private MathList?BuildInternal(bool oneCharOnly, char stopChar = '\0')
{
if (oneCharOnly && stopChar > '\0')
{
throw new InvalidCodePathException("Cannot set both oneCharOnly and stopChar");
}
var r = new MathList();
MathAtom?prevAtom = null;
while (HasCharacters)
{
if (Error != null)
{
return(null);
}
MathAtom atom;
switch (GetNextCharacter())
{
case '^' when oneCharOnly:
case '}' when oneCharOnly:
case '_' when oneCharOnly:
case '&' when oneCharOnly:
// this is not the character we are looking for. They are for the caller to look at.
UnlookCharacter();
return(r);
case var ch when stopChar > '\0' && ch == stopChar:
return(r);
case '^':
if (prevAtom == null || prevAtom.Superscript != null || !prevAtom.ScriptsAllowed)
{
prevAtom = new Ordinary(string.Empty);
r.Add(prevAtom);
}
// this is a superscript for the previous atom.
// note, if the next char is StopChar, it will be consumed and doesn't count as stop.
prevAtom.Superscript = this.BuildInternal(true);
continue;
case '_':
if (prevAtom == null || prevAtom.Subscript != null || !prevAtom.ScriptsAllowed)
{
prevAtom = new Ordinary(string.Empty);
r.Add(prevAtom);
}
// this is a subscript for the previous atom.
// note, if the next char is StopChar, it will be consumed and doesn't count as stop.
prevAtom.Subscript = this.BuildInternal(true);
continue;
case '{':
MathList?sublist;
if (_currentEnvironment != null && _currentEnvironment.Name == null)
{
// \\ or \cr which do not have a corrosponding \end
var oldEnv = _currentEnvironment;
_currentEnvironment = null;
sublist = BuildInternal(false, '}');
_currentEnvironment = oldEnv;
}
else
{
sublist = BuildInternal(false, '}');
}
if (sublist == null)
{
return(null);
}
prevAtom = sublist.Atoms.LastOrDefault();
r.Append(sublist);
if (oneCharOnly)
{
return(r);
}
continue;
#warning TODO Example
//https://phabricator.wikimedia.org/T99369
//https://phab.wmfusercontent.org/file/data/xsimlcnvo42siudvwuzk/PHID-FILE-bdcqexocj5b57tj2oezn/math_rendering.png
//dt, \text{d}t, \partial t, \nabla\psi \\ \underline\overline{dy/dx, \text{d}y/\text{d}x, \frac{dy}{dx}, \frac{\text{d}y}{\text{d}x}, \frac{\partial^2}{\partial x_1\partial x_2}y} \\ \prime,
case '}' when oneCharOnly || stopChar != 0:
throw new InvalidCodePathException("This should have been handled before.");
case '}':
SetError("Missing opening brace");
return(null);
case '\\':
var command = ReadCommand();
var done = StopCommand(command, r, stopChar);
if (done != null)
{
return(done);
}
if (Error != null)
{
return(null);
}
if (ApplyModifier(command, prevAtom))
{
continue;
}
if (LaTeXDefaults.FontStyles.TryGetValue(command, out var fontStyle))
{
var oldSpacesAllowed = _textMode;
var oldFontStyle = _currentFontStyle;
_textMode = (command == "text");
_currentFontStyle = fontStyle;
var childList = BuildInternal(true);
if (childList == null)
{
return(null);
}
_currentFontStyle = oldFontStyle;
_textMode = oldSpacesAllowed;
prevAtom = childList.Atoms.LastOrDefault();
r.Append(childList);
if (oneCharOnly)
{
return(r);
}
continue;
}
switch (AtomForCommand(command, stopChar))
{
case null:
SetError(Error ?? "Internal error");
return(null);
case var a:
atom = a;
break;
}
break;
case '&': // column separation in tables
if (_currentEnvironment != null)
{
return(r);
}
var table = BuildTable(null, r, false, stopChar);
if (table == null)
{
return(null);
}
return(new MathList(table));
case '\'': // this case is NOT in iosMath
int i = 1;
while (ExpectCharacter('\''))
{
i++;
}
atom = new Prime(i);
break;
case ' ' when _textMode:
atom = new Ordinary(" ");
break;
case var ch when ch <= sbyte.MaxValue:
if (LaTeXDefaults.ForAscii((sbyte)ch) is MathAtom asciiAtom)
{
atom = asciiAtom;
}
else
{
continue; // Ignore ASCII spaces and control characters
}
break;
case var ch:
// not a recognized character, display it directly
atom = new Ordinary(ch.ToStringInvariant());
break;
}
atom.FontStyle = _currentFontStyle;
r.Add(atom);
prevAtom = atom;
if (oneCharOnly)
{
return(r); // we consumed our character.
}
}
if (stopChar > 0)
{
if (stopChar == '}')
{
SetError("Missing closing brace");
}
else
{
// we never found our stop character.
SetError("Expected character not found: " + stopChar.ToStringInvariant());
}
}
return(r);
}
private MathAtom?AtomForCommand(string command, char stopChar)
{
switch (LaTeXDefaults.AtomForCommand(command))
{
case Accent accent:
var innerList = BuildInternal(true);
if (innerList is null)
{
return(null);
}
return(new Accent(accent.Nucleus, innerList));
case MathAtom atom:
return(atom);
}
switch (command)
{
case "frac":
var numerator = BuildInternal(true);
if (numerator is null)
{
return(null);
}
var denominator = BuildInternal(true);
if (denominator is null)
{
return(null);
}
return(new Fraction(numerator, denominator));
case "binom":
numerator = BuildInternal(true);
if (numerator is null)
{
return(null);
}
denominator = BuildInternal(true);
if (denominator is null)
{
return(null);
}
return(new Fraction(numerator, denominator, false)
{
LeftDelimiter = "(",
RightDelimiter = ")"
});
case "sqrt":
var degree = ExpectCharacter('[') ? BuildInternal(false, ']') : new MathList();
if (degree is null)
{
return(null);
}
var radicand = BuildInternal(true);
return(radicand != null ? new Radical(degree, radicand) : null);
case "left":
var oldInner = _currentInner;
var leftBoundary = BoundaryAtomForDelimiterType("left");
if (!(leftBoundary is Boundary left))
{
return(null);
}
_currentInner = new InnerEnvironment();
var innerList = BuildInternal(false, stopChar);
if (innerList is null)
{
return(null);
}
if (!(_currentInner.RightBoundary is Boundary right))
{
SetError("Missing \\right");
return(null);
}
_currentInner = oldInner;
return(new Inner(left, innerList, right));
case "overline":
innerList = BuildInternal(true);
if (innerList is null)
{
return(null);
}
return(new Overline(innerList));
case "underline":
innerList = BuildInternal(true);
if (innerList is null)
{
return(null);
}
return(new Underline(innerList));
case "begin":
var env = ReadEnvironment();
if (env == null)
{
return(null);
}
return(BuildTable(env, null, false, stopChar));
case "color":
switch (ReadColor())
{
case string s when BuildInternal(true) is
{
}
ml:
if (Structures.Color.Create(s.AsSpan()) is { } color)
{
return(new Color(color, ml));
}
SetError(@"Invalid color: " + s);
return(null);
default: return(null);
}
;
case "prime":
SetError(@"\prime won't be supported as Unicode has no matching character. Use ' instead.");
return(null);
case "kern":
case "hskip":
if (_textMode)
{
var(space, error) = ReadSpace();
if (error != null)
{
SetError(error);
return(null);
}
else
{
return(new Space(space));
}
}
SetError($@"\{command} is not allowed in math mode");
return(null);
case "mkern":
case "mskip":
if (!_textMode)
{
var(space, error) = ReadSpace();
if (error != null)
{
SetError(error);
return(null);
}
else
{
return(new Space(space));
}
}
SetError($@"\{command} is not allowed in text mode");
return(null);
case "raisebox":
if (!ExpectCharacter('{'))
{
SetError("Expected {"); return(null);
}
var(raise, err) = ReadSpace();
if (err != null)
{
SetError(err);
return(null);
}
if (!ExpectCharacter('}'))
{
SetError("Expected }"); return(null);
}
innerList = BuildInternal(true);
if (innerList is null)
{
return(null);
}
return(new RaiseBox(raise, innerList));
case "TeX":
return(TeX);
default:
SetError("Invalid command \\" + command);
return(null);
}
}
