compiler/psi/parser/buildLexer.xml

<project name="KotlinLexer" default="lexer">
    <property name="home" value="${basedir}"/>
    <property name="builddir" value="${basedir}/build"/>
    <property name="flex.classpath" value=""/>
    <property name="out.dir" value="${builddir}/tmpout"/>
    <!-- TODO: KT-77206 (Get rid of the skeleton downloading or use JFlex version instead of the commit hash) -->
    <property name="skeleton.version" value="486d14622bd240ceccd844a0e65d7c69e7e44735" />
    <property name="skeleton.download.path" value="${builddir}/idea-flex-${skeleton.version}.skeleton" />

    <macrodef name="flex">
      <attribute name="flexfile"/>
      <attribute name="destdir"/>
      <attribute name="skeleton" default="${skeleton.download.path}"/>
      <sequential>
        <delete dir="${out.dir}"/>
        <mkdir dir="${out.dir}"/>
        <java classname="jflex.Main"
              jvmargs="-Xmx512M"
              fork="true"
              failonerror="true">
          <arg value="-skel"/>
          <arg value="@{skeleton}"/>
          <arg value="-d"/>
          <arg value="${out.dir}"/>
          <arg value="@{flexfile}"/>
          <classpath>
            <pathelement path="${flex.classpath}"/>
          </classpath>
        </java>
        <move todir="@{destdir}">
          <fileset dir="${out.dir}">
            <include name="*.java"/>
          </fileset>
        </move>
        <delete dir="${out.dir}"/>
      </sequential>
    </macrodef>

    <target name="check-idea-flex.skeleton.exists">
        <available file="${skeleton.download.path}" property="skeleton.exists"/>
    </target>

    <target name="get-idea-flex.skeleton.if.not.exists" depends="check-idea-flex.skeleton.exists" unless="skeleton.exists">
        <get src="https://raw.githubusercontent.com/JetBrains/intellij-community/${skeleton.version}/tools/lexer/idea-flex.skeleton"
             dest="${skeleton.download.path}" usetimestamp="true"/>
    </target>

    <target name="lexer" depends="get-idea-flex.skeleton.if.not.exists">
        <flex flexfile="${home}/src/org/jetbrains/kotlin/lexer/Kotlin.flex"
              destdir="${home}/src/org/jetbrains/kotlin/lexer/"/>

        <!-- This is a hack, but we don't want to alter the skeleton we are using now, because being in sync with IDEA is more important-->
        <replaceregexp file="${home}/src/org/jetbrains/kotlin/lexer/_JetLexer.java"
                       match="throw new KotlinLexerException\(message\);"
                       replace="throw new KotlinLexerException(message + &quot;\\\\n at '&quot; + yytext() + &quot;'\\\\n&quot; + zzBuffer);"/>

        <flex flexfile="${home}/src/org/jetbrains/kotlin/kdoc/lexer/KDoc.flex"
              destdir="${home}/src/org/jetbrains/kotlin/kdoc/lexer/"/>
    </target>
</project>