author | wenzelm |
Sat, 17 Sep 2011 23:04:03 +0200 | |
changeset 44959 | 9476c856c4b9 |
parent 44698 | 0385292321a0 |
child 46831 | 4a6085849a37 |
permissions | -rw-r--r-- |
44698 | 1 |
(* Title: Pure/PIDE/yxml.ML |
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Author: Makarius |
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Efficient text representation of XML trees using extra characters X |
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and Y -- no escaping, may nest marked text verbatim. Suitable for |
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direct inlining into plain text. |
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Markup <elem att="val" ...>...body...</elem> is encoded as: |
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X Y name Y att=val ... X |
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... |
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body |
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... |
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X Y X |
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*) |
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signature YXML = |
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sig |
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val X: Symbol.symbol |
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val Y: Symbol.symbol |
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val embed_controls: string -> string |
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inner syntax supports inlined YXML according to Term_XML (particularly useful for producing text under program control);
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parents:
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val detect: string -> bool |
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val output_markup: Markup.T -> string * string |
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val element: string -> XML.attributes -> string list -> string |
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val string_of_body: XML.body -> string |
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val string_of: XML.tree -> string |
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type XML.body as basic data representation language;
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val parse_body: string -> XML.body |
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val parse: string -> XML.tree |
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end; |
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structure YXML: YXML = |
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struct |
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(** string representation **) |
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renamed YXML.binary_text to YXML.escape_controls to emphasize what it actually does;
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(* idempotent recoding of certain low ASCII control characters *) |
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robust representation of low ASCII control characters within XML/YXML text;
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c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
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fun pseudo_utf8 c = |
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
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if Symbol.is_ascii_control c |
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robust representation of low ASCII control characters within XML/YXML text;
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then chr 192 ^ chr (128 + ord c) |
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
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else c; |
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
31469
diff
changeset
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42 |
|
43772
c825594fd0c1
clarified YXML.embed_controls -- this is idempotent and cannot be nested;
wenzelm
parents:
43731
diff
changeset
|
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fun embed_controls str = |
34095
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
31469
diff
changeset
|
44 |
if exists_string Symbol.is_ascii_control str |
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
31469
diff
changeset
|
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then translate_string pseudo_utf8 str |
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
31469
diff
changeset
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else str; |
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
31469
diff
changeset
|
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|
c2f176a38448
robust representation of low ASCII control characters within XML/YXML text;
wenzelm
parents:
31469
diff
changeset
|
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(* markers *) |
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val X = chr 5; |
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val Y = chr 6; |
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val XY = X ^ Y; |
173d548ce9d2
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val XYX = XY ^ X; |
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val detect = exists_string (fn s => s = X orelse s = Y); |
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inner syntax supports inlined YXML according to Term_XML (particularly useful for producing text under program control);
wenzelm
parents:
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diff
changeset
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(* output *) |
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fun output_markup (markup as (name, atts)) = |
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uniform Markup.empty/Markup.Empty in ML and Scala;
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if Markup.is_empty markup then Markup.no_output |
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else (XY ^ name ^ implode (map (fn (a, x) => Y ^ a ^ "=" ^ x) atts) ^ X, XYX); |
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fun element name atts body = |
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let val (pre, post) = output_markup (name, atts) |
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in pre ^ implode body ^ post end; |
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fun string_of_body body = |
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let |
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fun attrib (a, x) = |
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Buffer.add Y #> |
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Buffer.add a #> Buffer.add "=" #> Buffer.add x; |
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simplified type XML.tree: embed Markup.T directly, avoid slightly odd triple;
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changeset
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fun tree (XML.Elem ((name, atts), ts)) = |
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Buffer.add XY #> Buffer.add name #> fold attrib atts #> Buffer.add X #> |
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trees ts #> |
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Buffer.add XYX |
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| tree (XML.Text s) = Buffer.add s |
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and trees ts = fold tree ts; |
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in Buffer.empty |> trees body |> Buffer.content end; |
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val string_of = string_of_body o single; |
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(** efficient YXML parsing **) |
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local |
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(* splitting *) |
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fun is_char s c = ord s = Char.ord c; |
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val split_string = |
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Substring.full #> |
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Substring.tokens (is_char X) #> |
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map (Substring.fields (is_char Y) #> map Substring.string); |
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(* structural errors *) |
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fun err msg = raise Fail ("Malformed YXML encoding: " ^ msg); |
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fun err_attribute () = err "bad attribute"; |
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fun err_element () = err "bad element"; |
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fun err_unbalanced "" = err "unbalanced element" |
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| err_unbalanced name = err ("unbalanced element " ^ quote name); |
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(* stack operations *) |
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fun add x ((elem, body) :: pending) = (elem, x :: body) :: pending; |
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fun push "" _ _ = err_element () |
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| push name atts pending = ((name, atts), []) :: pending; |
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fun pop ((("", _), _) :: _) = err_unbalanced "" |
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| pop ((markup, body) :: pending) = add (XML.Elem (markup, rev body)) pending; |
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(* parsing *) |
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fun parse_attrib s = |
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(case first_field "=" s of |
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NONE => err_attribute () |
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| SOME ("", _) => err_attribute () |
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| SOME att => att); |
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fun parse_chunk ["", ""] = pop |
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| parse_chunk ("" :: name :: atts) = push name (map parse_attrib atts) |
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| parse_chunk txts = fold (add o XML.Text) txts; |
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in |
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fun parse_body source = |
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reverted ce00462f,b3759dce, 7a165592: unwanted generalisation
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(case fold parse_chunk (split_string source) [(("", []), [])] of |
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[(("", _), result)] => rev result |
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| ((name, _), _) :: _ => err_unbalanced name); |
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fun parse source = |
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(case parse_body source of |
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YXML.parse: allow text without markup, potentially empty;
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[result] => result |
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YXML.parse: allow text without markup, potentially empty;
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| [] => XML.Text "" |
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| _ => err "multiple results"); |
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end; |
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end; |
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