1 files changed, 97 insertions, 0 deletions
diff --git a/src/mbgl/text/tagged_string.hpp b/src/mbgl/text/tagged_string.hpp
new file mode 100644
index 0000000000..476c2225f0
--- /dev/null
+++ b/src/mbgl/text/tagged_string.hpp
@@ -0,0 +1,97 @@
+#pragma once
+
+#include <mbgl/text/glyph.hpp>
+#include <mbgl/text/bidi.hpp>
+
+namespace mbgl {
+
+struct SectionOptions {
+    SectionOptions(double scale_, FontStackHash fontStackHash_)
+        : scale(scale_), fontStackHash(fontStackHash_)
+    {}
+    
+    double scale;
+    FontStackHash fontStackHash;
+};
+
+/**
+ * A TaggedString is the shaping-code counterpart of the Formatted type
+ * Whereas Formatted matches the logical structure of a 'format' expression,
+ * a TaggedString represents the same data at a per-character level so that
+ * character-rearranging operations (e.g. BiDi) preserve formatting.
+ * Text is represented as:
+ * - A string of characters
+ * - A matching array of indices, pointing to:
+ * - An array of SectionsOptions, representing the evaluated formatting
+ *    options of the original sections.
+ *
+ * Once the guts of a TaggedString have been re-arranged by BiDi, you can
+ * iterate over the contents in order, using getCharCodeAt and getSection
+ * to get the formatting options for each character in turn.
+ */
+struct TaggedString {
+    TaggedString() = default;
+
+    TaggedString(std::u16string text_, SectionOptions options)
+        : styledText(std::move(text_),
+                     std::vector<uint8_t>(text_.size(), 0)) {
+        sections.push_back(std::move(options));
+    }
+    
+    TaggedString(StyledText styledText_, std::vector<SectionOptions> sections_)
+        : styledText(std::move(styledText_))
+        , sections(std::move(sections_)) {
+    }
+
+    std::size_t length() const {
+        return styledText.first.length();
+    }
+    
+    std::size_t sectionCount() const {
+        return sections.size();
+    }
+    
+    bool empty() const {
+        return styledText.first.empty();
+    }
+    
+    const SectionOptions& getSection(std::size_t index) const {
+        return sections.at(styledText.second.at(index));
+    }
+    
+    char16_t getCharCodeAt(std::size_t index) const {
+        return styledText.first[index];
+    }
+    
+    const std::u16string& rawText() const {
+        return styledText.first;
+    }
+    
+    const StyledText& getStyledText() const {
+        return styledText;
+    }
+    
+    void addSection(const std::u16string& text, double scale, FontStackHash fontStack);
+    const SectionOptions& sectionAt(std::size_t index) const {
+        return sections.at(index);
+    }
+    
+    const std::vector<SectionOptions>& getSections() const {
+        return sections;
+    }
+    
+    uint8_t getSectionIndex(std::size_t characterIndex) const {
+        return styledText.second.at(characterIndex);
+    }
+    
+    double getMaxScale() const;
+    void trim();
+    
+    void verticalizePunctuation();
+   
+private:
+    StyledText styledText;
+    std::vector<SectionOptions> sections;
+};
+
+} // namespace mbgl