1 # HTML parser meant to run in a browser, in support of WYSIWYG editor
2 # Copyright 2015 Jason Woofenden
4 # This program is free software: you can redistribute it and/or modify it under
5 # the terms of the GNU Affero General Public License as published by the Free
6 # Software Foundation, either version 3 of the License, or (at your option) any
9 # This program is distributed in the hope that it will be useful, but WITHOUT
10 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
11 # FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
14 # You should have received a copy of the GNU Affero General Public License
15 # along with this program. If not, see <http://www.gnu.org/licenses/>.
18 # This file implements a parser for html snippets, meant to be used by a
19 # WYSIWYG editor. Hence it does not attempt to parse doctypes, <html>, <head>
20 # or <body> tags, nor does it produce the top level "document" node in the dom
21 # tree, nor nodes for html, head or body.
23 # Instead, the data structure produced by this parser is an array of nodes.
25 # Each node is an array. The first element in the array is an integer (one of
26 # the TYPE_* constants below) followed by the appropriate fields for that type
27 # (shown below in the comments after the TYPE_* definition.)
29 TYPE_TAG = 0 # name, {attributes}, [children]
30 TYPE_TEXT = 1 # "text"
33 # the following types are emited by the tokenizer, but shouldn't end up in the tree:
36 lc_alpha = "abcdefghijklmnopqrstuvwxqz"
37 uc_alpha = "ABCDEFGHIJKLMNOPQRSTUVWXQZ"
39 alnum = lc_alpha + uc_alpha + digits
40 hex_chars = digits + "abcdefABCDEF"
42 # some SVG elements have dashes in them
43 tag_name_chars = alnum + "-"
45 # http://www.w3.org/TR/html5/infrastructure.html#space-character
46 space_chars = "\u0009\u000a\u000c\u000d\u0020"
48 # https://en.wikipedia.org/wiki/Whitespace_character#Unicode
49 whitespace_chars = "\u0009\u000a\u000b\u000c\u000d\u0020\u0085\u00a0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u2028\u2029\u202f\u205f\u3000"
51 # These are the character references that don't need a terminating semicolon
52 # min length: 2, max: 6, none are a prefix of any other.
54 Aacute: 'Á', aacute: 'á', Acirc: 'Â', acirc: 'â', acute: '´', AElig: 'Æ',
55 aelig: 'æ', Agrave: 'À', agrave: 'à', AMP: '&', amp: '&', Aring: 'Å',
56 aring: 'å', Atilde: 'Ã', atilde: 'ã', Auml: 'Ä', auml: 'ä', brvbar: '¦',
57 Ccedil: 'Ç', ccedil: 'ç', cedil: '¸', cent: '¢', COPY: '©', copy: '©',
58 curren: '¤', deg: '°', divide: '÷', Eacute: 'É', eacute: 'é', Ecirc: 'Ê',
59 ecirc: 'ê', Egrave: 'È', egrave: 'è', ETH: 'Ð', eth: 'ð', Euml: 'Ë',
60 euml: 'ë', frac12: '½', frac14: '¼', frac34: '¾', GT: '>', gt: '>',
61 Iacute: 'Í', iacute: 'í', Icirc: 'Î', icirc: 'î', iexcl: '¡', Igrave: 'Ì',
62 igrave: 'ì', iquest: '¿', Iuml: 'Ï', iuml: 'ï', laquo: '«', LT: '<',
63 lt: '<', macr: '¯', micro: 'µ', middot: '·', nbsp: "\u00a0", not: '¬',
64 Ntilde: 'Ñ', ntilde: 'ñ', Oacute: 'Ó', oacute: 'ó', Ocirc: 'Ô', ocirc: 'ô',
65 Ograve: 'Ò', ograve: 'ò', ordf: 'ª', ordm: 'º', Oslash: 'Ø', oslash: 'ø',
66 Otilde: 'Õ', otilde: 'õ', Ouml: 'Ö', ouml: 'ö', para: '¶', plusmn: '±',
67 pound: '£', QUOT: '"', quot: '"', raquo: '»', REG: '®', reg: '®', sect: '§',
68 shy: '', sup1: '¹', sup2: '²', sup3: '³', szlig: 'ß', THORN: 'Þ', thorn: 'þ',
69 times: '×', Uacute: 'Ú', uacute: 'ú', Ucirc: 'Û', ucirc: 'û', Ugrave: 'Ù',
70 ugrave: 'ù', uml: '¨', Uuml: 'Ü', uuml: 'ü', Yacute: 'Ý', yacute: 'ý',
74 void_elements = ['area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input', 'keygen', 'link', 'meta', 'param', 'source', 'track', 'wbr']
75 raw_text_elements = ['script', 'style']
76 escapable_raw_text_elements = ['textarea', 'title']
77 # http://www.w3.org/TR/SVG/ 1.1 (Second Edition)
79 'a', 'altGlyph', 'altGlyphDef', 'altGlyphItem', 'animate', 'animateColor',
80 'animateMotion', 'animateTransform', 'circle', 'clipPath', 'color-profile',
81 'cursor', 'defs', 'desc', 'ellipse', 'feBlend', 'feColorMatrix',
82 'feComponentTransfer', 'feComposite', 'feConvolveMatrix',
83 'feDiffuseLighting', 'feDisplacementMap', 'feDistantLight', 'feFlood',
84 'feFuncA', 'feFuncB', 'feFuncG', 'feFuncR', 'feGaussianBlur', 'feImage',
85 'feMerge', 'feMergeNode', 'feMorphology', 'feOffset', 'fePointLight',
86 'feSpecularLighting', 'feSpotLight', 'feTile', 'feTurbulence', 'filter',
87 'font', 'font-face', 'font-face-format', 'font-face-name', 'font-face-src',
88 'font-face-uri', 'foreignObject', 'g', 'glyph', 'glyphRef', 'hkern',
89 'image', 'line', 'linearGradient', 'marker', 'mask', 'metadata',
90 'missing-glyph', 'mpath', 'path', 'pattern', 'polygon', 'polyline',
91 'radialGradient', 'rect', 'script', 'set', 'stop', 'style', 'svg',
92 'switch', 'symbol', 'text', 'textPath', 'title', 'tref', 'tspan', 'use',
96 # http://www.w3.org/TR/MathML/ Version 3.0 2nd Edition
98 'abs', 'and', 'annotation', 'annotation-xml', 'apply', 'approx', 'arccos',
99 'arccosh', 'arccot', 'arccoth', 'arccsc', 'arccsch', 'arcsec', 'arcsech',
100 'arcsin', 'arcsinh', 'arctan', 'arctanh', 'arg', 'bind', 'bvar', 'card',
101 'cartesianproduct', 'cbytes', 'ceiling', 'cerror', 'ci', 'cn', 'codomain',
102 'complexes', 'compose', 'condition', 'conjugate', 'cos', 'cosh', 'cot',
103 'coth', 'cs', 'csc', 'csch', 'csymbol', 'curl', 'declare', 'degree',
104 'determinant', 'diff', 'divergence', 'divide', 'domain',
105 'domainofapplication', 'emptyset', 'eq', 'equivalent', 'eulergamma',
106 'exists', 'exp', 'exponentiale', 'factorial', 'factorof', 'false', 'floor',
107 'fn', 'forall', 'gcd', 'geq', 'grad', 'gt', 'ident', 'image', 'imaginary',
108 'imaginaryi', 'implies', 'in', 'infinity', 'int', 'integers', 'intersect',
109 'interval', 'inverse', 'lambda', 'laplacian', 'lcm', 'leq', 'limit',
110 'list', 'ln', 'log', 'logbase', 'lowlimit', 'lt', 'maction', 'maligngroup',
111 'malignmark', 'math', 'matrix', 'matrixrow', 'max', 'mean', 'median',
112 'menclose', 'merror', 'mfenced', 'mfrac', 'mglyph', 'mi', 'mi', 'min',
113 'minus', 'mlabeledtr', 'mlongdiv', 'mmultiscripts', 'mn', 'mo', 'mode',
114 'moment', 'momentabout', 'mover', 'mpadded', 'mphantom', 'mprescripts',
115 'mroot', 'mrow', 'ms', 'mscarries', 'mscarry', 'msgroup', 'msline',
116 'mspace', 'msqrt', 'msrow', 'mstack', 'mstyle', 'msub', 'msubsup', 'msup',
117 'mtable', 'mtd', 'mtext', 'mtr', 'munder', 'munderover', 'naturalnumbers',
118 'neq', 'none', 'not', 'notanumber', 'notin', 'notprsubset', 'notsubset',
119 'or', 'otherwise', 'outerproduct', 'partialdiff', 'pi', 'piece',
120 'piecewise', 'plus', 'power', 'primes', 'product', 'prsubset', 'quotient',
121 'rationals', 'real', 'reals', 'reln', 'rem', 'root', 'scalarproduct',
122 'sdev', 'sec', 'sech', 'selector', 'semantics', 'sep', 'set', 'setdiff',
123 'share', 'sin', 'sinh', 'span', 'subset', 'sum', 'tan', 'tanh', 'tendsto',
124 'times', 'transpose', 'true', 'union', 'uplimit', 'variance', 'vector',
125 'vectorproduct', 'xor'
127 # foreign_elements = [svg_elements..., mathml_elements...]
128 #normal_elements = All other allowed HTML elements are normal elements.
131 # decode_named_char_ref()
133 # The list of named character references is _huge_ so ask the browser to decode
134 # for us instead of wasting bandwidth/space on including the table here.
136 # Pass without the "&" but with the ";" examples:
137 # for "&" pass "amp;"
138 # for "′" pass "x2032;"
141 textarea: document.createElement('textarea')
143 # TODO test this in IE8
144 decode_named_char_ref = (txt) ->
146 decoded = g_dncr.cache[txt]
147 return decoded if decoded?
148 g_dncr.textarea.innerHTML = txt
149 decoded = g_dncr.textarea.value
150 return null if decoded is txt
151 return g_dncr.cache[txt] = decoded
153 parse_html = (txt) ->
154 cur = 0 # index of next char in txt to be parsed
155 # declare tree and tokenizer variables so they're in scope below
157 tree_append_point = null
160 tok_cur = null # partially parsed tag
163 # the functions below implement the tokenizer stats described here:
164 # http://www.w3.org/TR/html5/syntax.html#tokenization
166 # http://www.w3.org/TR/html5/syntax.html#data-state
168 switch c = txt.charAt(cur++)
170 tok_state = tok_state_character_reference_in_data
172 tok_state = tok_state_tag_open
175 return [TYPE_TEXT, c]
177 return [TYPE_TEXT, c]
180 # http://www.w3.org/TR/html5/syntax.html#tag-open-state
181 tok_state_tag_open = ->
182 switch c = txt.charAt(cur++)
184 tok_state = tok_state_markup_declaration_open
186 tok_state = tok_state_end_tag_open
189 tok_state = tok_state_bogus_comment
191 if lc_alpha.indexOf(c) > -1
192 tok_cur = [TYPE_OPEN_TAG, c, {}, []]
193 tok_state = tok_state_tag_name
194 else if uc_alpha.indexOf(c) > -1
195 tok_cur = [TYPE_OPEN_TAG, c.toLowerCase(), {}, []]
196 tok_state = tok_state_tag_name
199 tok_state = tok_state_data
200 cur -= 1 # we didn't parse/handle the char after <
201 return [TYPE_TEXT, '<']
204 # http://www.w3.org/TR/html5/syntax.html#tag-name-state
205 tok_state_tag_name = ->
206 switch c = txt.charAt(cur++)
208 tok_state = tok_state_before_attribute_name
210 tok_state = tok_state_self_closing_start_tag
212 tok_state = tok_state_data
218 tok_cur[1] += "\ufffd"
220 if uc_alpha.indexOf(c) > -1
221 tok_cur[1] += c.toLowerCase()
226 # http://www.w3.org/TR/html5/syntax.html#character-reference-in-data-state
227 # & just got consumed
228 tok_state_character_reference_in_data = ->
229 tok_state = tok_state_data
231 return [TYPE_TEXT, '&']
232 switch c = txt.charAt(cur)
234 return [TYPE_TEXT, '&']
236 if cur + 1 >= txt.length
237 return [TYPE_TEXT, '&']
238 if txt.charAt(cur + 1).toLowerCase() is 'x'
247 while start + i < txt.length and charset.indexOf(txt.charAt(start + i)) > -1
250 return [TYPE_TEXT, '&']
251 if txt.charAt(start + i) is ';'
253 decoded = decode_named_char_ref(prefix + txt.substr(start, i).toLowerCase())
256 return [TYPE_TEXT, decoded]
257 return [TYPE_TEXT, '&']
260 if alnum.indexOf(txt.charAt(cur + i)) is -1
263 return [TYPE_TEXT, '&']
264 if txt.charAt(cur + i) is ';'
265 i += 1 # include ';' terminator in value
266 decoded = decode_named_char_ref txt.substr(cur, i)
269 return [TYPE_TEXT, decoded]
270 return [TYPE_TEXT, '&']
272 # no ';' terminator (only legacy char refs)
274 return [TYPE_TEXT, '&']
275 # FIXME: if we're inside an attribute:
276 # 1. don't parse refs that are followed by =
277 # 2. don't parse refs that are followed by alnum
279 for i in [2..max] # no prefix matches, so ok to check shortest first
280 c = legacy_char_refs[txt.substr(cur, i)]
282 cur += i # consume entity chars
283 return [TYPE_TEXT, c]
286 # the functions below impliment the Tree Contstruction algorithm here:
287 # http://www.w3.org/TR/html5/syntax.html#tree-construction
288 # FIXME this is just a bit of a hack that makes sense... read spec and do it that way
290 if t[0] is TYPE_TEXT and tree_append_point.length > 0 and tree_append_point[tree_append_point.length - 1][0] is TYPE_TEXT
291 tree_append_point[tree_append_point.length - 1][1] += t[1]
293 tree_append_point.push t
294 if t[0] is TYPE_OPEN_TAG
296 tree_append_point = t[3]
298 # tree constructor initialization
299 tree = [] # see comments on TYPE_TAG/etc for the structure of this data
300 tree_append_point = tree
301 tree_state = tree_append
303 # tokenizer initialization
304 tok_state = tok_state_data
307 while cur < txt.length
314 # everything below is tests on the above
315 test_equals = (description, fn, args..., expected_output) ->
316 output = fn.apply this, args
317 if output is expected_output
318 console.log "passed: #{description}."
320 console.log "FAILED: #{description}. Expected: #{expected_output}, actual: #{output}"
321 html_to_json = (html) ->
322 return JSON.stringify parse_html html
323 test_equals "empty", html_to_json, "", '[]'
324 test_equals "just text", html_to_json, "abc", '[[1,"abc"]]'
325 test_equals "named entity", html_to_json, "a&1234", '[[1,"a&1234"]]'
326 test_equals "broken named character references", html_to_json, "1&2&&3&aabbcc;", '[[1,"1&2&&3&aabbcc;"]]'
327 test_equals "numbered entity overrides", html_to_json, "1€€ ƒ", '[[1,"1€€ ƒ"]]'
328 test_equals "open_tag", html_to_json, "foo<span>bar", '[[1,"foo"],[0,"span",{},[[1,"bar"]]]]'