Fix comment according to Enricos explanation

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

diff --git a/src/mathed/MathParser.C b/src/mathed/MathParser.C
index c3a17c2875b72b2bf7d4706754789b307f444fd7..623b9234e87fede82fce8c24a6437066e50c966a 100644 (file)
--- a/src/mathed/MathParser.C
+++ b/src/mathed/MathParser.C
@@ -213,11 +213,22 @@ enum CatCode {
        catInvalid     // 15   <delete>
 };
 
-CatCode theCatcode[256];
+CatCode theCatcode[128];
 
 
-inline CatCode catcode(unsigned char c)
+inline CatCode catcode(char_type c)
 {
+       /* 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;
+
        return theCatcode[c];
 }
 
@@ -816,9 +827,13 @@ 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())
+                       if (p->nuc().size() == 1 &&
+                           p->nuc().back()->asBraceInset() &&
+                           p->nuc().back()->asBraceInset()->cell(0).empty())
                                p->nuc() = p->nuc().back()->asNestInset()->cell(0);
                        parse(p->cell(p->idxOfScript(up)), FLAG_ITEM, mode);
                        if (limits) {
@@ -1444,7 +1459,7 @@ void mathed_parse_normal(InsetMathGrid & grid, string const & str)
 
 void initParser()
 {
-       fill(theCatcode, theCatcode + 256, catOther);
+       fill(theCatcode, theCatcode + 128, catOther);
        fill(theCatcode + 'a', theCatcode + 'z' + 1, catLetter);
        fill(theCatcode + 'A', theCatcode + 'Z' + 1, catLetter);