# E.4 LaTeXML::Core::Stomach

Digests tokens into boxes, lists, etc.

## Description

LaTeXML::Core::Stomach digests tokens read from a LaTeXML::Core::Gullet (they will have already been expanded).

There are basically four cases when digesting a LaTeXML::Core::Token:

A plain character

is simply converted to a LaTeXML::Core::Box recording the current LaTeXML::Common::Font.

A primitive

If a control sequence represents LaTeXML::Core::Definition::Primitive, the primitive is invoked, executing its stored subroutine. This is typically done for side effect (changing the state in the LaTeXML::Core::State), although they may also contribute digested material. As with macros, any arguments to the primitive are read from the LaTeXML::Core::Gullet.

Grouping (or environment bodies)

are collected into a LaTeXML::Core::List.

Constructors

A special class of control sequence, called a LaTeXML::Core::Definition::Constructor produces a LaTeXML::Core::Whatsit which remembers the control sequence and arguments that created it, and defines its own translation into XML elements, attributes and data. Arguments to a constructor are read from the gullet and also digested.

### Digestion

$list =$stomach->digestNextBody;

Return the digested LaTeXML::Core::List after reading and digesting a ‘body’ from the its Gullet. The body extends until the current level of boxing or environment is closed.

$list =$stomach->digest($tokens); Return the LaTeXML::Core::List resuting from digesting the given tokens. This is typically used to digest arguments to primitives or constructors. @boxes =$stomach->invokeToken($token); Invoke the given (expanded) token. If it corresponds to a Primitive or Constructor, the definition will be invoked, reading any needed arguments fromt he current input source. Otherwise, the token will be digested. A List of Box’s, Lists, Whatsit’s is returned. @boxes =$stomach->regurgitate;

Removes and returns a list of the boxes already digested at the current level. This peculiar beast is used by things like $\backslash$choose (which is a Primitive in TeX, but a Constructor in LaTeXML).

### Grouping

$stomach->bgroup; Begin a new level of binding by pushing a new stack frame, and a new level of boxing the digested output.$stomach->egroup;

End a level of binding by popping the last stack frame, undoing whatever bindings appeared there, and also decrementing the level of boxing.

$stomach->begingroup; Begin a new level of binding by pushing a new stack frame.$stomach->endgroup;

End a level of binding by popping the last stack frame, undoing whatever bindings appeared there.

### Modes

$stomach->beginMode($mode);

Begin processing in $mode; one of ’text’, ’display-math’ or ’inline-math’. This also begins a new level of grouping and switches to a font appropriate for the mode.$stomach->endMode($mode); End processing in$mode; an error is signalled if $stomach is not currently in$mode. This also ends a level of grouping.