VRT expressions: Add compile-time options to enable/disable dialects

.github/workflows/ubuntu_20.04/build.sh

@@ -15,6 +15,7 @@ cmake "${GDAL_SOURCE_DIR:=..}" \
     -DCMAKE_INSTALL_PREFIX=/tmp/install-gdal \
     -DGDAL_USE_TIFF_INTERNAL=OFF \
     -DGDAL_USE_GEOTIFF_INTERNAL=OFF \
+    -DGDAL_VRT_ENABLE_EXPRTK=ON \
     -DECW_ROOT=/opt/libecwj2-3.3 \
     -DMRSID_ROOT=/usr/local \
     -DFileGDB_ROOT=/usr/local/FileGDB_API \

autotest/gdrivers/vrtderived.py

@@ -1202,51 +1202,69 @@ def vrt_expression_xml(tmpdir, expression, dialect, sources):
 )
 @pytest.mark.parametrize("dialect", ("exprtk", "muparser"))
 def test_vrt_pixelfn_expression(
-    tmp_path, expression, sources, result, dialect, dialects
+    tmp_vsimem, expression, sources, result, dialect, dialects
 ):
     pytest.importorskip("numpy")
 
+    if not gdaltest.gdal_has_vrt_expression_dialect(dialect):
+        pytest.skip(f"Expression dialect {dialect} is not available")
+
     if dialects and dialect not in dialects:
         pytest.skip(f"Expression not supported for dialect {dialect}")
 
-    xml = vrt_expression_xml(tmp_path, expression, dialect, sources)
+    xml = vrt_expression_xml(tmp_vsimem, expression, dialect, sources)
 
     with gdal.Open(xml) as ds:
         assert pytest.approx(ds.ReadAsArray()[0][0], nan_ok=True) == result
 
 
 @pytest.mark.parametrize(
-    "expression,sources,exception",
+    "expression,sources,dialect,exception",
     [
         pytest.param(
             "A*B + C",
             [("A", 77), ("B", 63)],
+            "exprtk",
             "Undefined symbol",
-            id="undefined variable",
+            id="exprtk undefined variable",
+        ),
+        pytest.param(
+            "A*B + C",
+            [("A", 77), ("B", 63)],
+            "muparser",
+            "Unexpected token",
+            id="muparser undefined variable",
         ),
         pytest.param(
             "(".join(["asin", "sin", "acos", "cos"] * 100) + "(X" + 100 * 4 * ")",
             [("X", 0.5)],
+            "exprtk",
             "exceeds maximum allowed stack depth",
             id="expression is too complex",
         ),
         pytest.param(
             " ".join(["sin(x) + cos(x)"] * 10000),
             [("x", 0.5)],
+            "exprtk",
             "exceeds maximum of 100000 set by GDAL_EXPRTK_MAX_EXPRESSION_LENGTH",
             id="expression is too long",
         ),
     ],
 )
-def test_vrt_pixelfn_expression_invalid(tmp_path, expression, sources, exception):
+def test_vrt_pixelfn_expression_invalid(
+    tmp_vsimem, expression, sources, dialect, exception
+):
     pytest.importorskip("numpy")
 
+    if not gdaltest.gdal_has_vrt_expression_dialect(dialect):
+        pytest.skip(f"Expression dialect {dialect} is not available")
+
     messages = []
 
     def handle(ecls, ecode, emsg):
         messages.append(emsg)
 
-    xml = vrt_expression_xml(tmp_path, expression, "exprtk", sources)
+    xml = vrt_expression_xml(tmp_vsimem, expression, dialect, sources)
 
     with gdaltest.error_handler(handle):
         ds = gdal.Open(xml)

autotest/gdrivers/vrtprocesseddataset.py

@@ -1347,6 +1347,9 @@ def test_vrtprocesseddataset_trimming_errors(tmp_vsimem):
 def test_vrtprocesseddataset_expression(
     request, tmp_vsimem, expression, src, expected, env, error
 ):
+    if not gdaltest.gdal_has_vrt_expression_dialect("exprtk"):
+        pytest.skip("exprtk not available")
+
     if "timeout" in request.node.name and "debug" not in gdal.VersionInfo(""):
         pytest.skip("Timeout tests only work on debug builds")
 
@@ -1362,7 +1365,7 @@ def test_vrtprocesseddataset_expression(
         src_ds.SetGeoTransform([0, 1, 0, 0, 0, 1])
 
     output_band_xml = "".join(
-        f"""<VRTRasterBand band="{i+1}" dataType="Float32" subClass="VRTProcessedRasterBand"/>"""
+        f"""<VRTRasterBand band="{i + 1}" dataType="Float32" subClass="VRTProcessedRasterBand"/>"""
         for i in range(expected_output_bands)
     )
 
@@ -1403,6 +1406,9 @@ def test_vrtprocesseddataset_expression(
 )
 def test_vrtprocesseddataset_expression_batchsize(tmp_vsimem, batch_size):
 
+    if not gdaltest.gdal_has_vrt_expression_dialect("muparser"):
+        pytest.skip("muparser not available")
+
     src_filename = tmp_vsimem / "in.tif"
 
     inputs = np.arange(12)

autotest/pymod/gdaltest.py

@@ -13,6 +13,7 @@
 ###############################################################################
 
 import contextlib
+import functools
 import io
 import json
 import math
@@ -2131,3 +2132,28 @@ def handler(lvl, no, msg):
     assert any(
         [err["level"] == type and match in err["message"] for err in errors]
     ), f'Did not receive an error of type {err_levels[type]} matching "{match}"'
+
+
+###############################################################################
+# Check VRT capabilities
+
+
+@functools.lru_cache()
+def gdal_has_vrt_expression_dialect(dialect):
+    with disable_exceptions(), gdal.quiet_errors():
+        vrt = f"""<VRTDataset rasterXSize="20" rasterYSize="20">
+          <VRTRasterBand dataType="Float64" band="1" subClass="VRTDerivedRasterBand">
+            <PixelFunctionType>expression</PixelFunctionType>
+            <PixelFunctionArguments expression="B1 + 5" dialect="{dialect}"/>
+            <ArraySource>
+                <Array name="test">
+                    <DataType>Float64</DataType>
+                    <Dimension name="Y" size="20"/>
+                    <Dimension name="X" size="20"/>
+                    <ConstantValue>10</ConstantValue>
+                </Array>
+            </ArraySource>
+          </VRTRasterBand>
+        </VRTDataset>"""
+        ds = gdal.Open(vrt)
+        return ds.ReadRaster() is not None

frmts/vrt/CMakeLists.txt

@@ -7,8 +7,6 @@ add_gdal_driver(
           vrtderivedrasterband.cpp
           vrtdriver.cpp
           vrtexpression.h
-          vrtexpression.cpp
-          vrtexpression_muparser.cpp
           vrtfilters.cpp
           vrtrasterband.cpp
           vrtrawrasterband.cpp
@@ -26,26 +24,38 @@ gdal_standard_includes(gdal_vrt)
 target_include_directories(gdal_vrt PRIVATE ${GDAL_RASTER_FORMAT_SOURCE_DIR}/raw
                                             $<TARGET_PROPERTY:ogrsf_generic,SOURCE_DIR>)
 
-target_include_directories(gdal_vrt SYSTEM PRIVATE ${PROJECT_SOURCE_DIR}/third_party/exprtk)
-if (MSVC)
-    set_source_files_properties(vrtexpression.cpp PROPERTIES COMPILE_FLAGS "/bigobj")
-elseif(MINGW)
-    set_source_files_properties(vrtexpression.cpp PROPERTIES COMPILE_FLAGS "-Wa,-mbig-obj")
+option(GDAL_VRT_ENABLE_EXPRTK "Enable exprtk library for VRT expressions" OFF)
+option(GDAL_VRT_ENABLE_MUPARSER "Enable muparser library for VRT expressions" ON)
+
+if (GDAL_VRT_ENABLE_EXPRTK)
+    target_sources(gdal_vrt PRIVATE vrtexpression_exprtk.cpp)
+        target_include_directories(gdal_vrt SYSTEM PRIVATE ${PROJECT_SOURCE_DIR}/third_party/exprtk)
+        if (MSVC)
+            set_source_files_properties(vrtexpression_exprtk.cpp PROPERTIES COMPILE_FLAGS "/bigobj")
+        elseif(MINGW)
+            set_source_files_properties(vrtexpression.cpp PROPERTIES COMPILE_FLAGS "-Wa,-mbig-obj")
+        endif()
+    target_compile_definitions(gdal_vrt PRIVATE GDAL_VRT_ENABLE_EXPRTK)
+endif()
+
+if (GDAL_VRT_ENABLE_MUPARSER)
+    target_sources(gdal_vrt PRIVATE vrtexpression_muparser.cpp)
+        add_library(muparser OBJECT
+            ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParser.cpp
+            ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserBase.cpp
+            ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserBytecode.cpp
+            ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserCallback.cpp
+            ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserError.cpp
+            ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserTokenReader.cpp
+        )
+        target_compile_definitions(muparser PRIVATE MUPARSERLIB_EXPORTS)
+        set_property(TARGET muparser PROPERTY POSITION_INDEPENDENT_CODE ${GDAL_OBJECT_LIBRARIES_POSITION_INDEPENDENT_CODE})
+        target_include_directories(muparser SYSTEM PRIVATE ${PROJECT_SOURCE_DIR}/third_party/muparser/include)
+        target_include_directories(gdal_vrt SYSTEM PRIVATE ${PROJECT_SOURCE_DIR}/third_party/muparser/include)
+        target_sources(${GDAL_LIB_TARGET_NAME} PRIVATE $<TARGET_OBJECTS:muparser>)
+    target_compile_definitions(gdal_vrt PRIVATE GDAL_VRT_ENABLE_MUPARSER)
 endif()
 
-add_library(muparser OBJECT
-    ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParser.cpp
-    ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserBase.cpp
-    ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserBytecode.cpp
-    ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserCallback.cpp
-    ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserError.cpp
-    ${PROJECT_SOURCE_DIR}/third_party/muparser/src/muParserTokenReader.cpp
-)
-target_compile_definitions(muparser PRIVATE MUPARSERLIB_EXPORTS)
-set_property(TARGET muparser PROPERTY POSITION_INDEPENDENT_CODE ${GDAL_OBJECT_LIBRARIES_POSITION_INDEPENDENT_CODE})
-target_include_directories(muparser SYSTEM PRIVATE ${PROJECT_SOURCE_DIR}/third_party/muparser/include)
-target_include_directories(gdal_vrt SYSTEM PRIVATE ${PROJECT_SOURCE_DIR}/third_party/muparser/include)
-target_sources(${GDAL_LIB_TARGET_NAME} PRIVATE $<TARGET_OBJECTS:muparser>)
 
 set(GDAL_DATA_FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/data/gdalvrt.xsd

frmts/vrt/pixelfunctions.cpp

@@ -1654,28 +1654,17 @@ static CPLErr ExprPixelFunc(void **papoSources, int nSources, void *pData,
     std::vector<double> adfValuesForPixel(nSources);
 
     const char *pszDialect = CSLFetchNameValue(papszArgs, "dialect");
-    if (pszDialect)
+    if (!pszDialect)
     {
-        if (EQUAL(pszDialect, "muparser"))
-        {
-            poExpression =
-                std::make_unique<gdal::MuParserExpression>(pszExpression);
-        }
-        else if (EQUAL(pszDialect, "exprtk"))
-        {
-            poExpression =
-                std::make_unique<gdal::ExprtkExpression>(pszExpression);
-        }
-        else
-        {
-            CPLError(CE_Failure, CPLE_AppDefined,
-                     "unknown expression dialect: %s", pszDialect);
-            return CE_Failure;
-        }
+        pszDialect = "muparser";
     }
-    else
+
+    poExpression = gdal::MathExpression::Create(pszExpression, pszDialect);
+
+    // cppcheck-suppress knownConditionTrueFalse
+    if (!poExpression)
     {
-        poExpression = std::make_unique<gdal::ExprtkExpression>(pszExpression);
+        return CE_Failure;
     }
 
     {
@@ -1686,7 +1675,11 @@ static CPLErr ExprPixelFunc(void **papoSources, int nSources, void *pData,
                                            &adfValuesForPixel[iSource++]);
         }
     }
-    poExpression->RegisterVector("BANDS", &adfValuesForPixel);
+    CPLString osExpression(pszExpression);
+    if (osExpression.find("BANDS") != std::string::npos)
+    {
+        poExpression->RegisterVector("BANDS", &adfValuesForPixel);
+    }
 
     double *padfResults =
         static_cast<double *>(CPLMalloc(nXSize * sizeof(double)));

frmts/vrt/vrtexpression.h

@@ -28,6 +28,9 @@ class MathExpression
   public:
     virtual ~MathExpression() = default;
 
+    static std::unique_ptr<MathExpression> Create(const char *pszExpression,
+                                                  const char *pszDialect);
+
     /**
     * Register a variable to be used in the expression.
     *
@@ -63,7 +66,8 @@ class MathExpression
      * the expression is evaluated.
      *
      * @return CE_None if the expression can be successfully parsed and all
-     *                 symbols have been registered, CE_Failure otherwise.
+     *                 symbols have been registe          vrtexpression_exprtk.cpp
+          vrtexpression_muparser.cppred, CE_Failure otherwise.
      *
      * @since 3.11
      */
@@ -92,6 +96,8 @@ class MathExpression
 
 /*! @cond Doxygen_Suppress */
 
+#if GDAL_VRT_ENABLE_EXPRTK
+
 /**
  * Class to support evaluation of an expression using the exprtk library.
  */
@@ -120,6 +126,10 @@ class ExprtkExpression : public MathExpression
     std::unique_ptr<Impl> m_pImpl;
 };
 
+#endif
+
+#if GDAL_VRT_ENABLE_MUPARSER
+
 /**
  * Class to support evaluation of an expression using the muparser library.
  */
@@ -148,6 +158,28 @@ class MuParserExpression : public MathExpression
     std::unique_ptr<Impl> m_pImpl;
 };
 
+#endif
+
+inline std::unique_ptr<MathExpression>
+MathExpression::Create(const char *pszExpression, const char *pszDialect)
+{
+#if GDAL_VRT_ENABLE_EXPRTK
+    if (EQUAL(pszDialect, "exprtk"))
+    {
+        return std::make_unique<gdal::ExprtkExpression>(pszExpression);
+    }
+#endif
+#if GDAL_VRT_ENABLE_MUPARSER
+    if (EQUAL(pszDialect, "muparser"))
+    {
+        return std::make_unique<gdal::MuParserExpression>(pszExpression);
+    }
+#endif
+    CPLError(CE_Failure, CPLE_IllegalArg, "Unknown expression dialect: %s",
+             pszDialect);
+    return nullptr;
+}
+
 /*! @endcond */
 
 }  // namespace gdal

frmts/vrt/vrtexpression.cpp → frmts/vrt/vrtexpression_exprtk.cpp

@@ -20,6 +20,7 @@
 #define exprtk_disable_rtl_io_file
 #define exprtk_disable_rtl_vecops
 #define exprtk_disable_string_capabilities
+#define exprtk_disable_advanced_features
 
 #if defined(__GNUC__)
 #pragma GCC diagnostic push

frmts/vrt/vrtprocesseddatasetfunctions.cpp

@@ -1491,25 +1491,6 @@ class ExpressionData
     {
     }
 
-    static std::unique_ptr<gdal::MathExpression>
-    CreateExpression(std::string_view osExpression, const char *pszDialect)
-    {
-        if (EQUAL(pszDialect, "exprtk"))
-        {
-            return std::make_unique<gdal::ExprtkExpression>(osExpression);
-        }
-        else if (EQUAL(pszDialect, "muparser"))
-        {
-            return std::make_unique<gdal::MuParserExpression>(osExpression);
-        }
-        else
-        {
-            CPLError(CE_Failure, CPLE_IllegalArg,
-                     "Unknown expression dialect: %s", pszDialect);
-            return nullptr;
-        }
-    }
-
     CPLErr Compile()
     {
         auto eErr = m_oNominalBatchEnv.Initialize(m_osExpression, m_osDialect,
@@ -1605,7 +1586,9 @@ class ExpressionData
         CPLErr Initialize(const CPLString &osExpression,
                           const CPLString &osDialect, int nBatchSize)
         {
-            m_poExpression = CreateExpression(osExpression, osDialect.c_str());
+            m_poExpression =
+                gdal::MathExpression::Create(osExpression, osDialect.c_str());
+            // cppcheck-suppress knownConditionTrueFalse
             if (m_poExpression == nullptr)
             {
                 return CE_Failure;
@@ -1676,6 +1659,10 @@ static CPLErr ExpressionInit(const char * /*pszFuncName*/, void * /*pUserData*/,
     }
 
     const char *pszDialect = CSLFetchNameValue(papszFunctionArgs, "dialect");
+    if (pszDialect == nullptr)
+    {
+        pszDialect = "muparser";
+    }
 
     const char *pszExpression =
         CSLFetchNameValue(papszFunctionArgs, "expression");