aricb HTML character entity references are defined as part of the HTML specification: http://www.w3.org/TR/REC-html40/sgml/entities.html
The following code defines two commands, htmlentities::insertentities and htmlentities::removeentities. The first command replaces Unicode characters with HTML character entity references; the second command replaces HTML character entity references with the literal Unicode characters they represent. There's nothing fancy about the code, but hopefully it's useful to somebody.
namespace eval htmlentities {
variable map [list \
\u00a0  \; \
\u00a1 ¡\; \
\u00a2 ¢\; \
\u00a3 £\; \
\u00a4 ¤\; \
\u00a5 ¥\; \
\u00a6 ¦\; \
\u00a7 §\; \
\u00a8 ¨\; \
\u00a9 ©\; \
\u00aa ª\; \
\u00ab «\; \
\u00ac ¬\; \
\u00ad ­\; \
\u00ae ®\; \
\u00af ¯\; \
\u00b0 °\; \
\u00b1 ±\; \
\u00b2 ²\; \
\u00b3 ³\; \
\u00b4 ´\; \
\u00b5 µ\; \
\u00b6 ¶\; \
\u00b7 ·\; \
\u00b8 ¸\; \
\u00b9 ¹\; \
\u00ba º\; \
\u00bb »\; \
\u00bc ¼\; \
\u00bd ½\; \
\u00be ¾\; \
\u00bf ¿\; \
\u00c0 À\; \
\u00c1 Á\; \
\u00c2 Â\; \
\u00c3 Ã\; \
\u00c4 Ä\; \
\u00c5 Å\; \
\u00c6 Æ\; \
\u00c7 Ç\; \
\u00c8 È\; \
\u00c9 É\; \
\u00ca Ê\; \
\u00cb Ë\; \
\u00cc Ì\; \
\u00cd Í\; \
\u00ce Î\; \
\u00cf Ï\; \
\u00d0 Ð\; \
\u00d1 Ñ\; \
\u00d2 Ò\; \
\u00d3 Ó\; \
\u00d4 Ô\; \
\u00d5 Õ\; \
\u00d6 Ö\; \
\u00d7 ×\; \
\u00d8 Ø\; \
\u00d9 Ù\; \
\u00da Ú\; \
\u00db Û\; \
\u00dc Ü\; \
\u00dd Ý\; \
\u00de Þ\; \
\u00df ß\; \
\u00e0 à\; \
\u00e1 á\; \
\u00e2 â\; \
\u00e3 ã\; \
\u00e4 ä\; \
\u00e5 å\; \
\u00e6 æ\; \
\u00e7 ç\; \
\u00e8 è\; \
\u00e9 é\; \
\u00ea ê\; \
\u00eb ë\; \
\u00ec ì\; \
\u00ed í\; \
\u00ee î\; \
\u00ef ï\; \
\u00f0 ð\; \
\u00f1 ñ\; \
\u00f2 ò\; \
\u00f3 ó\; \
\u00f4 ô\; \
\u00f5 õ\; \
\u00f6 ö\; \
\u00f7 ÷\; \
\u00f8 ø\; \
\u00f9 ù\; \
\u00fa ú\; \
\u00fb û\; \
\u00fc ü\; \
\u00fd ý\; \
\u00fe þ\; \
\u00ff ÿ\; \
\u0192 &fnof\; \
\u0391 &Alpha\; \
\u0392 &Beta\; \
\u0393 &Gamma\; \
\u0394 &Delta\; \
\u0395 &Epsilon\; \
\u0396 &Zeta\; \
\u0397 &Eta\; \
\u0398 &Theta\; \
\u0399 &Iota\; \
\u039a &Kappa\; \
\u039b &Lambda\; \
\u039c &Mu\; \
\u039d &Nu\; \
\u039e &Xi\; \
\u039f &Omicron\; \
\u03a0 &Pi\; \
\u03a1 &Rho\; \
\u03a3 &Sigma\; \
\u03a4 &Tau\; \
\u03a5 &Upsilon\; \
\u03a6 &Phi\; \
\u03a7 &Chi\; \
\u03a8 &Psi\; \
\u03a9 &Omega\; \
\u03b1 &alpha\; \
\u03b2 &beta\; \
\u03b3 &gamma\; \
\u03b4 &delta\; \
\u03b5 &epsilon\; \
\u03b6 &zeta\; \
\u03b7 &eta\; \
\u03b8 &theta\; \
\u03b9 &iota\; \
\u03ba &kappa\; \
\u03bb &lambda\; \
\u03bc &mu\; \
\u03bd &nu\; \
\u03be &xi\; \
\u03bf &omicron\; \
\u03c0 &pi\; \
\u03c1 &rho\; \
\u03c2 &sigmaf\; \
\u03c3 &sigma\; \
\u03c4 &tau\; \
\u03c5 &upsilon\; \
\u03c6 &phi\; \
\u03c7 &chi\; \
\u03c8 &psi\; \
\u03c9 &omega\; \
\u03d1 &thetasym\; \
\u03d2 &upsih\; \
\u03d6 &piv\; \
\u2022 &bull\; \
\u2026 &hellip\; \
\u2032 &prime\; \
\u2033 &Prime\; \
\u203e &oline\; \
\u2044 &frasl\; \
\u2118 &weierp\; \
\u2111 &image\; \
\u211c &real\; \
\u2122 &trade\; \
\u2135 &alefsym\; \
\u2190 &larr\; \
\u2191 &uarr\; \
\u2192 &rarr\; \
\u2193 &darr\; \
\u2194 &harr\; \
\u21b5 &crarr\; \
\u21d0 &lArr\; \
\u21d1 &uArr\; \
\u21d2 &rArr\; \
\u21d3 &dArr\; \
\u21d4 &hArr\; \
\u2200 &forall\; \
\u2202 &part\; \
\u2203 &exist\; \
\u2205 &empty\; \
\u2207 &nabla\; \
\u2208 &isin\; \
\u2209 ¬in\; \
\u220b &ni\; \
\u220f &prod\; \
\u2211 &sum\; \
\u2212 &minus\; \
\u2217 &lowast\; \
\u221a &radic\; \
\u221d &prop\; \
\u221e &infin\; \
\u2220 &ang\; \
\u2227 &and\; \
\u2228 &or\; \
\u2229 &cap\; \
\u222a &cup\; \
\u222b &int\; \
\u2234 &there4\; \
\u223c &sim\; \
\u2245 &cong\; \
\u2248 &asymp\; \
\u2260 &ne\; \
\u2261 &equiv\; \
\u2264 &le\; \
\u2265 &ge\; \
\u2282 &sub\; \
\u2283 &sup\; \
\u2284 &nsub\; \
\u2286 &sube\; \
\u2287 &supe\; \
\u2295 &oplus\; \
\u2297 &otimes\; \
\u22a5 &perp\; \
\u22c5 &sdot\; \
\u2308 &lceil\; \
\u2309 &rceil\; \
\u230a &lfloor\; \
\u230b &rfloor\; \
\u2329 &lang\; \
\u232a &rang\; \
\u25ca &loz\; \
\u2660 &spades\; \
\u2663 &clubs\; \
\u2665 &hearts\; \
\u2666 &diams\; \
\u0022 "\; \
\u0026 &\; \
\u003c <\; \
\u003e >\; \
\u0152 &OElig\; \
\u0153 &oelig\; \
\u0160 &Scaron\; \
\u0161 &scaron\; \
\u0178 &Yuml\; \
\u02c6 &circ\; \
\u02dc &tilde\; \
\u2002 &ensp\; \
\u2003 &emsp\; \
\u2009 &thinsp\; \
\u200c &zwnj\; \
\u200d &zwj\; \
\u200e &lrm\; \
\u200f &rlm\; \
\u2013 &ndash\; \
\u2014 &mdash\; \
\u2018 &lsquo\; \
\u2019 &rsquo\; \
\u201a &sbquo\; \
\u201c &ldquo\; \
\u201d &rdquo\; \
\u201e &bdquo\; \
\u2020 &dagger\; \
\u2021 &Dagger\; \
\u2030 &permil\; \
\u2039 &lsaquo\; \
\u203a &rsaquo\; \
\u20ac &euro\; ]
set reversemap [lreverse $map]
proc insertentities {string} {
variable map
return [string map $map $string]
}
proc removeentities {string} {
variable reversemap
return [string map $reversemap $string]
}
}AMG: Here's the same code, written in a somewhat more compressed manner. I took the liberty of using namespace ensembles and renaming the commands.
namespace eval htmlentities {
namespace ensemble create -subcommands {encode decode}
set encode [list {*}{
\u00a0  \; \u00a1 ¡\; \u00a2 ¢\; \u00a3 £\; \u00a4
¤\; \u00a5 ¥\; \u00a6 ¦\; \u00a7 §\; \u00a8 ¨\;
\u00a9 ©\; \u00aa ª\; \u00ab «\; \u00ac ¬\; \u00ad
­\; \u00ae ®\; \u00af ¯\; \u00b0 °\; \u00b1 ±\;
\u00b2 ²\; \u00b3 ³\; \u00b4 ´\; \u00b5 µ\; \u00b6
¶\; \u00b7 ·\; \u00b8 ¸\; \u00b9 ¹\; \u00ba º\;
\u00bb »\; \u00bc ¼\; \u00bd ½\; \u00be ¾\;
\u00bf ¿\; \u00c0 À\; \u00c1 Á\; \u00c2 Â\;
\u00c3 Ã\; \u00c4 Ä\; \u00c5 Å\; \u00c6 Æ\; \u00c7
Ç\; \u00c8 È\; \u00c9 É\; \u00ca Ê\; \u00cb
Ë\; \u00cc Ì\; \u00cd Í\; \u00ce Î\; \u00cf
Ï\; \u00d0 Ð\; \u00d1 Ñ\; \u00d2 Ò\; \u00d3
Ó\; \u00d4 Ô\; \u00d5 Õ\; \u00d6 Ö\; \u00d7
×\; \u00d8 Ø\; \u00d9 Ù\; \u00da Ú\; \u00db
Û\; \u00dc Ü\; \u00dd Ý\; \u00de Þ\; \u00df
ß\; \u00e0 à\; \u00e1 á\; \u00e2 â\; \u00e3
ã\; \u00e4 ä\; \u00e5 å\; \u00e6 æ\; \u00e7
ç\; \u00e8 è\; \u00e9 é\; \u00ea ê\; \u00eb
ë\; \u00ec ì\; \u00ed í\; \u00ee î\; \u00ef
ï\; \u00f0 ð\; \u00f1 ñ\; \u00f2 ò\; \u00f3
ó\; \u00f4 ô\; \u00f5 õ\; \u00f6 ö\; \u00f7
÷\; \u00f8 ø\; \u00f9 ù\; \u00fa ú\; \u00fb
û\; \u00fc ü\; \u00fd ý\; \u00fe þ\; \u00ff ÿ\;
\u0192 &fnof\; \u0391 &Alpha\; \u0392 &Beta\; \u0393 &Gamma\; \u0394
&Delta\; \u0395 &Epsilon\; \u0396 &Zeta\; \u0397 &Eta\; \u0398 &Theta\;
\u0399 &Iota\; \u039a &Kappa\; \u039b &Lambda\; \u039c &Mu\; \u039d
&Nu\; \u039e &Xi\; \u039f &Omicron\; \u03a0 &Pi\; \u03a1 &Rho\; \u03a3
&Sigma\; \u03a4 &Tau\; \u03a5 &Upsilon\; \u03a6 &Phi\; \u03a7 &Chi\;
\u03a8 &Psi\; \u03a9 &Omega\; \u03b1 &alpha\; \u03b2 &beta\; \u03b3
&gamma\; \u03b4 &delta\; \u03b5 &epsilon\; \u03b6 &zeta\; \u03b7 &eta\;
\u03b8 &theta\; \u03b9 &iota\; \u03ba &kappa\; \u03bb &lambda\; \u03bc
&mu\; \u03bd &nu\; \u03be &xi\; \u03bf &omicron\; \u03c0 &pi\; \u03c1
&rho\; \u03c2 &sigmaf\; \u03c3 &sigma\; \u03c4 &tau\; \u03c5 &upsilon\;
\u03c6 &phi\; \u03c7 &chi\; \u03c8 &psi\; \u03c9 &omega\; \u03d1
&thetasym\; \u03d2 &upsih\; \u03d6 &piv\; \u2022 &bull\; \u2026
&hellip\; \u2032 &prime\; \u2033 &Prime\; \u203e &oline\; \u2044
&frasl\; \u2118 &weierp\; \u2111 &image\; \u211c &real\; \u2122
&trade\; \u2135 &alefsym\; \u2190 &larr\; \u2191 &uarr\; \u2192 &rarr\;
\u2193 &darr\; \u2194 &harr\; \u21b5 &crarr\; \u21d0 &lArr\; \u21d1
&uArr\; \u21d2 &rArr\; \u21d3 &dArr\; \u21d4 &hArr\; \u2200 &forall\;
\u2202 &part\; \u2203 &exist\; \u2205 &empty\; \u2207 &nabla\; \u2208
&isin\; \u2209 ¬in\; \u220b &ni\; \u220f &prod\; \u2211 &sum\;
\u2212 &minus\; \u2217 &lowast\; \u221a &radic\; \u221d &prop\; \u221e
&infin\; \u2220 &ang\; \u2227 &and\; \u2228 &or\; \u2229 &cap\; \u222a
&cup\; \u222b &int\; \u2234 &there4\; \u223c &sim\; \u2245 &cong\;
\u2248 &asymp\; \u2260 &ne\; \u2261 &equiv\; \u2264 &le\; \u2265 &ge\;
\u2282 &sub\; \u2283 &sup\; \u2284 &nsub\; \u2286 &sube\; \u2287
&supe\; \u2295 &oplus\; \u2297 &otimes\; \u22a5 &perp\; \u22c5 &sdot\;
\u2308 &lceil\; \u2309 &rceil\; \u230a &lfloor\; \u230b &rfloor\;
\u2329 &lang\; \u232a &rang\; \u25ca &loz\; \u2660 &spades\; \u2663
&clubs\; \u2665 &hearts\; \u2666 &diams\; \u0022 "\; \u0026 &\;
\u003c <\; \u003e >\; \u0152 &OElig\; \u0153 &oelig\; \u0160
&Scaron\; \u0161 &scaron\; \u0178 &Yuml\; \u02c6 &circ\; \u02dc
&tilde\; \u2002 &ensp\; \u2003 &emsp\; \u2009 &thinsp\; \u200c &zwnj\;
\u200d &zwj\; \u200e &lrm\; \u200f &rlm\; \u2013 &ndash\; \u2014
&mdash\; \u2018 &lsquo\; \u2019 &rsquo\; \u201a &sbquo\; \u201c
&ldquo\; \u201d &rdquo\; \u201e &bdquo\; \u2020 &dagger\; \u2021
&Dagger\; \u2030 &permil\; \u2039 &lsaquo\; \u203a &rsaquo\; \u20ac
&euro\;
}]
set decode [lreverse $encode]
proc encode {string} {
variable encode
string map $encode $string
}
proc decode {string} {
variable decode
string map $decode $string
}
}By the way, that's a very interesting use for [lreverse]!
If you look in the page history, you'll find my failed attempts to upload a UTF-8 version which avoids using \uXXXX escapes. But neither Firefox 3.6.3 nor IE8 could hack it, and I got mojibake [L1 ]. I'm not sure where the problem lies. I triple-checked that I had UTF-8 encoding set in my browser, both when viewing and when editing. Funny: even though that didn't work, I'm able to paste this text in without problems: 文字化け.
aricb: Regarding [lreverse], it's probably an unorthodox usage, but it works in this code due to some special properties of the mapping between Unicode characters onto character entity references:
The practical consequence of these properties is that, as long as paired list elements are adjacent to each other, the order of the pairs is unimportant as far as [string map] is concerned. [lreverse] reorders everything, but it preserves the adjacency of paired elements, and it sticks all of the members of the original domain in odd-indexed slots, and all the members of the original codomain in even-indexed slots, which happens to be just what is needed for the reverse mapping.