptions.h"

#include <string>
#include <vector>

namespace lsst {
namespace pex {
namespace policy {

//@cond

using namespace std;

const string UrnPolicyFile::URN_PREFIX("urn:eupspkg:");
const string UrnPolicyFile::URN_PREFIX_ABBREV("@");

string stripPrefixes(string urn, bool strict) {
    // strip @'s
    int numAts = 0;
    while (urn.length() > 0 && urn.find(UrnPolicyFile::URN_PREFIX_ABBREV) == 0) {
        urn = urn.substr(UrnPolicyFile::URN_PREFIX_ABBREV.length());
        ++numAts;
    }

    // strip urn:eupspkg:
    string lowered(urn);
    transform(lowered.begin(), lowered.end(), lowered.begin(), ::tolower);
    bool hasPrefix = (lowered.find(UrnPolicyFile::URN_PREFIX) == 0);
    if (hasPrefix)
        urn = urn.substr(UrnPolicyFile::URN_PREFIX.length());

    // validate, if requested
    if (strict && (numAts > 1 || !hasPrefix))
        throw LSST_EXCEPT(BadNameError, ("URN must start with \"urn:eupspkg:\" or \"@urn:eupspkg:\""));

    return urn;
}

void splitAndValidate(const string& urn, vector<string>& a, bool strict) {
    // strip prefixes
    string stripped = stripPrefixes(urn, strict);

    // split
    while (true) {
        size_t i = stripped.find(":");
        if (i == string::npos) {
            if (stripped.length() > 0) a.push_back(stripped);
            break;
        }
        else {
            a.push_back(stripped.substr(0, i));
            stripped = stripped.substr(i + 1);
        }
    }

    // validate
    // - min size is 2 -- product:file
    // - max size is 3 -- product:repos:file
    if (a.size() < 2 || a.size() > 3)
        throw LSST_EXCEPT
            (BadNameError,
             "Wrong number of terms in policy file urn \"" + urn + "\".  "
             + "The expected form is "
             + "@urn:eupspkg:<product>:[<repository>:]<file> or "
             + "@@<product>:[<repository>:]<file>.  "
             + "Is there a typo in the urn?");
}

string UrnPolicyFile::productNameFromUrn(const string& urn, bool strictUrn) {
    vector<string> split;
    splitAndValidate(urn, split, strictUrn);
    return split[0];
}

string UrnPolicyFile::filePathFromUrn(const string& urn, bool strictUrn) {
    vector<string> split;
    splitAndValidate(urn, split, strictUrn);
    return split.back();
}

string UrnPolicyFile::reposFromUrn(const string& urn, bool strictUrn) {
    vector<string> split;
    splitAndValidate(urn, split, strictUrn);
    if (split.size() == 3) return split[1];
    else return "";
}

bool UrnPolicyFile::looksLikeUrn(const string& s, bool strict) {
    if (strict) {
        string lc(s);
        transform(lc.begin(), lc.end(), lc.begin(), ::tolower);
        while (lc[0] == '@') lc = lc.substr(1);
        if (lc.find(UrnPolicyFile::URN_PREFIX) != 0) return false;
    }
    const string& stripped = stripPrefixes(s, strict);
    return s.length() != stripped.length() && s.find(":") != s.npos;
}

//@endcond

} // namespace policy
} // namespace pex
} // namespace lsst