# MathAtom

## MathAtom

#### new MathAtom(mode: string, type: string, body: string,Array.<MathAtom>, fontFamilyopt, nullable: string, extrasopt, nullable: Object) → MathAtomprivate

An atom is an object encapsulating an elementary mathematical unit, independent of its graphical representation.

It keeps track of the content, while the dimensions, position and style are tracked by Span objects which are created by the decompose() functions.

mode string
type string
body string | Array.<MathAtom>
fontFamily string optional nullable = "main"
extras Object optional nullable = null

A set of additional properties to append to the atom

##### Properties
mode string

'display', 'command', etc...

type string

Type can be one of:

• mord: ordinary symbol, e.g. x, \alpha
• textord: ordinary characters used in text mode
• mop: operators, including special functions, \sin, \sum, \cap.
• mbin: binary operator: +, *, etc...
• mrel: relational operator: =, \ne, etc...
• mpunct: punctuation: ,, :, etc...
• mopen: opening fence: (, \langle, etc...
• mclose: closing fence: ), \rangle, etc...
• minner: special layout cases, overlap, \left...\right

In addition to these basic types, which correspond to the TeX atom types, some atoms represent more complex compounds, including:

• space and spacing: blank space between atoms
• mathstyle: to change the math style used: display or text. The layout rules are different for each, the latter being more compact and intended to be incorporated with surrounding non-math text.
• root: a group, which has no parent (only one per formula)
• group: a simple group of atoms, for example from a {...}
• font: set the font used. Used by \mathbb, \mathbb, etc...
• sizing: set the size of the font used
• color: set the foreground color
• rule: draw a line, for the \rule command
• line: used by \overline and \underline commands
• box: a border drawn around an expression and change its background color
• overlap: display a symbol over another
• overunder: displays an annotation above or below a symbol
• array: a group, which has children arranged in rows. Used by environments such as matrix, cases, etc...
• genfrac: a generalized fraction: a numerator and denominator, separated by an optional line, and surrounded by optional fences
• surd: a surd, aka root
• leftright: used by the \left and \right commands
• delim: some delimiter
• sizeddelim: a delimiter that can grow

The following types are used by the editor:

• command indicate a command being entered. The text is displayed in blue in the editor.
• error: indicate a command that is unknown, for example \xyzy. The text is displayed with a wavy red underline in the editor.
• placeholder: indicate a temporary item. Placeholders are displayed as a dashed square in the editor.
• first: a special, empty, atom put as the first atom in math lists in order to be able to position the caret before the first element. Aside from the caret, they display nothing.
fontFamily string
body string | Array.<MathAtom>
superscript Array.<MathAtom>
subscript Array.<MathAtom>
numer Array.<MathAtom>
denom Array.<MathAtom>
captureSelection boolean

if true, this atom does not let its children be selected. Used by the \enclose annotations, for example.

skipBoundary boolean

if true, when the caret reaches the first position in this element's body, it automatically moves to the outside of the element. Conversely, when the caret reaches the position right after this element, it automatically moves to the last position inside this element.

### Methods

#### toSpeakableText(atomsopt: Array.<MathAtom>, optionsopt: Object.<string, any>)static

atoms Array.<MathAtom> optional

The atoms to represent as speakable text. If omitted, this is used.

options Object.<string, any> optional

#### bind(context: Context, span: Span)

Add an ID attribute to both the span and this atom so that the atom can be retrieved from the span later on (e.g. when the span is clicked on)

context
span

#### decompose(context: Context, phantomBaseopt: Array.<Span>) → Array.<Span>

Return a representation of this, but decomposed in an array of Spans

context

Font variant, size, color, etc...

phantomBase Array.<Span> optional = null

If not null, the spans to use to calculate the placement of the supsub

Array.<Span>

#### decomposeGenfrac()

GENFRAC -- Generalized fraction

Decompose fractions, binomials, and in general anything made of two expressions on top of each other, optionally separated by a bar, and optionally surrounded by fences (parentheses, brackets, etc...)

Depending on the type of fraction the mathstyle is either display math or inline math (which is indicated by 'textstyle'). This value can also be set to 'auto', which indicates it should use the current mathstyle

#### decomposeLeftright()

\left....\right

Note that we can encounter malformed \left...\right, for example a \left without a matching \right or vice versa. In that case, the leftDelim (resp. rightDelim) will be undefined. We still need to handle those cases.

#### decomposeLine()

\overline and \underline

\rule

#### filter() → Array.<MathAtom>

Iterate over all the child atoms of this atom, this included, and return an array of all the atoms for which the predicate callback is true.

Array.<MathAtom>

#### makeSpan(context: Context, body: string,Array.<Span>) → Span

Create a span with the specified body and with a class attribute equal to the type ('mbin', 'inner', 'spacing', etc...)

context
body string | Array.<Span>