Make the RAND() and RANDBETWEEN() Calc functions non-random when requested

We don't want such a mode to affect other uses of randomness, though. Thus use
a separate random number generator object for these two functions, and use a
fixed seed for it if the SC_RAND_REPEATABLE environment variable is set.

As RAND() is implemented in sc, and RANDBETWEEN() is implemented in scaddins,
it was a bit hard to figure out where to add the new functions needed, without
having to over-engineer things with UNO. (This functionality is totally
Calc-specific, but neither sc nor scaddins has any public (non-UNO) API.)
Caolan suggested the formula module, which seems like a good enough place to
me.

Change-Id: I4b0cb327392e51a18bce28478af91b0174d6b726

formula/Library_for.mk

@@ -42,6 +42,7 @@ $(eval $(call gb_Library_add_exception_objects,for,\
     formula/source/core/api/FormulaCompiler \
     formula/source/core/api/FormulaOpCodeMapperObj \
     formula/source/core/api/grammar \
+    formula/source/core/api/random \
     formula/source/core/api/services \
     formula/source/core/api/token \
     formula/source/core/api/vectortoken \

formula/README

@@ -1,3 +1,5 @@
-Contains parts of the formula parser used outside Calc code.
+Contains parts of the formula parser used outside Calc code that has
+been pulled out from Calc's formula parser code.
 
-Has been pulled out from Calc's formula parser code.
+Also contains some functions that are needed by code in both sc and
+scaddins. Located here just for convenience. So sue me.

formula/source/core/api/random.cxx

@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <time.h>
+
+#include <random>
+
+#include <formula/random.hxx>
+#include <rtl/instance.hxx>
+
+namespace {
+
+struct CalcFormulaRandomGenerator
+{
+    std::mt19937 aRng;
+    CalcFormulaRandomGenerator()
+    {
+        // initialises the state of this RNG.
+        // should only be called once.
+        bool bRepeatable = (getenv("SC_RAND_REPEATABLE") != 0);
+        aRng.seed(bRepeatable ? 42 : time(NULL));
+    }
+};
+
+class theCalcFormulaRandomGenerator : public rtl::Static<CalcFormulaRandomGenerator, theCalcFormulaRandomGenerator> {};
+
+}
+
+namespace formula
+{
+
+namespace rng
+{
+
+double fRandom(double a, double b)
+{
+    std::uniform_real_distribution<double> dist(a, b);
+    return dist(theCalcFormulaRandomGenerator::get().aRng);
+}
+
+sal_Int32 nRandom(sal_Int32 a, sal_Int32 b)
+{
+    std::uniform_int_distribution<sal_Int32> dist(a, b);
+    return dist(theCalcFormulaRandomGenerator::get().aRng);
+}
+
+} // rng
+} // formula
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

include/formula/random.hxx

@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef INCLUDED_FORMULA_RANDOM_HXX
+#define INCLUDED_FORMULA_RANDOM_HXX
+
+#include <formula/formuladllapi.h>
+
+namespace formula
+{
+
+namespace rng
+{
+
+// These two functions obey the SC_RAND_REPEATABLE environment
+// variable: If it is set, use a fixed seed.
+double FORMULA_DLLPUBLIC fRandom(double a, double b);
+sal_Int32 FORMULA_DLLPUBLIC nRandom(sal_Int32 a, sal_Int32 b);
+
+} // rng
+} // formula
+
+#endif // INCLUDED_FORMULA_RANDOM_HXX
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

sc/source/core/opencl/formulagroupcl.cxx

@@ -16,7 +16,7 @@
 #include "tokenarray.hxx"
 #include "compiler.hxx"
 #include "interpre.hxx"
-#include <comphelper/random.hxx>
+#include <formula/random.hxx>
 #include <formula/vectortoken.hxx>
 #include "scmatrix.hxx"
 
@@ -703,7 +703,7 @@ threefry2x32 (threefry2x32_ctr_t in, threefry2x32_key_t k)\n\
     /// Create buffer and pass the buffer to a given kernel
     virtual size_t Marshal( cl_kernel k, int argno, int, cl_program ) SAL_OVERRIDE
     {
-        cl_int seed = comphelper::rng::uniform_int_distribution(0, SAL_MAX_INT32);
+        cl_int seed = formula::rng::nRandom(0, SAL_MAX_INT32);
         // Pass the scalar result back to the rest of the formula kernel
         SAL_INFO("sc.opencl", "Kernel " << k << " arg " << argno << ": cl_int: " << seed);
         cl_int err = clSetKernelArg(k, argno, sizeof(cl_int), (void*)&seed);

sc/source/core/tool/interpr1.cxx

@@ -22,6 +22,7 @@
 #include "scitems.hxx"
 #include <editeng/langitem.hxx>
 #include <editeng/justifyitem.hxx>
+#include <formula/random.hxx>
 #include <osl/thread.h>
 #include <svx/algitem.hxx>
 #include <unotools/textsearch.hxx>
@@ -1662,7 +1663,7 @@ void ScInterpreter::ScPi()
 
 void ScInterpreter::ScRandom()
 {
-    PushDouble(::comphelper::rng::uniform_real_distribution());
+    PushDouble(formula::rng::fRandom(0, 1));
 }
 
 void ScInterpreter::ScTrue()

scaddins/Library_analysis.mk

@@ -33,6 +33,7 @@ $(eval $(call gb_Library_use_libraries,analysis,\
 	comphelper \
 	cppu \
 	cppuhelper \
+	for \
 	sal \
 	tl \
 	i18nlangtag \

scaddins/source/analysis/analysis.cxx

@@ -22,8 +22,8 @@
 #include "bessel.hxx"
 #include <cppuhelper/factory.hxx>
 #include <comphelper/processfactory.hxx>
-#include <comphelper/random.hxx>
 #include <cppuhelper/supportsservice.hxx>
+#include <formula/random.hxx>
 #include <osl/diagnose.h>
 #include <rtl/ustrbuf.hxx>
 #include <rtl/math.hxx>
@@ -703,7 +703,7 @@ double SAL_CALL AnalysisAddIn::getRandbetween( double fMin, double fMax ) throw(
     if( fMin > fMax )
         throw lang::IllegalArgumentException();
 
-    double fRet = floor(comphelper::rng::uniform_real_distribution(fMin, nextafter(fMax+1, -DBL_MAX)));
+    double fRet = floor(formula::rng::fRandom(fMin, nextafter(fMax+1, -DBL_MAX)));
     RETURN_FINITE( fRet );
 }