Unify parsing of curly brackets in RML.

Include/RmlUi/Core/Factory.h

@@ -99,8 +99,8 @@ class RMLUICORE_API Factory
 	/// @return The instanced element, or nullptr if the instancing failed.
 	static ElementPtr InstanceElement(Element* parent, const String& instancer, const String& tag, const XMLAttributes& attributes);
 
-	/// Instances a single text element containing a string. The string is assumed to contain no RML markup, but will
-	/// be translated and therefore may have some introduced. In this case more than one element may be instanced.
+	/// Instances a text element containing a string.
+	/// More than one element may be instanced if the string contains RML or RML is introduced during translation.
 	/// @param[in] parent The element any instanced elements will be parented to.
 	/// @param[in] text The text to instance the element (or elements) from.
 	/// @return True if the string was parsed without error, false otherwise.

Samples/basic/databinding/data/databinding.rml

@@ -163,7 +163,7 @@ form h2
 	<img sprite="icon-invader" data-style-image-color="rating < 80 ? 'black' : 'green'"/>
 	<p>
 		For loop with data expressions:<br/>
-		<span style="padding-left: 1em;" data-for="i : list"> {{ i * 2 + (i > 10 ? ' wow!' | to_upper : '') }}</span>
+		<span style="padding-left: 1em;" data-for="i : list"> {{ i * 2 + (!(i < 10) ? ' wow!' | to_upper : '') }}</span>
 	</p>
 </panel>
 <tab>Invaders</tab>

Source/Core/BaseXMLParser.cpp

@@ -29,6 +29,7 @@
 #include "../../Include/RmlUi/Core/BaseXMLParser.h"
 #include "../../Include/RmlUi/Core/Profiling.h"
 #include "../../Include/RmlUi/Core/Stream.h"
+#include "XMLParseTools.h"
 #include <string.h>
 
 namespace Rml {
@@ -488,10 +489,12 @@ bool BaseXMLParser::FindString(const char* string, String& data, bool escape_bra
 
 		if(escape_brackets)
 		{
-			if (c == '{' && previous == '{')
-				in_brackets = true;
-			else if (c == '}' && previous == '}')
-				in_brackets = false;
+			const char* error_str = XMLParseTools::ParseDataBrackets(in_brackets, c, previous);
+			if (error_str)
+			{
+				Log::Message(Log::LT_WARNING, "XML parse error. %s", error_str);
+				return false;
+			}
 		}
 
 		if (c == string[index] && !in_brackets)

Source/Core/Factory.cpp

@@ -28,6 +28,7 @@
 
 #include "../../Include/RmlUi/Core/Factory.h"
 #include "../../Include/RmlUi/Core/StreamMemory.h"
+#include "../../Include/RmlUi/Core/SystemInterface.h"
 #include "../../Include/RmlUi/Core.h"
 
 #include "ContextInstancerDefault.h"
@@ -57,6 +58,7 @@
 #include "XMLNodeHandlerHead.h"
 #include "XMLNodeHandlerTemplate.h"
 #include "XMLParseTools.h"
+#include <algorithm>
 
 namespace Rml {
 namespace Core {
@@ -299,95 +301,50 @@ ElementPtr Factory::InstanceElement(Element* parent, const String& instancer_nam
 	return nullptr;
 }
 
-struct ElementTextTraits {
-	bool only_white_space = true;
-	bool has_xml = false;
-	bool has_curly_brackets = false;
-	const char* error_str = nullptr; // Is set if and only if a parse error occurred.
-};
-static ElementTextTraits ParseElementTextTraits(const String& text)
+// Instances a single text element containing a string.
+bool Factory::InstanceElementText(Element* parent, const String& in_text)
 {
-	ElementTextTraits result;
-
-	bool in_brackets = false;
-	char previous = 0;
-	for (const char c : text)
-	{
-		if (!StringUtilities::IsWhitespace(c))
-			result.only_white_space = false;
+	RMLUI_ASSERT(parent);
 
-		if (in_brackets)
-		{
-			if (c == '}' && previous == '}')
-				in_brackets = false;
-
-			else if (c == '{' && previous == '{')
-				result.error_str = "Nested double curly brackets are illegal.";
+	String text;
+	if (SystemInterface* system_interface = GetSystemInterface())
+		system_interface->TranslateString(text, in_text);
 
-			else if (previous == '}' && c != '}')
-				result.error_str = "Single closing curly bracket encountered, use double curly brackets to close data expression.";
+	// If this text node only contains white-space we don't want to construct it.
+	const bool only_white_space = std::all_of(text.begin(), text.end(), &StringUtilities::IsWhitespace);
+	if (only_white_space)
+		return true;
 
-			else if (previous == '/' && c == '>')
-				result.error_str = "Xml end node encountered inside double curly brackets.";
+	// See if we need to parse it as RML, and whether the text contains data expressions (curly brackets).
+	bool parse_as_rml = false;
+	bool has_data_expression = false;
 
-			else if (previous == '<' && c == '/')
-				result.error_str = "Xml end node encountered inside double curly brackets.";
-		}
-		else
+	bool inside_brackets = false;
+	char previous = 0;
+	for (const char c : text)
+	{
+		const char* error_str = XMLParseTools::ParseDataBrackets(inside_brackets, c, previous);
+		if (error_str)
 		{
-			if(c == '<')
-			{
-				result.has_xml = true;
-			}
-			else if (c == '{' && previous == '{')
-			{
-				in_brackets = true;
-				result.has_curly_brackets = true;
-			}
-			else if (c == '}' && previous == '}')
-			{
-				result.error_str = "Closing double curly brackets encountered outside data expression.";
-			}
+			Log::Message(Log::LT_WARNING, "Failed to instance text element '%s'. %s", text.c_str(), error_str);
+			return false;
 		}
 
-		if (result.error_str)
-			break;
+		if (inside_brackets)
+			has_data_expression = true;
+		else if (c == '<')
+			parse_as_rml = true;
 
 		previous = c;
 	}
 
-	return result;
-}
-
-// Instances a single text element containing a string.
-bool Factory::InstanceElementText(Element* parent, const String& text)
-{
-	RMLUI_ASSERT(parent);
-
-	String translated_data;
-	if (SystemInterface* system_interface = GetSystemInterface())
-		system_interface->TranslateString(translated_data, text);
-
-	// Look for XML tags and detect double curly brackets for data bindings.
-	ElementTextTraits traits = ParseElementTextTraits(text);
-
-	if (traits.error_str)
-	{
-		Log::Message(Log::LT_ERROR, "Parse error in text: %s  In element: %s", traits.error_str, parent->GetAddress().c_str());
-		return false;
-	}
-
-	// If this text node only contains white-space we don't want to construct it.
-	if (traits.only_white_space)
-		return true;
-
-	// If the text contains XML elements then run it through the XML parser again.
-	if (traits.has_xml)
+	// If the text contains RML elements then run it through the XML parser again.
+	if (parse_as_rml)
 	{
 		RMLUI_ZoneScopedNC("InstanceStream", 0xDC143C);
-		auto stream = std::make_unique<StreamMemory>(translated_data.size() + 32);
+		auto stream = std::make_unique<StreamMemory>(text.size() + 32);
 		stream->Write("<body>", 6);
-		stream->Write(translated_data);
+		stream->Write(text);
 		stream->Write("</body>", 7);
 		stream->Seek(0, SEEK_SET);
 
@@ -401,25 +358,25 @@ bool Factory::InstanceElementText(Element* parent, const String& text)
 		XMLAttributes attributes;
 
 		// If we have curly brackets in the text, we tag the element so that the appropriate data view (DataViewText) is constructed.
-		if(traits.has_curly_brackets)
+		if (has_data_expression)
 			attributes.emplace("data-text", Variant());
 
 		ElementPtr element = Factory::InstanceElement(parent, "#text", "#text", attributes);
 		if (!element)
 		{
-			Log::Message(Log::LT_ERROR, "Failed to instance text element '%s', instancer returned nullptr.", translated_data.c_str());
+			Log::Message(Log::LT_ERROR, "Failed to instance text element '%s', instancer returned nullptr.", text.c_str());
 			return false;
 		}
 
 		// Assign the element its text value.
 		ElementText* text_element = rmlui_dynamic_cast< ElementText* >(element.get());
 		if (!text_element)
 		{
-			Log::Message(Log::LT_ERROR, "Failed to instance text element '%s'. Found type '%s', was expecting a derivative of ElementText.", translated_data.c_str(), rmlui_type_name(*element));
+			Log::Message(Log::LT_ERROR, "Failed to instance text element '%s'. Found type '%s', was expecting a derivative of ElementText.", text.c_str(), rmlui_type_name(*element));
 			return false;
 		}
 
-		text_element->SetText(translated_data);
+		text_element->SetText(text);
 
 		// Add to active node.
 		parent->AppendChild(std::move(element));

Source/Core/XMLParseTools.cpp

@@ -154,5 +154,39 @@ Element* XMLParseTools::ParseTemplate(Element* element, const String& template_n
 	return parse_template->ParseTemplate(element);
 }
 
+const char* XMLParseTools::ParseDataBrackets(bool& inside_brackets, char c, char previous)
+{
+	if (inside_brackets)
+	{
+		if (c == '}' && previous == '}')
+			inside_brackets = false;
+
+		else if (c == '{' && previous == '{')
+			return "Nested double curly brackets are illegal.";
+
+		else if (previous == '}' && c != '}')
+			return "Single closing curly bracket encountered, use double curly brackets to close an expression.";
+
+		else if (previous == '/' && c == '>')
+			return "Closing double curly brackets not found, XML end node encountered first.";
+
+		else if (previous == '<' && c == '/')
+			return "Closing double curly brackets not found, XML end node encountered first.";
+	}
+	else
+	{
+		if (c == '{' && previous == '{')
+		{
+			inside_brackets = true;
+		}
+		else if (c == '}' && previous == '}')
+		{
+			return "Closing double curly brackets encountered outside an expression.";
+		}
+	}
+
+	return nullptr;
+}
+
 }
 }

Source/Core/XMLParseTools.h

@@ -61,6 +61,12 @@ class XMLParseTools
 	/// @param template_name Name of the template to apply, in TEMPLATE:ELEMENT_ID form
 	/// @returns Element to continue the parse from
 	static Element* ParseTemplate(Element* element, const String& template_name);
+
+    /// Determine the presence of data expression brackets inside XML data.
+    /// Call this for each iteration through the data string.
+    /// 'inside_brackets' should be initialized to false.
+    /// Returns nullptr on success, or an error string on failure.
+    static const char* ParseDataBrackets(bool& inside_brackets, char c, char previous);
 };
 
 }