we rely on Windows and maybe Linux on a Qt bug

[lyx.git] / src / mathed / MathParser.C

diff --git a/src/mathed/MathParser.C b/src/mathed/MathParser.C
index cb208ffca3c78798280fe2cb0b0a89a2f54185af..abbe9e90c4c9174924bb5251959994a539ae0910 100644 (file)
--- a/src/mathed/MathParser.C
+++ b/src/mathed/MathParser.C
@@ -216,13 +216,16 @@ enum CatCode {
 CatCode theCatcode[128];
 
 
-inline CatCode catcode(lyx::char_type c)
+inline CatCode catcode(char_type c)
 {
-       /* The fact that we use unicode internally does not change Knuth's TeX
-       engine. It is still 7bit only, not even latin1 or something like that.
-       Therefore, the catcode table needs only to have 128 entries.
-       Everything not in that range is catOther.
-       */
+       /* The only characters that are not catOther lie in the pure ASCII
+        * range. Therefore theCatcode has only 128 entries.
+        * TeX itself deals with 8bit characters, so if needed this table
+        * could be enlarged to 256 entries.
+        * Any larger value does not make sense, since the fact that we use
+        * unicode internally does not change Knuth's TeX engine.
+        * Apart from that a table for the full 21bit UCS4 range would waste
+        * too much memory. */
        if (c >= 128)
                return catOther;
 
@@ -824,14 +827,17 @@ void Parser::parse1(InsetMathGrid & grid, unsigned flags,
                                cell->back() = MathAtom(new InsetMathScript(cell->back(), up));
                        InsetMathScript * p = cell->back().nucleus()->asScriptInset();
                        // special handling of {}-bases
-                       // Test for empty brace inset, otherwise \xxx{\vec{H}}_{0}
-                       // where \xxx is an unknown command gets misparsed to
-                       // \xxx\vec{H}_{0}, and that is invalid LaTeX.
-                       // is this always correct?
-                       if (p->nuc().size() == 1 &&
-                           p->nuc().back()->asBraceInset() &&
-                           p->nuc().back()->asBraceInset()->cell(0).empty())
-                               p->nuc() = p->nuc().back()->asNestInset()->cell(0);
+                       // Here we could remove the brace inset for things
+                       // like {a'}^2 and add the braces back in
+                       // InsetMathScript::write().
+                       // We do not do it, since it is not possible to detect
+                       // reliably whether the braces are needed because the
+                       // nucleus contains more than one symbol, or whether
+                       // they are needed for unknown commands like \xx{a}_0
+                       // or \yy{a}{b}_0. This was done in revision 14819
+                       // in an unreliable way. See this thread
+                       // http://www.mail-archive.com/lyx-devel%40lists.lyx.org/msg104917.html
+                       // for more details.
                        parse(p->cell(p->idxOfScript(up)), FLAG_ITEM, mode);
                        if (limits) {
                                p->limits(limits);