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Tamarin:Strings: Difference between revisions
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=== General === | === General === | ||
The new String class contains strings of variable width. A string can either be 8, 16, or even 32 bits (if 32-bit support is enabled). 8-bit strings contain the first 256 characters of the Unicode alphabet, often referred to as Latin-1. UTF-8 is not supported directly, but there is a string creation method that accepts an UTF-8 string, and a <tt>toUTF8String()</tt> method that returns a | The new String class contains strings of variable width. A string can either be 8, 16, or even 32 bits (if 32-bit support is enabled). 8-bit strings contain the first 256 characters of the Unicode alphabet, often referred to as Latin-1. UTF-8 is not supported directly, but there is a string creation method that accepts an UTF-8 string, and a <tt>toUTF8String()</tt> method that returns a NUL--terminated UTF-8 string. | ||
Strings do not have a data buffer of its own; instead, strings are created with the data directly following the instance data. Therefore, there is no ''new'' operator; instead, there are a number of static <tt>create()</tt> methods that create and return a string. | Strings do not have a data buffer of its own; instead, strings are created with the data directly following the instance data. Therefore, there is no ''new'' operator; instead, there are a number of static <tt>create()</tt> methods that create and return a string. | ||
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The data inside a string can be stored in different ways. A substring contains a reference to the master string, the data pointers points into the master string, and the length also fits into the master string. String containing static data have a pointer to that data. | The data inside a string can be stored in different ways. A substring contains a reference to the master string, the data pointers points into the master string, and the length also fits into the master string. String containing static data have a pointer to that data. | ||
Very important: Strings are never | Very important: Strings are never NUL-terminated, because they may contain a 0 as a valid character. It can very well happen that e.g. a string seems to contain the string "abcd", while the length is just 2, so the actual contents are "ab". | ||
=== Creation === | === Creation === | ||
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The only way to create a string is to use one of the <tt>create()</tt> methods: | The only way to create a string is to use one of the <tt>create()</tt> methods: | ||
static Stringp String::create (const AvmCore* core, const char* buffer, | static Stringp String::create(const AvmCore* core, const char* buffer, | ||
int32_t len, Width desiredWidth = kAuto, bool staticBuf = false); | int32_t len, Width desiredWidth = kAuto, bool staticBuf = false); | ||
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// create a 16-bit string with 1024 characters | // create a 16-bit string with 1024 characters | ||
String* myString = String::create (core, NULL, 1024, String::k16); | String* myString = String::create(core, NULL, 1024, String::k16); | ||
// Access the string data; this string is new and referenced nowhere, | // Access the string data; this string is new and referenced nowhere, | ||
// so this is a safe operation. | // so this is a safe operation. | ||
wchar* myChars = (wchar*) myString->getData(); | wchar* myChars = (wchar*) myString->getData(); | ||
To get a string of a known fixed width, use the <tt>getFixedWidthString()</tt> method. The method returns ''this'' if the string already has the requested width; otherwise, it returns a copy of the string with the given width. Note that if the requested width is too narrow because e.g. a 16-bit string contains characters >= 0x0100, and a 8-bit string is requested, the return value is ''NULL''. ALso, the returned string is not | To get a string of a known fixed width, use the <tt>getFixedWidthString()</tt> method. The method returns ''this'' if the string already has the requested width; otherwise, it returns a copy of the string with the given width. Note that if the requested width is too narrow because e.g. a 16-bit string contains characters >= 0x0100, and a 8-bit string is requested, the return value is ''NULL''. ALso, the returned string is not NUL-terminated. | ||
Stringp s = getSomeString(); | Stringp s = getSomeString(); | ||
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if (ns) { | if (ns) { | ||
name = ns; | name = ns; | ||
name = name->append (":"); | name = name->append(":"); | ||
if (xml->isAttr) | if (xml->isAttr) | ||
name = name->append ("@"); | name = name->append("@"); | ||
name = name->append (xml->getName()); | name = name->append(xml->getName()); | ||
} else { | } else { | ||
name = xml->getName(); | name = xml->getName(); | ||
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Stringp s = ...; | Stringp s = ...; | ||
if (s->matches ("<?xml", 5)) ... | if (s->matches("<?xml", 5)) ... | ||
else if (s->matches ("<![CDATA[", 9)) ... | else if (s->matches("<![CDATA[", 9)) ... | ||
if (s->indexOf (":")) < 0) ... | if (s->indexOf(":")) < 0) ... | ||