API/unicode

Unicode API

Because all strings pass through Java at some point it can be useful to handle them with Unicode support (since Java's internal string representation is UTF-8 encoded). In particular, screens display UTF-8 strings, meaning the related GPU functions expect UTF-8 strings. Also, keyboard input will generally be UTF-8 encoded, especially the clipboard.

However, keep in mind that while wide characters can be displayed, input and output of those is not fully supported in OpenOS's software (i.e. the shell, edit and Lua interpreter).

The following functions are provided to allow basic UTF-8 handling:

• unicode.char(value: number, ...): string

UTF-8 aware version of string.char. The values may be in the full UTF-8 range, not just ASCII.

• unicode.charWidth(value: string, ...): number

Returns the width of the first character given. For example, for シ it'll return 2, where a would return 1.

• unicode.isWide(value: string, ...): boolean

Returns if the width of the first character given is greater than 1. For example, for シ it'll return true, where a would return false.

• unicode.len(value: string): number

UTF-8 aware version of string.len. For example, for Ümläüt it'll return 6, where string.len would return 9.

• unicode.lower(value: string): string

UTF-8 aware version of string.lower.

• unicode.reverse(value: string): string

UTF-8 aware version of string.reverse. For example, for Ümläüt it'll return tüälmÜ, where string.reverse would return tälm.

• unicode.sub(value: string, i:number[, j:number]): string

UTF-8 aware version of string.sub.

• unicode.upper(value: string): string

UTF-8 aware version of string.upper.

• unicode.wlen(value: string): number

Returns the width of the entire string.

• unicode.wtrunc(value: string, count: number): string

Truncates the given string up to but not including count width. If there are not enough characters to match the wanted width, the function errors.

For example, these are used when files are opened in non-binary mode. The original string functions are used for files opened in binary mode.

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