Implemented external "generate" function

* this function essentially provides the same functionality as FunctionTransform with the addition of directly committing the result to the filesystem
** this is needed if one wants to generate doctype-containing transformations from inside a transformation as "write-file" is not able to infer the doctype of a given xalan::XalanNode pointer
** this is a integral limitation of (at least) XSLT 1.0 as implemented in Apache Xalan
*** a document can of course only have a single document type
*** e.g. we can not include a doctype node in the result tree of FunctionTransform
* implemented test case for FunctionGenerate
* transformation "test.xsl" is shared between the FunctionTransform and FunctionGenerate test cases
* modified README.md accordingly

11 files changed, 186 insertions, 2 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9533c63..331aa2c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,6 +28,7 @@ set(
 	src/function/write_file.cc
 	src/function/read_directory.cc
 	src/function/transform.cc
+	src/function/generate.cc
 	src/function/external_text_formatter.cc
 	src/support/filesystem_context.cc
 	src/support/xalan_string.cc
diff --git a/README.md b/README.md
index 6531904..25b77e6 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,7 @@ Contrary to popular opinion I actually like XSLT as a content transformation lan
 - external `read-file` function for read-only access to both plain and xml files
 - external `read-directory` function for read-only directory traversal
 - external `transform` function for executing transformations inside transformations
+- external `generate` function for executing transformations and committing the result directly to the filesystem
 - external `external-text-formatter` function for executing text formatters and capturing their XML output
 - external `write-file` function for writing files
 
@@ -22,6 +23,7 @@ The `test` directory contains black-box test cases for every external function p
 - [`InputXSLT:read-file` (xml)](test/read_xml_file/transformation.xsl)
 - [`InputXSLT:read-directory`](test/read_directory/transformation.xsl)
 - [`InputXSLT:transform`](test/transform/transformation.xsl)
+- [`InputXSLT:generate`](test/generate/transformation.xsl)
 - [`InputXSLT:external-text-formatter`](test/external_text_formatter/transformation.xsl) (requires [markdown.pl](http://daringfireball.net/projects/markdown/))
 - [`InputXSLT:write-file`](test/write_file/transformation.xsl)
 
diff --git a/src/function/base.h b/src/function/base.h
index c3e1fb6..2d1e4c4 100644
--- a/src/function/base.h
+++ b/src/function/base.h
@@ -93,7 +93,7 @@ class FunctionBase : public xalan::Function {
 		template <std::size_t... Index>
 		inline xalan::XalanDocument* callConstructDocument(
 			const XObjectArgVectorType& parameters,
-			const xalan::Locator* locator,
+			const xalan::Locator*       locator,
 			Sequence<Index...>
 		) const {
 			XObjectValue valueGetter(
diff --git a/src/function/generate.cc b/src/function/generate.cc
new file mode 100644
index 0000000..4ece322
--- /dev/null
+++ b/src/function/generate.cc
@@ -0,0 +1,71 @@
+#include "generate.h"
+
+#include <xalanc/PlatformSupport/XalanOutputStreamPrintWriter.hpp>
+#include <xalanc/PlatformSupport/XalanStdOutputStream.hpp>
+#include <xalanc/XMLSupport/FormatterToXML.hpp>
+
+#include <boost/filesystem.hpp>
+#include <boost/filesystem/fstream.hpp>
+
+#include "transformer_facade.h"
+#include "support/xerces_string_guard.h"
+#include "support/dom/result_node_facade.h"
+#include "support/error/error_capacitor.h"
+
+namespace InputXSLT {
+
+DomDocumentCache::document_ptr FunctionGenerate::constructDocument(
+	xalan::XSLTInputSource  inputSource,
+	xalan::XSLTInputSource  transformationSource,
+	boost::filesystem::path targetPath
+) const {
+	DomDocumentCache::document_ptr domDocument(
+		DomDocumentCache::createDocument("content")
+	);
+
+	ResultNodeFacade result(domDocument.get(), "generation");
+	result.setAttribute("path", targetPath.string());
+
+	boost::filesystem::ofstream file(targetPath);
+
+	if ( file.is_open() ) {
+		TransformerFacade transformer(this->include_resolver_);
+
+		try {
+			xalan::XalanStdOutputStream         output(file);
+			xalan::XalanOutputStreamPrintWriter writer(output);
+			xalan::FormatterToXML               targetFormatter(writer);
+
+			targetFormatter.setDoIndent(true);
+
+			transformer.generate(
+				inputSource,
+				transformationSource,
+				targetFormatter
+			);
+
+			result.setAttribute("result", "success");
+		}
+		catch (const ErrorCapacitor::exception& exception) {
+			result.setAttribute("result", "error");
+
+			for ( auto&& error : *exception ) {
+				result.setValueNode("error", error);
+			}
+		}
+
+		WarningCapacitor::warning_cache_ptr warnings(
+			transformer.getCachedWarnings()
+		);
+
+		for ( auto&& warning : *warnings ) {
+			result.setValueNode("warning", warning);
+		}
+	} else {
+		result.setAttribute("result", "error");
+	}
+
+	return domDocument;
+}
+
+}
diff --git a/src/function/generate.h b/src/function/generate.h
new file mode 100644
index 0000000..43f5da1
--- /dev/null
+++ b/src/function/generate.h
@@ -0,0 +1,32 @@
+#ifndef INPUTXSLT_SRC_FUNCTION_GENERATE_H_
+#define INPUTXSLT_SRC_FUNCTION_GENERATE_H_
+
+#include <xalanc/XSLT/XSLTInputSource.hpp>
+
+#include "base.h"
+
+namespace InputXSLT {
+
+class FunctionGenerate : public FunctionBase<
+	FunctionGenerate,
+	xalan::XSLTInputSource,
+	xalan::XSLTInputSource,
+	boost::filesystem::path
+> {
+	public:
+		using FunctionBase::FunctionBase;
+
+	protected:
+		friend FunctionBase;
+
+		DomDocumentCache::document_ptr constructDocument(
+			xalan::XSLTInputSource,
+			xalan::XSLTInputSource,
+			boost::filesystem::path
+		) const;
+
+};
+
+}
+
+#endif  // INPUTXSLT_SRC_FUNCTION_GENERATE_H_
diff --git a/src/plattform_guard.cc b/src/plattform_guard.cc
index cc3c9c0..5d19e32 100644
--- a/src/plattform_guard.cc
+++ b/src/plattform_guard.cc
@@ -10,6 +10,7 @@
 #include "function/write_file.h"
 #include "function/read_directory.h"
 #include "function/transform.h"
+#include "function/generate.h"
 #include "function/external_text_formatter.h"
 
 namespace InputXSLT {
@@ -49,6 +50,12 @@ PlattformGuard::PlattformGuard(const std::vector<std::string>& path):
 
 	xalan::XalanTransformer::installExternalFunctionGlobal(
 		customNamespace,
+		xalan::XalanDOMString("generate"),
+		InputXSLT::FunctionGenerate(&this->include_resolver_)
+	);
+
+	xalan::XalanTransformer::installExternalFunctionGlobal(
+		customNamespace,
 		xalan::XalanDOMString("external-text-formatter"),
 		InputXSLT::FunctionExternalTextFormatter(&this->include_resolver_)
 	);
diff --git a/test/transform/test.xsl b/test/common/test.xsl
index a9f04a5..a9f04a5 100644
--- a/test/transform/test.xsl
+++ b/test/common/test.xsl
diff --git a/test/generate/reference.xml b/test/generate/reference.xml
new file mode 100644
index 0000000..1c702e8
--- /dev/null
+++ b/test/generate/reference.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<test_case>
+<input_entries>
+<entry>Hello 1</entry>
+<entry>Hello 2</entry>
+<entry>Hello 3</entry>
+<entry>Hello 4</entry>
+</input_entries>
+<parameter_value>42</parameter_value>
+</test_case>
diff --git a/test/generate/transformation.xsl b/test/generate/transformation.xsl
new file mode 100644
index 0000000..6e3d88b
--- /dev/null
+++ b/test/generate/transformation.xsl
@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsl:stylesheet
+	version="1.0"
+	xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+	xmlns:dyn="http://exslt.org/dynamic"
+	xmlns:xalan="http://xml.apache.org/xalan"
+	xmlns:InputXSLT="function.inputxslt.application"
+	exclude-result-prefixes="dyn xalan InputXSLT"
+>
+
+<xsl:import href="[testcase.xsl]"/>
+
+<xsl:template name="generator">
+	<xsl:param name="input"/>
+	<xsl:param name="transformation"/>
+	<xsl:param name="target"/>
+
+	<xsl:copy-of select="InputXSLT:generate(
+		$input,
+		string($transformation),
+		string($target)
+	)"/>
+</xsl:template>
+
+<xsl:template name="implementation">
+	<xsl:variable name="result">
+		<xsl:call-template name="generator">
+			<xsl:with-param name="input">
+				<test>
+					<entries>
+						<entry>Hello 1</entry>
+						<entry>Hello 2</entry>
+						<entry>Hello 3</entry>
+						<entry>Hello 4</entry>
+					</entries>
+					<parameter>
+						<test>21</test>
+					</parameter>
+				</test>
+			</xsl:with-param>
+			<xsl:with-param name="transformation">[test.xsl]</xsl:with-param>
+			<xsl:with-param name="target">test_actual.xml</xsl:with-param>
+		</xsl:call-template>
+	</xsl:variable>
+
+	<xsl:variable name="generation" select="xalan:nodeset($result)/generation"/>
+
+	<xsl:choose>
+		<xsl:when test="$generation/@result = 'success'">
+			<xsl:copy-of select="InputXSLT:read-file('test_actual.xml')/test_case/transform_test/*"/>
+		</xsl:when>
+		<xsl:otherwise>
+			<xsl:copy-of select="$generation/*"/>
+		</xsl:otherwise>
+	</xsl:choose>
+</xsl:template>
+
+</xsl:stylesheet>
diff --git a/test/read_directory/reference.xml b/test/read_directory/reference.xml
index 7d63a85..d2d9d1b 100644
--- a/test/read_directory/reference.xml
+++ b/test/read_directory/reference.xml
@@ -14,6 +14,9 @@
 <name>external_text_formatter</name>
 </item>
 <item type="directory">
+<name>generate</name>
+</item>
+<item type="directory">
 <name>read_directory</name>
 </item>
 <item type="directory">
diff --git a/test/transform/transformation.xsl b/test/transform/transformation.xsl
index 7cfb8f9..247a4c6 100644
--- a/test/transform/transformation.xsl
+++ b/test/transform/transformation.xsl
@@ -36,7 +36,7 @@
 					</parameter>
 				</test>
 			</xsl:with-param>
-			<xsl:with-param name="transformation">test.xsl</xsl:with-param>
+			<xsl:with-param name="transformation">[test.xsl]</xsl:with-param>
 		</xsl:call-template>
 	</xsl:variable>