Split UTF functions from String8/16
Split out all the UTF-8/16/32 handling code from String8/16 to its own
file to allow better reuse of code.
Change-Id: If9ce63920edc75472c38da4adce0d13cda9ad2f7
diff --git a/include/utils/Unicode.h b/include/utils/Unicode.h
new file mode 100644
index 0000000..6afb291
--- /dev/null
+++ b/include/utils/Unicode.h
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2005 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_UNICODE_H
+#define ANDROID_UNICODE_H
+
+#include <sys/types.h>
+#include <stdint.h>
+
+extern "C" {
+
+typedef uint32_t char32_t;
+typedef uint16_t char16_t;
+
+// Standard string functions on char16_t strings.
+int strcmp16(const char16_t *, const char16_t *);
+int strncmp16(const char16_t *s1, const char16_t *s2, size_t n);
+size_t strlen16(const char16_t *);
+size_t strnlen16(const char16_t *, size_t);
+char16_t *strcpy16(char16_t *, const char16_t *);
+char16_t *strncpy16(char16_t *, const char16_t *, size_t);
+
+// Version of comparison that supports embedded nulls.
+// This is different than strncmp() because we don't stop
+// at a nul character and consider the strings to be different
+// if the lengths are different (thus we need to supply the
+// lengths of both strings). This can also be used when
+// your string is not nul-terminated as it will have the
+// equivalent result as strcmp16 (unlike strncmp16).
+int strzcmp16(const char16_t *s1, size_t n1, const char16_t *s2, size_t n2);
+
+// Version of strzcmp16 for comparing strings in different endianness.
+int strzcmp16_h_n(const char16_t *s1H, size_t n1, const char16_t *s2N, size_t n2);
+
+// Standard string functions on char32_t strings.
+size_t strlen32(const char32_t *);
+size_t strnlen32(const char32_t *, size_t);
+
+/**
+ * Measure the length of a UTF-32 string in UTF-8. If the string is invalid
+ * such as containing a surrogate character, -1 will be returned.
+ */
+ssize_t utf32_to_utf8_length(const char32_t *src, size_t src_len);
+
+/**
+ * Stores a UTF-8 string converted from "src" in "dst", if "dst_length" is not
+ * large enough to store the string, the part of the "src" string is stored
+ * into "dst" as much as possible. See the examples for more detail.
+ * Returns the size actually used for storing the string.
+ * dst" is not null-terminated when dst_len is fully used (like strncpy).
+ *
+ * Example 1
+ * "src" == \u3042\u3044 (\xE3\x81\x82\xE3\x81\x84)
+ * "src_len" == 2
+ * "dst_len" >= 7
+ * ->
+ * Returned value == 6
+ * "dst" becomes \xE3\x81\x82\xE3\x81\x84\0
+ * (note that "dst" is null-terminated)
+ *
+ * Example 2
+ * "src" == \u3042\u3044 (\xE3\x81\x82\xE3\x81\x84)
+ * "src_len" == 2
+ * "dst_len" == 5
+ * ->
+ * Returned value == 3
+ * "dst" becomes \xE3\x81\x82\0
+ * (note that "dst" is null-terminated, but \u3044 is not stored in "dst"
+ * since "dst" does not have enough size to store the character)
+ *
+ * Example 3
+ * "src" == \u3042\u3044 (\xE3\x81\x82\xE3\x81\x84)
+ * "src_len" == 2
+ * "dst_len" == 6
+ * ->
+ * Returned value == 6
+ * "dst" becomes \xE3\x81\x82\xE3\x81\x84
+ * (note that "dst" is NOT null-terminated, like strncpy)
+ */
+void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst);
+
+/**
+ * Returns the unicode value at "index".
+ * Returns -1 when the index is invalid (equals to or more than "src_len").
+ * If returned value is positive, it is able to be converted to char32_t, which
+ * is unsigned. Then, if "next_index" is not NULL, the next index to be used is
+ * stored in "next_index". "next_index" can be NULL.
+ */
+int32_t utf32_from_utf8_at(const char *src, size_t src_len, size_t index, size_t *next_index);
+
+
+/**
+ * Returns the UTF-8 length of UTF-16 string "src".
+ */
+ssize_t utf16_to_utf8_length(const char16_t *src, size_t src_len);
+
+/**
+ * Converts a UTF-16 string to UTF-8. The destination buffer must be large
+ * enough to fit the UTF-16 as measured by utf16_to_utf8_length with an added
+ * NULL terminator.
+ */
+void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst);
+
+/**
+ * Returns the length of "src" when "src" is valid UTF-8 string.
+ * Returns 0 if src is NULL or 0-length string. Returns -1 when the source
+ * is an invalid string.
+ *
+ * This function should be used to determine whether "src" is valid UTF-8
+ * characters with valid unicode codepoints. "src" must be null-terminated.
+ *
+ * If you are going to use other utf8_to_... functions defined in this header
+ * with string which may not be valid UTF-8 with valid codepoint (form 0 to
+ * 0x10FFFF), you should use this function before calling others, since the
+ * other functions do not check whether the string is valid UTF-8 or not.
+ *
+ * If you do not care whether "src" is valid UTF-8 or not, you should use
+ * strlen() as usual, which should be much faster.
+ */
+ssize_t utf8_length(const char *src);
+
+/**
+ * Measure the length of a UTF-32 string.
+ */
+size_t utf8_to_utf32_length(const char *src, size_t src_len);
+
+/**
+ * Stores a UTF-32 string converted from "src" in "dst". "dst" must be large
+ * enough to store the entire converted string as measured by
+ * utf8_to_utf32_length plus space for a NULL terminator.
+ */
+void utf8_to_utf32(const char* src, size_t src_len, char32_t* dst);
+
+/**
+ * Returns the UTF-16 length of UTF-8 string "src".
+ */
+ssize_t utf8_to_utf16_length(const uint8_t* src, size_t srcLen);
+
+/**
+ * Convert UTF-8 to UTF-16 including surrogate pairs. The destination buffer
+ * must be large enough to hold the result as measured by utf8_to_utf16_length
+ * plus an added NULL terminator.
+ */
+void utf8_to_utf16(const uint8_t* src, size_t srcLen, char16_t* dst);
+
+}
+
+#endif