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// © 2018 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
#ifndef __LOCALEBUILDER_H__
#define __LOCALEBUILDER_H__

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#include "unicode/locid.h"
#include "unicode/localematcher.h"
#include "unicode/stringpiece.h"
#include "unicode/uobject.h"

/**
 * \file
 * \brief C++ API: Builder API for Locale
 */

U_NAMESPACE_BEGIN
class CharString;

/**
 * <code>LocaleBuilder</code> is used to build instances of <code>Locale</code>
 * from values configured by the setters. Unlike the <code>Locale</code>
 * constructors, the <code>LocaleBuilder</code> checks if a value configured by a
 * setter satisfies the syntax requirements defined by the <code>Locale</code>
 * class. A <code>Locale</code> object created by a <code>LocaleBuilder</code> is
 * well-formed and can be transformed to a well-formed IETF BCP 47 language tag
 * without losing information.
 *
 * The following example shows how to create a <code>Locale</code> object
 * with the <code>LocaleBuilder</code>.
 * <blockquote>
 * <pre>
 * UErrorCode status = U_ZERO_ERROR;
 * Locale aLocale = LocaleBuilder()
 * .setLanguage("sr")
 * .setScript("Latn")
 * .setRegion("RS")
 * .build(status);
 * if (U_SUCCESS(status)) {
 * // ...
 * }
 * </pre>
 * </blockquote>
 *
 * LocaleBuilders can be reused; <code>clear()</code> resets all
 * fields to their default values.
 *
 * LocaleBuilder tracks errors in an internal UErrorCode. For all setters,
 * except setLanguageTag and setLocale, LocaleBuilder will return immediately
 * if the internal UErrorCode is in error state.
 * To reset internal state and error code, call clear method.
 * The setLanguageTag and setLocale method will first clear the internal
 * UErrorCode, then track the error of the validation of the input parameter
 * into the internal UErrorCode.
 *
 * @stable ICU 64
 */
class U_COMMON_API LocaleBuilder : public UObject {
public:
 /**
 * Constructs an empty LocaleBuilder. The default value of all
 * fields, extensions, and private use information is the
 * empty string.
 *
 * @stable ICU 64
 */
 LocaleBuilder();

/**
     * Destructor
     * @stable ICU 64
     */
    virtual ~LocaleBuilder();

/**
 * Resets the <code>LocaleBuilder</code> to match the provided
 * <code>locale</code>. Existing state is discarded.
 *
 * All fields of the locale must be well-formed.
 * This method clears the internal UErrorCode.
 *
 * @param locale the locale
 * @return This builder.
 *
 * @stable ICU 64
 */
 LocaleBuilder& setLocale(const Locale& locale);

/**
 * Resets the LocaleBuilder to match the provided IETF BCP 47 language tag.
 * Discards the existing state.
 * The empty string causes the builder to be reset, like {@link #clear}.
 * Legacy language tags (marked as “Type: grandfathered” in BCP 47)
 * are converted to their canonical form before being processed.
 * Otherwise, the <code>language tag</code> must be well-formed,
 * or else the build() method will later report an U_ILLEGAL_ARGUMENT_ERROR.
 *
 * This method clears the internal UErrorCode.
 *
 * @param tag the language tag, defined as IETF BCP 47 language tag.
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& setLanguageTag(StringPiece tag);

/**
 * Sets the language. If <code>language</code> is the empty string, the
 * language in this <code>LocaleBuilder</code> is removed. Otherwise, the
 * <code>language</code> must be well-formed, or else the build() method will
 * later report an U_ILLEGAL_ARGUMENT_ERROR.
 *
 * The syntax of language value is defined as
 * [unicode_language_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_language_subtag).
 *
 * @param language the language
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& setLanguage(StringPiece language);

/**
 * Sets the script. If <code>script</code> is the empty string, the script in
 * this <code>LocaleBuilder</code> is removed.
 * Otherwise, the <code>script</code> must be well-formed, or else the build()
 * method will later report an U_ILLEGAL_ARGUMENT_ERROR.
 *
 * The script value is a four-letter script code as
 * [unicode_script_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_script_subtag)
 * defined by ISO 15924
 *
 * @param script the script
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& setScript(StringPiece script);

/**
 * Sets the region. If region is the empty string, the region in this
 * <code>LocaleBuilder</code> is removed. Otherwise, the <code>region</code>
 * must be well-formed, or else the build() method will later report an
 * U_ILLEGAL_ARGUMENT_ERROR.
 *
 * The region value is defined by
 * [unicode_region_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_region_subtag)
 * as a two-letter ISO 3166 code or a three-digit UN M.49 area code.
 *
 * The region value in the <code>Locale</code> created by the
 * <code>LocaleBuilder</code> is always normalized to upper case.
 *
 * @param region the region
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& setRegion(StringPiece region);

/**
 * Sets the variant. If variant is the empty string, the variant in this
 * <code>LocaleBuilder</code> is removed. Otherwise, the <code>variant</code>
 * must be well-formed, or else the build() method will later report an
 * U_ILLEGAL_ARGUMENT_ERROR.
 *
 * Note: This method checks if <code>variant</code>
 * satisfies the
 * [unicode_variant_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_variant_subtag)
 * syntax requirements, and normalizes the value to lowercase letters. However,
 * the <code>Locale</code> class does not impose any syntactic
 * restriction on variant. To set an ill-formed variant, use a Locale constructor.
 * If there are multiple unicode_variant_subtag, the caller must concatenate
 * them with '-' as separator (ex: "foobar-fibar").
 *
 * @param variant the variant
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& setVariant(StringPiece variant);

/**
 * Sets the extension for the given key. If the value is the empty string,
 * the extension is removed. Otherwise, the <code>key</code> and
 * <code>value</code> must be well-formed, or else the build() method will
 * later report an U_ILLEGAL_ARGUMENT_ERROR.
 *
 * Note: The key ('u') is used for the Unicode locale extension.
 * Setting a value for this key replaces any existing Unicode locale key/type
 * pairs with those defined in the extension.
 *
 * Note: The key ('x') is used for the private use code. To be
 * well-formed, the value for this key needs only to have subtags of one to
 * eight alphanumeric characters, not two to eight as in the general case.
 *
 * @param key the extension key
 * @param value the extension value
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& setExtension(char key, StringPiece value);

/**
 * Sets the Unicode locale keyword type for the given key. If the type
 * StringPiece is constructed with a nullptr, the keyword is removed.
 * If the type is the empty string, the keyword is set without type subtags.
 * Otherwise, the key and type must be well-formed, or else the build()
 * method will later report an U_ILLEGAL_ARGUMENT_ERROR.
 *
 * Keys and types are converted to lower case.
 *
 * Note:Setting the 'u' extension via {@link #setExtension}
 * replaces all Unicode locale keywords with those defined in the
 * extension.
 *
 * @param key the Unicode locale key
 * @param type the Unicode locale type
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& setUnicodeLocaleKeyword(
 StringPiece key, StringPiece type);

/**
     * Adds a unicode locale attribute, if not already present, otherwise
     * has no effect.  The attribute must not be empty string and must be
     * well-formed or U_ILLEGAL_ARGUMENT_ERROR will be set to status
     * during the build() call.
     *
     * @param attribute the attribute
     * @return This builder.
     * @stable ICU 64
     */
    LocaleBuilder& addUnicodeLocaleAttribute(StringPiece attribute);

/**
 * Removes a unicode locale attribute, if present, otherwise has no
 * effect. The attribute must not be empty string and must be well-formed
 * or U_ILLEGAL_ARGUMENT_ERROR will be set to status during the build() call.
 *
 * Attribute comparison for removal is case-insensitive.
 *
 * @param attribute the attribute
 * @return This builder.
 * @stable ICU 64
 */
 LocaleBuilder& removeUnicodeLocaleAttribute(StringPiece attribute);

/**
 * Resets the builder to its initial, empty state.
 * This method clears the internal UErrorCode.
 *
 * @return this builder
 * @stable ICU 64
 */
 LocaleBuilder& clear();

/**
     * Resets the extensions to their initial, empty state.
     * Language, script, region and variant are unchanged.
     *
     * @return this builder
     * @stable ICU 64
     */
    LocaleBuilder& clearExtensions();

/**
 * Returns an instance of <code>Locale</code> created from the fields set
 * on this builder.
 * If any set methods or during the build() call require memory allocation
 * but fail U_MEMORY_ALLOCATION_ERROR will be set to status.
 * If any of the fields set by the setters are not well-formed, the status
 * will be set to U_ILLEGAL_ARGUMENT_ERROR. The state of the builder will
 * not change after the build() call and the caller is free to keep using
 * the same builder to build more locales.
 *
 * @return a new Locale
 * @stable ICU 64
 */
 Locale build(UErrorCode& status);

/**
     * Sets the UErrorCode if an error occurred while recording sets.
     * Preserves older error codes in the outErrorCode.
     * @param outErrorCode Set to an error code that occurred while setting subtags.
     *                  Unchanged if there is no such error or if outErrorCode
     *                  already contained an error.
     * @return true if U_FAILURE(outErrorCode)
     * @stable ICU 65
     */
    UBool copyErrorTo(UErrorCode &outErrorCode) const;

private:
    friend class LocaleMatcher::Result;

void copyExtensionsFrom(const Locale& src, UErrorCode& errorCode);

UErrorCode status_;
    char language_[9];
    char script_[5];
    char region_[4];
    CharString *variant_;  // Pointer not object so we need not #include internal charstr.h.
    icu::Locale *extensions_;  // Pointer not object. Storage for all other fields.

};

U_NAMESPACE_END

#endif /* U_SHOW_CPLUSPLUS_API */

#endif  // __LOCALEBUILDER_H__

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