74 lines
2.1 KiB
Nim
74 lines
2.1 KiB
Nim
# SPDX-FileCopyrightText: 2021 ☭ Emery Hemingway
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# SPDX-License-Identifier: Unlicense
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## NPEG rules for Preserves.
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import npeg, npeg/lib/utf8
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when defined(nimHasUsed): {.used.}
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grammar "Preserves":
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Document <- Value * ws * !1
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Value <-
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(ws * (Record | Collection | Atom | Embedded | Compact)) |
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(ws * '@' * Value * Value) |
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(ws * ';' * @'\n' * Value)
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Collection <- Sequence | Dictionary | Set
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Atom <- Boolean | Float | Double | SignedInteger | String | ByteString | Symbol
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Record <- '<' * Value * *Value * ws * '>'
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Sequence <- '[' * ws * *(Value * ws) * ']'
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Dictionary <- '{' * ws * *(Value * ws * ':' * ws * Value * ws) * '}'
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Set <- "#{" * ws * *(Value * ws) * '}'
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Boolean <- "#f" | "#t"
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Float <- >flt * 'f'
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Double <- flt
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SignedInteger <- int
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nat <- '0' | (Digit-'0') * *Digit
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int <- ?'-' * nat
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frac <- '.' * +Digit
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exp <- 'e' * ?('-'|'+') * +Digit
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flt <- int * ((frac * exp) | frac | exp)
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String <- '"' * *(escaped | (utf8.any - '"')) * '"'
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ByteString <- charByteString | hexByteString | b64ByteString
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charByteString <- '#' * >('"' * >(*binchar) * '"')
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hexByteString <- "#x\"" * ws * >(*(Xdigit[2] * ws)) * '"'
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b64ByteString <- "#[" * ws * >(*(base64char * ws)) * ']'
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binchar <- binunescaped | (escape * (escaped | '"' | ('x' * Xdigit[2])))
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binunescaped <- {'\20'..'\21', '#'..'[', ']'..'~'}
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base64char <- {'A'..'Z', 'a'..'z', '0'..'9', '+', '/', '-', '_', '='}
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Symbol <- (symstart * *symcont) | ('|' * *symchar * '|')
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symstart <- Alpha | sympunct | symustart
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symcont <- Alpha | sympunct | symustart | symucont | Digit | '-'
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sympunct <- {'~', '!', '$', '%', '^', '&', '*', '?', '_', '=', '+', '/', '.'}
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symchar <- unescaped | '"' | (escape * (escaped | '|' | ('u' * Xdigit)))
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symustart <- utf8.any - {0..127}
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symucont <- utf8.any - {0..127}
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# TODO: exclude some unicode ranges
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Embedded <- "#!" * Value
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Compact <- "#=" * ws * ByteString
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unescaped <- utf8.any - escaped
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unicodeEscaped <- 'u' * Xdigit[4]
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escaped <- '\\' * ({'{', '"', '|', '\\', 'b', 'f', 'n', 'r', 't'} | unicodeEscaped)
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escape <- '\\'
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ws <- *(' ' | '\t' | '\r' | '\n' | ',')
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