Throw error/exception for non-implemented latex command?

[datamove]

Dear Philippe,
Thanks for your work!
I wonder if latex_to_text should throw an exception if it faces a latex command that it can not convert? For example, the following Latex code is a matrix:
\left (\begin{array}{llll}25 & 31 & 17 & 43\\75 & 94 & 53 & 132\\75 & 94 & 54 & 134\\25 & 32 & 20 & 48\end{array}\right )
and all I get is
< a r r a y >
but I'd like to catch a conversion erro rin order to deal with it.

Is there a way to do that?
Thanks in advance!

[phfaist]

The original philosophy behind latex_to_text has been to obtain as useful text as possible for the given latex input, which is the reason why latex_to_text does not fail for unknown macros and why it provides a placeholder text for some usual constructs like graphics/arrays. But the behavior is customizable, try:

from pylatexenc import macrospec, latexwalker, latex2text

def raise_l2t_unknown_latex(n):
    if n.isNodeType(latexwalker.LatexMacroNode):
        raise ValueError("Unknown macro: '\\{}'".format(n.macroname))
    elif n.isNodeType(latexwalker.LatexEnvironmentNode):
        raise ValueError("Unknown environment: '\\begin{{{}}}'".format(n.environmentname))
    raise ValueError("Unknown latex construct: '{}'".format(n.latex_verbatim()))

l2t_db = latex2text.get_default_latex_context_db()
l2t_db.add_context_category(
    'my-error-category',
    prepend=True,
    macros=[
        latex2text.MacroTextSpec('includegraphics', simplify_repl=raise_l2t_unknown_latex)
    ],
    environments=[
        latex2text.EnvironmentTextSpec('array', simplify_repl=raise_l2t_unknown_latex),
        latex2text.EnvironmentTextSpec('pmatrix', simplify_repl=raise_l2t_unknown_latex),
        latex2text.EnvironmentTextSpec('bmatrix', simplify_repl=raise_l2t_unknown_latex),
        latex2text.EnvironmentTextSpec('smallmatrix', simplify_repl=raise_l2t_unknown_latex),
    ]
)
l2t_db.set_unknown_macro_spec(
    latex2text.MacroTextSpec('', simplify_repl=raise_l2t_unknown_latex)
)
l2t_db.set_unknown_environment_spec(
    latex2text.EnvironmentTextSpec('', simplify_repl=raise_l2t_unknown_latex)
)


result = latex2text.LatexNodes2Text(latex_context=l2t_db).latex_to_text(r'''
\textbf{Hello} world.
\begin{equation}
  A = X + \begin{array}{cc}1 & 2\\3 & 4\end{array}
\end{equation}
And here is an undefined macro: \undefinedMacro.
''')

print(result)

Here, macros/environments "array", "includegraphics", etc. (which are those macros/environments that provide a <p l a c e h o l d e r>) have replacement functions that simply raise an error, and unknown macros/environments will also raise an error.

Thanks for the feedback & hope this helps.

[phfaist]

In the meantime, the code in my earlier comment can be simplified using context-db category choices from the default context db:

from pylatexenc import macrospec, latexwalker, latex2text

def raise_l2t_unknown_latex(n):
    if n.isNodeType(latexwalker.LatexMacroNode):
        raise ValueError("Unknown macro: '\\{}'".format(n.macroname))
    elif n.isNodeType(latexwalker.LatexEnvironmentNode):
        raise ValueError("Unknown environment: '\\begin{{{}}}'".format(n.environmentname))
    raise ValueError("Unknown latex construct: '{}'".format(n.latex_verbatim()))

l2t_db = latex2text.get_default_latex_context_db().filter_context(
    exclude_categories=['latex-placeholders',],
)
l2t_db.set_unknown_macro_spec(
    latex2text.MacroTextSpec('', simplify_repl=raise_l2t_unknown_latex)
)
l2t_db.set_unknown_environment_spec(
    latex2text.EnvironmentTextSpec('', simplify_repl=raise_l2t_unknown_latex)
)


result = latex2text.LatexNodes2Text(latex_context=l2t_db).latex_to_text(r'''
\textbf{Hello} world.

\begin{equation}
  A = X + \begin{array}{cc}1 & 2\\3 & 4\end{array}
\end{equation}

% raises an error:
And here is an undefined macro: \undefinedMacro.

% this would also raise an error:
\includegraphics{fig-test-graphics}
''')

print(result)
# raises error for \undefinedMacro. If you remove \undefinedMacro, raises
# an error for \includegraphics, which is only defined in the 'latex-placeholders'
# category in the default context db and which we've filtered out of our context db.