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authorlouiz’ <louiz@louiz.org>2016-06-15 00:38:43 +0200
committerlouiz’ <louiz@louiz.org>2016-06-15 00:38:43 +0200
commit6235fb2d0326b18a9e013ae13dfb1fd0577ffd9f (patch)
tree7ded753bdaff3722ddf155c02981cd5dad289b03 /louloulibs
parent80d0c19c5a8d548a8c6019033bf574ff2be4c0ce (diff)
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Add get_next_codepoint_size
Diffstat (limited to 'louloulibs')
-rw-r--r--louloulibs/utils/encoding.cpp28
-rw-r--r--louloulibs/utils/encoding.hpp5
2 files changed, 21 insertions, 12 deletions
diff --git a/louloulibs/utils/encoding.cpp b/louloulibs/utils/encoding.cpp
index f738ce2..507f38a 100644
--- a/louloulibs/utils/encoding.cpp
+++ b/louloulibs/utils/encoding.cpp
@@ -23,6 +23,17 @@ namespace utils
/**
* Based on http://en.wikipedia.org/wiki/UTF-8#Description
*/
+ std::size_t get_next_codepoint_size(const unsigned char c)
+ {
+ if ((c & 0b11111000) == 0b11110000) // 4 bytes: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+ return 4;
+ else if ((c & 0b11110000) == 0b11100000) // 3 bytes: 1110xxx 10xxxxxx 10xxxxxx
+ return 3;
+ else if ((c & 0b11100000) == 0b11000000) // 2 bytes: 110xxxxx 10xxxxxx
+ return 2;
+ return 1; // 1 byte: 0xxxxxxx
+ }
+
bool is_valid_utf8(const char* s)
{
if (!s)
@@ -32,38 +43,31 @@ namespace utils
while (*str)
{
- // 4 bytes: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
- if ((str[0] & 0b11111000) == 0b11110000)
+ const auto codepoint_size = get_next_codepoint_size(str[0]);
+ if (codepoint_size == 4)
{
if (!str[1] || !str[2] || !str[3]
|| ((str[1] & 0b11000000) != 0b10000000)
|| ((str[2] & 0b11000000) != 0b10000000)
|| ((str[3] & 0b11000000) != 0b10000000))
return false;
- str += 4;
}
- // 3 bytes: 1110xxx 10xxxxxx 10xxxxxx
- else if ((str[0] & 0b11110000) == 0b11100000)
+ else if (codepoint_size == 3)
{
if (!str[1] || !str[2]
|| ((str[1] & 0b11000000) != 0b10000000)
|| ((str[2] & 0b11000000) != 0b10000000))
return false;
- str += 3;
}
- // 2 bytes: 110xxxxx 10xxxxxx
- else if (((str[0]) & 0b11100000) == 0b11000000)
+ else if (codepoint_size == 2)
{
if (!str[1] ||
((str[1] & 0b11000000) != 0b10000000))
return false;
- str += 2;
}
- // 1 byte: 0xxxxxxx
else if ((str[0] & 0b10000000) != 0)
return false;
- else
- str++;
+ str += codepoint_size;
}
return true;
}
diff --git a/louloulibs/utils/encoding.hpp b/louloulibs/utils/encoding.hpp
index 6b7ccd2..3f55055 100644
--- a/louloulibs/utils/encoding.hpp
+++ b/louloulibs/utils/encoding.hpp
@@ -6,6 +6,11 @@
namespace utils
{
/**
+ * Return the size, in bytes, of the next UTF-8 codepoint, based on
+ * the given char.
+ */
+ std::size_t get_next_codepoint_size(const unsigned char c);
+ /**
* Returns true if the given null-terminated string is valid utf-8.
*
* Based on http://en.wikipedia.org/wiki/UTF-8#Description