Class: MathToItex::Parser

Inherits:

Object

• Object
• MathToItex::Parser

Defined in:

lib/math-to-itex/parser.rb

Constant Summary

ENVIRONMENTS =

%w[align align\* alignat alignat\* aligned alignedat array Bmatrix bmatrix cases displaymath eqnarray eqnarray\* equation equation\* gather gather\* gathered math matrix multline multline\* pmatrix smallmatrix split subarray svg Vmatrix vmatrix].freeze

JOINED_ENVIRONMENTS =

ENVIRONMENTS.join('|')

REGEX =

stackoverflow.com/questions/14182879/regex-to-match-latex-equations

/
(?<!\\)    # negative look-behind to make sure start is not escaped
(?:       # start non-capture group for all possible match starts
    # group 1, match dollar signs only
    # single or double dollar sign enforced by look-arounds
    ((?<!\$)\${1,2}(?!\$))|
    # group 2, match escaped parenthesis
    (\\\()|
    # group 3, match escaped bracket
    (\\\[)|
    # group 4, match begin equation
    \\begin\{(#{JOINED_ENVIRONMENTS})\}
)
(.*?(\g<1>)?.*?)  # match everything in between including nested LaTeX equations
(?<!\\)  # negative look-behind to make sure end is not escaped
    # if group 1 was start, match \1
    (?(1)(?<!\$)\1(?!\$|\d)|
    # if group 2 was start, escaped parenthesis is end
    (?(2)\\\)|
    # if group 3 was start, escaped bracket is end
    (?(3)\\\]|
    # otherwise group 4 was start, match end equation
    \\end\{\4\}
)))
/xm.freeze