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  <header>
    <copyright>
      <year>2001</year><year>2016</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed 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

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      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
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    </legalnotice>

    <title>megaco_flex_scanner</title>
    <prepared>Micael Karlberg</prepared>
    <responsible>Micael Karlberg</responsible>
    <docno></docno>
    <approved>Micael Karlberg</approved>
    <checked></checked>
    <date>2009-05-04</date>
    <rev>%VSN%</rev>
    <file>megaco_flex_scanner.xml</file>
  </header>
  <module>megaco_flex_scanner</module>
  <modulesummary>Interface module to the flex scanner linked in driver.</modulesummary>
  <description>
    <p>This module contains the public interface to the flex scanner 
      linked in driver. The flex scanner performs the scanning phase
      of text message decoding.</p>

    <p>The flex scanner is written using a tool called <em>flex</em>. 
      In order to be able to compile the flex scanner driver, this
      tool has to be available. </p>

    <p>By default the flex scanner reports line-number of an error.
      But it can be built without line-number reporting. Instead
      token number is used. This will speed up the scanning some
      5-10%. Use <c><![CDATA[--disable-megaco-flex-scanner-lineno]]></c> when
      configuring the application.</p>

    <p>The scanner will, by default, be built as a reentrant scanner <em>if</em> the 
      flex utility supports this (it depends on the version of flex). 
      It is possible to explicitly disable this even when flex support this.
      Use <c><![CDATA[--disable-megaco-reentrant-flex-scanner]]></c> when
      configuring the application.</p>

  </description>

  <section>
    <title>DATA TYPES</title>
    <code type="none"><![CDATA[

megaco_ports() = term()
megaco_version() = integer() >= 1
 
    ]]></code>

    <marker id="start"></marker>
  </section>


  <funcs>
    <func>
      <name>start() -> {ok, PortOrPorts} | {error, Reason}</name>
      <fsummary></fsummary>
      <type>
        <v>PortOrPorts = megaco_ports()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>This function is used to start the flex scanner. 
          It locates the library and loads the linked in driver.</p>

        <p>On a single core system or if it's a non-reentrant scanner,
          a single port is created. On a multi-core system with a reentrant 
          scanner, several ports will be created (one for each scheduler). </p>

        <p>Note that the process that calls this function <em>must</em> 
          be permanent. If it dies, the port(s) will exit and the driver unload.</p>

        <marker id="stop"></marker>
      </desc>
    </func>

    <func>
      <name>stop(PortOrPorts) -> stopped</name>
      <fsummary></fsummary>
      <type>
        <v>PortOrPorts = megaco_ports()</v>
      </type>
      <desc>
        <p>This function is used to stop the flex scanner. It also
          unloads the driver.</p>

        <marker id="is_reentrant_enabled"></marker>
      </desc>
    </func>

    <func>
      <name>is_reentrant_enabled() -> Boolean</name>
      <fsummary></fsummary>
      <type>
        <v>Boolean = boolean()</v>
      </type>
      <desc>
        <p>Is the flex scanner reentrant or not.</p>

        <marker id="is_scanner_port"></marker>
      </desc>
    </func>

    <func>
      <name>is_scanner_port(Port, PortOrPorts) -> Boolean</name>
      <fsummary></fsummary>
      <type>
        <v>Port = port()</v>
        <v>PortOrPorts = megaco_ports()</v>
        <v>Boolean = boolean()</v>
      </type>
      <desc>
        <p>Checks if a port is a flex scanner port or not (useful when
          if a port exits). </p>

        <marker id="scan"></marker>
      </desc>
    </func>

    <func>
      <name>scan(Binary, PortOrPorts) -> {ok, Tokens, Version, LatestLine} | {error, Reason, LatestLine} </name>
      <fsummary></fsummary>
      <type>
        <v>Binary = binary()</v>
        <v>PortOrPorts = megaco_ports()</v>
        <v>Tokens = list()</v>
        <v>Version = megaco_version()</v>
        <v>LatestLine = integer()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Scans a megaco message and generates a token list to be passed on the parser. </p>
      </desc>
    </func>

  </funcs>

</erlref>

