Class Parser

site-packages/matplotlib/mathtext.py:2202–3197

This is the pyparsing-based parser for math expressions. It actually parses full strings *containing* math expressions, in that raw text may also appear outside of pairs of ``$``. The grammar is based directly on that in TeX, though it cuts a few corners.

    return empty

class Parser(object):
    """
    This is the pyparsing-based parser for math expressions.  It
    actually parses full strings *containing* math expressions, in
    that raw text may also appear outside of pairs of ``$``.

    The grammar is based directly on that in TeX, though it cuts a few
    corners.
    """

    _math_style_dict = dict(displaystyle=0, textstyle=1,
                            scriptstyle=2, scriptscriptstyle=3)

    _binary_operators = set('''
      + * -
      \\pm             \\sqcap                   \\rhd
      \\mp             \\sqcup                   \\unlhd
      \\times          \\vee                     \\unrhd
      \\div            \\wedge                   \\oplus
      \\ast            \\setminus                \\ominus
      \\star           \\wr                      \\otimes
      \\circ           \\diamond                 \\oslash
      \\bullet         \\bigtriangleup           \\odot
      \\cdot           \\bigtriangledown         \\bigcirc
      \\cap            \\triangleleft            \\dagger
      \\cup            \\triangleright           \\ddagger
      \\uplus          \\lhd                     \\amalg'''.split())

    _relation_symbols = set('''
      = < > :
      \\leq            \\geq             \\equiv           \\models
      \\prec           \\succ            \\sim             \\perp
      \\preceq         \\succeq          \\simeq           \\mid
      \\ll             \\gg              \\asymp           \\parallel
      \\subset         \\supset          \\approx          \\bowtie
      \\subseteq       \\supseteq        \\cong            \\Join
      \\sqsubset       \\sqsupset        \\neq             \\smile
      \\sqsubseteq     \\sqsupseteq      \\doteq           \\frown
      \\in             \\ni              \\propto          \\vdash
      \\dashv          \\dots            \\dotplus         \\doteqdot''&#x27;.split())

    _arrow_symbols = set(''&#x27;
      \\leftarrow              \\longleftarrow           \\uparrow
      \\Leftarrow              \\Longleftarrow           \\Uparrow
      \\rightarrow             \\longrightarrow          \\downarrow
      \\Rightarrow             \\Longrightarrow          \\Downarrow
      \\leftrightarrow         \\longleftrightarrow      \\updownarrow
      \\Leftrightarrow         \\Longleftrightarrow      \\Updownarrow
      \\mapsto                 \\longmapsto              \\nearrow
      \\hookleftarrow          \\hookrightarrow          \\searrow
      \\leftharpoonup          \\rightharpoonup          \\swarrow
      \\leftharpoondown        \\rightharpoondown        \\nwarrow
      \\rightleftharpoons      \\leadsto''&#x27;.split())

    _spaced_symbols = _binary_operators | _relation_symbols | _arrow_symbols

    _punctuation_symbols = set(r', ; . ! \ldotp \cdotp'.split())