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LaTeX reader: \DeclareMathOperator, optional arguments with a default, empty macro bodies #23

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LaTeX reader: \DeclareMathOperator, optional arguments with a default, empty macro bodies #23

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42 changes: 38 additions & 4 deletions src/SharpEquations/Internal/LaTeX/LaTeXReader.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,8 @@ private LaTeXReader(IDictionary<string, string> macros, bool display)
}

/// <summary>
/// TeX2UnicodeMath: the UnicodeMath of LaTeX math (without its $ or \[ delimiters). Macros defined with \def
/// or \newcommand, and environments defined with \newenvironment, go to <paramref name="macros"/>, where later conversions find them. In a display equation the
/// TeX2UnicodeMath: the UnicodeMath of LaTeX math (without its $ or \[ delimiters). Macros defined with \def,
/// \newcommand or \DeclareMathOperator, and environments defined with \newenvironment, go to <paramref name="macros"/>, where later conversions find them. In a display equation the
/// scripts of a large operator other than an integral (\sum, \prod, \bigcup...) go under and over it, as TeX
/// puts them. The \ce and \pu of mhchem are rewritten as plain LaTeX first (<see cref="Mhchem"/>).
/// </summary>
Expand Down Expand Up @@ -605,6 +605,15 @@ private static string RewriteTeXOnly(string latex)
i = end;
continue;
}
if (cw == "DeclareMathOperator" && Argument(tex, tex[j] == "*" ? j + 1 : j) is var (operatorName, afterOperatorName) && afterOperatorName >= 0 &&
BracedArgument(tex, afterOperatorName) is var (operatorBody, afterOperatorBody) && afterOperatorBody >= 0)
{
// \DeclareMathOperator{\name}{text}: \name defined as \operatorname{text}, \operatorname*{text} when starred
result.Append("\\newcommand{").Append(operatorName.Trim()).Append("}{")
.Append(RewriteTeXOnly("\\operatorname" + (tex[j] == "*" ? "*" : "") + "{" + operatorBody + "}")).Append('}');
i = afterOperatorBody;
continue;
}
if (cw == "renewcommand")
{
result.Append("\\newcommand");
Expand Down Expand Up @@ -1394,6 +1403,9 @@ private string Convert(string latex)
var tex = new Text(EscapeOddBars(RewriteTeXOnly(Limits(NewEnvironments(latex)))));
var cwPrev = "";
bool needMacroPass = false;
// whether a macro was named and its body is next, and where that body starts: an empty body expands to nothing
bool macroNamed = false;
int macroBody = -1;
var uniTeX = new StringBuilder();

for (int i = 0; i < tex.Length;)
Expand Down Expand Up @@ -1440,6 +1452,7 @@ private string Convert(string latex)
i++;
needMacroPass = true;
macros[cw] = "";
macroNamed = true;
continue;
}
cwPrev = cw;
Expand Down Expand Up @@ -1517,10 +1530,16 @@ private string Convert(string latex)
i++;
continue;
}

if (macroNamed)
{
macroNamed = false;
macroBody = i;
}
uniTeX.Append(tex[i++]);
break;
case "}":
if (i > 0 && tex[i - 1] == "{")
if (i > 0 && tex[i - 1] == "{" && i - 1 != macroBody)
uniTeX.Append('⬚');
uniTeX.Append(tex[i++]);
break;
Expand Down Expand Up @@ -1659,12 +1678,20 @@ private static (string, int) ApplyMacro(Text tex, int i, bool accentsAfter)
{
int k;
int cArg = 0;
string optional = null;
if (tex[i] == "[")
{
cArg = Js.CodeAt(tex[i + 1], 0) - '0';
if (tex[i + 2] != "]" || cArg < 0 || cArg > 9)
return ("", i);
k = i + 3;
// [n][default]: the first argument optional, with that default
if (tex[k] == "[" && cArg > 0)
{
(optional, k) = OptionalArgument(tex, k);
if (optional == null)
return ("", i);
}
}
else
{
Expand Down Expand Up @@ -1692,6 +1719,13 @@ private static (string, int) ApplyMacro(Text tex, int i, bool accentsAfter)
var arg = "";
while (tex[i] == " ")
i++;
if (j == 0 && optional != null)
{
var (given, afterGiven) = OptionalArgument(tex, i);
args.Add(given ?? optional);
i = afterGiven;
continue;
}
if (tex[i] == "{")
{
k = FindClosingBrace(tex, i + 1);
Expand All @@ -1712,7 +1746,7 @@ private static (string, int) ApplyMacro(Text tex, int i, bool accentsAfter)
args.Add(arg);
}
while (args.Count < cArg)
args.Add("");
args.Add(args.Count == 0 && optional != null ? optional : "");

var val = new StringBuilder();
// an accent passed as an argument (\hat, a combining mark) goes on the character after it, as in LaTeX
Expand Down
9 changes: 9 additions & 0 deletions tests/SharpEquations.Tests/LaTeX/LaTeXReaderTests.cs
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Expand Up @@ -365,6 +365,15 @@ public async Task ReadsDelimitersAsDisplay(string latex, bool display)
[Arguments(@"\def\R{\mathbb{R}} x\in\R", @"x\in\mathbb{R}")]
[Arguments(@"\newcommand{\pd}[2]{\frac{\partial #1}{\partial #2}}\pd{f}{x}", @"\frac{\partial f}{\partial x}")]
[Arguments(@"\newcommand{\N}{\mathbb{N}}\N", @"\mathbb{N}")]
[Arguments(@"\newcommand{\f}[2][y]{#1+#2} \f{a}+\f[b]{c}", @"y+a+b+c")]
[Arguments(@"\newcommand{\g}[1][Hello]{#1} \g{world}", @"Helloworld")]
[Arguments(@"\newcommand{\g}[1][a]{#1^2} \g", @"a^2")]
[Arguments(@"\newcommand{\e}{} \e x", @"x")]
[Arguments(@"\def\e{}\e x+\e y", @"x+y")]
[Arguments(@"\newcommand{\h}[2]{} \h{a}{b}x", @"x")]
[Arguments(@"\DeclareMathOperator{\Res}{Res} \Res_{z=0}", @"\operatorname{Res}_{z=0}")]
[Arguments(@"\DeclareMathOperator\Tr{Tr} \Tr A", @"\operatorname{Tr}A")]
[Arguments(@"\DeclareMathOperator*{\argmax}{argmax} \argmax_x f", @"\operatorname{argmax}_xf")]
public async Task ExpandsMacros(string latex, string expected)
{
await Assert.That(Equation.Parse(latex, EquationFormat.LaTeX).ToString(EquationFormat.LaTeX)).IsEqualTo(expected);
Expand Down
11 changes: 4 additions & 7 deletions tests/SharpEquations.Tests/LaTeX/Latex2MathMLCorpusTests.cs
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Expand Up @@ -220,12 +220,9 @@ private static string Canonical(Equation equation)

private static readonly HashSet<string> ReadOtherwise = new HashSet<string>(NotInWordLaTeX.Concat(HeldOtherwise).Concat(NotLaTeX));

// the macros the reader does not expand as LaTeX does: \DeclareMathOperator, the default of an optional argument,
// and an empty body (which leaves an empty group)
private static readonly HashSet<string> NotExpanded = new HashSet<string>
{
"declare-math-operator", "newcommand-optional-default", "newcommand-empty-body",
};
// the macros that latex2mathml expands otherwise than LaTeX: \greeting{world}, whose one argument is optional,
// which LaTeX gives its default (Hello), leaving {world} after it, where latex2mathml takes world as the argument
private static readonly HashSet<string> ExpandedOtherwise = new HashSet<string> { "newcommand-optional-default" };

private static string? Check(Func<string?> check)
{
Expand Down Expand Up @@ -290,7 +287,7 @@ public async Task LaTeXReadsAsLatex2MathMLReadsIt()
[Test]
public async Task MacrosExpandToTheirEquivalent()
{
var unexpected = Unexpected(Macros(), m => m.id, m => m.latex, NotExpanded, m =>
var unexpected = Unexpected(Macros(), m => m.id, m => m.latex, ExpandedOtherwise, m =>
{
var expected = Equation.Parse(m.equivalent, EquationFormat.LaTeX, Options(m.display));
var actual = Equation.Parse(m.latex, EquationFormat.LaTeX, Options(m.display));
Expand Down
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