--- /dev/null
+#lang racket
+(require racket/control) ; this tells Scheme to let us use shift and reset
+
+(define (visit yield t)
+ (cond [(pair? t) (visit yield (car t)) (visit yield (cdr t))]
+ [else (yield t)]))
+
+
+; delimcc-based implementation of coroutines, following http://okmij.org/ftp/continuations/implementations.html#caml-shift
+(define (coroutine2 main start thread)
+ (letrec ([yield (lambda (x) (shift0 k (cons x k)))]
+ [loop (lambda (curk data)
+ (let ([x (car data)] [k (cdr data)])
+ (cond
+ [(eq? k 'finished) (loop curk (curk x))]
+ [(eq? k 'exit) x]
+ [else (loop k (curk x))])))])
+ (loop (lambda (x) (reset0 (cons (thread yield x) 'finished))) (reset0 (cons (main yield start) 'exit)))))
+
+; call/cc-based, following Xavier Leroy's ocaml-callcc
+(define (coroutine2^ main start thread)
+ (let/cc initk (let* ([curk initk]
+ [yield (lambda (x) (let/cc k (let ([oldk curk]) (set! curk k) (oldk x))))])
+ (main yield (begin (thread yield (let/cc k2 (set! curk k2) start)))))))
+
+(define (proc coroutine2 max1 max2)
+ (letrec ([proc1 (lambda (yield n) (if (>= n max1) (begin (displayln "1: exit") 100) (begin (display "1: received ") (displayln n) (proc1 yield (yield (+ 1 n))))))]
+ [proc2 (lambda (yield n) (if (>= n max2) (begin (displayln "2: finished") -2) (begin (display "2: received ") (displayln n) (proc2 yield (yield (+ 1 n))))))])
+ (coroutine2 proc1 0 proc2)))
+
+; the following is meant to be a general-purpose handler with the following behavior:
+; 1. call main with start
+; 2. first yield to proc1, which yields back to main,
+; 3. then main yields to proc2, which yields back to main; and so on
+; 4. when either proc finishes, subsequent yields from main which would have gone to that procedure instead always return #f
+; 5. we stop looping only when main finishes
+(define (coroutine3 main start proc1 proc2)
+ (letrec ([yield (lambda (x) (shift0 k (cons x k)))]
+ [false (lambda (x) (reset0 (false (shift0 k (cons #f k)))))]
+ [loop (lambda (inmain curk otherk data)
+ (let ([x (car data)] [k (cdr data)])
+ (cond
+ [(eq? k 'finished) (loop #t otherk false (curk x))]
+ [(eq? k 'exit) x]
+ [inmain (loop #f k otherk (curk x))]
+ [else (loop #t otherk k (curk x))])))])
+ (loop #t (lambda (x) (reset0 (cons (proc1 yield x) 'finished)))
+ (lambda (x) (reset0 (cons (proc2 yield x) 'finished)))
+ (reset0 (cons (main yield start) 'exit)))))
+
+; the same-fringe application doesn't make use of the 'start or 'restart parameters
+; the 'blah values yielded to the leaf-iterators are ignored too
+(define (same-fringe1 tree1 tree2)
+ (letrec ([next1 (lambda (yield x) (visit yield tree1))]
+ [next2 (lambda (yield x) (visit yield tree2))]
+ [main (lambda (yield x)
+ (let* ([leaf1 (yield 'blah)]
+ [leaf2 (yield 'blah)])
+ (cond [(and leaf1 leaf2) (and (equal? leaf1 leaf2) (main yield 'blah))]
+ [(or leaf1 leaf2) #f]
+ [else #t])))])
+ (coroutine3 main 'restart next1 next2)))
+
+
+; another delimcc solution, based on Biernacki, Danvy and Shan "On the static and dynamic extents of delimited continuations" 2006, section 4.1.4
+; here, next1 = '(leaf1 . thunk_for_more_leaves); final thunk => '(finished . #f)
+(define (make-enumerator2 tree)
+ (define (yield x) (shift k (cons x k)))
+ (reset (visit yield tree) '(finished . #f)))
+
+(define (same-fringe2 tree1 tree2)
+ (define next1 (make-enumerator2 tree1))
+ (define next2 (make-enumerator2 tree2))
+ (letrec ([loop (lambda (res1 res2)
+ (let* ([leaf1 (car res1)]
+ [leaf2 (car res2)]
+ [next1 (cdr res1)]
+ [next2 (cdr res2)])
+ (cond
+ [(and next1 next2) (and (equal? leaf1 leaf2) (loop (next1) (next2)))]
+ [(or next1 next2) #f]
+ [else #t])))])
+ (loop next1 next2)))
+
+
+; call/cc solution, from http://c2.com/cgi/wiki?SameFringeProblem ("Scheme Language, using CoRoutines")
+; here, (next1) => '(1 . #t); (next1) => '(2 . #t); (next1) => '(finished . #f)
+(define (make-enumerator3 t)
+ (letrec ([resk #f]
+ [yieldk #f]
+ [resume (lambda () (let/cc k
+ (set! yieldk k)
+ (cond [(eq? resk #f)
+ (visit yield t)
+ (set! resk 'finished)
+ (yieldk (cons 'finished #f))]
+ [(eq? resk 'finished)
+ #;(error "End of generator")
+ (yieldk (cons 'finished #f))
+ ]
+ [else (resk)])))]
+ [yield (lambda (x) (let/cc k
+ (set! resk k)
+ (yieldk (cons x #t))))])
+ resume))
+
+(define (same-fringe3 tree1 tree2)
+ (define next1 (make-enumerator3 tree1))
+ (define next2 (make-enumerator3 tree2))
+ (letrec ([loop (lambda (res1 res2)
+ (let* ([leaf1 (car res1)]
+ [leaf2 (car res2)]
+ [isleaf1 (cdr res1)]
+ [isleaf2 (cdr res2)])
+ (cond
+ [(and isleaf1 isleaf2) (and (equal? leaf1 leaf2) (loop (next1) (next2)))]
+ [(or isleaf1 isleaf2) #f]
+ [else #t])))])
+ (loop (next1) (next2))))
+
+
+
+(define (test same-fringe)
+ (define tree1 '(((1 . 2) . (3 . 4)) . (5 . 6)))
+ (define tree2 '(1 . (((2 . 3) . (4 . 5)) . 6)))
+ (define tree3 '(1 . (((2 . 3) . (4 . 5)) . 7)))
+ (define tree4 '(((1 . 2) . (4 . 5)) . 7))
+ (define tree5 '(((1 . 2) . (3 . 4)) . 5))
+ (define tree6 '(((10 . 2) . (3 . 4)) . 5))
+ (define tree7 8)
+ (and (same-fringe tree1 tree2)
+ (same-fringe tree7 tree7)
+ (not (or
+ (same-fringe tree1 tree3)
+ (same-fringe tree1 tree4)
+ (same-fringe tree4 tree1)
+ (same-fringe tree5 tree1)
+ (same-fringe tree1 tree5)
+ (same-fringe tree1 tree6)
+ (same-fringe tree6 tree1)
+ (same-fringe tree6 tree7)
+ ))))
+
+#|
+
+In Lua, using CoRoutines:
+ function tree_leaves(tree)
+ if tree.leaf then
+ coroutine.yield(tree.leaf)
+ else
+ tree_leaves(tree.left)
+ tree_leaves(tree.right)
+ end
+ end
+ function same_fringe(tree1, tree2)
+ local iter1 = coroutine.wrap(tree_leaves)
+ local iter2 = coroutine.wrap(tree_leaves)
+ for node in iter1, tree1 do
+ if node ~= iter2(tree2) then
+ return false
+ end
+ end
+ return iter2() == nil
+ end
+
+In OCaml:
+# #require "delimcc";;
+# open Delimcc;;
+# type seq = End | Next of int * seq computation
+ and 'a computation = unit -> 'a;;
+# type 'a tree = Leaf of 'a | Node of 'a tree * 'a tree;;
+# let rec visit p = function Leaf i -> shift p (fun a -> Next (i, a)) | Node (t1,t2) -> let () = visit p t1 in visit p t2;;
+# let prompt mid = let p = new_prompt() in push_prompt p (mid p);;
+val prompt : ('a Delimcc.prompt -> unit -> 'a) -> 'a = <fun>
+# let make_seq t = prompt (fun p () -> let () = visit p t in End);;
+val make_seq : int tree -> seq = <fun>
+# let tree1 = Node (Node (Node(Leaf 1,Leaf 2), Node(Leaf 3,Leaf 4)), Node(Leaf 5,Leaf 6));;
+# let next1 = make_seq tree1;;
+val next1 : seq = Next (1, <fun>)
+# let next2 = match next1 with Next(_,f) -> f ();;
+val next2 : seq = Next (2, <fun>)
+# let next3 = match next2 with Next(_,f) -> f ();;
+val next3 : seq = Next (3, <fun>)
+# let next4 = match next3 with Next(_,f) -> f ();;
+val next4 : seq = Next (4, <fun>)
+# let next5 = match next4 with Next(_,f) -> f ();;
+val next5 : seq = Next (5, <fun>)
+# let next6 = match next5 with Next(_,f) -> f ();;
+val next6 : seq = Next (6, <fun>)
+# let next7 = match next6 with Next(_,f) -> f ();;
+val next7 : seq = End
+
+|#
--- /dev/null
+body {
+ font-family: sans-serif;
+ font-size: small;
+ border: solid #d9d8d1;
+ border-width: 1px;
+ margin: 10px;
+ background-color: #ffffff;
+ color: #000000;
+}
+
+a {
+ color: #0000cc;
+}
+
+a:hover, a:visited, a:active {
+ color: #880000;
+}
+
+span.cntrl {
+ border: dashed #aaaaaa;
+ border-width: 1px;
+ padding: 0px 2px 0px 2px;
+ margin: 0px 2px 0px 2px;
+}
+
+img.logo {
+ float: right;
+ border-width: 0px;
+}
+
+img.avatar {
+ vertical-align: middle;
+}
+
+a.list img.avatar {
+ border-style: none;
+}
+
+div.page_header {
+ height: 25px;
+ padding: 8px;
+ font-size: 150%;
+ font-weight: bold;
+ background-color: #d9d8d1;
+}
+
+div.page_header a:visited, a.header {
+ color: #0000cc;
+}
+
+div.page_header a:hover {
+ color: #880000;
+}
+
+div.page_nav {
+ padding: 8px;
+}
+
+div.page_nav a:visited {
+ color: #0000cc;
+}
+
+div.page_path {
+ padding: 8px;
+ font-weight: bold;
+ border: solid #d9d8d1;
+ border-width: 0px 0px 1px;
+}
+
+div.page_footer {
+ height: 17px;
+ padding: 4px 8px;
+ background-color: #d9d8d1;
+}
+
+div.page_footer_text {
+ float: left;
+ color: #555555;
+ font-style: italic;
+}
+
+div#generating_info {
+ margin: 4px;
+ font-size: smaller;
+ text-align: center;
+ color: #505050;
+}
+
+div.page_body {
+ padding: 8px;
+ font-family: monospace;
+}
+
+div.title, a.title {
+ display: block;
+ padding: 6px 8px;
+ font-weight: bold;
+ background-color: #edece6;
+ text-decoration: none;
+ color: #000000;
+}
+
+div.readme {
+ padding: 8px;
+}
+
+a.title:hover {
+ background-color: #d9d8d1;
+}
+
+div.title_text {
+ padding: 6px 0px;
+ border: solid #d9d8d1;
+ border-width: 0px 0px 1px;
+ font-family: monospace;
+}
+
+div.log_body {
+ padding: 8px 8px 8px 150px;
+}
+
+span.age {
+ position: relative;
+ float: left;
+ width: 142px;
+ font-style: italic;
+}
+
+span.signoff {
+ color: #888888;
+}
+
+div.log_link {
+ padding: 0px 8px;
+ font-size: 70%;
+ font-family: sans-serif;
+ font-style: normal;
+ position: relative;
+ float: left;
+ width: 136px;
+}
+
+div.list_head {
+ padding: 6px 8px 4px;
+ border: solid #d9d8d1;
+ border-width: 1px 0px 0px;
+ font-style: italic;
+}
+
+.author_date, .author {
+ font-style: italic;
+}
+
+div.author_date {
+ padding: 8px;
+ border: solid #d9d8d1;
+ border-width: 0px 0px 1px 0px;
+}
+
+a.list {
+ text-decoration: none;
+ color: #000000;
+}
+
+a.subject, a.name {
+ font-weight: bold;
+}
+
+table.tags a.subject {
+ font-weight: normal;
+}
+
+a.list:hover {
+ text-decoration: underline;
+ color: #880000;
+}
+
+a.text {
+ text-decoration: none;
+ color: #0000cc;
+}
+
+a.text:visited {
+ text-decoration: none;
+ color: #880000;
+}
+
+a.text:hover {
+ text-decoration: underline;
+ color: #880000;
+}
+
+table {
+ padding: 8px 4px;
+ border-spacing: 0;
+}
+
+table.diff_tree {
+ font-family: monospace;
+}
+
+table.combined.diff_tree th {
+ text-align: center;
+}
+
+table.combined.diff_tree td {
+ padding-right: 24px;
+}
+
+table.combined.diff_tree th.link,
+table.combined.diff_tree td.link {
+ padding: 0px 2px;
+}
+
+table.combined.diff_tree td.nochange a {
+ color: #6666ff;
+}
+
+table.combined.diff_tree td.nochange a:hover,
+table.combined.diff_tree td.nochange a:visited {
+ color: #d06666;
+}
+
+table.blame {
+ border-collapse: collapse;
+}
+
+table.blame td {
+ padding: 0px 5px;
+ font-size: 100%;
+ vertical-align: top;
+}
+
+th {
+ padding: 2px 5px;
+ font-size: 100%;
+ text-align: left;
+}
+
+/* do not change row style on hover for 'blame' view */
+tr.light,
+table.blame .light:hover {
+ background-color: #ffffff;
+}
+
+tr.dark,
+table.blame .dark:hover {
+ background-color: #f6f6f0;
+}
+
+/* currently both use the same, but it can change */
+tr.light:hover,
+tr.dark:hover {
+ background-color: #edece6;
+}
+
+/* boundary commits in 'blame' view */
+/* and commits without "previous" */
+tr.boundary td.sha1,
+tr.no-previous td.linenr {
+ font-weight: bold;
+}
+
+/* for 'blame_incremental', during processing */
+tr.color1 { background-color: #f6fff6; }
+tr.color2 { background-color: #f6f6ff; }
+tr.color3 { background-color: #fff6f6; }
+
+td {
+ padding: 2px 5px;
+ font-size: 100%;
+ vertical-align: top;
+}
+
+td.link, td.selflink {
+ padding: 2px 5px;
+ font-family: sans-serif;
+ font-size: 70%;
+}
+
+td.selflink {
+ padding-right: 0px;
+}
+
+td.sha1 {
+ font-family: monospace;
+}
+
+.error {
+ color: red;
+ background-color: yellow;
+}
+
+td.current_head {
+ text-decoration: underline;
+}
+
+table.diff_tree span.file_status.new {
+ color: #008000;
+}
+
+table.diff_tree span.file_status.deleted {
+ color: #c00000;
+}
+
+table.diff_tree span.file_status.moved,
+table.diff_tree span.file_status.mode_chnge {
+ color: #777777;
+}
+
+table.diff_tree span.file_status.copied {
+ color: #70a070;
+}
+
+/* noage: "No commits" */
+table.project_list td.noage {
+ color: #808080;
+ font-style: italic;
+}
+
+/* age2: 60*60*24*2 <= age */
+table.project_list td.age2, table.blame td.age2 {
+ font-style: italic;
+}
+
+/* age1: 60*60*2 <= age < 60*60*24*2 */
+table.project_list td.age1 {
+ color: #009900;
+ font-style: italic;
+}
+
+table.blame td.age1 {
+ color: #009900;
+ background: transparent;
+}
+
+/* age0: age < 60*60*2 */
+table.project_list td.age0 {
+ color: #009900;
+ font-style: italic;
+ font-weight: bold;
+}
+
+table.blame td.age0 {
+ color: #009900;
+ background: transparent;
+ font-weight: bold;
+}
+
+td.pre, div.pre, div.diff {
+ font-family: monospace;
+ font-size: 12px;
+ white-space: pre;
+}
+
+td.mode {
+ font-family: monospace;
+}
+
+/* progress of blame_interactive */
+div#progress_bar {
+ height: 2px;
+ margin-bottom: -2px;
+ background-color: #d8d9d0;
+}
+div#progress_info {
+ float: right;
+ text-align: right;
+}
+
+/* format of (optional) objects size in 'tree' view */
+td.size {
+ font-family: monospace;
+ text-align: right;
+}
+
+/* styling of diffs (patchsets): commitdiff and blobdiff views */
+div.diff.header,
+div.diff.extended_header {
+ white-space: normal;
+}
+
+div.diff.header {
+ font-weight: bold;
+
+ background-color: #edece6;
+
+ margin-top: 4px;
+ padding: 4px 0px 2px 0px;
+ border: solid #d9d8d1;
+ border-width: 1px 0px 1px 0px;
+}
+
+div.diff.header a.path {
+ text-decoration: underline;
+}
+
+div.diff.extended_header,
+div.diff.extended_header a.path,
+div.diff.extended_header a.hash {
+ color: #777777;
+}
+
+div.diff.extended_header .info {
+ color: #b0b0b0;
+}
+
+div.diff.extended_header {
+ background-color: #f6f5ee;
+ padding: 2px 0px 2px 0px;
+}
+
+div.diff a.list,
+div.diff a.path,
+div.diff a.hash {
+ text-decoration: none;
+}
+
+div.diff a.list:hover,
+div.diff a.path:hover,
+div.diff a.hash:hover {
+ text-decoration: underline;
+}
+
+div.diff.to_file a.path,
+div.diff.to_file {
+ color: #007000;
+}
+
+div.diff.add {
+ color: #008800;
+}
+
+div.diff.from_file a.path,
+div.diff.from_file {
+ color: #aa0000;
+}
+
+div.diff.rem {
+ color: #cc0000;
+}
+
+div.diff.chunk_header a,
+div.diff.chunk_header {
+ color: #990099;
+}
+
+div.diff.chunk_header {
+ border: dotted #ffe0ff;
+ border-width: 1px 0px 0px 0px;
+ margin-top: 2px;
+}
+
+div.diff.chunk_header span.chunk_info {
+ background-color: #ffeeff;
+}
+
+div.diff.chunk_header span.section {
+ color: #aa22aa;
+}
+
+div.diff.incomplete {
+ color: #cccccc;
+}
+
+div.diff.nodifferences {
+ font-weight: bold;
+ color: #600000;
+}
+
+div.index_include {
+ border: solid #d9d8d1;
+ border-width: 0px 0px 1px;
+ padding: 12px 8px;
+}
+
+div.search {
+ font-size: 100%;
+ font-weight: normal;
+ margin: 4px 8px;
+ float: right;
+ top: 56px;
+ right: 12px
+}
+
+p.projsearch {
+ text-align: center;
+}
+
+td.linenr {
+ text-align: right;
+}
+
+a.linenr {
+ color: #999999;
+ text-decoration: none
+}
+
+a.rss_logo {
+ float: right;
+ padding: 3px 0px;
+ width: 35px;
+ line-height: 10px;
+ border: 1px solid;
+ border-color: #fcc7a5 #7d3302 #3e1a01 #ff954e;
+ color: #ffffff;
+ background-color: #ff6600;
+ font-weight: bold;
+ font-family: sans-serif;
+ font-size: 70%;
+ text-align: center;
+ text-decoration: none;
+}
+
+a.rss_logo:hover {
+ background-color: #ee5500;
+}
+
+a.rss_logo.generic {
+ background-color: #ff8800;
+}
+
+a.rss_logo.generic:hover {
+ background-color: #ee7700;
+}
+
+span.refs span {
+ padding: 0px 4px;
+ font-size: 70%;
+ font-weight: normal;
+ border: 1px solid;
+ background-color: #ffaaff;
+ border-color: #ffccff #ff00ee #ff00ee #ffccff;
+}
+
+span.refs span a {
+ text-decoration: none;
+ color: inherit;
+}
+
+span.refs span a:hover {
+ text-decoration: underline;
+}
+
+span.refs span.indirect {
+ font-style: italic;
+}
+
+span.refs span.ref {
+ background-color: #aaaaff;
+ border-color: #ccccff #0033cc #0033cc #ccccff;
+}
+
+span.refs span.tag {
+ background-color: #ffffaa;
+ border-color: #ffffcc #ffee00 #ffee00 #ffffcc;
+}
+
+span.refs span.head {
+ background-color: #aaffaa;
+ border-color: #ccffcc #00cc33 #00cc33 #ccffcc;
+}
+
+span.atnight {
+ color: #cc0000;
+}
+
+span.match {
+ color: #e00000;
+}
+
+div.binary {
+ font-style: italic;
+}
+
+div.remote {
+ margin: .5em;
+ border: 1px solid #d9d8d1;
+ display: inline-block;
+}
+
+/* Style definition generated by highlight 2.4.5, http://www.andre-simon.de/ */
+
+/* Highlighting theme definition: */
+
+.num { color:#2928ff; }
+.esc { color:#ff00ff; }
+.str { color:#ff0000; }
+.dstr { color:#818100; }
+.slc { color:#838183; font-style:italic; }
+.com { color:#838183; font-style:italic; }
+.dir { color:#008200; }
+.sym { color:#000000; }
+.line { color:#555555; }
+.kwa { color:#000000; font-weight:bold; }
+.kwb { color:#830000; }
+.kwc { color:#000000; font-weight:bold; }
+.kwd { color:#010181; }