plugins/header_rewrite/parser.cc

/*
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/
//////////////////////////////////////////////////////////////////////////////////////////////
// parser.cc: implementation of the config parser
//
//
#include <utility>
#include <boost/tokenizer.hpp>

#include <ts/ts.h>

#include "parser.h"

// Tokenizer separators
static boost::escaped_list_separator<char> token_sep('\\', ' ', '\"');
static boost::char_separator<char> comma_sep(",");


// This is the core "parser", parsing rule sets
void
Parser::preprocess(std::vector<std::string>& tokens)
{
  // Special case for "conditional" values
  if (tokens[0].substr(0, 2) == "%{") {
    _cond = true;
  } else if (tokens[0] == "cond") {
    _cond = true;
    tokens.erase(tokens.begin());
  }

  // Is it a condition or operator?
  if (_cond) {
    if ((tokens[0].substr(0, 2) == "%{") && (tokens[0][tokens[0].size() - 1] == '}')) {
      std::string s = tokens[0].substr(2, tokens[0].size() - 3);

      _op = s;
      if (tokens.size() > 1)
        _arg = tokens[1];
      else
        _arg = "";
    } else {
      TSError("%s: conditions must be embraced in %%{}", PLUGIN_NAME);
      return;
    }
  } else {
    // Operator has no qualifiers, but could take an optional second argumetn
    _op = tokens[0];
    if (tokens.size() > 1) {
      _arg = tokens[1];
      if (tokens.size() > 2)
        _val = tokens[2];
      else
        _val = "";
    } else {
      _arg = "";
      _val = "";
    }
  }

  // The last token might be the "flags" section
  if (tokens.size() > 0) {
    std::string m  = tokens[tokens.size() - 1];

    if (!m.empty() && (m[0] == '[')) {
      if (m[m.size() - 1] == ']') {
        m = m.substr(1, m.size() - 2);
        if (m.find_first_of(',') != std::string::npos) {
          boost::tokenizer<boost::char_separator<char> > mods(m, comma_sep);
          std::copy(mods.begin(), mods.end(), std::back_inserter(_mods));
        } else {
          _mods.push_back(m);
        }
      } else {
        // Syntax error
        TSError("%s: mods have to be embraced in []", PLUGIN_NAME);
        return;
      }
    }
  }
}


Parser::Parser(const std::string& line) :
  _cond(false), _empty(false)
{
  TSDebug(PLUGIN_NAME_DBG, "Calling CTOR for Parser");

  if (line[0] == '#') {
    _empty = true;
  } else {
    boost::tokenizer<boost::escaped_list_separator<char> > elem(line, token_sep);
    std::vector<std::string> tokens;

    for (boost::tokenizer<boost::escaped_list_separator<char> >::iterator it = elem.begin(); it != elem.end(); it++) {
      // Skip "empty" tokens (tokenizer is a little brain dead IMO)
      if ((*it) != "")
        tokens.push_back(*it);
    }

    if (tokens.empty()) {
      _empty = true;
    } else {
      preprocess(tokens);
    }
  }
}