83 lines
3.0 KiB
Lua
83 lines
3.0 KiB
Lua
-- Copyright (c) 2018. tangzx(love.tangzx@qq.com)
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--
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-- Licensed under the Apache License, Version 2.0 (the "License"); you may not
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-- use this file except in compliance with the License. You may obtain a copy of
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-- the License at
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--
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-- http://www.apache.org/licenses/LICENSE-2.0
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--
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-- Unless required by applicable law or agreed to in writing, software
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-- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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-- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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-- License for the specific language governing permissions and limitations under
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-- the License.
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utf8 = {}
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---
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--- Receives zero or more integers, converts each one to its corresponding
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--- UTF-8 byte sequence and returns a string with the concatenation of all
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--- these sequences.
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---@return string
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function utf8.char(...) end
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---
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--- The pattern (a string, not a function) "`[\0-\x7F\xC2-\xF4][\x80-\xBF]*`",
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--- which matches exactly one UTF-8 byte sequence, assuming that the subject
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--- is a valid UTF-8 string.
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---@type string
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utf8.charpattern = ""
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---
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--- Returns values so that the construction
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--- > `for p, c in utf8.codes(s) do` *body* `end`
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--- will iterate over all characters in string `s`, with `p` being the position
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--- (in bytes) and `c` the code point of each character. It raises an error if
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--- it meets any invalid byte sequence.
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---@param s string
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---@return string
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function utf8.codes(s) end
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---
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--- Returns the codepoints (as integers) from all characters in `s` that start
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--- between byte position `i` and `j` (both included). The default for `i` is
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--- 1 and for `j` is `i`. It raises an error if it meets any invalid byte
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--- sequence.
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---@overload fun(s:string):number
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---@param s string
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---@param i number
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---@param j number
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---@return number
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function utf8.codepoint (s, i, j) end
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---
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--- Returns the number of UTF-8 characters in string `s` that start between
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--- positions `i` and `j` (both inclusive). The default for `i` is 1 and for
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--- `j` is -1. If it finds any invalid byte sequence, returns a false value
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--- plus the position of the first invalid byte.
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---@overload fun(s:string):number
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---@param s string
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---@param i number
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---@param j number
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---@return number
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function utf8.len(s, i, j) end
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---
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--- Returns the position (in bytes) where the encoding of the `n`-th character
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--- of `s` (counting from position `i`) starts. A negative `n` gets
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--- characters before position `i`. The default for `i` is 1 when `n` is
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--- non-negative and `#s + 1` otherwise, so that `utf8.offset(s, -n)` gets the
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--- offset of the `n`-th character from the end of the string. If the
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--- specified character is neither in the subject nor right after its end,
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--- the function returns nil. As a special case, when `n` is 0 the function
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--- returns the start of the encoding of the character that contains the `i`-th
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--- byte of `s`.
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---
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--- This function assumes that `s` is a valid UTF-8 string.
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---@overload fun(s:string):number
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---@param s string
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---@param n number
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---@param i number
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---@return number
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function utf8.offset (s, n, i) end
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