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Add dfdlx:currentPosition function
This is for some DFDL experiments with data formats that DFDL can't currently represent. The function is only meaningful at parse time. DAFFODIL-2974
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‎daffodil-core/src/main/scala/org/apache/daffodil/core/dpath/Expression.scala‎

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@@ -1802,6 +1802,21 @@ case class FunctionCallExpression(functionQNameString: String, expressions: List
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DFDLXBitBinaryExpr(functionQNameString, functionQName, args, DFDLXBitOr(_, _))
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case (RefQName(_, "bitNot", DFDLX), args) =>
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DFDLXBitUnaryExpr(functionQNameString, functionQName, args, DFDLXBitNot(_, _))
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//
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// Returns the current position in bits or bytes. This is 1-based.
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// Experimental Feature: Why? because well... is this even well defined
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// when unparsing given that expressions can get
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// retried, and the position may not be well known yet at that time.
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//
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case (RefQName(_, "currentPosition", DFDLX), args) =>
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FNOneArgExpr(
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functionQNameString,
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functionQName,
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args,
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NodeInfo.Long,
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NodeInfo.String,
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DFDLXCurrentPosition(_, _)
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)
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case (RefQName(_, "year-from-dateTime", FUNC), args) =>
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FNOneArgExpr(

‎daffodil-core/src/main/scala/org/apache/daffodil/runtime1/dpath/DFDLXFunctions.scala‎

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@@ -347,3 +347,28 @@ case class DFDLXDoubleToRawLong(recipes: CompiledDPath, argType: NodeInfo.Kind)
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JDouble.doubleToRawLongBits(value.getDouble)
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}
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}
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/**
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* Computes the current position in the data stream in unis of bits or bytes.
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*
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* Not well defined for unparsing since an absolute position may not be available
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* at the time this is called.
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*/
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case class DFDLXCurrentPosition(recipes: CompiledDPath, argType: NodeInfo.Kind)
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extends FNOneArg(recipes, NodeInfo.String) {
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Assert.invariant(argType == NodeInfo.String)
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override def computeValue(arg1: DataValuePrimitive, dstate: DState): DataValueLong = {
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val units = arg1.getString
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val maybeState = dstate.parseOrUnparseState
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val bitpos1b =
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if (maybeState.isDefined) maybeState.get.bitPos1b
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else throw new IllegalStateException() // when constant folding, this can't be folded.
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val res: Long = units match {
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case "bits" => bitpos1b
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case "bytes" =>
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maybeState.get.bytePos1b // note: if bitpos is not on a byte boundary, this will be first prior byte pos.
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case _ => dstate.SDE("Units argument was not 'bits' or 'bytes'. Value was: '%s'.", units)
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}
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res
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}
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}

‎daffodil-test/src/test/resources/org/apache/daffodil/section23/dfdl_functions/CurrentPosition.tdml‎

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@@ -0,0 +1,80 @@
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<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<tdml:testSuite suiteName="CurrentPosition" description="Current Position DFDL Extension Function"
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xmlns:dfdlx="http://www.ogf.org/dfdl/dfdl-1.0/extensions"
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xmlns:tdml="http://www.ibm.com/xmlns/dfdl/testData" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xmlns:dfdl="http://www.ogf.org/dfdl/dfdl-1.0/" xmlns:xs="http://www.w3.org/2001/XMLSchema"
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xmlns:fn="http://www.w3.org/2005/xpath-functions"
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xmlns:math="http://www.w3.org/2005/xpath-functions/math"
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xmlns:ex="http://example.com"
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xmlns:home="http://home.com"
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xmlns:first="http://first.com"
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defaultRoundTrip="onePass">
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<tdml:defineSchema elementFormDefault="unqualified" useDefaultNamespace="false"
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name="cp">
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<xs:include schemaLocation="/org/apache/daffodil/xsd/DFDLGeneralFormat.dfdl.xsd"/>
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<dfdl:format
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ref="ex:GeneralFormat"
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representation="binary"
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binaryNumberRep="binary"
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lengthUnits="bits"
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alignmentUnits="bits"
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alignment="1"/>
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<xs:simpleType name="uLongN" dfdl:lengthKind="explicit">
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<xs:restriction base="xs:unsignedLong"/>
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</xs:simpleType>
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<xs:element name="bits1">
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<xs:complexType>
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<xs:sequence>
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<xs:element name="bitPos1bAtStart" type="xs:long" dfdl:inputValueCalc='{ dfdlx:currentPosition("bits") }'/>
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<xs:element name="oneBit" type="ex:uLongN" dfdl:length="1"/>
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<xs:element name="bitPos1bAfterOneBit" type="xs:long" dfdl:inputValueCalc='{ dfdlx:currentPosition("bits") }'/>
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<xs:element name="bytePos1bAfterOneBit" type="xs:long" dfdl:inputValueCalc='{ dfdlx:currentPosition("bytes") }'/>
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<xs:element name="eightBits" type="ex:uLongN" dfdl:length="8"/>
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<xs:element name="bitPos1bAfter9Bits" type="xs:long" dfdl:inputValueCalc='{ dfdlx:currentPosition("bits") }'/>
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<xs:element name="bytePos1bAfter9Bits" type="xs:long" dfdl:inputValueCalc='{ dfdlx:currentPosition("bytes") }'/>
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<xs:element name="sevenBits" type="ex:uLongN" dfdl:length="7"/>
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</xs:sequence>
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</xs:complexType>
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</xs:element>
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</tdml:defineSchema>
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<tdml:parserTestCase name="testCurrentPosition1" root="bits1" model="cp">
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<tdml:document>
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<tdml:documentPart type="bits">1000 0010 1001 1111</tdml:documentPart>
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</tdml:document>
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<tdml:infoset>
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<tdml:dfdlInfoset>
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<ex:bits1>
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<bitPos1bAtStart>1</bitPos1bAtStart>
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<oneBit>1</oneBit>
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<bitPos1bAfterOneBit>2</bitPos1bAfterOneBit>
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<bytePos1bAfterOneBit>1</bytePos1bAfterOneBit>
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<eightBits>5</eightBits>
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<bitPos1bAfter9Bits>10</bitPos1bAfter9Bits>
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<bytePos1bAfter9Bits>2</bytePos1bAfter9Bits>
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<sevenBits>31</sevenBits>
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</ex:bits1>
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</tdml:dfdlInfoset>
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</tdml:infoset>
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</tdml:parserTestCase>
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</tdml:testSuite>

‎daffodil-test/src/test/scala/org/apache/daffodil/section23/dfdl_expressions/TestCurrentPositionFunction.scala‎

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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.daffodil.section23.dfdl_expressions
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import org.apache.daffodil.junit.tdml.{ TdmlSuite, TdmlTests }
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import org.junit.Test
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object TestCurrentPositionFunction extends TdmlSuite {
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val tdmlResource = "/org/apache/daffodil/section23/dfdl_functions/CurrentPosition.tdml"
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}
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class TestCurrentPositionFunction extends TdmlTests {
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val tdmlSuite = TestCurrentPositionFunction
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@Test def testCurrentPosition1 = test
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}

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