93 lines
3.6 KiB
Plaintext
93 lines
3.6 KiB
Plaintext
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_title: Strings
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_section: Strings
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Tra la la
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_subsection: Bytes32String @<bytes32-string>
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A string in Solidity is length prefixed with its 256-bit (32 byte)
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length, which means that even short strings require 2 words (64 bytes)
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of storage.
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In many cases, we deal with short strings, so instead of prefixing
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the string with its length, we can null-terminate it and fit it in a
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single word (32 bytes). Since we need only a single byte for the
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null termination, we can store strings up to 31 bytes long in a
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word.
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_definition: **Note:**
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Strings that are 31 __//bytes//__ long may contain fewer than 31 __//characters//__,
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since UTF-8 requires multiple bytes to encode international characters.
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_property: utils.parseBytes32String(aBytesLike) => string
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Returns the decoded string represented by the ``Bytes32`` encoded data.
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_property: utils.formatBytes32String(text) => string
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Returns a ``bytes32`` string representation of //text//. If the
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length of //text// exceeds 31 bytes, it will throw an error.
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_subsection: UTF-8 Strings @<utf8-string>
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_property: utils.toUtf8Bytes(text [ , form = current ] ) => Uint8Array
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Returns the UTF-8 bytes of //text//, optionally normalizing it using the
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[[unicode-normalization-form]] //form//.
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_property: utils.toUtf8CodePoints(aBytesLike [ , form = current ] ) => Array<number>
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Returns the Array of codepoints of //aBytesLike//, optionally normalizing it using the
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[[unicode-normalization-form]] //form//.
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**Note:** This function correctly splits each user-perceived character into
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its codepoint, accounting for surrogate pairs. This should not be confused with
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``string.split("")``, which destroys surrogate pairs, spliting between each UTF-16
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codeunit instead.
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_property: utils.toUtf8String(aBytesLike [ , ignoreErrors = false ] ) => string
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Returns the string represented by the UTF-8 bytes of //aBytesLike//. This will
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throw an error for invalid surrogates, overlong sequences or other UTF-8 issues,
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unless //ignoreErrors// is specified.
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_heading: UnicodeNormalizationForm @<unicode-normalization-form>
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There are several [commonly used forms](https://en.wikipedia.org/wiki/Unicode_equivalence)
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when normalizing UTF-8 data, which allow strings to be compared or hashed in a stable
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way.
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_property: utils.UnicodeNormalizationForm.current
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Maintain the current normalization form.
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_property: utils.UnicodeNormalizationForm.NFC
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The Composed Normalization Form. This form uses single codepoints
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which represent the fully composed character.
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For example, the **é** is a single codepoint, ``0x00e9``.
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_property: utils.UnicodeNormalizationForm.NFD
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The Decomposed Normalization Form. This form uses multiple codepoints
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(when necessary) to compose a character.
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For example, the **é**
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is made up of two codepoints, ``"0x0065"`` (which is the letter ``"e"``)
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and ``"0x0301"`` which is a special diacritic UTF-8 codepoint which
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indicates the previous character should have an acute accent.
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_property: utils.UnicodeNormalizationForm.NFKC
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The Composed Normalization Form with Canonical Equivalence. The Canonical
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representation folds characters which have the same syntactic representation
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but different semantic meaning.
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For example, the Roman Numeral **I**, which has a UTF-8
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codepoint ``"0x2160"``, is folded into the capital letter I, ``"0x0049"``.
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_property: utils.UnicodeNormalizationForm.NFKD
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The Decomposed Normalization Form with Canonical Equivalence.
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See NFKC for more an example.
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_definition: **Note:**
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Only certain specified characters are folded in Canonical Equivalence, and thus
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it should not be considered a method to acheive //any// level of security from
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[homoglyph attacks](https://en.wikipedia.org/wiki/IDN_homograph_attack).
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