tplgen: Add package

* test/core/suite.xml: Import new tplgen package.
* test/core/tplgen.xml: Add test.
* tplgen.xml: Add package.

core/test/core/suite.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <!--
-  Copyright (C) 2015 R-T Specialty, LLC.
+  Copyright (C) 2015, 2018 R-T Specialty, LLC.
 
   This file is part of tame-core.
 
@@ -26,12 +26,15 @@
   <import package="../../base" />
   <import package="../spec" />
 
-  <import package="insurance" />
   <import package="numeric/round" />
   <import package="numeric/convert" />
   <import package="numeric/percent" />
   <import package="vector/interpolate" />
   <import package="vector/length" />
+
+  <import package="insurance" />
+  <import package="tplgen" />
+
   <!-- XXX broken!
   <import package="ui" />
   -->

core/test/core/tplgen.xml

@@ -0,0 +1,67 @@
+<?xml version="1.0"?>
+<!--
+  Copyright (C) 2018 R-T Specialty, LLC.
+
+  This file is part of tame-core.
+
+  tame-core is free software: you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation, either version 3 of the
+  License, or (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+-->
+<package xmlns="http://www.lovullo.com/rater"
+         xmlns:c="http://www.lovullo.com/calc"
+         xmlns:t="http://www.lovullo.com/rater/apply-template"
+         desc="Template Generation Package Specification">
+
+  <import package="../../test/spec" />
+
+  <import package="../../base" />
+  <import package="../../tplgen" />
+
+
+  <t:describe name="_for-each-n_">
+    <t:describe name="given a positive step">
+      <t:it desc="produces body N times exposing current N">
+        <t:given>
+          <c:sum>
+            <t:for-each-n start="2" end="6" step="2">
+              <c:const value="@current_n@" desc="Current N" />
+            </t:for-each-n>
+          </c:sum>
+        </t:given>
+
+        <t:expect>
+          <!-- 2 + 4 + 6 -->
+          <t:match-result eq="12" />
+        </t:expect>
+      </t:it>
+    </t:describe>
+
+
+    <t:describe name="given a negative step">
+      <t:it desc="produces body N times exposing current N">
+        <t:given>
+          <c:sum>
+            <t:for-each-n start="4" end="1" step="-1">
+              <c:const value="@current_n@" desc="Current N" />
+            </t:for-each-n>
+          </c:sum>
+        </t:given>
+
+        <t:expect>
+          <!-- 4 + 3 + 2 + 1 = 4! (4 factorial) -->
+          <t:match-result eq="10" />
+        </t:expect>
+      </t:it>
+    </t:describe>
+  </t:describe>
+</package>

core/tplgen.xml

@@ -0,0 +1,73 @@
+<?xml version="1.0"?>
+<!--
+  Copyright (C) 2018 R-T Specialty, LLC.
+
+  This file is part of tame-core.
+
+  tame-core is free software: you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation, either version 3 of the
+  License, or (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+-->
+<package xmlns="http://www.lovullo.com/rater"
+         xmlns:c="http://www.lovullo.com/calc"
+         xmlns:t="http://www.lovullo.com/rater/apply-template"
+         core="true"
+         desc="Template Generation">
+
+
+  This package provides various templates for generating templates and
+    iterating using templates.
+  In essense,
+    this package is intended to abstract away certain implementation details
+    and complexities that make groking code more difficult;
+      they should be used when possible to improve code maintenance.
+
+
+  <section title="Iteration">
+    \ref{_for-each-n_} recurisvely produces the body~\tt{@values@} given a
+      numeric range and step.
+    This can also be used to generate sequences at compile-time rather than
+      using functions,
+        provided that the sequence data are static.
+
+    <template name="_for-each-n_"
+              desc="Recursively apply body with counter and step">
+      <param name="@values@" desc="Body" />
+      <param name="@start@"  desc="Counter start" />
+      <param name="@end@"    desc="Counter end" />
+      <param name="@step@"   desc="Counter step" />
+
+
+      <param name="@next_n@" desc="Next iteration value">
+        <param-add name="@start@" value="@step@" />
+      </param>
+
+
+      <!-- inefficient trick to expose @current_n@ to the body -->
+      <inline-template>
+        <for-each>
+          <set current_n="@start@" />
+        </for-each>
+
+        <param-copy name="@values@" />
+      </inline-template>
+
+
+      <!-- repeat body for each step, as sibling -->
+      <unless name="@start@" eq="@end@">
+        <t:for-each-n start="@next_n@" end="@end@" step="@step@">
+          <param-copy name="@values@" />
+        </t:for-each-n>
+      </unless>
+    </template>
+  </section>
+</package>