bp.bp - bp

(92 lines)
   1 # This is a file defining the BP grammar using BP syntax
   2 #
   3 # This is a complete definition of the grammar of BP grammar files, but it's
   4 # mainly intended to be used as a proof-of-concept, and a stress-test for BP.
   5 # The grammar files provided with BP are not otherwise intended to be full
   6 # language grammars.
   7 
   8 Grammar: __ *(Def [__`;])%__ __ [@error=(+(./\n) => "Could not parse this code: @0")]
   9 Def: @name=id __ 1-2`: __ (
  10       @definition=extended-pat
  11     / $$ @error=(=>"No definition for rule")
  12     / @error=(..%\n>(`;/id_`:/$) => "Invalid definition: @0"))
  13 
  14 # This is used for command line arguments:
  15 String-pattern: ..%(\n / Nodent / Identifier-char / Identifier-start / Escape / `\ pat [`;])$$
  16 
  17 pat: simple-pat !(__("!~"/"~")) / suffixed-pat
  18 simple-pat: (Upto-and / Dot / Word-boundary/ String / Chars / Nodent / Curdent
  19     / Identifier-char / Identifier-start / Escape-range
  20     / Escape / Repeat / Optional / No / After / Before / Capture
  21     / Start-of-File / Start-of-Line / End-of-File / End-of-Line / Ref / parens)
  22 
  23 suffixed-pat: (
  24       Match-pat
  25     / Not-match-pat
  26 )
  27 
  28 Match-pat: @first=(suffixed-pat / simple-pat)__"~"__@second=(pat / @error=(=>"Expected pattern after '~'"))
  29 Not-match-pat: @first=(suffixed-pat / simple-pat)__"!~"__@second=(pat / @error=(=>"Expected pattern after '!~'"))
  30 
  31 Dot: `. !`.
  32 String: (
  33         `" @s=.. (`" / $ @error=(=>"Expected closing quote here"))
  34       / `' @s=.. (`' / $ @error=(=>"Expected closing quote here"))
  35     )
  36 Chars: `` @+(Char-range/Char) % `,
  37 Char-range: @low=. `- (@high=. / @error=(=>"Expected a second character to form a character range"))
  38 Char: (@s=. / @error=(=>"Expected a character following the '`'"))
  39 Escape-range: `\ @low=escape-sequence `- @high=escape-sequence
  40 Escape: `\ (@s=escape-sequence
  41     / $ @error=(=>"Backslashes are used for escape sequences, not splitting lines")
  42     / @error=(. *(Abc/`0-9) => "Invalid escape sequence: '@0'")
  43 )
  44 escape-sequence: (
  45        `n,t,r,e,b,a,v
  46       / 1-3 `0-7
  47       / `x 2 `0-9,a-f,A-F
  48     )
  49 No: `! (__@pat / @error=(=>"Expected a pattern after the exclamation mark"))
  50 Nodent: "\N"
  51 Curdent: "\C"
  52 Word-boundary: `| / "\b"
  53 Identifier-char: "\i"
  54 Identifier-start: "\I"
  55 Upto-and: ".." [__(`%/`=)__@second=simple-pat] [__@first=simple-pat]
  56 Repeat: (
  57         @min=(=>'0') (`*=>"-") @max=(=>'∞')
  58       / @min=int __ `- __ @max=int
  59       / @min=(int / =>'1') __ (`+=>"-") @max=(=>'∞')
  60       / @min=@max=int
  61     ) __ @repeat-pat=pat [__`%__@sep=pat]
  62 Optional: `[ __ extended-pat (__`] / @error=(=>"Expected closing square bracket here"))
  63 After: `< __ pat
  64 Before: `> __ pat
  65 Capture: `@ [__ @capture-name=(id/`!) __ !"=>" `=,:] __ (@capture=pat / @error=(=>"Expected pattern to capture"))
  66 Replace: (
  67       @replace-pat=[Chain-noreplace / pat] __ "=>" (__ @replacement=String / @error=(=>"Expected replacement string"))
  68     )
  69 Replace-chain: Replace-chain __ "=>" (__ @replacement=String / @error=(=>"Expected replacement string"))
  70 Empty-replacement: (
  71        (=>"EMPTY") @replace-pat=(=>"''") "=>" (__ @replacement=String / @error=(=>"Expected replacement string"))
  72     )
  73 Ref: @name=id !(__`:)
  74 Start-of-File: "^^"
  75 Start-of-Line: "^"
  76 End-of-File: "$$"
  77 End-of-Line: "$"
  78 
  79 parens: `( __ extended-pat (__ `) / @error=(=>"Expected closing parenthesis here"))
  80 
  81 Chain: @(Replace/pat) __ @(Chain/Replace/pat)
  82 Chain-noreplace: @pat __ @(Chain-noreplace/pat)
  83 Otherwise: 2+@(Chain / Replace / pat)%(__`/__)
  84 extended-pat: Otherwise / Chain / Replace / pat
  85 
  86 # Special-symbol rules:
  87 _:  *(`  / \t)
  88 __: *(`  / \t / \r / \n / comment)
  89 
  90 id: "__" / "_" / `a-z,A-Z *`a-z,A-Z,0-9,-
  91 
  92 comment: `# .. $