initial commit, 4.5 stable

thirdparty/icu4c/common/unicode/appendable.h

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+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+*******************************************************************************
+*   Copyright (C) 2011-2012, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*******************************************************************************
+*   file name:  appendable.h
+*   encoding:   UTF-8
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2010dec07
+*   created by: Markus W. Scherer
+*/
+
+#ifndef __APPENDABLE_H__
+#define __APPENDABLE_H__
+
+/**
+ * \file
+ * \brief C++ API: Appendable class: Sink for Unicode code points and 16-bit code units (char16_ts).
+ */
+
+#include "unicode/utypes.h"
+
+#if U_SHOW_CPLUSPLUS_API
+
+#include "unicode/uobject.h"
+
+U_NAMESPACE_BEGIN
+
+class UnicodeString;
+
+/**
+ * Base class for objects to which Unicode characters and strings can be appended.
+ * Combines elements of Java Appendable and ICU4C ByteSink.
+ *
+ * This class can be used in APIs where it does not matter whether the actual destination is
+ * a UnicodeString, a char16_t[] array, a UnicodeSet, or any other object
+ * that receives and processes characters and/or strings.
+ *
+ * Implementation classes must implement at least appendCodeUnit(char16_t).
+ * The base class provides default implementations for the other methods.
+ *
+ * The methods do not take UErrorCode parameters.
+ * If an error occurs (e.g., out-of-memory),
+ * in addition to returning false from failing operations,
+ * the implementation must prevent unexpected behavior (e.g., crashes)
+ * from further calls and should make the error condition available separately
+ * (e.g., store a UErrorCode, make/keep a UnicodeString bogus).
+ * @stable ICU 4.8
+ */
+class U_COMMON_API Appendable : public UObject {
+public:
+    /**
+     * Destructor.
+     * @stable ICU 4.8
+     */
+    ~Appendable();
+
+    /**
+     * Appends a 16-bit code unit.
+     * @param c code unit
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool appendCodeUnit(char16_t c) = 0;
+
+    /**
+     * Appends a code point.
+     * The default implementation calls appendCodeUnit(char16_t) once or twice.
+     * @param c code point 0..0x10ffff
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool appendCodePoint(UChar32 c);
+
+    /**
+     * Appends a string.
+     * The default implementation calls appendCodeUnit(char16_t) for each code unit.
+     * @param s string, must not be nullptr if length!=0
+     * @param length string length, or -1 if NUL-terminated
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool appendString(const char16_t *s, int32_t length);
+
+    /**
+     * Tells the object that the caller is going to append roughly
+     * appendCapacity char16_ts. A subclass might use this to pre-allocate
+     * a larger buffer if necessary.
+     * The default implementation does nothing. (It always returns true.)
+     * @param appendCapacity estimated number of char16_ts that will be appended
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool reserveAppendCapacity(int32_t appendCapacity);
+
+    /**
+     * Returns a writable buffer for appending and writes the buffer's capacity to
+     * *resultCapacity. Guarantees *resultCapacity>=minCapacity.
+     * May return a pointer to the caller-owned scratch buffer which must have
+     * scratchCapacity>=minCapacity.
+     * The returned buffer is only valid until the next operation
+     * on this Appendable.
+     *
+     * After writing at most *resultCapacity char16_ts, call appendString() with the
+     * pointer returned from this function and the number of char16_ts written.
+     * Many appendString() implementations will avoid copying char16_ts if this function
+     * returned an internal buffer.
+     *
+     * Partial usage example:
+     * \code
+     *  int32_t capacity;
+     *  char16_t* buffer = app.getAppendBuffer(..., &capacity);
+     *  ... Write n char16_ts into buffer, with n <= capacity.
+     *  app.appendString(buffer, n);
+     * \endcode
+     * In many implementations, that call to append will avoid copying char16_ts.
+     *
+     * If the Appendable allocates or reallocates an internal buffer, it should use
+     * the desiredCapacityHint if appropriate.
+     * If a caller cannot provide a reasonable guess at the desired capacity,
+     * it should pass desiredCapacityHint=0.
+     *
+     * If a non-scratch buffer is returned, the caller may only pass
+     * a prefix to it to appendString().
+     * That is, it is not correct to pass an interior pointer to appendString().
+     *
+     * The default implementation always returns the scratch buffer.
+     *
+     * @param minCapacity required minimum capacity of the returned buffer;
+     *                    must be non-negative
+     * @param desiredCapacityHint desired capacity of the returned buffer;
+     *                            must be non-negative
+     * @param scratch default caller-owned buffer
+     * @param scratchCapacity capacity of the scratch buffer
+     * @param resultCapacity pointer to an integer which will be set to the
+     *                       capacity of the returned buffer
+     * @return a buffer with *resultCapacity>=minCapacity
+     * @stable ICU 4.8
+     */
+    virtual char16_t *getAppendBuffer(int32_t minCapacity,
+                                   int32_t desiredCapacityHint,
+                                   char16_t *scratch, int32_t scratchCapacity,
+                                   int32_t *resultCapacity);
+};
+
+/**
+ * An Appendable implementation which writes to a UnicodeString.
+ *
+ * This class is not intended for public subclassing.
+ * @stable ICU 4.8
+ */
+class U_COMMON_API UnicodeStringAppendable : public Appendable {
+public:
+    /**
+     * Aliases the UnicodeString (keeps its reference) for writing.
+     * @param s The UnicodeString to which this Appendable will write.
+     * @stable ICU 4.8
+     */
+    explicit UnicodeStringAppendable(UnicodeString &s) : str(s) {}
+
+    /**
+     * Destructor.
+     * @stable ICU 4.8
+     */
+    ~UnicodeStringAppendable();
+
+    /**
+     * Appends a 16-bit code unit to the string.
+     * @param c code unit
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool appendCodeUnit(char16_t c) override;
+
+    /**
+     * Appends a code point to the string.
+     * @param c code point 0..0x10ffff
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool appendCodePoint(UChar32 c) override;
+
+    /**
+     * Appends a string to the UnicodeString.
+     * @param s string, must not be nullptr if length!=0
+     * @param length string length, or -1 if NUL-terminated
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool appendString(const char16_t *s, int32_t length) override;
+
+    /**
+     * Tells the UnicodeString that the caller is going to append roughly
+     * appendCapacity char16_ts.
+     * @param appendCapacity estimated number of char16_ts that will be appended
+     * @return true if the operation succeeded
+     * @stable ICU 4.8
+     */
+    virtual UBool reserveAppendCapacity(int32_t appendCapacity) override;
+
+    /**
+     * Returns a writable buffer for appending and writes the buffer's capacity to
+     * *resultCapacity. Guarantees *resultCapacity>=minCapacity.
+     * May return a pointer to the caller-owned scratch buffer which must have
+     * scratchCapacity>=minCapacity.
+     * The returned buffer is only valid until the next write operation
+     * on the UnicodeString.
+     *
+     * For details see Appendable::getAppendBuffer().
+     *
+     * @param minCapacity required minimum capacity of the returned buffer;
+     *                    must be non-negative
+     * @param desiredCapacityHint desired capacity of the returned buffer;
+     *                            must be non-negative
+     * @param scratch default caller-owned buffer
+     * @param scratchCapacity capacity of the scratch buffer
+     * @param resultCapacity pointer to an integer which will be set to the
+     *                       capacity of the returned buffer
+     * @return a buffer with *resultCapacity>=minCapacity
+     * @stable ICU 4.8
+     */
+    virtual char16_t *getAppendBuffer(int32_t minCapacity,
+                                   int32_t desiredCapacityHint,
+                                   char16_t *scratch, int32_t scratchCapacity,
+                                   int32_t *resultCapacity) override;
+
+private:
+    UnicodeString &str;
+};
+
+U_NAMESPACE_END
+
+#endif /* U_SHOW_CPLUSPLUS_API */
+
+#endif  // __APPENDABLE_H__