1 files changed, 272 insertions, 0 deletions
diff --git a/intl/icu/source/i18n/formatted_string_builder.h b/intl/icu/source/i18n/formatted_string_builder.h
new file mode 100644
index 0000000000..32e0900ae2
--- /dev/null
+++ b/intl/icu/source/i18n/formatted_string_builder.h
@@ -0,0 +1,272 @@
+// © 2017 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_FORMATTING
+#ifndef __NUMBER_STRINGBUILDER_H__
+#define __NUMBER_STRINGBUILDER_H__
+
+
+#include <cstdint>
+#include <type_traits>
+
+#include "cstring.h"
+#include "uassert.h"
+#include "fphdlimp.h"
+
+U_NAMESPACE_BEGIN
+
+class FormattedValueStringBuilderImpl;
+
+/**
+ * A StringBuilder optimized for formatting. It implements the following key
+ * features beyond a UnicodeString:
+ *
+ * <ol>
+ * <li>Efficient prepend as well as append.
+ * <li>Keeps track of Fields in an efficient manner.
+ * </ol>
+ *
+ * See also FormattedValueStringBuilderImpl.
+ *
+ * @author sffc (Shane Carr)
+ */
+class U_I18N_API FormattedStringBuilder : public UMemory {
+  private:
+    static const int32_t DEFAULT_CAPACITY = 40;
+
+    template<typename T>
+    union ValueOrHeapArray {
+        T value[DEFAULT_CAPACITY];
+        struct {
+            T *ptr;
+            int32_t capacity;
+        } heap;
+    };
+
+  public:
+    FormattedStringBuilder();
+
+    ~FormattedStringBuilder();
+
+    FormattedStringBuilder(const FormattedStringBuilder &other);
+
+    // Convention: bottom 4 bits for field, top 4 bits for field category.
+    // Field category 0 implies the number category so that the number field
+    // literals can be directly passed as a Field type.
+    // Exported as U_I18N_API so it can be used by other exports on Windows.
+    struct U_I18N_API Field {
+        uint8_t bits;
+
+        Field() = default;
+        constexpr Field(uint8_t category, uint8_t field);
+
+        inline UFieldCategory getCategory() const;
+        inline int32_t getField() const;
+        inline bool isNumeric() const;
+        inline bool isUndefined() const;
+        inline bool operator==(const Field& other) const;
+        inline bool operator!=(const Field& other) const;
+    };
+
+    FormattedStringBuilder &operator=(const FormattedStringBuilder &other);
+
+    int32_t length() const;
+
+    int32_t codePointCount() const;
+
+    inline char16_t charAt(int32_t index) const {
+        U_ASSERT(index >= 0);
+        U_ASSERT(index < fLength);
+        return getCharPtr()[fZero + index];
+    }
+
+    inline Field fieldAt(int32_t index) const {
+        U_ASSERT(index >= 0);
+        U_ASSERT(index < fLength);
+        return getFieldPtr()[fZero + index];
+    }
+
+    UChar32 getFirstCodePoint() const;
+
+    UChar32 getLastCodePoint() const;
+
+    UChar32 codePointAt(int32_t index) const;
+
+    UChar32 codePointBefore(int32_t index) const;
+
+    FormattedStringBuilder &clear();
+
+    /** Appends a UTF-16 code unit. */
+    inline int32_t appendChar16(char16_t codeUnit, Field field, UErrorCode& status) {
+        // appendCodePoint handles both code units and code points.
+        return insertCodePoint(fLength, codeUnit, field, status);
+    }
+
+    /** Inserts a UTF-16 code unit. Note: insert at index 0 is very efficient. */
+    inline int32_t insertChar16(int32_t index, char16_t codeUnit, Field field, UErrorCode& status) {
+        // insertCodePoint handles both code units and code points.
+        return insertCodePoint(index, codeUnit, field, status);
+    }
+
+    /** Appends a Unicode code point. */
+    inline int32_t appendCodePoint(UChar32 codePoint, Field field, UErrorCode &status) {
+        return insertCodePoint(fLength, codePoint, field, status);
+    }
+
+    /** Inserts a Unicode code point. Note: insert at index 0 is very efficient. */
+    int32_t insertCodePoint(int32_t index, UChar32 codePoint, Field field, UErrorCode &status);
+
+    /** Appends a string. */
+    inline int32_t append(const UnicodeString &unistr, Field field, UErrorCode &status) {
+        return insert(fLength, unistr, field, status);
+    }
+
+    /** Inserts a string. Note: insert at index 0 is very efficient. */
+    int32_t insert(int32_t index, const UnicodeString &unistr, Field field, UErrorCode &status);
+
+    /** Inserts a substring. Note: insert at index 0 is very efficient.
+     *
+     * @param start Start index of the substring of unistr to be inserted.
+     * @param end End index of the substring of unistr to be inserted (exclusive).
+     */
+    int32_t insert(int32_t index, const UnicodeString &unistr, int32_t start, int32_t end, Field field,
+                   UErrorCode &status);
+
+    /** Deletes a substring and then inserts a string at that same position.
+     * Similar to JavaScript Array.prototype.splice().
+     *
+     * @param startThis Start of the span to delete.
+     * @param endThis End of the span to delete (exclusive).
+     * @param unistr The string to insert at the deletion position.
+     * @param startOther Start index of the substring of unistr to be inserted.
+     * @param endOther End index of the substring of unistr to be inserted (exclusive).
+     */
+    int32_t splice(int32_t startThis, int32_t endThis,  const UnicodeString &unistr,
+                   int32_t startOther, int32_t endOther, Field field, UErrorCode& status);
+
+    /** Appends a formatted string. */
+    int32_t append(const FormattedStringBuilder &other, UErrorCode &status);
+
+    /** Inserts a formatted string. Note: insert at index 0 is very efficient. */
+    int32_t insert(int32_t index, const FormattedStringBuilder &other, UErrorCode &status);
+
+    /**
+     * Ensures that the string buffer contains a NUL terminator. The NUL terminator does
+     * not count toward the string length. Any further changes to the string (insert or
+     * append) may invalidate the NUL terminator.
+     *
+     * You should call this method after the formatted string is completely built if you
+     * plan to return a pointer to the string from a C API.
+     */
+    void writeTerminator(UErrorCode& status);
+
+    /**
+     * Gets a "safe" UnicodeString that can be used even after the FormattedStringBuilder is destructed.
+     */
+    UnicodeString toUnicodeString() const;
+
+    /**
+     * Gets an "unsafe" UnicodeString that is valid only as long as the FormattedStringBuilder is alive and
+     * unchanged. Slightly faster than toUnicodeString().
+     */
+    const UnicodeString toTempUnicodeString() const;
+
+    UnicodeString toDebugString() const;
+
+    const char16_t *chars() const;
+
+    bool contentEquals(const FormattedStringBuilder &other) const;
+
+    bool containsField(Field field) const;
+
+  private:
+    bool fUsingHeap = false;
+    ValueOrHeapArray<char16_t> fChars;
+    ValueOrHeapArray<Field> fFields;
+    int32_t fZero = DEFAULT_CAPACITY / 2;
+    int32_t fLength = 0;
+
+    inline char16_t *getCharPtr() {
+        return fUsingHeap ? fChars.heap.ptr : fChars.value;
+    }
+
+    inline const char16_t *getCharPtr() const {
+        return fUsingHeap ? fChars.heap.ptr : fChars.value;
+    }
+
+    inline Field *getFieldPtr() {
+        return fUsingHeap ? fFields.heap.ptr : fFields.value;
+    }
+
+    inline const Field *getFieldPtr() const {
+        return fUsingHeap ? fFields.heap.ptr : fFields.value;
+    }
+
+    inline int32_t getCapacity() const {
+        return fUsingHeap ? fChars.heap.capacity : DEFAULT_CAPACITY;
+    }
+
+    int32_t prepareForInsert(int32_t index, int32_t count, UErrorCode &status);
+
+    int32_t prepareForInsertHelper(int32_t index, int32_t count, UErrorCode &status);
+
+    int32_t remove(int32_t index, int32_t count);
+
+    friend class FormattedValueStringBuilderImpl;
+};
+
+static_assert(
+    // std::is_pod<> is deprecated.
+    std::is_standard_layout<FormattedStringBuilder::Field>::value &&
+        std::is_trivial<FormattedStringBuilder::Field>::value,
+    "Field should be a POD type for efficient initialization");
+
+constexpr FormattedStringBuilder::Field::Field(uint8_t category, uint8_t field)
+    : bits((
+        U_ASSERT(category <= 0xf),
+        U_ASSERT(field <= 0xf),
+        static_cast<uint8_t>((category << 4) | field)
+    )) {}
+
+/**
+ * Internal constant for the undefined field for use in FormattedStringBuilder.
+ */
+constexpr FormattedStringBuilder::Field kUndefinedField = {UFIELD_CATEGORY_UNDEFINED, 0};
+
+/**
+ * Internal field to signal "numeric" when fields are not supported in NumberFormat.
+ */
+constexpr FormattedStringBuilder::Field kGeneralNumericField = {UFIELD_CATEGORY_UNDEFINED, 1};
+
+inline UFieldCategory FormattedStringBuilder::Field::getCategory() const {
+    return static_cast<UFieldCategory>(bits >> 4);
+}
+
+inline int32_t FormattedStringBuilder::Field::getField() const {
+    return bits & 0xf;
+}
+
+inline bool FormattedStringBuilder::Field::isNumeric() const {
+    return getCategory() == UFIELD_CATEGORY_NUMBER || *this == kGeneralNumericField;
+}
+
+inline bool FormattedStringBuilder::Field::isUndefined() const {
+    return getCategory() == UFIELD_CATEGORY_UNDEFINED;
+}
+
+inline bool FormattedStringBuilder::Field::operator==(const Field& other) const {
+    return bits == other.bits;
+}
+
+inline bool FormattedStringBuilder::Field::operator!=(const Field& other) const {
+    return bits != other.bits;
+}
+
+U_NAMESPACE_END
+
+
+#endif //__NUMBER_STRINGBUILDER_H__
+
+#endif /* #if !UCONFIG_NO_FORMATTING */