On Wed, Jul 4, 2012 at 12:05 PM, Alan Manuel Gloria <[email protected]> wrote: > The parser below has the following positions on the recent discussions > (as the discussions are not yet final at this writing, any position > below is not final): > > 1. "any expression can be postfixed with () [] {}" - accept this proposal > 2. ". as indentation whitespace LAWLZ TROLL3D U" - reject this proposal > 3. "GROUP / SPLICE / ENLIST semantics and syntax" - merge GROUP and > SPLICE meanings, use "\" for SPLICE, reject current SPLICE rule 1 > (SPLICE-at-the-eol), accept current SPLICE rules 2 (SPLICE-inline) and > 3 (SPLICE-at-the-start), reject ENLIST. > 4. Err this is the parser spec > 5. "QUOTE WHITESPACE as abbreviation for quote symbol" - reject this proposal > 6. "empty lines as expression delimiter" - disallow empty lines > inside top-level expressions, allow comment lines of any indentation > inside top-level expressions. > 7. "top-level expression not at left edge" - DISABLE indentation > processing for next expression. > > > any-space -> SPACE | TAB | VTAB | FORMFEED | CR | LF | comment > > ; the core implementations here need to be > ; factored out, as the sweet-expr parser needs > ; to do similar processing when differentating > ; between QUOTE SPACE and the QUOTE mdn-expr > ; case. > mdn-expr -> QUOTE any-space* mdn-expr > (list 'quote $3) > mdn-expr -> QUASIQUOTE any-space* mdn-expr > (list 'quasiquote $3) > mdn-expr -> UNQUOTE any-space* mdn-expr > (list 'unquote $3) > mdn-expr -> UNQUOTE-SPLICING any-space* mdn-expr > (list 'unquote-splicing $3) > mdn-expr -> mdn-expr-post-quote > $1 > > mdn-expr-post-quote -> base-expr post-mdn-expr > ($2 $1) > mdn-expr-post-quote -> base-expr > $1 > > post-mdn-expr -> post-mdn-expr-1 post-mdn-expr > (lambda (e) ($2 ($1 e))) > post-mdn-expr -> post-mdn-expr-1 > $1 > > post-mdn-expr-1 -> list-notation > (lambda (e) (cons e $1)) > post-mdn-expr-1 -> LBRACKET list-content RBRACKET > (lambda (e) (cons 'bracketaccess (cons e $2))) > post-mdn-expr-1 -> curly-infix > (lambda (e) (list e $1)) > > list-notation -> LPARENS list-content RPARENS > $2 > ; CONS = . i.e. the dotted-pair operator > list-content -> any-space* CONS any-space+ mdn-expr any-space* > $4 > list-content -> any-space* mdn-expr list-content > (cons $2 $3) > list-content -> any-space* > '() > > base-expr -> list-notation > $1 > base-expr -> bracket-notation > $1 > base-expr -> curly-infix > $1 > ; basically, these cases involve calling > ; the built-in reader. > base-expr -> STRING > $1 > base-expr -> NUMBER > $1 > base-expr -> OTHER ; i.e. for #x reader > $1 > base-expr -> SYMBOL > $1 > > ; hook for language-specific bracket meanings > bracket-notation -> bracket-notation-scheme > $1 > bracket-notation-scheme -> LBRACKET list-content RBRACKET > $2 > bracket-notation-arc -> LBRACKET list-content RBRACKET > (list 'lambda (list '_) $2) > > ; ignore completely empty and comment lines at start of > ; sweet expressions > swt-expr -> empty-line* swt-expr-core > $2 > > ; some simple utility parsers > empty-line -> comment-or-hspace* eol > comment -> COMMENT-MARKER (not eol)* > comment-line -> hspace* comment eol > eol -> CR | LF > hspace -> SPACE | TAB | FORMFEED | VTAB > comment-or-hspace -> hspace | comment > > ; for exact indentation > ; this part is tricky > (initial-indent ()) -> ; empty > (initial-indent ($1 . l)) -> (initial-indent l) hspace > > ; implements "whitespace at top-level > ; DISABLES I-expressions" > swt-expr-core -> hspace+ mdn-expr > $2 > ; I-expressions must start at > ; indent 0. Sorry dwheeler. > ; Most consistent seems > ; too complex or has other > ; problems. > swt-expr-core -> (i-expr ()) > $1 > > ; implements dwheeler's spec fix. > (i-expr lvl) -> QUOTE hspace+ (i-expr lvl) > (list 'quote $3) > (i-expr lvl) -> QUASIQUOTE hspace+ (i-expr lvl) > (list 'quasiquote $3) > (i-expr lvl) -> UNQUOTE hspace+ (i-expr lvl) > (list 'unquote $3) > (i-expr lvl) -> UNQUOTE-SPLICING hspace+ (i-expr lvl) > (list 'unquote-splicing $3) > ; NB: because of the hspace requirement, > ; implementing the above means that we > ; must take over some of mdn-expr's > ; work; if after finding QUOTE et al. > ; we DON'T find hspace, recurse into > ; mdn-expr and add to the current head. > > ; merge of GROUP and SPLICE character. > (i-expr lvl) -> SPLICE head eol-comment-lines (body inlvl), if {lvl > perfect-tail-sublist-of inlvl} > (append $2 $4) > (i-expr lvl) -> SPLICE eol-comment-lines (body inlvl), if {lvl > perfect-tail-sublist-of inlvl} > $3 > (i-expr lvl) -> SPLICE head eol-comment-lines > (if (= (length $2) 1) > (car $2) > $2) > (i-expr lvl) -> head eol-comment-lines (body inlvl), if {lvl > perfect-tail-sublist-of inlvl} > (append $1 $3) > (i-expr lvl) -> head eol-comment-lines > > (if (= (length $1) 1) > (car $1) > $1) > > ; another simple utility parser > eol-comment-lines -> comment-or-hspace* eol comment-line* > > head -> mdn-expr hspace* head > (cons $1 $3) > head -> mdn-expr > (list $1) > > ; body handles the final part of the > ; new "splice" concept, viz., splice > ; on same line > ; NB: in the implementation, we expect body to ALSO return > ; the indentation that initial-indent failed at, because of > ; the one-char lookahead. Also in the implementation > ; initial-indent probably returns the initial indent, not > ; accept it as a parameter. > (body lvl) -> (initial-indent lvl) (sub-body lvl) > $2 > (body lvl) -> ; empty > '() > > (sub-body lvl) -> (i-expr lvl) hspace* SPLICE hspace* (sub-body lvl) > (cons $1 $5) > (sub-body lvl) -> (i-expr lvl) eol-comment-lines (body lvl) > (cons $1 $3)
sweet-expr.scm
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