USING: combinators kernel lazy-lists math math.parser
namespaces parser parser-combinators parser-combinators.simple
promises sequences strings ;
USING: continuations io prettyprint ;
IN: regexp

: 'any-char'
    "." token [ drop any-char-parser ] <@ ;

: 'escaped-char'
    "\\" token any-char-parser &> ;

: 'ordinary-char'
    [ "*+?|(){}" member? not ] satisfy ;

: 'char' 'escaped-char' 'ordinary-char' <|> ;

: 'string' 'char' <+> [ >string token ] <@ ;

: exactly-n ( parser n -- parser' )
    swap <repetition> and-parser construct-boa ;

: at-most-n ( parser n -- parser' )
    dup zero? [
        2drop epsilon
    ] [
        2dup exactly-n
        -rot 1- at-most-n <|>
    ] if ;

: at-least-n ( parser n -- parser' )
    dupd exactly-n swap <*> <&> ;

: from-m-to-n ( parser m n -- parser' )
    >r [ exactly-n ] 2keep r> swap - at-most-n <&> ;

DEFER: 'regexp'

TUPLE: group-result str ;

C: <group-result> group-result

: 'grouping'
    "(" token
    'regexp' [ [ <group-result> ] <@ ] <@
    ")" token <& &> ;

: 'term'
    'any-char'
    'string' <|>
    'grouping' <|>
    <+> [
        dup length 1 =
        [ first ] [ and-parser construct-boa ] if
    ] <@ ;

: 'interval'
    'term'
    "{" token
    'integer' <?> &>
    "," token <?> <:&:>
    'integer' <?> <:&:>
    "}" token <& <&> [
        first2 dup length {
            { 1 [ first exactly-n ] }
            { 2 [ first2 dup integer?
                    [ nip at-most-n ]
                    [ drop at-least-n ] if ] }
            { 3 [ first3 nip from-m-to-n ] }
        } case
    ] <@ ;

: 'character-range'
    any-char-parser "-" token <& any-char-parser &> ;

: 'character-class-inside'
    any-char-parser
    'character-range' <|> ;

: 'character-class-inclusive'
    "[" token
    'character-class-inside'
    "]" token ;

: 'character-class-exclusive'
    "[^" token
    'character-class-inside'
    "]" token ;

: 'character-class'
    'character-class-inclusive'
    'character-class-exclusive' <|> ;

: 'repetition'
    'term'
    [ "*+?" member? ] satisfy <&> [
        first2 {
            { CHAR: * [ <*> ] }
            { CHAR: + [ <+> ] }
            { CHAR: ? [ <?> ] }
        } case
    ] <@ ;

: 'simple' 'term' 'repetition' <|> 'interval' <|> ;

LAZY: 'union' ( -- parser )
    'simple'
    'simple' "|" token 'union' &> <&> [ first2 <|> ] <@
    <|> ;

LAZY: 'regexp' ( -- parser )
    'repetition' 'union' <|> ;

: <regexp> 'regexp' just parse-1 ;


GENERIC: >regexp ( obj -- parser )
M: string >regexp 'regexp' just parse-1 ;
M: object >regexp ;

: matches? ( string regexp -- ? ) >regexp just parse nil? not ;

: parse-regexp ( accum end -- accum )
    lexer get dup skip-blank [
        [ index* dup 1+ swap ] 2keep swapd subseq swap
    ] change-column  <regexp> parsed ;

: R/ CHAR: / parse-regexp ; parsing
: R| CHAR: | parse-regexp ; parsing
: R" CHAR: " parse-regexp ; parsing
: R' CHAR: ' parse-regexp ; parsing
: R` CHAR: ` parse-regexp ; parsing