90 lines
3.3 KiB
Plaintext
90 lines
3.3 KiB
Plaintext
# This is a file defining the BP grammar using BP syntax
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#
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# This is a complete definition of the grammar of BP grammar files, but it's
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# mainly intended to be used as a proof-of-concept, and a stress-test for BP.
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# The grammar files provided with BP are not otherwise intended to be full
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# language grammars.
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Grammar: __ *(Def [__`;])%__ __ [@error=(+(./\n) => "Could not parse this code")]
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Def: @name=id __ `: __ (
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@definition=extended-pat
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/ $$ @error=(=>"No definition for rule")
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/ @error=(..%\n>(`;/id_`:/$) => "Invalid definition: @0"))
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# This is used for command line arguments:
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String-pattern: ..%(\n / Nodent / Identifier-char / Identifier-start / Escape / `\ pat [`;])$$
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pat: simple-pat !(__("!~"/"~")) / suffixed-pat
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simple-pat: (Upto-and / Dot / Word-boundary/ String / Chars / Nodent
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/ Identifier-char / Identifier-start / Escape-range
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/ Escape / Repeat / Optional / No / After / Before / Capture / Empty-replacement
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/ Start-of-File / Start-of-Line / End-of-File / End-of-Line / Ref / parens)
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suffixed-pat: (
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Match-pat
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/ Not-match-pat
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)
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Match-pat: @first=(suffixed-pat / simple-pat)__"~"__@second=(pat / @error=(=>"Expected pattern after '~'"))
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Not-match-pat: @first=(suffixed-pat / simple-pat)__"!~"__@second=(pat / @error=(=>"Expected pattern after '!~'"))
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Dot: `. !`.
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String: (
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`" @s=.. (`" / $ @error=(=>"Expected closing quote here"))
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/ `' @s=.. (`' / $ @error=(=>"Expected closing quote here"))
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)
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Chars: `` @+(Char-range/Char) % `,
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Char-range: @low=. `- (@high=. / @error=(=>"Expected a second character to form a character range"))
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Char: (@s=. / @error=(=>"Expected a character following the '`'"))
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Escape-range: `\ @low=escape-sequence `- @high=escape-sequence
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Escape: `\ (@s=escape-sequence
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/ $ @error=(=>"Backslashes are used for escape sequences, not splitting lines")
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/ @error=(. *(Abc/`0-9) => "Invalid escape sequence: '@0'")
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)
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escape-sequence: (
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`n,t,r,e,b,a,v
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/ 1-3 `0-7
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/ `x 2 `0-9,a-f,A-F
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)
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No: `! (__@pat / @error=(=>"Expected a pattern after the exclamation mark"))
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Nodent: "\N"
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Word-boundary: `| / "\b"
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Identifier-char: "\i"
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Identifier-start: "\I"
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Upto-and: ".." [__(`%/`=)__@second=simple-pat] [__@first=simple-pat]
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Repeat: (
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@min=(=>'0') (`*=>"-") @max=(=>'∞')
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/ @min=int __ `- __ @max=int
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/ @min=(int / =>'1') __ (`+=>"-") @max=(=>'∞')
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/ @min=@max=int
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) __ @repeat-pat=pat [__`%__@sep=pat]
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Optional: `[ __ extended-pat (__`] / @error=(=>"Expected closing square bracket here"))
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After: `< __ pat
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Before: `> __ pat
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Capture: `@ [__ @capture-name=(id/`!) __ !"=>" `=] __ (@capture=pat / @error=(=>"Expected pattern to capture"))
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Replace: (
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@replace-pat=(Replace / Chain / pat) __ "=>" (__ @replacement=String / @error=(=>"Expected replacement string"))
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)
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Empty-replacement: (
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@replace-pat=(=>"''") "=>" (__ @replacement=String / @error=(=>"Expected replacement string"))
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)
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Ref: @name=id !(__`:)
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Start-of-File: "^^"
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Start-of-Line: "^"
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End-of-File: "$$"
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End-of-Line: "$"
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parens: `( __ extended-pat (__ `) / @error=(=>"Expected closing parenthesis here"))
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Chain: 2+@(pat !(__"=>") / Replace)%__
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Otherwise: 2+@(Replace / Chain / pat)%(__`/__)
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extended-pat: Otherwise / Replace / Chain / pat
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# Special-symbol rules:
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_: *(` / \t)
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__: *(` / \t / \r / \n / comment)
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id: "__" / "_" / `a-z,A-Z *`a-z,A-Z,0-9,-
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comment: `# .. $
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