138 lines
4.0 KiB
XML
138 lines
4.0 KiB
XML
<?xml version="1.0"?>
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<!--
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Copyright (C) 2017 R-T Specialty, LLC.
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This file is part of tame-core.
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tame-core is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as
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published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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-->
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<package xmlns="http://www.lovullo.com/rater"
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xmlns:c="http://www.lovullo.com/calc"
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xmlns:t="http://www.lovullo.com/rater/apply-template"
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core="true"
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desc="Operations Based on Vector Length">
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<import package="../base" />
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<import package="../numeric/common" export="true" />
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See the respective test specification for examples.
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<section title="Non-empty Vectors">
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\ref{_first-nonempty_} will yield the result of the first toplevel
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expression that is not an empty vector.
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This template yields an empty vector if no non-empty vectors are found.
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<template name="_first-nonempty_"
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desc="Return the first non-empty vector">
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<param name="@values@" desc="List of vectors" />
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<c:let>
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<c:values>
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<!-- avoid having to copy @values@ multiple times -->
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<c:value name="_list" type="float"
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desc="Result of body expression">
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<c:set>
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<param-copy name="@values@" />
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</c:set>
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</c:value>
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</c:values>
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<c:apply name="_first_nonempty">
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<c:arg name="list">
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<c:value-of name="_list" />
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</c:arg>
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<c:arg name="index">
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<c:const value="0" desc="First element" />
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</c:arg>
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<c:arg name="length">
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<c:length-of>
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<c:value-of name="_list" />
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</c:length-of>
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</c:arg>
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</c:apply>
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</c:let>
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</template>
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Its helper function is \ref{_first_nonempty},
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which recurses through each vector element until a non-empty vector is
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encountered.
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<function name="_first_nonempty"
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desc="Return the first non-empty vector">
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<param name="list" type="float" set="vector"
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desc="List of vectors to process" />
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<param name="index" type="integer"
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desc="Current index (for recursion), decrementing" />
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<param name="length" type="integer"
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desc="Length of list" />
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<c:let>
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<c:values>
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<c:value name="cur_len" type="integer"
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desc="Length of current vector">
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<c:length-of>
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<c:value-of name="list" index="index" />
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</c:length-of>
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</c:value>
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</c:values>
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<c:cases>
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<!-- if none were found (end of list), return empty vector -->
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<c:case>
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<c:when name="index">
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<c:gte>
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<c:value-of name="length" />
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</c:gte>
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</c:when>
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<c:set />
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</c:case>
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<!-- non-empty vector, return it -->
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<c:case>
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<c:when name="cur_len">
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<c:gt>
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<c:const value="0" desc="Vector length" />
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</c:gt>
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</c:when>
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<c:value-of name="list" index="index" />
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</c:case>
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<!-- vector was empty, keep going (decrement index) -->
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<c:otherwise>
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<c:recurse>
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<c:arg name="index">
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<t:inc>
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<c:value-of name="index" />
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</t:inc>
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</c:arg>
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</c:recurse>
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</c:otherwise>
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</c:cases>
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</c:let>
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</function>
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</section>
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</package>
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