HTMLEncoding.h

//  HTMLEncoding.h
//
//  Public domain. https://github.com/nolanw/HTMLReader

#import <Foundation/Foundation.h>

/// Tags a string encoding with a confidence that the parser can use to help determine how to decode bytes into a document.
typedef struct {
    NSStringEncoding encoding;
    enum {
        Tentative,
        Certain,
        Irrelevant
    } confidence;
} HTMLStringEncoding;

/**
    Returns a string encoding that likely encodes the data.
 
    @param contentType The value of the HTTP Content-Type header, if present.
 
    For more information, see https://html.spec.whatwg.org/multipage/syntax.html#determining-the-character-encoding
 */
extern HTMLStringEncoding DeterminedStringEncodingForData(NSData *data, NSString *contentType);

/// Returns the string encoding labeled according to the WHATWG Encoding Standard. Returns InvalidStringEncoding() if the label is unknown.
extern NSStringEncoding StringEncodingForLabel(NSString *label);

/// An invalid NSStringEncoding. Equal to CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingInvalidId).
extern NSStringEncoding InvalidStringEncoding(void);

/**
    Returns YES if encoding "is a single-byte or variable-length encoding in which the bytes 0x09, 0x0A, 0x0C, 0x0D, 0x20 - 0x22, 0x26, 0x27, 0x2C - 0x3F, 0x41 - 0x5A, and 0x61 - 0x7A, ignoring bytes that are the second and later bytes of multibyte sequences, all correspond to single-byte sequences that map to the same Unicode characters as those bytes in Windows-1252".
 
    For more information, see https://html.spec.whatwg.org/multipage/infrastructure.html#ascii-compatible-character-encoding
 */
extern BOOL IsASCIICompatibleEncoding(NSStringEncoding encoding);

/// Returns YES if encoding is UTF16-LE or UTF16-BE.
extern BOOL IsUTF16Encoding(NSStringEncoding encoding);